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MG MGB Technical - Batteries

I am fed up with replacing the 6volt batteries which only seem to last 14months or so. Can anyone tell me the model number of the small 12volt battery which will fit in the battery cradle please? Also do you need to remove the protective plastic insert to fit it? Many thanks in anticipation.
P J Wilgoss

I replaced my 6v batteries with a new pair this week and the old ones had lasted nearly 9 years. The previous pair lasted 8 years with me and had been fitted before that by the previous owner. I considered switching to a single 12v battery partly on grounds of cost, but my supplier assured me that it would not last anything like as long as two 6v units. Maybe you need to find a different supplier?
Miles Banister

Hi PJ

The most popular size is 063, which fits in nicely, leaving the other box for other uses - or another 12v one, but I can't get my head around that!!!

I have both in mine - 6vs in the BGT and 12v in the roadster - and will likely change to 12V when they die ....
rachmacb

Ditto Miles Bannister, still on my 3rd set in 22 years. If the batteries are only lasting 18 months I'd be looking at the car, not the batteries. Is the car left long periods unused? Do you have after-market stuff like alarm, radio etc? Do you have a cutoff switch? Have you checked for drains and charging?
PaulH Solihull

I paid less than £40 for an 063, It's been in the car 18 months now. I recon I can buy another two at least, and still be better off than buying 6 volts.
c cummins

I use a Bosch S4000. It fits easily and it works. What more do you want?
Richard Coombs

The Westco battery, designed for the Miata MX5, is maintenance free and small enough to fit where one of the 6 volt batteries did. 14 months of life indicates that you have deeper problems were your electrical system. My last pair of 6 volt batteries lasted 13 years and the pair before them lasted 8 years. RAY
rjm RAY

063 is a way to go but they will be very tight in the plastic bin liner. BUT you do need to check your charging system and the electrics for causes of discharging when at a standstill. New batteries should last at least 4 years and more like 5 to 6 as the norm.

Rach, whats not to get? One set in series (6v) the other parallel (12v) giving plenty of grunt when needed ;-)

MGmike
M McAndrew

I have been using an 063 12 volt for the last 5 years in the roadster without any problems, at the time two 6volt I was quoted over a £100, the 063 cost me less than £20. it would be more now of course.
I had to trim a little off the bottom edge to get it to fit snug but that is no problem.
Trevor Harvey

The new 12v battery to get is the varta b35 which is the same size as a 6v so no need for any feet cutting

Ste
Ste Brown

LOL Mike - you're showing your lack of true tightness ;) One 12v gives plenty :P
rachmacb

LOL Rach.. I've only been here for 30 years and as such, I'm only adopted. True tightness only comes with breeding ;o)



M McAndrew

LOL THAT would explain it ;)


Seriously though, I haven't noticed any difference in power between the 2x6vs and the 1x12v, but I've never driven one that's 2x12v, so, can't really compare, but, 1x12v works fine and is only about £40!!!

I just don't know why they had to put them in such a silly place anyway - it's so annoying.
rachmacb

Rach, I've fallen for it... I guess you won't be interested in this but I'll explain just the same..
You won't notice any difference when driving just in starting or getting home if the charging circuit fails!
Now for the techie bit!
The standard 6v batteries are in the region 60 Ah (which is 1 amp for 60 hours) the 063 12v battery gives 44 Ah. So the originals will get you a bit further if the charging circuit fails. 2x 063 are the duracell option:0)
Of real importance is the amount of grunt available to start the car from cold (especially up here!). The cold cranking current or CCA of the standard battery is around 360 amp and the 063 has 400 which equals faster spinning of the starter (assuming all the cables are in good nick). The duracell option will give a shed load more time to get it started.....

PaulH covers all this on his site and if anyone hasn't been there, they should....

