View Single Post
Old 12-24-2012, 12:20 PM
DaveInDenver's Avatar
DaveInDenver DaveInDenver is offline
Hard Core 4+
Join Date: Jun 2006
Location: Larimer County
Posts: 7,093

If they are not separated you should try to keep both of the same type and condition. Although, if they are only paralleled during active charging and are disconnected when the charging system is not running it would less of an issue.

I think over time you'll probably see one battery age quicker than the other. If I had to guess I think you'll ruin the deep cycle faster than the starter in this scenario, unless there's some sort of current limiting on it when they are brought into parallel. Deep cycles do not like a high current, short duration load and the in-rush of a depleted starting battery would want all the current it can get. In this case the second battery would react much faster than the alternator to fill it, thus the need for a current limit.
'91 Pickup - Imelda
'08 Tacoma TRD - Donna
'09 Kawasaki KLR650
'12 Gunnar Rockhound 29

"Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty. Nobody is able to achieve this completely, but the striving for such achievement is in itself a part of the liberation and a foundation for inner security. " --Albert Einstein
Reply With Quote