Started by MountainDon, January 13, 2009, 02:18:39 AM
0 Members and 1 Guest are viewing this topic.
Quote from: MountainDon on December 02, 2009, 12:11:57 AMOh, I understand now OJH. In that case we need another look. But that charge controller has to go or that panel would cook it.But before that, what is the amp-hour rating of those batteries? You want two in parallel as I understand it.OR pick a panel that's smaller.... have to run some numbers.....
Quote from: MountainDon on December 02, 2009, 01:12:40 AMThe specs didn't come up on the link, but I'll wager a donut that you have group 27's with 105 amp-hours at 12 VDC.So if you put two of them in parallel you have 210 amp-hours total.Limit running them down to a max of 50% so that gives you 105 amp-hours of usable power.Keep in mind the available capacity decreases with cold. Anyhow 105 amp hours @ 12 vdc = 1260 KwHI ran two such batteries in our RV for years, when it was a real RV that we drove around in. Those batteries would give us a good day/night of use in cold weather with most of the power being used by the RV furnace blower. I think ours draws about 4 amps. So if you used up 1200 watts of power and a panel puts out 85 watts, you would need 14 hours to recharge. Not good. It would be best to not use that much power, batteries last longer i not sucked down so much. To regain that sort of power fast you need 20 amps or more going into the batteries. That's about 240 watts. The 85 watt panel would slowly charge the batteries up over a few days with no use and would definitely maintain the charge over a period of time with no use.
Quote from: MountainDon on December 02, 2009, 02:35:27 PMWe had issues with running the battery down in cold weather when we had one battery. Those RV furnaces are power hungry. When we went with two batteries it was much better and the last time I replaced the batteries I went with 4 six volt golf carts batteries in a series/parallel set up. That's even better. I never bothered with solar panels as I figured I needed more than I had space for. Plus I didn't want a system for the RV once the cabin was built. I knew I wanted more PV for the cabin and I had also decided the cabin would be based on a 24 VDC system so 12 VDC things like the charge controller and the inverter would not be usable in the cabin. That's how it worked out for us.
Quote from: Beavers on December 02, 2009, 10:21:54 PMIn a full system the generator hookup is through the inverter, and then back into the batteries? Looking at inverters it looks like only the higher dollar inverters are set up for generator use. So with a cheaper inverter you still need a charger like the Iota to have a generator backup?
Quote from: MountainDon on December 03, 2009, 12:22:40 PMSomething like that would help keep the battery temperature up with the excess power. It would be akin to Glenn's use of excess power being used to pump water.
Quote from: MountainDon on December 04, 2009, 06:20:06 PMThose guys have a whole world of available heaters. They would be able to supply whatever was needed by the looks of it. Whether or not their equipment would be cost effective is the thing. This will need some more thought and research. The first step will be to come up with a realistic estimate of how much excess PV power there is in summer and winter...... more to come. I'm going to park this link to those guys website here as a handy thing.http://watlow.com/products/heaters/ht_flex.cfm
Quote from: Pritch on December 04, 2009, 06:41:25 PMWell Don, now you have to start planning your battery box insulation retrofit!