Costco Batteries

get the 27s or 31s
bumpy

The GRP ** BCI numbers will have little effect when using two batteries. Look at a battery information chart and the box sizing (if using one) to get an accurate fitment.
FWIW, 6V GC2 batteries have the same footprint as a grp 24 battery. I'd suggest to buy two 6V GC2 batteries.

If you have a battery box I would measure the inside dimensions before purchasing a couple GC-2 batterys. The GC-2 is 10.30 inches (long) X 7.13 inches (wide) X 11.15 inches (high).
The GC-2 (6 volt) is about 1/2 inch wider and 2 inches taller than a GRP-24.

er78mph wrote:
I was wondering what batteries to buy, Costco had two different batteries. One was a 24DC (Fitment code 13) and the other was a 27DC (Fitment code 14). I currently only have one battery and would like to add a pair. I mostly do weekend trips with full hookups but want to get into dry camping eventually.

Between these two you might as well go with the larger Group 27 battery for the minor increase in cost over the Group 24. However, if dry camping is your ultimate goal you'd be still better off going with a pair of 12 volt Group 31 batteries if you have the space to mount them or a pair of GC-2 6 volt batteries. The 12 volts you'd of course wire in parallel, the 6 volts you'd run in series, but either way these banks would each offer about the same capacity, around 230 AH. FWIW, this spring I plan to replace my aging 8 yr old Group 27 Interstate battery with a pair of Group 31 batteries so I can more easily get through a few days of camping without shore power. :)

You want what fits. Measure first then buy. The 24 and 27 are similar with the 27 being larger with more capacity. If it fits you want the pair of 27s.

You might do better with a pair of GC2 Golf Car batteries. These are six volt and so you run them in series.

Either way will work fine. As you get off-grid you will also be looking at 100 to 200 watts solar and LED lighting.

The 12 Volt Side of Life

When we got our used Georgetown at 8 years old, it still had its original batteries.One Class 27 for the chassis and another one for the house. They were getting pretty tired.

The battery box was big enough for two 27-size, so I got Costco's deep-cycle 12V batteries for that location. I got one of their regular truck batteries to replace the chassis unit.

Four years camping (RV and State Parks), no battery problems at all.

Someone, somewhere else, mentioned that you can squeeze in 4 golf cart batteries in the battery tray under the steps of a class c. I'm getting our class c back from the shop today and will be doing some measuring to see if this is accurate, at least for us.

Well. I will give you my opinion: NEITHER

Those will be either Starting or MARINE/Deep cycle (Almost starting) batteries, Not at all the best thing for RV use as house batteries, Good for ENGINES though.

If you have room. then get TWO GC-2 batteies (not all Costco Stores stock these, Most Sam's do) These are roughly the same footprint as a G-24 (the first one you listed) but are TALLER.. They are also six volt so you wire them like this

-{bat}+=-{ery}+12V to make one BIG 12 volt battery (220 amp hour +/-10 AH)

The two of them together still = one 12 volt battery (Size 4D or 8D depening on + or - on the other line) so you charge them the same, You treat them the same (Save for inspection and cleaning and adding DISTILLED WATER to aboutr 1/8 to 1/4 inch below the filler tube from time to time) and they last and last both per-charge (yoru Group 27 is like 95 AH, group 24 about 75) and with proper care Years and Years before replacement (mine went 9 years).

But alas only if you have the room

If you do not have the room for two, Measure your battery box and get the largst one that fits.

Listen to the recommendation for a pair of GC2s in series. I did a lot of work on performance cruising boats (read retired keel boat sloops) before the depression shut us down.

There are VERY few real deep cycle 12V batteries available. A "Marine" battery is not one. What is sold as a Marine battery is an automotive battery with a small (if any) compromise. (That compromise is usually in the warranty.)

Then there is the problem that without jumping through flaming hoops, a pair of jars in parallel will never provide capacity X2. You will be lucky if you can get 1.75 but more than likely it will be about 1.5 and I can tell you why, but I have other things to do this morning. Just remember that Lead/Acid batteries do not play nicely in parallel.

Matt

My Costco "Deep Cycle" batteries have performed well for 4 years now. I have been careful to avoid discharging below half. They say "deep cycle" on the side. What can one do to find out if they are truly deep cycle?