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MG Midget and Sprite Technical - another alternator wiring thread
|So i'm trying to make sure all the wiring is sorted and neat & tidy before I get the engine back in. I'm replacing the dynamo with an 18ACR alternator and I'll be keeping the control box (rb340) so that I can keep the wiring simple as per Robert Welch's article here... http://www.spridgettechnical.co.uk/index.php?option=com_content&view=article&id=90&Itemid=66|
Looking at the wiring diagram for type 5 pages 18 and 19 I'm wondering if it's really necessary to wire in an extra cable from the solenoid to the alternator as the existing brown cable from the solenoid now goes to the alternator via the new connection in the control box. Can I add an extra connector to the alternator end of the main brown/green cable or is there a specific reason for the additional wire I'm not aware of?
Please feel free to treat me like an idiot - auto wiring is not my forte.
|Is forte spelled correctly.... :)|
I can only offer this golden nugget... "Single wire alt" with built in electronic regulater...super easy...one wire from alt to battry and boom your done
Or maybe it is the selinoid on 2nd thought
|Prop and the Blackhole Midget|
The typical output from a dynamo would be in the range of 25 to 30 amps, an 18ACR is capable of an output of 65 amps. There's 2 possible problems wiring it the way you're suggesting, the first, is the wire from the A terminal on the control box to the solenoid big enough to handle the extra current? Second, by going via the control box you're adding two extra connections, as most electrical failures are connector related you're adding two extra potential points of failure.
When making the extra cable you need to ensure the terminals at both ends are well crimped as any extra resistance could cause you problems.
|Bob has it: that single brown wire isn't capable of 65 Amps. Modern cars would have a much thicker wire there, but good old BL probably found it cheaper to run another one in parallel when needed.|
|Thanks guys. I told you I knew nothing about electrics (beyond following a diagram) so I'll be making up a nice thick cable for this.|
|So, I'm making a new lead to go to the Solenoid from the Alternator - 50amp - should be heavy enough. Anyway, I was looking at the wiring and comparing it with the diagrams in haynes and found a discrepancy. My car is a GAN5 in the 895000 range but all the wiring (before I started stripping it down years ago) corresponded to the next model in Haynes i.e later fuse box, (4 fuses) and RB340 control box. One specific thing of note - the solenoid on my original loom only had one Brown and the white/red from the ignition switch. Checking the replacement loom I bought from Moss, everything (*) is exactly the same except there is an extra brown wire for the solenoid. Checking the diagrams, the older model had an extra brown but none of the others do. Anyone care to guess what this lead is for? As the rest of the loom is the same I can't figure out where the other end would terminate (i'm at work typing this. I'll get the multimeter out tonight and see if I can track it down but i figure there's bound to be someone here that already knows).|
back to the alternator, it took me a while staring at robert welch's diagrams to realise that I have to reterminate the brown/yellow and brown/green leads at the alternator end - made sense eventually.
(*) 1 more - does the boot lamp have it's own loom segment? My loom has a short purple lead that would terminate somewhere near the switch but I can't find any loose wiring in my boxes of bits from the strip down - there's nothing attached to the lamp so I'm guessing I took that off before I stripped the old loom.
|uhm, well, Haynes I've found can have the odd error ot two that's why I refer to the Driver's Handbook|
I'm a bit lost with where you are but in the Driver's Handbook page 39, diagram for negative earth 1971-3 shows from solenoid - white/red to ignition switch and one brown to control box
my 1974 print of Haynes (with errors and supplement to around the end of 1972) page 197, diagram for cars from GAN5 89515, shows from solenoid - white/red to ignition switch and two browns - one to lighting switch and the other joints two browns going to ignition switch and control box
|Thanks for the reply Nigel. However, that's just confused me even more :-)|
The original loom corresponded with your driver handbook i.e. white/red and one brown. However, the car is 89562 so your haynes would suggest it should have had the two browns. As the new loom has two browns I'm just going to fit them both to the battery side connector and hope for the best. The new lead I'm making will also go to the battery side connector direct from one of the large alternator terminals.
|don't trust Haynes or production change dates or numbers to be exact|
according to Terry Horler's book:-
'GAN5-89515 (Jul 70)
Horn control returned to steering wheel centre boss. Revised steering wheel, now with horizontal upper spokes. Sprite now without a motif on the horn push. Door and boot courtesy lights fitted.'
