# 12V vs. 6V Batteries



## cdtomlinson (Apr 3, 2009)

I understand that 6 volt batteries have a greater energy density than 12 volt batteries, though I'm not sure what that means to me as a hopeful EV builder/driver. The question is, does it make any difference for a 120VDC system if I use 10 each 12 volt batteries, or 20 each 6 volt batteries? 

Secondary, if I later want to change the type of battery, say from flooded cell to Lithium, are there design/ parts choice options I should consider?


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## 86Honda (Apr 15, 2009)

I have been disappointed with the 12V lead acid batteries I have used. While they take up less room and make a lighter pack, they just don't hold as much power as I need. If you've got the room, 6 or 8 V might give better results.

Can't say much about conversion to lithium, since I'm in the process now and still learning.

BTW, first post!


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## speculawyer (Feb 10, 2009)

This is a simple but true observation . . . since 12V batteries have 6 cells in them, they are twice as likely to go bad as a 6V battery. Of course, since you'll need twice as many 6V it may see like a wash. Not really true . . . when a cell goes bad in a 12V battery, you need to replace the full 12V battery (that has 1 bad cell and 5 good cells). That is going to cost more than replacing a 6V battery (that has 1 bad cell and 2 good cells).

This is a nice thing about the single cell Li-Ions . . . at least when there is a bad cell, you only have to replace that one expensive bad cell.


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## CPLTECH (Sep 14, 2007)

For ultimate driving pleasure, do your utmost to go with the 6V [although some say the 8V is a good choice if space is an issue). Most of the decent LA batteries that we use have the 20 hr rate listed. Mine is 250AH. Divide that by 20 hr & it means that I can get 12.5A for 20 hr. You & I both know that minimal usage isn’t feasible in the EV world, but it’s the yardstick the companies use. Now add the Peukert Effect & it can reduce that AH figure to about half the rated capacity. If you do that with the 12V package, it leaves much to be desired, as stated by the previous poster.

94 S10 20-6V USBatt145


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