Can Two 6 Volt batteries Connected in Series be Charged at the Same Time

Question:

i have a childs electric car that uses 2 sp6-12 , 6 volt batteries in series making 12 volts , it didnt have a charger with it when we got it. sigmas tek says to use a 6 volt .5 amp charger for 1 battery. what should i use to charge the 2 in series in the car ? im thinking just double what they suggest and use a 12v 1000 mah charger, is that correct ? Thank You for any assistance !

asked by: Kevin

Expert Reply:

Yes, you can charge multiple batteries simultaneously while wired together in series or parallel as long as your charger works at the final output voltage of your battery bank, and the charger is designed for the final output amp hours (Ah).

For instance, if you have two # BRW74FR batteries rated for 6 volts and 220Ah, then you can connect them in parallel for a 2-battery bank that is 6 volts and 440Ah. Alternatively you could connect them in series for 2-battery bank that is 12 volts and 220Ah. This 12-volt arrangement is a very common upgrade for RVs.

I would choose the NOCO # 329-GENIUS10 charger for 6 or 12 volt batteries up to 230Ah. It works with wet cell, gel cell, enhanced flooded, maintenance-free, AGM, and Lithium-ion batteries with BMS.

If you had other batteries with higher amp hours, or if you thought you would upgrade batteries in the future, you might consider the CTEK # CTEK56674 12-Volt, 500Ah 12-volt battery charger and maintainer that will charge your batteries fast. Features an 8-step rejuvinating charge cycles. Works with flooded cell, AGM, and most gel batteries. Not recommended for Lithium.

It should be noted that you will get marginally better battery performance over the course of a couple of years if you disconnect all the batteries from each other and the RV and charge them individually due to an issue called "balancing" where the end batteries you connect to in your bank, charge better then the ones in between. If you wanted to go this route you could use the NOCO # NOC34FR for 2 batteries, or NOCO # NOC84FR for 4 batteries.