I didn't realise your car was a 1970 as you've got '72 on your profile
this might help -
in Drivers Handbook the wiring diagrams for the 1969-70 and 1970-71, shows from solenoid - white/red to ignition switch and two browns - one to lighting switch and the other joints two browns going to ignition switch and control box
|"I didn't realise your car was a 1970 as you've got '72 on your profile"|
Oops. Log book says 1971. I've changed my profile accordingly
|V5 says '71, Terry Horler's book would have it built around July/August 1970, perhaps it wasn't registered straight away or perhaps it's inaccuracy of the build records or interpretation of the records - shows that perhaps you can't get pin point accuracy on these cars|
boot light -
loom with purple tail
purple to boot light
from boot light purple/white to switch
switch earths to body
|Thanks Nigel. I eventually found my bootlamp in a box behind a load of stuff in the loft last night and luckily it has it's loom attached so i'm back in business there. Interesting that Moss, MGOS etc sell the lamp but don't list a seperate accessory loom for it.|
will be posting a couple of pics in my 'Some Progress' thread in General.
|Graeme, not sure where I've been this week but I've completely missed your post...|
Electrics are in my skill set (well at least the certificates say so!). If you need help just give me a shout (you've got my number right?).
|Hi MG Mike|
I've not half as bright as Graeme but could I possibly ask you if I could pm you to ask my questions. I have bought an alternator conversion set from Greg at Sussex Classic car parts so think I have all the bits but I'm VERY confused as to what goes where. I have read every posting in the archives but remain confused!
My best personal e-mail is firstname.lastname@example.org if you want to say Hi so I can pick up your address( or to tell me to get stuffed!)
1972 midget Mk III GAN 5 series
I got my wiring finished at the weekend with the help of this article...
I've removed all the insides from the RB340 control box and added the extra wire between the contacts as shown in the photo so the RB340 is now just an empty box.
I then made up a new lead (from 50amp wire to run from one of the large alternator contacts direct to the alternator (following the loom so I could tape it all together and keep it neat - it follows the route of the reverse switch lead until just under the solenoid). The Solenoid end of this new lead has a ring connector so it'll fit under the battery lead.
The rest of the wiring is exactly as per the diagram on page 19. One thing that wasn't immediately clear is that the alternator ends of the original dynamo cable have to be snipped and reterminated with the correct sized terminals as they switch round - i.e. the large alternator brown/yellow end is now a small connector at the alternator and the small brown/green wire now terminates with a large connector at the alternator end. My replacement alternator came with a new plug which makes the whole thing look very neat.
I'll try to post photos of all this tonight.
" then made up a new lead (from 50amp wire to run from one of the large alternator contacts direct to the alternator "
Obviously i meant direct to the battery side of the solenoid.
|here's the photos..|
RB340 control box - looks normal from the outside but I've drilled out the rivets holding all the internals in and soldered the wire across the relevant terminals shown on the diagram. If I can find them I'll be putting the wiring back into the original connector blocks.
|the new alternator connector showing the reterminated green/brown (big connector) and green/yellow (small connector) plus the new 50amp brown (big connector) - crimping the small connector onto the large brown/yellow was a struggle so I've soldered all the new connections aswell..|
|The solenoid end..|
|and a final one showing the cable routing - the 50 amp cable from the alternator to the solenoid follows the dull black tape - couldn't get any shiny tape to match the new loom..
|Graeme, all nice and smart but I'm afraid you've got a potentially dangerous set of wiring there. I've been studying the links you used and the instructions therein and I'm of the opinion the setup is a potential fire risk in extreme use conditions. The first thing that started me worrying was the link cable on the back of the regulator and the more I studied the more concerned I've become. This is going to be difficult to explain in writing (especially for me!) and perhaps I'll do some drawings to support the theory at the weekend.|
My main concerns are:
1, The small cable on the large connector of the alternator is undersized and will overheat when a high demand is called for.
2, the 50A cable on the other main terminal is overkill as this connector will never see move than 50% of the total output eg 30 to 35 Amps depending on alternator used.
3, the link cable should be sized to carry 30A (but to be fair it's only likely to see that level if one of the other cables fail).
okay now for the hard bits...
if you follow the big wire from the alternator to the B terminal via the solenoid and then back again to the other alternator terminal via the link cable (note the terminals are connected together inside the alternator) you will see that it can be drawn as a ring with "taps" off to power stuff eg charging the battery and powering the car. With the set-up you have this ring changes size from big to small at various points. Unfortunately current is no respecter of size and will flow equally around each half of the ring to the point of demand. Therefore, if we assume the battery is fully charged and not drawing any current, the only load is the car electrics. If we also assume the demand from the car is 40A (without doing the full maths but with lights high beam, wipers and heater on and car running it should get close to that) you will have 20A running down each side of the ring. This is probably on or over the limit of the small Brown and Green wire. If you add the charging of a battery on a cold morning after a difficult start you could see an additional demand of 10A. This 10A is equally split between the two cables from the alternator so, in effect, the small cable supplies more of the car demand and the big cable supplies the battery charge and a smaller amount to run the car. If the load increases to the 60A max the alternator can deliver, 30A will be flowing in the small cable and it will overheat. This also applies to the link cable on the back of the regulator and possibly the wire from the regulator to the solenoid.
