Combine grp 24 with grp 27 batteries?

Have you performed a power audit to determine what you need? What are your intentions? Will a second group 24 get you there?

I agree with Don. Going with a pair 24s of the same make would be better. If a pair of 24s doesn't get you there then adding a 27 would be marginally better and they won't play well together as they age.

Sheep in wolf clothing, flooded Car Jar RV batteries are not worth fussing over. I figure if the OP did not determine he needed more than 85-amp hours, he wouldn't have asked about adding a 27.

"Spend Other People's Money As If It Were Your Own" is one of the lynch Pins of my thinking.

NinerBikes wrote:
I'd run the group 24 until it dies, which it will, in a year or two ...

That's a bit dramatic ... many if not most of us get far more than just "a year or two" out of a deep cycle battery, heck my own G27 Interstate is in it's 8th year and still taking a charge. So much depends on usage and maintenance that determines just how long any battery may last ... but just a year or two is hardly typical with even a modicum of care.

I'd run the group 24 until it dies, which it will, in a year or two, then replace with a pair of matched batteries of what you really want. You'll have a couple of years on here by then to have done a search on batteries for your rig, and know what will work best for your particular type of camping, pedestal or dry camping.

I would try and find out who made the original battery. i.e. Johnson Controls, US Battery..etc...

Then match it. Chemistry is what is important. Not size. When a battery ages its chemistry changes.

No issues.

richy2 wrote:
My new trailer came with a group 24 battery. Would there be any issues if I added a group 27 battery in parallel?

"New trailer" suggests a battery that is "new" as well. If your intention is to dry camp on a regular basis then when it comes to battery reserve more is always better. If that's the case have you considered asking your dealer if he'd replace the "new" G24 for a larger size provided you agree to pay the difference and buy a second of the same? Also, if you have the footprint available I'd even go to a pair of G31 12 volt batteries OR (personal preference) a pair of GC-2 6 volt batteries wired in series.

This is what is balanced and best for twin twelve volt batteries.



The group 24 will end up as a parasite on the group 27 over time.

I'd add a group 24. The capacity difference isn't that much different than adding a group 27.

The problem that usually arises is when they are being charged. If the cables paths are different lengths or the older batteries charge at a different rate than the newer batteries etc you may end up having one group of batteries charged up more than the other group.

Continuing to do this will eventually do harm to battery bank that doesn't charge up enough.

Roy Ken

While not the absolute best solution, it will work.

The absolute best solution is matching batteries. However, if that battery is in good shape, I would not replace it. I would go ahead and add the group 27 battery.