6 volt batteries linked

lalakailalakai Registered Users Posts: 12 ✭✭
quick question on the possibility of linking three 6 volt batteries with an end result of 12 volt output??  Linking them for 18 volts is okay but not sure if there's a way to use the three but keep it at 12 volts?  Any input would be appreciated.  Thanks.  (Reason I'm asking is that I have the chance to pick up three Trojan 6 volt AGM's, that are currently set up for 18 volts.  I could probably find a fourth battery of same characteristics and may go that route down the road, but for right now the three is what I'm considering.  Thanks again.)


  • BB.BB. Super Moderators, Administrators Posts: 30,520 admin
    What is possible vs what is practical...

    With DC to DC converter(s)--It is possible to drop the output from 18 volts to 12 volts to run lights/radio/etc. And some charge controllers, it should be possible to set them to charge your battery bank at 18 volts (technically 21.6 volts).

    You would probably spend a fair amount of time and money to make this configuration work for you... Probably better off just running 2x 6 volts as a 12 volt bank and keep third battery as a spare (recharge it every few months).

    Or, you can get a 4th battery and make a 12 volt bank (two strings of batteries) or a 24 volt bank. We suggest people do not mix old and new batteries together in one bank (new would be ~1 year old or less). If you do get a 4th battery, probably would not plan on it outlasting the other 3 batteries (you can replace 1 battery at a time as each fails, but you end up with a battery bank that is always on the edge of one battery or another failing--I.e., more or less random failures over a couple of years until all batteries are replaced--But you still have a battery bank with "mixed age" batteries, and the random failures will begin again a few years in the future).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • lalakailalakai Registered Users Posts: 12 ✭✭
    just what I need to know.  thanks for the help.
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