As I said, the problem only presents when demand is high and you may feel you are unlikely to encounter conditions such as these. In that case you can leave it as is but if it was me I'd increase the size of the Brown and Green wire, use 6mm2 wire for the link and increase the size of the cable from the solenoid to the regulator.
If you want me to drop around and explain further, let me know.
|Thanks for that Mike. i'm always happy to take advice wherever I can - especially on this stuff - charging circuts are a black art.|
if I've read your reply correctly, I guess I should have left the connectors at the Alternator end alone and swapped the thick brown/yellow and thin brown/green at the control box end (with replacement connectors of the correct size) so looking back at the final diagram on the link I posted, the thin Brown/green would run from the small alternator terminal to the 'D' terminal and the thick Brown/yellow wire would run from one of the large alternator terminals to the 'F' connector on the control box.
is there a safety/performance issue with having the 50 amp wire from te alternator to the solenoid or is it just that it's a bit over the top for the application? (I'd rather not have to replace it if i don't have to.
And finally, is the brown/green wire heavy enough for purpose if it's now going from the small alternator terminal to the ignition light? it is the same thickness as the wire that runs from the control box to the ignition warning light at present.
I imagine this must be ok as all the photos i can find of similar 3 wire alternator plubs have 2 thick and 1 thin wire .
|Graeme, spot on. |
Although the F terminal is a bit small for the high demand current (it's probably rated somewhere around 20A max) but your options are limited if you want to use the regulator as a connection box. Personally I would use a larger "piggy back" connector on the B and forget the F and the link cable, but that won't look as nice.
There's no problem (safety or performance) with the 50A cable now it's in there.
Brown and Green wire is more than capable for the WL (Warning Lamp) as it passes little or no current when the engine is running. Actually it only passes current when the engine is stopped and the ignition light is on. Once you start the engine the alternator puts out 12v which means there is no current flow and causes the lamp to go out.
Don't forget to increase the size of the link cable on the back of the regulator. and the cable from the solenoid to the B terminal.
I understand your concern and personally I'd have done away the old control box and wired it straight in. Your arguments are almost correct but I don't think the situation is as quite as bad as you believe. The 2 cables won't carry equal currents because the thinner cable will be a slightly higher resistance than the thick cable, the thick cable will therefore carry the bulk of the current. The use of one thin and one thick wire was standard practice, see photo of the wiring on my B, and both of the brown wires go straight from the alternator to the solenoid. Admittedly the thin brown wire in the photo looks a bit thicker than the brown/green wire on Graeme's car, but not much. I think the use of one thick and one thin wire is a hangover from the early days of alternators where the thin wire was used as a battery sense wire.
If you could find someone that's got a current clamp multimeter it would be interesting to see just how much current this cable is passing.
|"Graeme, all nice and smart but I'm afraid you've got a potentially dangerous set of wiring there."|
"My main concerns are:"
2, the 50A cable on the other main terminal is overkill as this connector will never see move than 50% of the total output eg 30 to 35 Amps depending on alternator used."
Well apart from consuming too much of the earths mineral recosurces, why does this concern you? Just because it's current carrying capacity is more than required, does not mean that it can cause a situation that will cause it to draw more current than is safe.
How is this dangerous?
|Bob, I did wonder if anyone would pick up on the resistance of the smaller wire. And yes it will have an effect but... its negligible over the lengths of wires in a car (until it gets hot!). The big difference with the B is that both cables run between the same points and therefore can be considered as one cable. In this case they will share the current relative the available electrons in the copper ie self balancing the load in each cable. I think the use of one thick and one thin is just a cost exercise of not over specifying the cables needed. Two small is not enough, two big is too much and one very big causes problems with the area of the available connector size (hence moderns use a single bolted connection).|
If you consider Graeme's configuration which is very similar to the ring main in your house. The house uses 2.5mm2 cables (in the UK) which are rated at about 20A and yet the fuse is 32A. That's because the ring shares the flow and it now has a 40A capability, well above the fuse or MCB rating. Yet if you run a single cable for an electric shower which requires a 32A supply the cable size required will be 6mm2 (4mm2 is too small and 5mm2 is not an available size in a single cable).
