Where to put the batteries.

[windmillnut]

The misses and I have decided to go all electric.

The misses does not like hot weather so A/C is a must when we are in an improved campsite or roughing it.

The Lil Diner had a dropped floor to provide space in the seating area. I am thinking about building a similar vented dropped floor area just behind the axle to hold the batteries to run the A/C, the micorwave and everything else.

Access to the batteries would be through the rear of the sleeping area. There would also be a metal lid on the dropped floor area over the batteries. The batteries would be two AGM 4D batteries. The batteries are 120 pounds a piece and are 10" high and 20" long.

Any comments or concerns with the idea. I am worried about explosions and acid leaks. I read the battery explosion thread. That is what got me concerned.

[rasp]

the trojan AGM 4D, is a sealed unit, so no spills there. though no battery is explosion proof, charge or discharge at to great a rate and boom there ya go. a lid with latches is a must and proper vernting is a must. putting in an explosion panel, might be a good idea, may the back or the sides.

[Sonetpro]

I run 2 two AGM 4D batteries. I don't know what kind of A/C you have. But I have a 2000 BTU petcool. I had the idea of running it off the battery's through a inverter. It didn't work. I run a small genset to run the A/C

[jimqpublic]

With AGM you don't need to be concerned with hydrogen outgassing during normal operation, but there is still the danger of thermal runaway and catastrophic failure. I think you're prudent in planning on a metal box- just be doubly sure to make sure that all terminals are insulated in case the batteries move during transit. It might be good to line the sides of the box with plastic to reduce the risk.

Mounted low just in front of the axle is the perfect place for ballast (batteries).

Have you considered the charging side of the equation? 440 amp hours of AGM can handle a HUGE charge current. Probably the best value/output for a combined inverter/charger/transfer relay system is the Xantrex DR line. The size would depend on your chosen generator but the DR2412 will charge the batteries at up to 120 amps and put out 2400 watts of MSW AC. The charge portion is temperature compensated with a remote battery temperature sensor (so no thermal runaway risk even at high charge rates and a bad battery).

Price is about $880 vs. $2000+ for the true sine wave units of similar capacity. The DR1512 offers 70 amps of charging for $680. I think I'd pay the extra amount for the 2412 assuming you're running at least a 2000 watt generator. It will allow you to run AC & microwave simultaneously.

Manufacturer:
http://www.xantrex.com/web/id/57/p/197/pt/25/product.asp

Store offering them:
http://store.solar-electric.com/dr2412.html

[jimqpublic]

PS-

An online acquaintance had a Chalet like mine and used 4x 6v Golf Cart batteries. for the same roughly 440 amp hour capacity. He could run his 5000 btu air conditioner overnight through an inverter and only use about half the battery capacity. The AC draws 4.4 amps AC or about 50 amps DC including the inverter loss. Overnight though it would cycle off most of the time.

He would pre-cool the trailer while the generator was running so overnight the battery power just had to keep the trailer cool. Make sure you size the inverter with a continuous rating of at least double the running draw of the AC. That will give it enough capacity to handle the compressor startup surge, which is probably 4x the running amperage.

[windmillnut]

Thanks for the information. As usual the people on this site are very helpful.