I like Trojan batteries. I will look into those. I am looking to replace my house batteries this summer. Hight is not a problem. Now, 2 or 4?
4 is obviously better. Especially since you need to not go below 50% DoD. If you have two 6-volts wired to give 12-volts at 405 AH then you can only use 200 AH before you drop below 50%. You need four at 810 AH in order to use the entire 405 AH.
I am running a 110v fridge. It claims to draw a max of .09 amps at peak. It ran last night for 8 hours without the APU kicking in. I would like to extend that time as long as I can without getting silly.
Couple of things. OK, more than a couple. One, when does the APU kick in? At what voltage? In other words, are they kicking in when the battery bank gets down to 50%, or are they being drawn down much further than that?
You may need a battery monitor, like the Xantrex. You can set the "alarm" on the Xantrex to a specific "AH remaining" level and then wire it to have to APU fire up when the battery bank hits the alarm level.
Also, .09 amps at peak seems like a really low number for any 110v appliance, especially a fridge. A 25Watt light bulb draws .227 amps at 110 volts. 10 Watts is .09 amps. So .09 seems wrong for a fridge.
It's probably .9 amps, not .09. Most fridges, the smaller ones, anyway, are in the .8 to 1.5 amp range. At .9 amps, that's 100 Watts. My Microfridge draws 1.3 amps, according to the plate inside the door, and .8 when defrosting, but usually draws at most about .9 or 1.0 (around 10 or 12 amps out of the batteries at 12-volts).
Check the plate inside the door to be sure. You also might want to pick up a Kill-A-Watt meter. You plug it into an outlet, and then plug the fridge into the Kill-A Watt meter, and the meter will track how many Watts something uses over time. It's really great for something like a fridge which is sometimes on and sometimes off. It'll tell you exactly how many Watts are drawn out over an 8 or 24 hour period. The meter is lists for $30 and can be had for that price at Walmart and Radio Shack and Home Depot, but Sears has it for $18.50, and Newegg has it for $17. I think I paid $22 for mine at Camping World. Here's the
Wikipedia page on it, and
here's the Google Shopping page for it.
I used it in the van to check the actually Wattage draw of nearly everything in here. Did it several times over several time frames, to get a good idea of what draws what. It's nifty. It lets you know just how much money you're spending at home on those televisions and DVRs that suck electricity when they're turned off. My satellite receiver box draws nearly 5 amps from the batteries when turned off, so I got one of those remote extension cords so I can actually cut the power to the receive when I'm not watching television.