I agree it would be better to do away with the control box altogether and it would useful to get a clamp ammeter to check what is actually flowing. I might do so when Graeme gets the engine back in (next week at the rate he's going ;0).
|Lawrence, I've already conceded this point as not a problem now it's there. See my follow up post.|
The dangerous bit is the varying cable sizes around the ring. the 50A cable is still over kill for the current available and I'm sure Graeme had a pig of a time getting the connector on. And yes it uses more resources than absolutely necessary and adds to the cost (slightly).
Why spend a pound when 50p will do the job and (at the risk of upsetting a lot of Scots) I've been North of the boarder so long it's rubbing off ;0)
|Thanks again Mike and everyone else that's contributed. At least it's an easy enough fix that I'll hopefully get sorted at the weekend.|
Getting the engine running may take a bit longer though - I'm under orders to finish some decorating before christmas and time's slipping away.
1st thing, changing to an alternator, without adding more current consuming devices to the car, won't cause a greater current flow. An alternator has a greater capacity to provide more current than the original dynamo, but it won't if there is no increased demand.
Second thing, I can't see anything dangerous about varying cable sizes in this setup, if graeme has followed the diagram in type 5 for an RB340 conversion. This is not a domestic ring final circuit. It's a parallel circuit.
There are two wires, of different cross sectional area (csa), connected at one end to a common point in the alternator. At the other end, they are connected between terminals F and B in the RB340, using a link cable that joins F to B. They are in effect in parallel. The link cable between them, whilst of a smaller csa, is extremely short, and extremely unlikely to heat up.
If that link cable breaks, then the existing brown and green wire connected to terminal F, will cease doing anything at all. There will be zero current flow in this conductor. Terminal F will now be floating, because it isn't connected to anything else.
Instead, all the current -- when the engine is running -- being delivered from the alternator to the battery and the rest of the car, will flow via the new 50A cable connected at the solenoid. The existing brown cable will supply the car via terminal B in the RB340, and the large black cable that runs directly to the +ve on the battery, will supply the battery. When the battery is fully charged, no current will flow into the battery.
When the engine isn't running, hence no alternator output, or the alternator output ceases, or drops below the current demand of the car, then the large black cable from the battery +ve, will supply the car, via the existing brown cable connected to terminal B at the RB340, which is much the same as it was prior to conversion, and didn't pose a risk.
"Unfortunately current is no respecter of size and will flow equally around each half of the ring to the point of demand." That's not true.
Current flow in a conductor, is inversely proportional to the resistance of the conductor. If you wire two conductors in parallel, current will flow in each, in direct proportion to the resistance of each conductor.
If both conductors are of equal length, size, and material, and hence are of the same overall resistance, then current flow will be equal in each conductor. If you halve the resistance in one conductor, by either halving the length, doubling the size, or changing the conductor for a material with half the reisitivity of the original conductor, then it will act as a "shunt" and under the same conditions, double the current will flow in that conductor. Simple ohms law. Or have I got that wrong?
"And yes it uses more resources than absolutely necessary and adds to the cost"
I call it redundancy, but then I don't care too much about saving the planet, or global warming, ;)
I was hoping we wouldn’t get in to the whole electrical principles discussion but as you’ve asked the questions and made the statements it’s only polite that I respond…. So here goes…
>1st thing, changing to an alternator, without adding more current consuming devices to the car, won't cause a greater current flow.
>An alternator has a greater capacity to provide more current than the original dynamo,
>but it won't if there is no increased demand.
So why upgrade? Well it’s because a dynamo can’t meet the “design maximum” demand. This occurring on a cold, wet, dark day with the navigator reading a map, disco music blaring on the radio when you hit the brakes and the horn to chase the deer off the road (or perhaps it’s a Kentish Clown on a bike. You do ride a bike don’t you?). Typically a dynamo provides 25A maximum output and that only when spinning at high speed. A typical car demands closer to 36A (see the table below) at times of high demand. At these times the battery supplements the dynamo output. One of the worst possible scenarios is sitting in traffic with the lights, heater and wipes on and your foot on the brake (a typical summer day commute in the UK ;0)
high beam 110 9.17
side lights 35 2.92
wiper 14 1.17
blower 75 6.25
radio 45 3.75
ignition 36 3.00
battery Cold day after starting circa 10.00
with safety factor 54.38 Amps
>Second thing, I can't see anything dangerous about varying cable sizes in this setup,
That’s because you have failed to understand the impact of doing so and hopefully this will become clear as we progress through the post
>This is not a domestic ring final circuit.
Agreed that analogy was used for illustration purposes as most people can relate to the conditions, and the principles still apply.
