2 different Amp Hr batteries

[geeman]

Can I tie together 2 different rated Amp Hr batteries?
12 volt, One is 88.5Ah and the other is 60Ah...

[Canonman]

You can add them together (parallel wiring) but it's questionable if you'll get the desired storage you're looking for. You'd be better off to buy a couple of $90, 100 A/H deep cycle RV batteries to get the 200 amps possible if finances permit. Mis-matched batteries will work but likely not as well as you're hoping they will.

[flybouy]

Installing 2 dissimilar 12 v batteries will limit the batteries to the lower of the two capacities. The common recommendation from all the "experts" is to use 2 identical new batteries. That 60 ah battery may only be holding less than 1/2 of it's original rating if it has not been maintained or used properly.

[JRTJH]

Originally Posted by geeman

Can I tie together 2 different rated Amp Hr batteries?
12 volt, One is 88.5Ah and the other is 60Ah...

If you think about it for a moment, the two batteries (different sizes) are going to be recharged by the same converter, using the same single wiring connections. What that means is that one battery (the smaller one) will reach the "fully charged condition" before the other. IF the converter shuts off at that point, the other battery will never reach full charge condition"

On the other hand, if the converter doesn't shut off, it will continue to charge BOTH batteries until the "larger battery" reaches full charge condition. That means the smaller battery will be "overcharging" during the time that both batteries are receiving the additional charge from the converter/charger....

Either way, one battery will either be "boiling as it's overcharged" or the other battery will be "never fully charged.

Onn the "discharge end of the equation" the smaller battery will be "fully depleted" before the larger battery reaches the 70% or 50% discharge state, so both batteries will be "at different charge status" when reconnected to the converter/charger. That will hamper effective, efficient recharging.

The generally accepted battery "rules for use" recommend that all batteries in a battery system should be the same size, same age, same capacity, same brand (if possible) and connected so they all are "fully utilized" based on the wiring arrangement.

Short answer: I wouldn't hook up two different "amp hour" batteries in parallel to the same charger.