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MG MGB Technical - Batteries - smart charging/replacement

Well, my battery seems to be kaput. Little use, but a long period (couple of years) of inactivity after purchase and before use in anger. 6 months of normal use and it won't turn engine over after charging. So I will replace it.

Is there any argument against using a Battery Fighter smart charger to charger the battery if it is going to be left idle for more than a few weeks?
The model I have is a BFA-012, 12Volt.1.25A "intelligent battery charger and maintainer".
I only ask because in shopping around for a new DIN44 battery, some sales people get worried about me using such a charger on "modern batteries" (as they put it).

I have been checking prices of batteries - all in a range of within $35. Exide (Marshall) is most expensive - then Delkor (from Korea) and Supercharge made by Ramcar in Philippines (I think.
Reviews of the Supercharge seem positive (no pun intended!). (other brands made by Ramcar are Motolite, Energy Plus, Federal, AC Heavy Duty, International)

Any bad experiences with Supercharge or equivalent?


John Minchin

John - Those go by a number of different names and most definitely should be used when the car is idle for more than a couple of weeks. The battery tender, battery buddy, smart charger, etc. will keep the battery plates from developing a coating of lead sulphate, which is what causes the early demise of batteries that are left idle for long periods of time. I have a battery tender that is plugged into an outlet in the ceiling of the garage where our TD is parked all the time and it has greatly extended the life of the batteries in the car. Cheers - Dave
David DuBois

The first think to check is the battery connections to the starter. Monitor the voltage on the battery posts (not the connectors) and if that barely drops below 12v then you have one or more bad connections and quite likely a good battery. However if the voltage on the posts drops right down then the battery is indeed knackered.

Given the usage or rather non-usage your battery has had I would be putting the conditioner on that and seeing if it can be revived, often they can.

battery conditioners are designed to be left connected permanently (i.e. all the time the car is not being used), they vary the charge according to the condition of the battery. Your sales people may be thinking of an old-fashioned 'trickle' charger which overcharges over time.

The argument against using a conditioner all the time is that it may be the conditioner that is allowing the car to start at home each time. Go elsewhere and park it overnight and it may not start next morning.

Paul Hunt

Thanks for the advice
Got the local Royal Auto Club to test the battery - meter said it was dead and needed replacement.

So I got one (DIN 44) but it seems longer than the one I had. Wouldn't you think that if it is a "standard ", that the size would be standard too? Will check in the morning to see if it is just snug, or weather some plastic filing is needed.
John Minchin

We've used the conditioner type charger on our boat, which hibernates at the back of the garage for about 8 months each year. The last batteries we bought for it were January 2006 and they are still going well, albeit they got transferred to the cars this year when the batteries of the latter died and the boat got the new ones instead, on the grounds that it's harder to push start.
So yes, the conditioner charger seems to work quite well.
Paul Walbran

I use Battery Tenders on my '67 B, with twin six volt batteries and also on my motorcycle. They will extend the life of your batteries by a huge factor. I sometimes go for several months between starts of my MG and it always fires right up. The last pair of Interstate batteries lasted thirteen years using the Battery Tender and the pair, before them, lasted eight years. They are definitely worth the investment. RAY
rjm RAY

Battery replaced - tight fit but still some clearance between the top and the battery compartment lid.

Engine is turning over but still doesn't want to start (ref previous thread - nothing has been touched or adjusted since my last driving 3 months ago) - fires enough to flick the starter gear off the pinion but then nothing. Tried some starter spray ( same result) I pulled the plugs again - checked the spark, and it looks very weak.

I'm hesitating to start adjusting all the things that could be adjusted as it was running fine before so timing, carbs etc must have been (reasonably ) OK Battery obviously died. Could coil also be suspect?

Is there an easy/safe way to test the coil or should I pull it and take it to an auto-electric shop?

John Minchin

I had a similar problem after changing the headgasket. The engine started after I had topped up the oil in the carbs (one was empty) and starts first time now. The forum here didn't believe me.... You could try it, it doesn't take a minute.

One thing to check is that the choke is pulling the jets down far enough. The car can run fine but be a pig to start if these aren't correct. My other favourite is the condenser. I have had one go overnight and the car refuse to start the next day. You can connect a good one in parallel to check before taking the distributor to pieces.

HTH, Mike
Mike Standring

" tight fit but still some clearance between the top and the battery compartment lid."

I sincerely hope it is clamped down.

