6 volt /12 volt charge levels?

[D+C4106]

We are changing from 12 volt 8 D to 6 volt golf cart batteries.  As I remember a 12 volt battery is fully charged near 12.7 volts,  50% at 12.25 volts and dead at 12.0 volts.  Is there a similar comparison for the 6 volt battery bank?  They will be connected as 12 volts output.  Will I be able to use the 12 volt info as before?    Thanks for your help,  Denis

[TomC]

Most likely- but make sure you get the voltage information from the battery manufacturer.  Just to illustrate this, I have two 8D Lifeline AGM batteries.  Their voltages are- Charge at 14.3 volts, Float at 13.2 volts, 50% charge is considered 12.0v and dead at 10.5v.  Lifeline highly recommends not to take them under the 50% charge level for maximum life.  As with anything you buy, weather it be batteries, tires, etc, always get the manufacturers suggestions at settings, not a generic table.  Good Luck, TomC

[belfert]

I would assume you are putting these in series for 12 volts, so you will want to monitor the level at 12 volts.  I don't know why you couldn't take the recommendations at 6 volts and double them.  I suppose you could monitor each battery seperately, but why go to the hassle since you are almost certainly going to charge at 12 voilts.

I have eight 6 volt batteries and I monitor them at 24 volts.

Brian Elfert

[Buffalo SpaceShip]

Determining state of charge(SOC) based upon voltage alone is tricky at best. You have to let the batts sit for awhile after charging to let the surface charge dissipate, and even then SOC is temperature sensitive.

IMHO, a battery monitor panel coupled with an RV-style inverter-charger for the house bank is the best way to handle life on DC power. I have a Xantrex Link 100 connected to my inverter and it takes care of monitoring, usage, etc.

[Barn Owl]

I was wondering why specific gravity has not been mentioned. You can use a hydrometer or a refractometer and check each cell. By using the results of the specific gravity and the voltage reading, you should be able to determine voltage points that indicate your state of charge for future reference.  Brian mentioned the problem with surface charge readings which can give an incorrect indication of true battery charge. By using a specific gravity reading, you will have a better indication of battery health. Before everyone jumps on me, I realize that it would not be practical to check specific gravity everyday while you're out on an excursion. I am talking about the higher level PM's.

[D+C4106]

Thanks everyone, 
Tom,  I am still trying to locate mfg. info for Johnson Controls - Energizer GC2 batteries.  Thank you,
Brian E.  Yes they are in series to 12 volts, I would like to monitor them as 12volts if practical.
Brian B.  I looked at Xantrex,  is your Link a 100 ? or 10?  Not an easy site to find info!  How involved is this to install / connect in an existing coach?  Thanks.
Barn Owl,  My first concern was the routine checking of battery status, but I now realize I need to be more in tune with these than I thought!  Thank you.