Originally Posted by BPL
in series or? parallel. Otherwise I don't follow you.
The drawing from thread no1 may be misleading and the batteries are not connected at the + 24 side, but are 3 individual sets of 2 batteries in serial.
If you charge each set separately for a period of time and the sets are not connected at the 24 side (not even through the charger) then you will have little problems. If they are connected at the 24 Volt side, your charger need to be able to supply 3 x the current for your 3 sets.
First at all you need to understand that a Lead Acid battery charges chemically already at 12 Volt. The fact that nobody wants to wait for 24 hours before the battery is charged, means one has to go to a higher Voltage and most Lead Acid batteries are charged at 14.4 Volt.
As soon the battery is fully charged, the excess current, because of the 14,4 Volt will create gassing . This process start a 13.8 Volt. Thus the trick is to measure a battery immediately when you take the charger off. (Most batteries today are sealed and you cannot, like somebody else said, measure the status of the liquid). Thus if your battery is slowly dropping from 13.8 Volt to a lower level, your battery is pretty well charged.
If you connect 10 batteries of "12 Volt" type in serial and you are so lucky to have a high Voltage charger, all what is needed is to check constantly the voltage of each battery. If the one falls behind the others in Voltage, you need to isolate this battery and charge it seperately with a 12 Volt charger. If you have 10 batteries of each cell of 2,25 Volt, you also need to monitor each battery, but the voltage you need to compare is only 2.3 Volt. (gassing threashold)
If you have a charger which charge only at 13.6 Volt, (or a multiple number x 13.6 Volt for batteries in series) it will take longer, but you cannot damage your battery. You just need lots of time.