6 Volt Battery Question

Maybe there's a guru here amongst us; Interstate Battery was USELESS :X

A healthy, charged 12V battery will read 12.6 to about 12.9 - 13V at rest with no draw, right?
My 7 month old twin 6 volters spend most of their down time on a little automatic battery tender (trickle charger). When on their own they settle after approx. 6 hrs to a combined V of 12.3 - 12.5 (6.15 to 6.25 ea.)and stay there; they bounce back after a brief draw.

I know they're healthy and properly watered; all I'm wondering is if that's to spec with 6 volters (Interstate Group 17HF industrial) I get huge cranking power in this mild to hot climate and no dimming at idle at night even with all the halogen bulb amp draw and orig. 30 amp Lucas alternator (tu) I changed all the cables to big fat marine grade 2 gauge w/ brass terminals.

You'd think the vendor would know? Hmmmph 8-)

Why do I have 6 volters, you ask - came brand new with the car last May - they WORK.

I've got the same setup that you have. My 6 volt batteries show similar readings to what you're getting. One thing of note, you should seal the battery terminals with Vasoline to keep out oxygen. This will keep your batteries almost maintenance free for extended periods of time. Only adding some distilled water, every few months, will be required. RAY

I get the same readings with my twin 6 volt batteries. I think the modern 12V batts are a bit more efficent in their design and materials and eek out an extra .1 or .2 volts when measured fully charged across the terminals. So long as my 6 volt batts remain serviceable, I'll keep them in there! Yours sound fine! I have an OLD auto shop textbook that shows specific gravity corrected for temprature of 6 volts batteries and a statement that says a fully charged 6 volt batt should measure 6.2 to 6.3 volts, FWIW...

This is an easy question. Both the 6v and 12v batteries are lead acid cells. In the case of the 6v battery, it has 3 cells. The 12v has 6 cells. A fully charged 12v battery will read 12.6v (if I recall correctly) - or 2.1v/cell. So, a 3 cell battery should read 6.3v.

The use for 6 volt batteries evolves out of the generator days. As we all know, the generators on the older cars like A's by example don't have enough juice to run all the appliances at once. That draws down the batteries. The two 6 volts can stand the draw down longer than a single 12 v, hence the two 6 volt batteries in a car with a generator and the engineering just carried through.

Hi all
Hope you realise vasaline is inflammable,(thats why its called petroleum jelly)

The cells of the batteries produce 2.2 volts each, 6 or 12 volt. A 12V battery is actually 13.2 volts but because of internal resistance you only get 2 volts (approx.) per cell. This is why a 12 volt source will not charge the battery. It takes 13.2 or 6.6 just to get flow thru the battery. 13.8 to 14.2 is a very good range for an alternator. The GM alt.(63 amp) I installed on the B produces 14.7V no load and 13V at a 75 amp load (alt. shop tested). I'll never overwork the alt. on the B.

Interstate wants $135 (list $162) a pop on there web site. Use the Westco Miata battery for the same price for quantity of one from Moss. The Westco is an AGM battery with no liquid acid to deal with; and it fits fine in a early MGB with twin 6's. The car starts easy, even in cold NY metro weather.

What a great education; thanks all! :)-D I'm Italian and the "need to know" gene is very dominant in us LOL. Those medieval batteries of mine stay charged and are gonna be with me a long time (tu)

My last pair of Interstate batteries only lasted 13 years. The pair before them failed after only 8 years. Quality nowadays. RAY