MGmike
M McAndrew

Call it 'Overkill' but I replaced the 6 Volts batteries on the V8 with two 12 Volts 44Amps from a FIAT Tipo. It was cheaper this way than two Lucas 6Volts ones and made a real (positive) difference!!
BTW, the batteries I bought were FIAT OEM items, made by EXIDE and have lasted for more than 6 years up to now. Acid density is still perfect.
R.S. Ralph Siebenhaar

While we are on the subject of batteries and cold cranking 'grunt'. What is every-ones thoughts on starter upgrading? My starter appears fine and really, I am impressed how well the car fires up after a long stand, but just to log in the useful information book, These high torque starters, how is it they work and what are their advantages over the standard starter? Mike
J.M. Doust

The 6v seem to vary , my previous pair lasted 10 years and gave excellent service. The pair supplied by MG Motor Sport in Bovingdon are about to come out after 2 years of dreadful battery problems despite being babied with the conditioer on them and living in a garage. I thought these were " budget" when I had to make up a filler plate for the bottom of the carrier as they were too small to engage properly on the ledges.
I dont want to go through that agian so I think an 063 is one job for this winter.
Stan Best

Two 12v in parallel is just doubling the cost for no benefit if everything else is in good order. As the batteries age one will start discharging into the other.
PaulH Solihull

LOL Paul seems to be disagreeing with his website?!

Plus, whilst a few years we get down to -10C out here in the middle of the Fens, we don't have the longer lasting bad weather that you can get in Lothian ;)

PS my car isn't coming north (again) imminently - although it did actually come south from Dumfries - but, when it does, I might attempt to visit with it ...!
rachmacb

The "high torque" starters use a gear reduction to increase starting motor torque. Unless your present starter is on its last legs, there is no noticeable improvement in using the high torque starter over the stock unit. I'm running a '68 stock standard pre-engaged starter on my '67 supercharged 1860cc engine. It has never been rebuilt and still works just fine. RAY
rjm RAY

Hi, on the battery issue, see my thread earlier this year in MGB general (battery boxes), and Joern from Germany gave me some good pics of fitting a 12V in the engine bay rather than under a seat, it seems the way to go,

1 12V Vs 2 6V 1/2 the cost

2 under the seat hard to get to, not practical

3 under the bonnet easy to maintain and easy access

4 shorter length of cables

I'm in the process of changing my MGB GT

you know it makes sense!

cheers Jack.
Jack New Forest

Thanks for your answer rjm Ray. When you say that your starter has never been rebuilt, is that a suggestion that starters CAN be rebuilt? I suppose it depends on what has failed? I see places here stating that 'Motors re-wound.' If the winding goes this must be feasable, although perhaps not economic. If the gears are worn, they could be changed etc So yes I see your point.So unless a standard starter is not available one does not necessarily need a high torque starter. So when would one use one? Colosally high compression? Race use? Mike
J.M. Doust

"LOL Paul seems to be disagreeing with his website?!"

Que?

Can't agree with the comment that *geared* starters offer no improvement over a good standard starter. They spin the engine faster and take less current which takes less out of the battery. When I fitted one to my V8 my heart sank at the first crank as thought it wasn't turning the engine it was so quiet and smooth, then the engine burst into life. The motor detached itself from the adapter plate a couple of days later so I went back to a conventional, but that is another story.

You need to be careful with 'hi-torque', it can refer to geared starters but is also applied to some conventional types. With geared it is the solenoid that is in line with the pinion, and can even be bigger than the motor, as opposed to the other way round with conventional. The drawback with geared is their high cost.

Moss and others advertise 'rebuilt, exchange' starters as well as 'new', surely indicating starters, like alternators and other components, *are* rebuilt.
PaulH Solihull

The problem is how many times have the starters been "rebuilt" and by whom. When I'm asked to replace a starter, I dismantle the old unit and look it over to see what made it fail. Often, a new solenoid and Bendix drive, along with cleaning the commutator will return a starter to like new performance. New brushes are cheap insurance. Occasionally, new bushes will be required if the old ones have worn down. I prefer to overhaul the original starter in that I know what has been done to it and can stand behind my work, instead of having to hope that some other person did the job correctly. RAY
rjm RAY

Hi Folks:
Be mindful about 12volt batteries in parallel. If one of the batteries shorts out; you will have a potential fire. Not a wise solution. I replaced by 6 volt bateries with a Westco Miata battery from Moss. Easy to install and plenty of current to start my 67B in the cold New York winters.

Rich Boris 67B
Rich Boris

This thread was discussed between 15/12/2011 and 22/12/2011

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