Originally Posted by 16bounder
My motorhome as 4 batteries arranged in series, and it seems my inverter may be on the fritz, as it is showing fault ac overload. So, in my thinking (not too sure of) since they are not being charged via inverter, I will revert to using a "regular" battery charger. The batteries are 6volt-can I just plug positive and negative to the ends of bank of batteries? Negative on one end and positive on other end....basically charging ALL as one???
As noted in previous post, 6 volt batteries are wired in series/parallel. So, 4 six volt batteries will be two pairs, each pair in series to make 12 volts. The two 12 volt pairs are then wired in parallel to increase capacity.
Connect the external charger to the 12 volt output of each pair. Do not connect to an individual 6 volt battery.
Portable automotive 12 volt chargers come in many different flavors. Some are as smart as your built in charger. Some are not. Older designs could damage storage capacity and boil batteries dry in a day.
Newer designs are closely regulated and will not harm your batteries. How can you tell?
Advertising on the charger may tell or may just confuse.
Get a digital voltmeter from your local hardware store. It may cost $20.
Measure voltage from battery terminals to ground (RV frame or other metal structure).
Connect the positive charger cable to the 12 volt positive battery terminal.
Connect the negative charger cable to the frame or metal structure. If area around batteries is well ventilated, you can connect to the 12 volt negative battery terminal. (Sparks can cause a fire. Charging batteries emit hydrogen gas.)
Turn portable automotive charger "on".
Monitor battery terminal voltage with your new digital voltmeter. Voltages should slowly rise to the preprogrammed voltage of the charger. The voltage may be 13.2, 13.6, 14.4 volts.
It takes 14 to 18 hours to fully charge lead acid batteries. 24 hours may be useful for batteries that have been abused. Charger may be left in place for long periods as long as terminal voltage is 13.8 volts or less.
14.4 volts is OK for a few hours. Many chargers bring voltage up to 14.4 volts for a few hours then drop back to 13.6. 13.6 is good for long term occupied use.
Higher than that will be a problem after a while. 15 volts or more, for more than an hour is bad but it may be enough to restart your built in battery charger. Some built in chargers refuse to charge when terminal voltage is below say 11 volts.
I wish you good luck and happy trails ahead!