Weak spark sounds like condenser more than anything else - as long as there is 12v at the SW or +ve coil terminal with the points closed of a chrome bumper 12v coil, or 6v at the +ve terminal of a 6v coil. Add another between the coil -ve or CB terminal and earth to check. If you don't have one to hand compare the spark opening and closing the point by hand with connecting and disconnecting the points lead from the coil. If they are the same the condenser has failed (open-circuit), and another symptom of that is much sparking and spitting when you open the points/disconnect the points wire from the coil.
Paul Hunt

I think there is a spare condenser in one of my boxes - if not I'll get a new one as they are cheap.

Battery is clamped down - the problem is that unless you remove the cover, it is out of sight/out of mind.

Either a CCTV installed inside (joke!), or a layer of insulation under the lid so if the clamp fails and the battery bounces up (hey!, my driving style is under question here!) it won't short out.


John Minchin

>>if not I'll get a new one as they are cheap<<
yeah and if they're anything like they are over here they could easily be faulty from new or soon go faulty unless you buy from a very reliable source such as the Distributor Doctor

better to use a known good s/h or good NOS

(same for CB points and rotor arms still I believe)
Nigel Atkins

I replaced the Condenser - fitted a Bosch. The "old" one actually looked quite new (but as you say, that doesn't necessarily equate to serviceable)
Checked dashpot oil Mike - was OK

Still no go, although with the aid of some starter spray it fired for a brief few seconds then died.
The spark still looks pretty weak to me (but then again, I haven't got anything to compare with)
The primary resistance of the coil measured as 3.4 ohms, the secondary 7.4k Ohms.
I dug out the old Bosch coil that came in the car when I got it - 3.6 and 7.91K.
I connected this one up and tried again - no change . The spark looked much the same.
As I have been cranking quite a lot, I will fully charge the battery over the next day or so and have a look at the spark again.

To me it seems that the spark is strong enough to ignite the starter "fumes, but not the fuel vapour. After a bit of cranking I'm sure there is a lot of fuel in the cylinders, so the mixture is quite "wet" and the spark won't ignite it. Possible?

John Minchin

Yes, if you crank for some time with the choke out you will flood the engine and have wet plugs. Crank some more with the choke pushed home and full throttle to clear it, and when it catches be ready to release the throttle and half-pull the choke.

Both those coils should be OK, measure the voltage on the coil +ve with the points closed and you should see 12v, dropping to about 10v when cranking with a good battery. Less than that will give a weak spark.

Then measure the voltage on the coil -ve i.e. the points terminal with the points closed, and open. Should be 0v closed and 12v open. If more than 0v that will also give a weak spark.

Have you tried flicking the points open by hand?

Have you tried comparing the spark by flicking the points open and closed with just tapping the points wire on and off the coil -ve?

You say you think it is weak, but what are you comparing it with? How far does the spark jump when you flick the points open by hand? Should be a minimum of 1/4", but be careful which end you hold. Hold the plug end of a lead and move that away from a metal rod in the coil terminal. If you move a plug away from the block or a lead away from the plug you will get a belt when the spark can no longer jump the gap.
Paul Hunt

You've checked fuel delivery? (Remove hose from carb and get assistant to turn on key while pointing the hose into a can). Pumps don't like sitting around, a light corrosion film can affect the points. If this has happened a jolt is usually all it needs.
Paul Walbran

yes Paul (Kiwi) - pump is fine - plenty of fuel.

Paul (Pommy! - no offence intended) - checked both coils in situ. Results are -

Old Bosch:
+ve terminal - 12.17 dropping to 10.3V on cranking
-ve terminal - 0.19V pts closed, 12.65V pts open

Newer unbranded
+ve terminal - 12.19 dropping to 10.25V on cranking
-ve terminal - 0.17V pts closed, 12.61V pts open

Is the >zero volts at the -ve terminal (ie 0.17-0.19V) enough to cause weak spark?

With these questions you can see why I opted not to do electrical engineering!!

I will go and check the spark as you suggested
John Minchin

Update -
Spark easily jumps 6mm from end of plug to the block.
I did also find the screw holding No1 lead to the dist cap was very loose.

When resting the plug body against the block, the spark across the plug gap doesn't look anywhere near as strong. Normal?

Anyway back to the garage....
John Minchin

Just tried to start the car. It seemed that with a little perseverance it might start. But I'm wondering if I have a separate problem that is compounding the issue.

When turning the key (or pushing the starter solenoid button, or even a remote starter button)the starter keeps stopping and starting. Quite a loud "clatter as it engages , turns the engine a bit, then momentarily cuts out and disengages, then energises and re-engages and cranks the engine a bit more.
I've eliminated the ignition switch as a problem (by using a remote starter) So does it sound like a faulty solenoid chattering in and out and turning power to starter on and off?

It looks like a fairly old unit, and I gather they are not really serviceable or repairable.

I had a look in the archives but didn't find any comments about chattering solenoids - maybe my choice of search words!

