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MG MGA - Which Interstate battery for '56 MGA?


Hey all,

I am in need of a new battery for my '56 roadster. It is running a single 12 volt battery (still positive earth - not that it matters). If anyone here is running an Interstate battery in their 'A, can you fill me in on which one you're using?

Also, it seems that the "IGNITION" lamp is always illuminated when I drive my car. On the MGA is this indicating a low charge or lack of charge from the dynamo? If that's the case, I assume a modern alternator conversion is the way to go? Is there a Bosch unit that can be fitted?

Sorry for all the questions but I'm excitedly learning my way around my MGA!

Cheers,
Aaron
Aaron Greenberg

If the light is permanently on you need to check the brushes on your dynamo. I recently had to change my dynamo as the commutator was worn out - picked up a good 2nd hand one from an autojumble. One of our club members used a 12 volt battery from a Fiat (Punto I think)- seems to fit OK - cheers Cam
Cam Cunningham

There is nothing wrong with the original Generator design. It has basically the same voltage output as an alternator. Yes it is a bit more maintenance. Oil the rear bush and change the brushes every 100,000 miles or so. The generator voltage will drop as you come to a stop. This will cause headlights to dim a bit and the gen light to slightly glow, but who needs headllights to be at their brightest when you are sitting still? The MGA has a very light electrical load and a properly operating Generator system is certainly up to the task. Now, if you are running air conditioning, extra driving lights and a 500Watt stereo system.......you might want to change to an alternator. If so, plan on making some mods to the wiring to handle the increased demand.

The constant glowing of the light is not normal and perhaps the changing of the brushes will solve your immediate problem. This is a lot less work than changing to an alternator system.

Chuck
C Schaefer

The light being on is an indication that there is more voltage from the battery than the generator. If the light is on you are not charging the battery. A single # 35 battery on the right (passenger) side is the way to go.
R J Brown


Thanks all, I ordered a new generator today and will fit it as soon as it's on the doorstep!

Aaron Greenberg

If your light is on, you should also check the connections to your voltage regulator mounted on your firewall. If the voltage regulator is not working properly, you will be running the car off of your battery not the generator. You may have had a failure of your voltage regular or the points in it may be worn out. My regulator once failed on a trip, but I was able to drive the car just on the battery and still get home from 200 miles away. So if you haven't driven your car very far, you may be generating just fine but still just running on the battery
Dick Wallrich

Aron, I also have a 1956 MGA and its white. I still use two 6 volt Interstate batteries hocked in a series for the 12 volt system. I just refurbished both
using a solution and method I bought on e-bay. This method completely recharged both batteries I thought I had to through out. I saved or $200.00 for a small investment of $10.00. Call me if you want that infor mation or e-mail me. 920-233-5197 or tpeotter1@new.rr.com
Tom Peotter

This thread was discussed between 07/05/2009 and 13/05/2009

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