Thread: 12V batts in series?

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I helped a friend with his skidsteer today.

It has two 12V batteries in series, but it is a 12V system, so it seems to me the batteries must be charging to 6V. Is that a problem? I think he would be better off with them in parallel.

Also, something odd: my Schumacher charger/ starter would not give power if I connected it across the two. ( connections are good).

It would only charge when clamped to a single battery. Maybe the charger somehow sensed the multiple batteries and didn't like it?

Are you sure that they are 12 volt batteries wired in series (positive terminal is connected to the negative terminal on the other battery)? Most of my equipment has either two 6 volt batteries wired in series giving us a 12 volt system or two or four 12 volt batteries wired in parallel (negative to negative, positive to positive), still a 12 volt system.

Is there a center tap between the batteries? There may be one to run certain functions like lights, while the 24 volt series circuit is for the motors.

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No center tap, I'll take a volt meter out tomorrow and verify voltage and battery ratings

Ok. Pretty common for two 6 volt batteries. They can usually be identfied by three caps (holes for the acid) on each battery. Each cell is usually 2 volts.

It is a 24 V system. But, the batteries in my fluke are dead, so I grabbed my little analog meter, and it looked like it read 24. What is the proper charging (running) voltage ?

How has he been charging it heretofore? Or is it a new-to-him machine? They usually have a dedicated charging station, or a built in charger system. I think we need more info to properly work this out.

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Here's a link to the Heavy Equipment Forum, where somone asked the same question, and the answers given provided a lot of detail - Battery Charger hookup

Rrumbler: it's a diesel. One battery is refurbished, so I'm suspicious of it. The alternator is only a few months old, but I'm suspicious of it too. I'll get a good digital meter on it tomorrow. But, seems to me, if 14V is needed to charge a 12V batt, then 28V would be needed to charge two of 'em.

Humph!! Never thought of that, makes perfect sense, though; ol' A-S-S-U-M-E got me again.

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