>It's a parallel circuit.
WRONG. A circuit with more than one demand point connected with two possible current paths must be considered as a ring circuit. Only when the battery is not drawing current can this be considered a parallel circuit. As this never happens in practice (however small the trickle charge may be) it therefore should always be considered a ring when connected at described.
>There are two wires, of different cross sectional area (csa), connected at one end to a common point in the alternator.
>At the other end, they are connected between terminals F and B in the RB340, using a link cable that joins F to B.
WRONG, they are connected at the B terminal where the demand comes from the car. The link cable and F connector are part of the ring.
>They are in effect in parallel.
I’ll go along with this for now in order to explore the principles.
>The link cable between them, whilst of a smaller csa, is extremely short, and extremely unlikely to heat up.
WRONG. Yes, its short and yes it will overheat if it’s carrying a current higher than it’s capable of doing so. Take this to the extreme and fit a single strand of small wire and see what happens? It becomes a fuse! So the csa of the link is just as important as the other cables in the circuit
>If that link cable breaks, then the existing brown and green wire connected to terminal F, will cease doing anything at all.
Agreed, however I’m more concerned by the size of the brown and green wire than the link.
>There will be zero current flow in this conductor.
>Terminal F will now be floating, because it isn't connected to anything else.
>Instead, all the current -- when the engine is running -- being delivered from the alternator to the battery and the rest of the car, will flow via the new 50A cable connected at the solenoid. The existing brown cable will supply the car via terminal B in the RB340,
So how does the current get from the solenoid to the B terminal to supply the existing Brown wire to the car? Via the small brown wire which runs from the solenoid to the B terminal. This cable (csa approx 1.5mm2) is not designed/rated to carry the full load of the car and will overheat. In addition all of the spade connectors in use are not rated to carry the full load current and will also overheat.
>and the large black cable that runs directly to the +ve on the battery, will supply the battery.
>When the battery is fully charged, no current will flow into the battery.
Not sure I agree with this but will conceded the current will be very low when fully charged say 0.25A trickle.
>When the engine isn't running, hence no alternator output, or the alternator output ceases, or drops below the current demand of the car, then the large black cable from the battery +ve, will supply the car, via the existing brown cable connected to terminal B at the RB340, which is much the same as it was prior to conversion, and didn't pose a risk.
You’re actually right on this one and I needed to have a good think as to why this is the case :0) The conclusion I’ve made is that the “design maximum capacity” is unlikely to be reached and hence a small cable from the solenoid to the control box is acceptable. How come? Well, either the car will be stationary with the engine not running and therefore no requirement for the wipers, blower, lights etc. If the engine is running the driver, on seeing the warning lamp would either stop the car and seek help or if they are somewhat knowledgeable to understand that the battery would quickly go flat when drawing full load, would act according by switching off as much as possible to allow the car to “limp home” on battery power alone. In this case the demand would be low and the small(ish) wire from the solenoid to the control box operates within its design limits.
"Unfortunately current is no respecter of size and will flow equally around each half of the ring to the point of demand."
>That's not true.
It is within the context of the wire lengths in a car.
>Current flow in a conductor, is inversely proportional to the resistance of the conductor.
WRONG WRONG WRONG
Current flow in a circuit is inversely proportional to the resistance of the circuit.
>If you wire two conductors in parallel, current will flow in each, in direct proportion to the resistance of each conductor.
Current will flow in each proportional to the TOTAL resistance of the circuit.
The typical resistance of a copper conductor of 16mm2 is .00115 ohms per meter and 1.5mm2 is .012 ohms per meter.
If both are wired separately in circuits with a resistance of 2.4 ohms the difference in current flow will be 4.99760531 – 4.97512438 =0.02248A or 22.5mA. Put them together and the effective resistance is .001 and the current in each as near to the same as makes no difference. And this is the fire risk because the smaller cable is not capable of carrying that amount of current without generating heat.
So if we consider the circuit as described; each leg of the ring will be no more than 2m long when run around the car and the design current demand from the car (with a safety factor of 1.5) will be near enough 50A which makes the effective circuit resistance 0.24 ohms
The current in each leg away from the alternator will be, near as makes no difference, 25A. The cable required to carry this level of current is on the limit of 2.5mm2. I must admit here that this is not as bad as I initially thought it would be and proves that fitting massive cables is not required in a ring configuration. It further explains why in “normal” operating conditions an undersized circuit works quite happily. However, to ensure continued safe operation in the event of a connection or cable failure 10mm2 should be used.
>If both conductors are of equal length, size, and material, and hence are of the same overall resistance, then current flow will be equal in each conductor.
