MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Are battery/charging problems common?

It seems each year I need to buy a new battery and of course I buy one that fits the space and is the least expensive. But last night after driving my car all day I parked to go into a restaurant and when I tried start the car 30 minutes later the battery was too weak to start. (it started easily with a jump) I can not find any issues with the alternator so should I be using a more powerful battery? How many cranking amps should I be looking for?
gerard hutchinson

Gerard - Do you really have an alternator in your MGA, or do you have the OEM generator? If you have a generator, you may want to have your voltage regulator checked and if it is not operating properly, either replace it or send it to Jerry Felper (contact at felperg@earthlink.net). The other thing that should be considered is the purchase of a battery maintainer to hook up to the battery during the winter months to keep the battery in a properly charged state during the down period (I use a Battery Tender Jr. for our TD - even installed a plug under the dash so I can plug the output of the Battery Tender in every time the car is parked in the garage for more than a day.

A battery maintainer, regardless of the brand, puts a charge on the battery until it reaches a certain maximum voltage, then shuts off and lets the battery drain down to a preset voltage, at which point it again, charges the battery. This constant charge/discharge keeps the battery working and in good condition. It will make the battery last more than the standard life expectancy. Cheers - Dave
DW DuBois

One problem with the MGA is that you have no voltmeter or ammeter to tell you what's going on with the battery and charging system, which if original is a dynamo, not an alternator.

I have fitted a voltmeter to my dash. A good thing too as my new generator regulator was putting out the best part of 16v!

Read through the section about charging in the manual. Although the regulator is a little complex it is actually very easy to adjust correctly.

That aside, Dave's advice about maintenance for lead acid batteries is good. A battery isolator switch is mandatory as well.

Lead acid batteries hate being over discharged or allowed to go flat as this permanently damages them. Well maintained even a cheapo battery should last for years.
A Bowie

Batteries on MGAs should survive th winter fine as long as there is nothing wrong with the battery so you have some other problem. It sounds to me as if you have are consuming a slight amount of power so disconnect battery or at least isolate over winter.

Paul
Paul Dean

As cheap as a new Dynamo are the alternators that look like a dynamo, and you can dispense with the regulator completely, it needs a wire moving and thereafter functions only as a junction box.

There re two brands, dynamator (which is hugely expensive) and the much cheaper brand from Accuspark. I have the accuspark unit on my car and have fitted a few others with similarly good results.

If you are overcharging your battery with an out of spec regulator, it will die as you describe. If it's I undercharging, you will also have problems.

I have given up on the repro regulators as they all appear to be utter cr@p. AUtoelectricalsupplies in the UK does original restored and recalibrate units off the shelf.
dominic clancy

I had an odd issue a while back. THe link cable between the two batteries had been rubbing on the propshaft although visually there seemed to be ample clearance.
Although the cable wasn't severed it could provide low power but any attempt to start the engine just killed everything until I turned the ignition off and then on again. It push started and got me home although at that point I wasn't aware of the problem.
I still don't understand why starting power didn't take the whole cable out like a fuse.
Graeme Williams

As always gentlemen, your advice keeps me and my little car in good working order.

I do have a related question: How effective is the "hand crank engine starter?" On those rare occasions when my car battery only has enough "juice" to run the gas pump but not enough to run the starter (and I'm not pointed down hill) would a hand crank be a viable option?
gerard hutchinson

Yes it works well but I would suggest some practice before you ever need to do it in anger as there is a bit of knack.

Paul
Paul Dean

As Paul says, with caution if you have not done it before. Thumbs have been broken if you grip the crank between the thumb and first finger. The kick back can be quite vicious.

Steve
Steve Gyles

This thread was discussed between 04/04/2016 and 09/04/2016

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.