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MG MGA - Battery mod.

A lot has been written before about replacing the 2x6v batteries with one 12v, so I thought I'd share my very cheap solution with you. I've already fitted an 063 size battery in my MGC and it has never had any problem cranking the 3L engine, and it drops into the battery tray with little problem. The MGA battery trays are much smaller, however, and the only way to fit an 063 would be by cutting the tray and extending it rearwards. I didn't particularly want to alter the standard structure so I made a tray that drops on top of the existing tray. It is made from two pieces of square section steel tube which are the same depth and length as the existing tray and an L -section piece is welded across one end of the tubes to act as a restraint for the new battery. I bent a steel plate to extend the length of the tubes to accommodate the length of the new battery and welded at the other end of the square tubes to finish off the new tray. All made with scrap material. The battery is held down with the original J-clamps, and these also hold the new tray in place when the wingnuts are tightened, so no need to drill the existing tray. Here's a few pictures.

D Jacobs

Here's a picture of the battery in the new tray.

D Jacobs

Does your new battery fit under the metal cover ok?

I have a small 12V in my car which fits into the standard battery tray and I use the spare tray for holding spares and tools.
The battery is ok most of the time but if the car has been stood for a long time or in really cold weather, it struggles a little to turn the car over.

So I quite like the idea of using a bigger battery.

Colyn
Colyn Firth

Hi Colyn
Yes it does fit under the battery cover ok. I suppose it's because the 063 is somewhat shorter in height than the old 6v batteries, so even though it is now virtually "on top" of the standard battery tray, there is still room under the cover. The only thing I've had to do is to lengthen the main supply lead because the terminals are further inboard. The battery I chose provides 52AH and 520 Cold cranking amps.
David
D Jacobs

The Varta B35 is becoming a popular fit in the B.

390 CCA and 42Ah.

Dave O'Neill2

"The battery is ok most of the time but if the car has been stood for a long time or in really cold weather, it struggles a little to turn the car over."

Get a Battery Tender/Battery Minder/Battery buddy and connect it to the battery any time the car will sit for a long period of time without being driven. These products are not the old time trickle chargers (which will over charge a battery over long periods of time. Instead, they apply a trickle charge until the battery is at a optimum level, then shut down and monitor the battery and when the battery reaches a predetermined low charge level, it starts the charge/discharge cycle over again. More than just keeping the battery charged, the up and down cycle keeps the plates from developing a lead sulphate coating on them, thus rendering the battery useless. Cheers - Dave
David DuBois

battery chargerquick Aldi has them at
Neil McG

I having been mulling over whether to be controversial here or not, so please forgive me. Once you change the car from 2 x 6 volt batteries you have effectively destroyed some of the originality, so I fail to see the problem in cutting and welding the battery tray to suit the battery of your choice. After all, the tray can always be rewelded back to original with little fuss. Actually, my wreck of a car came to me in 1996 with only one tray. I was able to purchase a complete new tray to original specifications without any problem. It was a very basic job to weld in place.

Steve
Steve Gyles

A few of us are running around with the Varta 35B. It sits inside the original tray with no metalwork change needed.

regards
Colin

C Manley

I finally fixed my starting problems a couple of years ago with a modern 12V battery and a dedicated earth return cable from battery to engine mount earth strap.

Bear in mind that modern batteries will have a lower internal resistance than the old lead-acid ones. This means that the voltage regulator settings in the handbook may give a charging voltage that is higher than specified for new technology batteries. This can result in an excessively high charging current, reducing the battery's working life.

A decent battery will come with a recommended maximum charging voltage (my Bosch battery did, anyway) and you can re-set the voltage regulator by following the very clear Lucas handbooks - I'm sure Barney has these on his site - otherwise search for 'Lucas Technical Training'

David
D Brown

Colin

Is that a standard earthing strap bolt hole in the middle of the chassis cross tube? I have not got that on mine. Seems a totally sensible place to have one.

Steve
Steve Gyles

David D, yes I have a battery conditioner installed and yes Neil it is an Aldi one like yours.

I think the problem is that my old concrete garage was not insulated at all, had a leaky roof and the temperature inside was often down to well below freezing. So the little Fiat Punto size battery does really well to turn my 1900cc tuned MGB engine over at all.

I am in the process of building a new brick garage which will be warm, dry and hopefully give the battery an easier time.

Probably Steves set up with two 12 volt batteries (if I remember correctly) wired in parallel would be the best solution but I am very tempted to try Daves solution.

Colyn
Colyn Firth

I concur with the use of the 063 - been using one for 25 years (but sadly not always the same one, because a battery costs 150 USD with recycling levies........)
dominic clancy

Recycling levies !!!

You're being ripped off Dominic, over here the recyclers pay me if I take a battery in, 3 for one from a MGB recently.

But, many thanks for your COUPE_BOLTS list, a great help in my rebuild.

Jim
J N Gibson

Hi Steve,
As you note, it's not an original hole - they cost more....

When i went to single 12v, I drilled into the tube and tapped a 5/16 UNF thread after cleaning of the paint and slightly rounding the cable lug to get contact area plus conductive grease on the surfaces. Very easy to get to if needed.

regards
Colin
C Manley

Jim

I wish I'd known. I've just taken those two 6v batteries in the above pic to the local tip.
Dave O'Neill2

I put a piece of particle board (about half or three quarter inch) on or in the battery tray and use the existing clamps. Then most 12 volt batteries will fit. I keep "charge and maintain" devices on all of my cars (TC and F2 in the dashboard sockets, small sockets from an electronics store to the ramp panel on my MGA's and MGC). On the other side I made a box and have a jack and a few "get me home" tools.
Barry Bahnisch

Ground - I welded a stainless steel tab to the battery frame.
Art Pearse

Hi Steve - controversy's ok with me, but I never mentioned the word "original". How could I - what with installing an 1800 MGB engine, a 5-speed conversion, front disc brakes + servo unit, change of original colour, alternator, Neg. earth, 1600 style rear light housings, anti-roll bar etc etc... What I meant was that I couldn't be ar*ed to crawl underneath with a welding torch to alter the standard battery tray now that the body has been bolted in place. I was just looking for a simple solution. I also intend to use some of your superb ideas that you've listed on your web-site. If God had intended us to keep MGA's original then Barney wouldn't have been born!!
Regards
Dave
D Jacobs

Dave

You could almost have been describing my car there. Very similar spec. I demodded my electrics today. Colyn mentioned above that I was running two 12 volt batteries in parallel. I have taken the second one out as it was beginning to drop off in performance. I only put it in because I thought it would be more useful in the car than on the garage floor. I was delighted to note that my isolator system was as recommended by Barney. I thought I had the live feed isolated, but it was the ground.

Steve
Steve Gyles

This thread was discussed between 23/10/2013 and 27/10/2013

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