Agreed and that is why I’m advocating the conductors all the way around the ring need to have a csa’s appropriate to the current flow expected.
>If you halve the resistance in one conductor, by either halving the length, doubling the size, or changing the conductor for a material with half the reisitivity of the original conductor, then it will act as a "shunt" and under the same conditions, double the current will flow in that conductor. Simple ohms law. Or have I got that wrong?
You have it wrong again I’m afraid. This would apply when the cable lengths are so long as to have a material effect on the total circuit resistance. In the case of a car they don’t.
"And yes it uses more resources than absolutely necessary and adds to the cost"
>I call it redundancy,
Wrong again. It’s increased capacity that will never be used.
Redundancy (in electrical terms) is to provide an alternative route or path to maintain the full design specification in the event of a single point failure. Which, to be fair, the ring would do if correctly sized in all segments.
>but then I don't care too much about saving the planet, or global warming, ;)
or, it appears, wasting money on things you will never use ;0)
To summarise; don’t waste money on over sized cables, don't use the skinny Brown and Green from the alternator to the RB340, put in a 10mm2 cable. Ensure the link on the RB340 is of the same size and change the cable to/from the solenoid and RB340 for a 10mm2 cable and all’s well with the world….. except you will overheat some of the connectors if you have a single point failure..... final word, dump the RB340 and install suitably robust connection points for 10mm2 cables
Now go out and enjoy your weekend run in the warm south and spare a thought for your poor cousins up north with the wipers, heater and lights on all the time ;0)
All the best
|Crickey, that took you long enough, where have you been? |
I guess you were studying electrical principles from your coures notes. lol. I'll read that lot later, IPA prevents me from taking you too seriously at the mo. ttfn.:)
|Ah the fresh light of dawn, and nice cuppa. However, I owe you an apology Mikey. I find that even though I'm once again in the realms of reality, that wonderful illusion fuelled by a lack of IPA or similar substance, I'm still unable to take you seriously. Sorry about that my love.|
And I can't help wondering if that's why you feel so angry, and the need to lash out and throw insults, when someone challenges something you say. Maybe nobody 'ever' takes you seriously enough, – for your liking. Were you a deprived child, mummy didn't love you enough? Or maybe you were bullied at school? Wife won't let you have any, or maybe you just can't perform too well in that department? Well never mind, it's all part of life. But whatever it is, you shouldn't feel it to be sufficient reason to insult the good people of Kent.
Kentish Clown? Not an expression I've heard in my sweet short life. Certainly not of one on a bike in kent. I did a quick search on the web, and still no luck. So clearly this is a personal impression you have of the people in this garden of England county. Where does that come from then? Is it something to do with your desire for independence? Are you a Salmond follower, that would be latter-day Robert the Bruce? -- Mind you, I might feel the same way about a divorce from England, given some of the antics down here, like for example, our dismal inability to kick out a certain religious cleric. – Then again, maybe your not a Scot at all, and have some other reason. No matter the reason, you do the Men of Kent down, without just cause, since I myself, am not one. I'm a Londoner, merely residing in this pleasant, mild, and green landscape.
And here, I owe you another apology. I have insufficient time this a.m. to respond to all your charges ( no pun intended, as I suspect your light shines a little too low to grasp the humour), since I must rush north to cold London, to see a man about a circus, where I might seek employment. However, fear not, I'll consult the beano and the beezer, and respond in full later.
But here's a thought for you.
You probably weren't aware, that electricity was discovered by that famous baker, Thomas Farriner of pudding lane London, when he stood on a bun, and a current shot up his leg, thus causing the spark that set the great fire. Bye for now luvvy.
no anger here, sorry if came over that way. Mate
Took me a while to respond because I do have a full life off the board (and I mean full in all respects I'm happy to report :0).
I must admit the Clown reference came from the deep recesses of my mind (what that say's about me I'm not quite sure or really want to know). It was meant a bit tongue in cheek as a bit of fun but being a Londoner you might struggle to understand such finer points (a joke don't react I can tell from you posts you have a sense of humor ;0) and when you read a bit more about them you might even like the comparison. A Google search did come up with one Telegraph Motoring article from 2005 referring to a Boxing day racing event held in Kent in the 50's and 60's.
Although I'm not sure if the clowns are the organisers who thought they could run a mid winter race meet or the 40,000 "locals" who turned up, draw your own conclusions on that one.
BTW, like you I'm an incomer and concerned about the state of the union but unlike you I try not to waste resources (except fossil fuel in petrol form when driving purely for fun ;0). And that's where I'm off to now... after I fix the electrics ;0)
"Current will flow in each proportional to the TOTAL resistance of the circuit.