John Minchin

Just had a thought.
If the solenoid is operating intermittently then I would expect to see the output voltage (ie on the starter motor terminal) fluctuate.
Well it does but between 9.5 and 11 volts but mostly between 10 and 11(measured with a digital multimeter which is a bit hard to get an accurate reading from in volatile situations)
Measured the voltage at the terminal on the starter itself - much the same voltages.
John Minchin

Did you measure the voltage at the starter terminals during cranking when the starter was misbehaving? If the voltage at the starter terminals is 'normal' during cranking and with the symptoms you have described, then I would suspect the starter motor itself (brushes, maybe).
Brian Shaw

Have you tried push starting it, or even towing it? The car might run and you can at least narrow it down to the starter components.

Mike Standring

John - those voltages are fine, as is a 6mm spark. If the spark at a plug i.e. after it has gone through the distributor cap and rotor is noticeably less than than the spark direct from the coil that implies possible problems with cap and rotor. There is supposed to be a very small gap between the rotor and the cap contacts, but ordinarily that isn't a problem. It could be that one or other isn't fully breaking down but *is* leaking some of the voltage away from the plug lead. What type of leads do you have? The original carbon string go very high resistance over time which eventually impacts on spark. Anything that makes the HT voltage difficult to get to the plug causes the HT voltage to rise, and that can start breaking down the insulation along the way.

A chattering solenoid will make it difficult to start as it isn't turning the engine over as it should, and that is a common failure mode of the V8 starter for example, the solenoid winding loses the ability to stay in with the lower cranking voltage.

It can also happen if there is insufficient voltage reaching the solenoid, which can be from bad relay contacts or any other bad connections along the way. See if you can measure the voltage on the solenoid operate spade and compare that to the voltage on the battery cable stud. If noticeably lower test both sides of the relay contact brown and white/brown - if you have a relay. They were provided from 1970, but I don't think we know the year of your car yet.
Paul Hunt

To answer your questions;
Firstly, its a 1963 car with the long inertia type starter, separate solenoid.

Mike - sorry can't push start as car is in garage at the bottom of a steep driveway :-(
Brian - voltage at starter OK
Paul - Voltage at solenoid OK

But I think I have made some headway.

With ignition off, starter engages and cranks steadily (using push button on solenoid).
With ignition on (hence possibility of sparks getting to cylinders) and cranking using push button on solenoid, the starter flicks in and out of engagement - ie the engine is firing intermittently on 1 or more of the cylinders - enough to throw the pinion off the flywheel, but not to start.

So I think I can forget the starter and solenoid for the present and concentrate on the ignition circuit looking for leakage as Paul suggests.
I have -
Original 25D distributor
Newish points
New condenser
Original rotor (ie came with car)
Old dist cap (likewise)
New copper cored leads.
new Lucas type screw on plug ends.
New plugs
New unbranded" coil with screw in HT cable attachment
New battery

Before all this non starting business, car was running fine, albeit it sometimes took a bit of cranking to get it started from cold. After a few weeks unused, and in cold weather the problems started and at that point the battery gave up.

So I am focusing on spark as I haven't touched the carbs and there is fuel getting through

I'll keep you posted
Thanks for advice so far

John Minchin

The only thing I can think of is to ask, are the correct leads connected up to the spark plugs? You will have taken the leads off to change them but you might have put them back wrongly. They do look the same and have similar lengths.

When I bought my MGB it ran really badly. It turned out to be plug leads 2 and 3 were swapped over!


PS: You could check the damper oil in the carbs.... It worked for me when my 1964 MGB had identical symptoms last month. One was empty, the other full.
Mike Standring

"With ignition off, starter engages and cranks steadily (using push button on solenoid).
With ignition on (hence possibility of sparks getting to cylinders) and cranking using push button on solenoid, the starter flicks in and out of engagement -"

In that case it looks kike it's trying to fire, although that should flick the pinion out of engagement with the flywheel which would make the starter whine until you release the ignition key or starter button, it shouldn't be jumping back in again while you still have power connected to the solenoid.

Back to comparing coil spark with plug lead spark, I think.
Paul Hunt

You suggested I check the choke. I finally did.

The front jet only pulls down about 3mm and the rear one doesn't move at all. My understanding is they should move down about 8mm (5/16")

So I have probably not been getting sufficient fuel to start in the cold weather.

That would also explain why the rear plugs looked dry and the front ones wet after cranking. Probably the engine is only firing on the front cylinders and not the rear - hence the starter being thrown out of engagement.

So the task tomorrow is to pull the air cleaners off and get the adjustment done properly


John Minchin

This thread was discussed between 11/09/2013 and 05/10/2013

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