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MG TD TF 1500 - CHARGING OR NOT
|My TD is hibernating (so am I). But I am thinking about it and counting months. I want to take a long trip with it in Norway next summer, but I am worried about one thing.|
In Norway, everybody has to drive with lights, day and night. (Not to see better, but to be better seen). I have noticed that when I drive without lights, the ampmeter shows a little on the plus side. When I put the lights on, it goes to the negative side.
I talked to another TD owner about this and he said this is normal, nothing much to do about it.
Is that really so?
|Perhaps your voltage regulator is in need of adjustment or cleaning of the points in it. If it needs to be replaced, think about a solid state voltage regulator conversion. Bob Jeffers in the USA does this conversion using your original unit. He reworked mine and does very nice work. When completed, there is no change in the outward appearance of it.|
If you want to change to solid state that's up to you, but in my experience the original Lucas units are very reliable and last for decades. The same cannot be said for the 'repro' units now available - if you have one of those change to s/h Lucas or a Bob Jeffers solid state unit.
The Lucas unit needs adjusting every few years, the voltage tends to drop. You need a volt meter and follow the instructions in the workshop manual. It's simple, concentrate on the max volts rather than the contact opening voltage which really needs two sets of eyes!
|J C Mitchell|
1. You might try adding 2 items to your light circuit, a heavy resistor that'll handle current and a good switch across it to switch back to full lighting.
My first choice for a resistor that sheds heat is an old ignition ballast resistor. It just so happens, I bought one off ebay last week for wife's TD and got a new chrome plated coil along with it. ebay 290388050622 Your lights will be "on" but dim. A switch mounted across the ballast resistor terminals will restore full lighting when switched on, shorting across the resistor. You don't even need to cut and splice. There's a snap connector to the "dipper switch" you can plug into; blue wire #1. If you want, I'll test a pair of headlight with ours.
2. If you disconnect 1 headlight, you'll cut the draw, but may risk getting a ticket.
3. As for voltage regulator, I'm not taking any chances, I'm upgrading a TD with a new 1958 Edsel voltage regulator. No joke! It has a clear cover. I always wanted one of those when I was a kid! Just won it on ebay about hour ago. 230422246885
To answer your original question, with lights on, the generator will not keep up with the draw and dip into the negative side at idle, but it had better slide over to the positive charging side while driving or you may have to use the crank starter. My wife is experienced in push starting her TDs. (The best generator/regulator in the world won't help when lights are left on while parked.)
I'm going with LED tailights, etc, to save a little juice, but that raises ground polarity and turn signal issues.
|Raymond The generator in the TD was either 17 or 19 Amps (early/late).Your ignition draws 3 or 4 amps. I measured the current draw of the standard sealed beam headlights as 8.9 Amp (lo-beam) while the battery was reading 12.34 volts.|
17-4-8.9 = 5.9 amps should be available. That doesn't account for the sidelamps which I didn't measure because my tailights are LED's. But they would be about 2.5 Amps. 5.9-2.5 = 3.4 Never did get the 3.4 Amp charge with the headlights on. More like .5 to 1 Amp.
I spent a lot of time adjusting the RB106 regulator and finally gave up trying to solve this problem. Hence the solid-state version.
Care must be taken because the generators will put out 22-25 Amps very easily. Until they overheat and burn up the armature.
One solution is a generator from an AH Sprite. They have the tachometer take-off and are rated 22 Amps.
|R. K. Jeffers|
|Another alternative is an alternator modified for a mechanical tach drive.|
|This is much more of a problem with always on lights as you are now required to do in Norway. I had the same problem with my motorcycle as they have the same law for motorcycles here - headlamps must always be on and my system just couldn't hold a charge long enough.|
I was up against other problems as well, the engine on my motorcycle was a diesel I installed myself and it had a very small alternator.
There are a number of things you can do. Firstly, of course, check all the equipment as suggested by others. Voltage regulators etc can all be checked. You can save a little juice by using LED lamps in your dashboard and disconnecting the clock and any other item you just don't use.
Secondly, if you still have a problem, you may find a good electric motor shop can rewire your generator to get more power... I had my alternator rewired and got about 50% more power out of it. Not sure if this applies to generators but I can't see why not. Essentially they either add more windings or use thicker copper wire, either way there is generally room to add more in any electrical motor.
Thirdly (but this should only be done if you are already running negative ground), you may also be able to switch to HID headlamps. HID headlamps require only about half the power of regular halogens; my motorcycle runs a 35W HID which produces four times the light output of a 70W halogen!
By the way, your ammeter uses some current too. If you switched to a voltmeter you would use less. Not original, I know!
|The original set up will handle lights on whether day or night? I have two driving lights and if I run high beams plus the two, it will run slightly negative....but with just the regular lights, low or high, it is fine....!!!|
|Geoff Baker -- I am not sure I understand your statement that "your ammeter uses some current too".The ammeter is in series with the wire running from the starter switch to the voltage regulator. It has very low resistance and has no connection to chassis. So while there is a tiny voltage drop across the ammeter the power lost is in the milliwatt range.|
Please explain what you ment.
|R. K. Jeffers|
|My ammeter apparently doesn't work, as it shorted out when I tried to connect it. I have driven it over 7 hours on some trips with lights on and flame thrower driving lights on and have never had a problem with battery draw down. I think I will leave it that way so its one less thing to worry about. If I saw the needle dip to negative it would be one more thing to worry about. Sometimes reading these threads causes worrys I don't need. Still would like to fix the ammeter anyway. Cheers to the coming of spring! Bob|
|R.AF. Robert Finucane|
This thread was discussed between 14/01/2010 and 17/01/2010
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