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 - New dry 6v batteries & battery acid

I've got a couple new dry 6v batteries and the needed battery acid for them (in separate containers). I need to bring the two of them together without screwing up.
All I've been able to find out is to fill up the cells to the indicated fill line and wait 30 minutes. After that, I haven't found out how to proceed further. I have a battery charger with a 6v option with automatic turn-off. Do I just go ahead and charge them up as I'd normally do or are there cautionary dos' & don'ts to watch out for during this initial charging? Thanks for any help..
Rick deOlazarra

Rick
Most, if not all new wet cell batteries come dry charged @ about 80% charge. They have a very long shelf(storage) life dry without having to be filled with acid.
Just fill the cells with the supplied acid and top up the charge before using the battery.
If the battery has lost it's dry charge it isn't an issue,just fill and charge until fully charged.
With your auto cutout charger you can't go wrong either way, just fill to the full level mark and charge the battery until your charger tells you it's fully charged and you're ready to go.
Cheers
willy
William Revit

Adding to what willy has said, if you have 2 x 6 volt batteries wired in series (which is how they should be wired), you can charge them both at the same time at 12 volts - ie its as if you have a 12 v battery
Graham V

To add to previous comments:

1.) Do make sure you are using the specific diluted sulfuric acid solution to fill the batteries as recommended by the battery manufacturer. Last time I did this was years ago and as I remember the spec on the solution was 1.265 specific gravity.

2.) Fill each cell equally (this is important) to a level just below the cap ring, about 1/4"; you should have equal "air" gaps in each cell. Make sure the battery plates are fully submerged and do not overfill.

3.) Charge the battery; then go back and check the cells one more time because its not unusual for the solution level to drop after its initial charge; refill as necessary & keep an equal level in each cell. Do not overfill.

4.) Any future top off's of the battery should be with distilled water only; do not use the charging solution.

Rick, quick question, I'm not aware of any US distributor selling 6v car batteries, but the UK has a few sellers. Did you import them and just curious as to why you decided on a pair of 6v's vs. one 12v?

Nick Kopernik

Thanks to all for your feedback...
Willy; your comments neutralized any anxiety I had right out of the starting gate; thanks.. it also inspired me to look up Tasmania on Wikipedia, which led to an interesting/fascinating 15 minute slow scroll.

Graham; thanks.. instead of charging each separately, I can do both at the same time.

Nick; a query about the initial comment regarding making sure I'm using the specific diluted sulfuric acid solution.. I obtained & intend to use battery acid I purchased at a local auto parts store. The comment seems to infer that what I'll be using may or may not be correct..(?) Your remaining advise is appreciated.
As for two 6v versus one 12v, yes, there appears to be no end to being advised of the error of my ways on this matter.. truth is, I've got this originality thing going on, and yes, it's cost me a few hundred more than actually needed. I'm only aware of their availability from the U.K. and a couple distributors in Canada.
Rick deOlazarra

Different battery types have varying specs for the final acid to water ratio so its important to have the right mix. If the battery manufacturer did not specify a specific type, then I'd expect your store bought mix will be OK. But do make sure it is a mix (acid/water) and not pure sulfuric acid! I attached a chart which lists battery types & their specific gravity recommendations so you can se that there can be a difference depending on type.

As for your interest in maintaining originality, I do understand the pull!



Nick Kopernik

Thanks, Nick, for getting back to me on that..

As for the continuing drama; I added the battery acid to both batteries & let it all settle in for half an hour, came back, checked whether topping up was in order and then connected one of the batteries to my charger at the 6v setting (one at a time in case it screwed up only one battery would be affected).
Came back about half an hour later and all 3 cells looked like boiling water on a stove top.. Unhooked the charger leads and the cells continued to boil for another minute or so before settling down... huh? What happened and why? Obviously something's not right. The charger used was an older Schumacher 10 amp 6v/12v charger.
Rick deOlazarra

Small amounts of bubbling can be typical when a battery is charged, but your description of boiling is atypical and usually the result of overcharging; you're very fortunate that the battery did not explode. The battery may still be good to use in the short term but its longevity will be affected.
Nick Kopernik

Thanks, Nick..
I can only guess, but it looks like a trickle charger should've been used.
Ignorance can be such a pain.
Thanks to all for the help & suggestions.
Rick deOlazarra

This thread was discussed between 06/02/2025 and 10/02/2025

MG MGA index

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