The typical resistance of a copper conductor of 16mm2 is .00115 ohms per meter and 1.5mm2 is .012 ohms per meter.
If both are wired separately in circuits with a resistance of 2.4 ohms the difference in current flow will be 4.99760531 – 4.97512438 =0.02248A or 22.5mA. Put them together and the effective resistance is .001 and the current in each as near to the same as makes no difference. And this is the fire risk because the smaller cable is not capable of carrying that amount of current without generating heat."
WRONG WRONG WRONG WRONG
Using the examples you've provided, if we assume the load has a resistance 2.4 ohms and a battery voltage of 13V and this is feed by the 2 wires in parallel and each wire is 1 meter long. To determine the current flowing in each cable we need to calculate the combined resistance of the 2 cables, from this we can determine the voltage drop across the combined cables and from that we can determine the current through each of the 2 cables.
The large cable has a resistance of 0.00115 ohms the thin cable 0.012 ohms, the overall resistance of these 2 cables in parallel is 0.0010494 ohms.
The current through this circuit will be approximately 5.42 amps. This current will cause a voltage drop of 0.00592948V across the 2 wires.
From this we can calculate the current through each wire. For the thick cable it will be 0.00592948 / 0.00115 = 5.156A
For the thin cable it will be 0.00592948 / 0.012 = 0.49A
I'm sure you'll notice that 5.156A plus 0.49A = 5.646A not 4.42A this is due mainly to rounding errors and although I could calculate it more accurately life's too short. Suffice it to say the large cable is carrying approximately 90% of the current and the small cable 10%. You'll notice that the proportion of current flowing in each cable is inversely proportional to their resistances.
Your mistake is treating each of the cables separately and then comparing them.
|Bob, hands up got that bit wrong and realised earlier today that considering them as a whole was required. Thanks for the correction.|
I'll take another look at the full circuit and if I find it's fit for purpose I post saying so.
|Sorry for not posting rebuttal myself, but I've been v/busy, and I'm off back to the smoke today, so can't post decent reply until later today either.|
However, if you read what R.A Davis has posted (and stole my thunder, lol) you'll not go wrong.
Mike, study up on resistance values in // circuits, and note: In a resistive // circuit, the total current is the sum of the currents through the individual components, in accordance with Kirchhoff’s current law.
Extract, Dandy, page 6 regular features by Desperate Dan. :)
|Guys. this thread seems to have devolved into a bit of a slagging match which wasn't my intention.|
For what it's worth I've now swapped the alternator wires so the thin brown/green now goes from the small alternator connector and the thick Brown/yellow connects to the larger terminal. I've also increased the size of the new wire linking the B and F terminals.
Mike - once I have a battery and have got the engine in and running you're more than welcome to come round and give it all a safety check. - of course you're welcome anytime.
|Good job Graeme, I'm pleased you're still about. Hopefully you were able to filter out all the sh*t and pickout the snippets of useful information. It really isn't that hard, join a thick wire to bat, alt and electrics at solenoid and a thin wire from IND on alt to warning light. Thats's it! |
We all try and help but sometimes we forget we're here to help others, not get mixed up in a p*ssing comp.
Electrical questions are always entertaining threads on here. Perhaps next time stick to a mechanical query. lol.
I didn't think it 'was' a pissing comp'. I just posted to contradict some incorrect statements, which I think should be corrected.
graeme, don't worry about it. Nobody gets hurt on here, it's just text in the ether. If they do, then they need a thicker skin. :)
|Just for interest, here's a couple of pics of a late '73 GAN5 (factory fitted alternator) 'original' solenoid wiring.|
The thicker brown wire comes straight from the Alternator, and the thinner brown goes off into the the loom --- I assume without looking at the wiring diagram --- to feed the fuse box, etc.
So there really shouldn't be a concern about the wiring mix in the "type 5" conversion diagram, since it was good enough for the factory.
|Lawrence I know that's not you and with regard to correcting incorrect posts I'd be the first to do exactly the same.|
Are those pics off a going car or a parts car in the back paddock? I hope it's the later.
