Opinions on auxillary battery mounting

[Taranwanderer]

I recently won a small inverter (400W) in a raffle, so I thought it might be a nice option to have 120V AC when dry camping (even if it is only for short periods.) The more I'm reading on these forums, the more I want this inverter to have it's own dedicated battery and not have anything to do with the TT's electrical system. So I'd like to mount a second, inverter only battery, with it's own charging system (possibly a combination of solar and a small smart charger when needed.) If this works, I can always bump up to a larger inverter in the future.

The tongue of the TT is pretty jammed with the existing battery, 2 30# propane tanks, and the jack, and I don't really want to mess with any of that (cutting, etc.) Has anyone tried mounting a battery on the rear bumper, in a weatherproof box, and running the wiring back under the TT to wherever it's needed? Just looking for opinions on the battery mounting. The Salem has very little outside storage (it only has one exterior compartment, which is right beneath the master bed and not somewhere I want to mount a battery, not to mention its in a slide.) I don't want a battery mounted inside, even a gel or AGM, so that's out. Back bumper is looking like the best option, plus it wouldn't be hard to run wiring down from a solar panel in the rear. So, let the ideas flow...

Thanks!

[caper]

The back bumper is a rough ride. The extra bounce might cause harm to the battery.

[Great Horned Owl]

It seems to me that with a separate charging system, you are creating a lot of complication for little (if any) benefit. Loads of people add small inverters with no problems at all. Just make sure to fuse the line from the battery to the inverter. A 400w, that would be a 50 amp fuse.

Joel

[Herk7769]

Originally Posted by Taranwanderer

If this works, I can always bump up to a larger inverter in the future.

You mean that if it works you can jump to a bigger BATTERY in the future.
Remember Watts out is the same as Watts IN.

So 400 watts at 120 volts is about 3 amps of AC power; but to make that requires 400 watts of DC power IN at 12 volts (or 33.3 amps). A draw this big will deplete a motorcycle sized battery (about 15AH) in about 20 minutes.

I doubt you will need 400 watts any time soon. A flat screen TV runs on about 75 watts for example; add a DVD player and it will be about 100 watts.

That motorcycle battery at THAT draw (about 8 amps of DC) should last about 2 hours.

[Taranwanderer]

Originally Posted by caper

The back bumper is a rough ride. The extra bounce might cause harm to the battery.

Good point. If the back bumper was the mounting point, it would (a) have to be an AGM battery that's less prone to vibration damage, and (b) fabricate some sort of vibration absorbing mat beneath it to minimize the bumps. As Scotty would say.

Originally Posted by herk7769

You mean that if it works you can jump to a bigger BATTERY in the future.

That's also a good point, Lou. If I would jump up to a bigger inverter, I'd have to go with a bigger battery. But now that I think about it, by that point, I think I'd just invest in the generator to supply my power needs if they were that great. This is just a small unit to suppy a small amount of power--cell chargers, laptops, iPads, etc. You have me thinking about a motorcycle or tractor battery--smaller capacity but smaller size, I might be able to mount that on the tongue next to the main battery with little or no modification.

Keep the ideas coming, folks!