More Power.

[digimark]

My trailer came with a wimpy Interstate HD24-DP Group 24 battery in a white vented battery box mounted to the floor. With a Fantastic Fan, two overhead LED dome lights and sporadic use of the incandescent patio lamps and an iPod USB charger, I'm finding that the battery seems to last most of a two-day weekend, and I'm probably drawing down below 50%, which I know I shouldn't do.

So I want to upgrade. I don't have a lot of room, but I think I can fit two
larger batteries in the same space if I ditch the battery box.

Advice?

Should I go with one larger battery, like a Group 31 monster? Or two smaller batteries? Two 6V batteries or 12V batteries? And where can I get the appropriate cables?

Thanks. -Gary

[Miriam C.]

You can get cables and attachments at any auto store or Walmart. If you have the need you might want to go with two larger capacity batteries. I am not sure I would ditch the box. There is nothing like battery acid to ruin your stuff. Perhaps you can cover the box in plastic so both will be protected and vented.

[Steve_Cox]

I would ditch the box and use 2 AGM batteries, little or no gassing off, and maintenance free. Sorry Miriam, just thinking outside the box.

[Shadow Catcher]

One thing to remember if you go with two batteries they must be matched/identical. You have two separate components here, demand and useful battery capacity. Conserve what you have i.e. LED lights find what your loads are, use a VOM.
There are calculators that can tell you what your likely need is based on loads.

[digimark]

Thanks for the replies. Definitely AGM batteries, or I'd need to vent them outside. Using those I should be covered against battery acid leaks, although I'll still cover the pos/neg poles to prevent injury or short circuit.

I've just re-read through the battery guides/FAQs and the electrical sticky posts. I'll use two 12V parallel-connected AGM batteries.

Is there a sweet spot I should be looking for in battery amp-hours and pricing? I'm guessing, but I'd think two 100 AH batteries in parallel should give me enough deep-cycle runtime to 50% that I can stop thinking about it for a long weekend. (Any more than a weekend and I have to have AC available!)

I'm not sure what Group # to aim for either. My space for the batteries is 20"l x 14"w x 10" h. Based on the size measurements at
http://www.rtpnet.org/~teaa/bcigroup.html . two of any of Groups 24, 27, 29 and 31 will fit side by side. I'll need to build a cover for them. The batteries will be sitting on the floor, against the front wall of the cargo trailer, and they will certainly be the heaviest items in the very front of the trailer. (My TV's battery is a Group 49 H8 battery, I believe.)

Batteries are heavy -- probably better to buy local than to mail-order?

The local BJ's Warehouse Club has Exide batteries but I haven't seen any good reviews of them. If you can suggest a reliable vendor with
fresh batteries and good prices, please let me know. -Gary.

[bdosborn]

Definitely AGM batteries, or I'd need to vent them outside.

AGM batteries still need to be vented. While they don't vent very often (hopefully never), they *can* vent and you don't want the offgass to be trapped in your trailer. You'll also want to make sure you have a charger that's meant for AGM batteries as they have different charge requirements from lead acid.

VRLA Thermal Runaway

I'm running two golf cart batteries (as do a lot of RVers) and I'm very pleased with them. They are true deep cycle batteries and I think its the lowest $/amp-hr route you can go. But, you'll need to water your batteries every month or two. AGMs don't require watering. Costco and Sams Club golf cart batteries are pretty popular over at the big rv forum. The Trojan T-105 is the gold standard and priced accordingly.
Bruce