cancel
Showing results forย 
Search instead forย 
Did you mean:ย 

Adding a 3rd battery

BC_Explorer
Explorer
Explorer
Looking to add a 3rd battery to my 2 existing group 27 deep cycle battery setup. I have read that adding a new battery to old should not be done as the new battery charge will be affected by the older?

Any truth to this?


The 2 existing batteries are 2 years old and do not see a lot of heavy use. Typically they are used 5-6 times per summer season to mainly power a 2 door compact fridge in the trailer. Batteries are charged with solar and or a generator and are kept up to charge in the off season. No issues with the existing batteries, but would just like some more amp hour reserve.
9 REPLIES 9

BC_Explorer
Explorer
Explorer
BFL13 wrote:
The starting/deep cycle is pretty much the same as the marine/RV for what you want to do.


Thanks. That is what I thought, but wanted to make sure before I purchased. I'll stop by Costco again tomorrow to purchase one.

MEXICOWANDERER
Explorer
Explorer
Oxymoron: BCI groups 24, 27, 31 "Deep Cycle Battery (flooded)"

BFL13
Explorer II
Explorer II
The starting/deep cycle is pretty much the same as the marine/RV for what you want to do.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.

BC_Explorer
Explorer
Explorer
Thanks all. Much to my disappointment, the 2 Costco stores in my area are not carrying the same group 27 deep cycle batteries that I currently have. However they do have a group 27, starting / deep cycle battery.

Any potential pitfalls of mixing different types of batteries?

Lwiddis
Explorer II
Explorer II
Adding a third battery will add a usable 50 amps or so and 65 pounds. Trojan's group 27 is about $250. Is the real answer buying a couple of good golf cart batteries?
Winnebago 2101DS TT & 2022 Chevy Silverado 1500 LTZ Z71, WindyNation 300 watt solar-Lossigy 200 AH Lithium battery. Prefer boondocking, USFS, COE, BLM, NPS, TVA, state camps. Bicyclist. 14 yr. Army -11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad

ppine
Explorer II
Explorer II
Great idea, 4 are even better.

MEXICOWANDERER
Explorer
Explorer
Yep with solar I'm in agreement with BFL13 -- happy camper

time2roll
Nomad
Nomad
The only issue might be slightly lower resting voltage of the older batteries. No concern while in use. Remove the parallel connection if stored without float voltage.

If the old batteries are expected to last 3 more years then expect your new battery to be done at the same time.

BFL13
Explorer II
Explorer II
It won't hurt the two, and when it does pull down the new one to be like them, so what? Go for it.

If the two were on their last legs, then that would be another story.
1. 1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
Photo in Profile
2. 1991 Bighorn 9.5ft Truck Camper on 2003 Chev 2500HD 6.0 Gas
See Profile for Electronic set-ups for 1. and 2.