battery isolation?

[ncc74656]

i had some issues at sears but now finially got my order placed. i got 2 group 49 AGM batteries for my truck. i currently have 2 group 31 lead acid batteries that still work (sort of) but are rather lack luster for starting the truck. so my thought was i save 15.00 on the order per battery to trade my 120.00 group 31's in (they are 1 year old) OR i could keep these 2 as a secondary isolated battery bank that i could abuse as i wanted with out much worry. do we think this is a decent idea or should i just core charge them? they are 1150CCA 195RC batteries.

the truck has its stereo and a 16K Lbs recover winch on the front. my thought was that while the truck is running it should not matter what batter is plugged in where as the alternator is handling it all. however i would want to have 2nd ignition relayed into a isolater so the liquid batteries do not drain the charge from the AGM's.

i was thinking of wiring these batteries into the system while the truck is running to give more over all battery power for the entire system and power grid to use and while off the accessories could run off these older batteries and i could install a switch to put hte winch on just these guys so i dont drain the AGM's.

thoughts?

[Skullz]

No need for an isolator as they can cause more problems than they solve, just wire them all in parallel, and nothing wrong with having a lot of capacity.

[ncc74656]

my worry is that the liquid acid batteries will have a different peak charge and discharge rate to the AGM's, add to that the agm's are new and the lead acids are old i could easily see the AGM's being killed by the liquid acids due to voltage equalization. if i dont go isolation i will just chuck the old batteries. dont want to destroy 500.00 in new batteries.

[Skullz]

Most everyone on this forum mixes agm and wet cell batteries all the time with no adverse affects, just do not mix dry cells with agm and wet cell batteries and you'll be fine.