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MG MGB Technical - BATTERY 6V - 12V

I am a proud owner of a 1970 MG B, acquired in 2001 and now the 2 6V batteries are gone. So they lasted at least 8 years. Price for 2 batteries 6V are Eur 80/each that I suppose is very expensive. What do I loose if I mount 12V battery? Is there any special advise?
ALFREDO SIMOES

Only loss is originality and period charm. A single 12v is cheaper less contacts to fail has more VA and weighs less.I run my car with 2 x 6v :-)
Stan Best

As installing a single 12 volt battery involves no body modifications to the car you could always return it to 2 x 6 volt at any time afterwards should you wish to.

Best battery is a type 063 which fits into the 6v battery bin and gives a higher cranking power than 2 x 6 volt.
Mike

"No body modifications"

You must do something about clamping the battery down, the original 6v clamps can't be used, which could involve drilling more holes in the cradle. Unclamped the battery will rattle around shortening its life, and over bumps its terminals could short out on the underside of the metal cover. I've heard of some people packing foam under the cover but if that gets damp it will trickle discharge the battery.
Paul Hunt

One of the cables is too short to connect to the 12V battery. Is there any special form of extending that cable or do I have to replace it?
Thanks for the previous informations.
alfredo simoes

I used a webbing strap to 'clamp' the battery. Passed an MOT and sprint scrutineer. I'd never go back to two £80 6Vs having gone to a £60 top of the range 12V from Halfords. The 12V holds it charge, doesn't fur up, and doesn't split leaking acid all over the garage floor...
Neil
Neil

Alfredo,
It is easy enough to put the 12V battery on the right side and use a new cable from the - post to ground. The original + cable should be ok.
David "Boa sorte!" Lieb
David Lieb

Alfredo,
While you are changing the battery arrangement, you could add a Battery cutoff switch, use the current earth cable between the battery and the switch, and then get a new earth cable from the switch to earth (this can be quite short)This will be handy when you want to isolate the battery, particularly if you want a bit more "anti theft" security

John
John Minchin

Alfredo.

Using one 12v also frees up the space for the other battery for another storage compartment. I use it for spares that I may need such as a complete ready to go distributor.
Bruce-C

Or you can use a DMS red top battery and fit it in the engine compartment - these relatively tiny batteries are perfectly capable of starting and running an MGB - I have fitted them to stage 2 tuned engined cars with no trouble at all.
Chris at Octarine Services

I have two 12v (063 type) fitted, never short of cranking power..
K Harris

"I have two 12v (063 type) fitted"

That is just perverse!
Paul Hunt

I made the change from 2x6V to a single 12V on my 69. The 12V resides in the LHS (opposit to driver) battery box.

I used the original battery securing rods and bar, angling the rods backward to position the bar across the rearward top lip of the battery. Totally secure, no movement at all.

I did have to replace the cable to the starter as the original was just that bit short to reach across to the LHS - it had connected to the positive terminal on the RHS battery originally. Was probably a good move as there was a good amount of oxidisation on the copper cable ends in view and in all probability extending under the plastic shielding on the cable.

I took the new extended cable through the circular holes in the battery box sides and secured it where the original battery connecting cable for the 2x6V batteries was secured up under the centre of the car body.

I don'r recall the length of the new cable but do remember that I measured the length required by tape from the end of the original to the positive terminal of the to be replaced LHS 6V.

Regards
Roger
Roger T

"That is just perverse! "

lol, but a cheap and effective way of doing things:-)
K Harris

"I have two 12v (063 type) fitted, never short of cranking power."

That is OK if the two batteries are perfectly matched, but if one is weaker than the other, the stronger one will continually try to charge it and you will lose capacity!!
Chris at Octarine Services

Why put the single battery on the left and give yourself the trouble and cost of installing a new battery cable? When they went to single batteries anyway they were on the right.
Paul Hunt

Hi Folks:

Having same problem: my Interstate twin 6 volt(type 17HF) batteries which are dying after 7 years; and are very hard to find and expensive. I thought about twin Moss Westco (Miata) 12 volt batteries, but high current batteries in parallel is a very dangerous situation, because if 1 one shorts-out it could cause a fire.

Since my MGB is a Mk 1 with a generator I have decided to use a single 12 Westco battery in lieu of a group 26R lead acid conventional battery. The Westco is an Absorbed Glass Mat (AGM) battery design, and tolerates a higher charging voltage of 15.5 volts from a generator. I had lead acid 12 volt batteries in my old 66B, but it didn't like the generator charge voltage, constant electrolyte boil-off & ultimate failure. Sears got fed up with the warranty returns, and I then returned to twin 6's with no issues. Lead acid 12 v are fine for alternator cars which charge at 14.5 volts.

Moss sells the Westco for $99, with 4 year warranty compared to close to $125 + each for 17HF 6 volt batteries.

I will install one when the spring weather arrives.

Thanks: Rich Boris 67B roadster
Rich Boris

This thread was discussed between 25/02/2009 and 01/03/2009

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