|I'm guessing it might be Lawrence's daily used 46 year old car, possibly not highly polished but highly used|
the more use the less problems and on non-service replacement items the working life can be many decades so the new appearance can be lost whilst functioning remains
polished cars are very nice as long as they go well too ;)
|actually L's photo has prompted me to put somethings I've been thing|
you'll notice in L's photo that insulating/protective rubber boot on the main battery supply I'd also add one to cover the connections on the other main post on the solenoid - all connections need to be clean, secure and protected
and, you might have changed it anyway but, in your photo of the alternator plug you have the brown/green wire long than the other two and wound around the brown/yellow - Sod's Law any unnecessary wire loop will cause some problem sometime
I bought two plugs as the first was such thin plastic and thin spade plugs unfortunately the second was just as bad
|Gees Nigel I felt that sharp blow in the kidneys. I had a chuckle because of how appropriate the comment was. What you may not have realised is that all the parts that have gone into my money pit is what's been keeping the UK economy out of recession for the last 2 years. I'm almost done now so you better hope another foreigner takes on a Midget. :)|
At least with my car not going I don't have to buy a handbook. There's a saving. and before you respond, it'll take a bit more than a hand book. lol
The black grime under the solenoid, is the result of underseal around the whole engine bay. The car was zeibarted, possibly from new, and for some reason, the engine bay was included.
Anyway, the pics are in fact not from my daily '66 Sprite, they are from a '73 midget that's just come my way as it happens. My thoughts were, very fleetingly, of a spares car, however, it's way too good for that, so it's very much a going car in need of a little attention.
Btw, my gf thinks it might look nice pink. What can you do huh? On the other hand, for a bit of fun I might make it pink and white striped. lol.
You're right, i have already changed the alternator plug so not ony are the thick wires in the right place, all three are nice and straight coming out of the loom.
I think it might be a bit of a OCD thing with me
at least it was only a blow to the kidneys :)
the shine on my comment has been somewhat lost by L's putting it is his spare car
just before my present Midget I had a 25 year old Capri that was Ziebarted in engine bay and all over which showed that some of the franchises done a good job as the car had very little rust on it despite the previous ten years of living outside, the enthusiast that had it from me because all the panels were original carried out a full rolling restoration, whilst using it, to a show standard
as for keeping the UK economy going with Midget bits, thanks for your help, I bet I've (unwilling a lot of times) spent more in the last two years than yourself whilst also helping the Chinese economy, repeatedly
I've probably spent more on my Midget in 5 years than L has in 37 years - I should get a CBE
having seen A Few Good Men last night - "You want to see receipts, you couldn't take the receipts" :)
|Just wondering MGMike, have you reconsidered your view about the whole circuit being "fit for purpose"?|
|What a trouble maker is what I'm thinking while shaking my head with a smirk. A caring person would have been checking on Graeme to see that he got his car sorted ok. :)|
|Thanks for your concern Greg :-) |
it'll be a few months before I'm ready to start the car but i now have two thick wires coming from the alternator plug large terminals and one thin one coming from the small alternator terminal.
once I'm up and running mike's offered to come round and check I'm not overloading any of the circuits.
Currently I'm installing a new 2 speed wiper motor and trying to figure the wiring for that. However, I don't think I'll ask about that on here- wouldn't want anyone to ocme to blows :-)
|Well, :), in my defence, I was concerned about graeme (and others) too.|
In as much as, I wanted to establish that the contents of the link to the "type 5" wiring, that graeme posted earlier, were no longer the subject of a dispute about being fit for purpose.
I was jogging MGMikes memory about coming back with confirmation, in a friendly way. :)
Trouble maker? Where? Who's that then?
hadn't forgotten just that full life getting in the way ;) I've done some maths with a couple of assumptions on cable sizes but want to run them again with actual sizes. To that end I think I should have an old dynamo loom buried in the garage somewhere to cut up at some point. If anyone knows the actual size of the Brown and Green used on the WL leg and the solenoid to control box cable let me know.
|My car was 67 UK spec with generator loom and I believe being an Aus car was converted to alternator before it left the factory in 69. This was done by joining a the wires where the regulator once went. I assume it was a BMC approved modification and the smoke hasn't escaped in 40 years so can't be too risky.|
Lawrence don't feel that you need to defend yourself, I'm sure I just misinterpeted it, but I'm still chuckling.
|You had me right the first time Greg. ;).|
And mine was converted too Greg, although mine's a '66 Sprite, and it was I who converted it. I used a 30A connecter block instead of the RB340, which was then redundant. I had a UB40 at the time as well, because I was also redundant, but it wasn't much use either. LOL.
Anyway, I haven't noticed any smoke yet either. The battery charges and the lights work.
Glad to see your still thinking about it then Mike. It won't be safe until it's approved. ;-). But I wouldn't bother if I was you. As said, BMC probably got it right, and the extra wire in that type 5a circuit should cover it.
Thanks to Robert Welch of spridgettechnical.co.uk, hope you don't mind me pasting the diagram here. :)
This thread was discussed between 05/11/2012 and 28/11/2012
This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.