Battery Charging Voltage

It depends on Battery cell type/ make/ model. All reputed manufacturers mark/label this voltage on the product.

Take account of the specific gravity of the electrolyte and not the voltage of charger.

Specific gravity at full charge is 1.26, half charge is 1.197 and discharged is 1.135.

Terminal voltage per cell is an approximate measure since applying load on the battery will cause the voltage to dip or considerably increse if load is removed.

Float voltage 2.15 volts per cell

To maintain float voltage 2.25 - 2.30 volts per cell

Charge voltage 2.30 - 2.35 volts per cell

I recommend a charger that has an equalizer setting as it will reduce sulfation

Equalizer voltage 2.40 - 2.45 volts per cell.

Talk to the manufacturer only - no one should be making suggestions about charging rates or float current without the manufacturers recommendation in hand.

It varies-

Well put and really accurate. The first one reading down from the top!!

Good answer. No other approach makes sense. Do it right or risk damaging the batteries. Recommended charging currents and voltages at every stage in the charge and equalizing process should be followed.

TALK TO THE MANUFACTURER ONLY, and its website. Even if I assume lead/acid cells, the maker sets charging / discharging / floating. Those values are dependent on the acid density and temperature strongly. Without those curves and charts you are whistling in the dark. The same applies for maintenance schedule. The resulting voltage variation for the whole set is established by the individual cells, and it is whatever it turns out to be.

The manufacturers recommendation is very important, particularly with sealed batteries as overcharging can be fatal, but also the depth of charge is important, as in deep cycle situations, with proper deep cycle batteries, (flooded) the equalisation or even daily max. voltage can exceed 2.5 volts. Electrolyte readings are good but one must be aware that many deep cycle batteries have dilute electrolyte (to reduce acid corrosion of plates) and maximum specific gravity is 1.24. Also, many modern (often called smart) regulators, have provision for temperature measurement and corresponding adjustment and again that is something the Manufacturers specifications will have input on. Cheers, Geoff Thomas.