Post in 'The Green Room' started by Hiram Maxim, Jan 3, 2012.
Keep em coming folks!
Really really appreciate the input
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The first thing he needs to do is figure out how much power he needs. What is he going to be running and how many watts it needs to start what ever he is going to run.
The hart of the system is the battery bank if its not big enough to run everything it just won't work out. If he is mainly going up weekends it should be big enough to run two days. Also in cold weather the batterys don't put out as much power so it needs to be over sized if using in the winter. Also the batteys need to have enough to power to run the inverter at full power. Lets say you are using a 5000 watt inveter on 12v. That would require 416 amps for as long as you are using that much power.
I feel its more important to get enough battery and inverter first. And worry how to charge it second. And the bigger the battery bank the better if you batterys are just enough to run your outputs they are going to cycle more and build more heat and will severely cut their life spans.
As far as charge controllers I personally would not bother with anything other than a MPPT. While they are 2-3 times the cost of others I feel they are more than 3 times better. The cheep charge controllers just cut off any voltage past what charging voltage you need and wastes it. With a MPPT controller you can run much higher voltage than the battery and it uses it all. Having higher voltage to the controller allows you to charge the batter on cloudy low light days where with a cheep controller you would get nothing. With a MPPT running higher voltage you can run smaller wire from the panels to the controller for the same wattage. Which really becomes important if you have a long run from the panels to the controller. And where you put the panels is very important especially in winter. I have a tree line 200+ feet from my panels but in the winter the sun is so low its shaded most of the day.
I prefer one forklift battery to a battery bank. It takes up less room and I don't have a bunch of batter cable connections to worry about cleaning. Also you cannot tell the batterys state of charge by voltage thats just a rough guide. The only real way to check the SOC is checking each cell with a hydrometer. And there is a lot less cells to check with one big battery. The one big problem with a forklift battery is that if one cell goes bad the whole thing goes bad. But a cell can be cut out and replaced. And they are built a lot more heavy duty and less likely to go bad and last longer. I have heard of then lasting 30+ years on a solar system.
For the last four year we have been running a very used 24v 510 amp hr 1100lb forklift battery and 24v power inverter. With two 110w solar panels ad cheep charge controller just to keep the battery charged while we are not around. And we run off that 3 days or so then charge it with the generator. Which generally takes five hrs and 2 1/2 gal of diesel.
We just bought a new forklift batter from GB battery. 750 amp hrs 1500 lbs. And we are going to put up 10 230 solar panels we got from sunn elec. And yes it did take a while to get them. With a outback 80 amp MPPT controller.
A small 12v forklift battery from GB is 450 amp hrs (670 at a 20 hr rate) 528 lbs and is $1309. The same power inverter I have but in 12v is $399. And the outback 60 amp MPPT controller is around $500. which comes to $2208 leaving you with $800 for solar panels. To which you could add more latter.
http://gbindustrialbattery.com/Forklift_Battery_Sizes_and_Specifications_Zone15.html GB battery price list
http://www.theinverterstore.com/the-inverter-store-product.php?model=pwrinv500012w power inverter. While you can go smaller the bigger ones just seem to work better and you always end up needing more power than you think.
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