Battery banks and bank size calculations?

Post anything about batteries here. Lead acid, rechargeable, whatever.
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OutOfPlaceNinja
Posts: 49
Joined: Sat Jan 24, 2015 3:37 pm
Location: USA

Battery banks and bank size calculations?

Post by OutOfPlaceNinja » Sat Oct 10, 2015 2:21 pm

It seems battery banks and calculating the size of and figuring out the wiring of battery banks for off grid solar setups is rather complicated. So here is a thread about it lol.

The solar panel thread is here.

I've been considering moving off grid electrically and the timeline is presently by next summer. However I was startled at the high cost of batteries and how many I would need to have any sort of semblance to my current electrical use (100-200kwh a month). If my calculations are correct, I would need about 20-25 200 amp hour (20 hour rate) deep cycle batteries to meet my current demands. At about $100 USD each, I might be better off just getting a big forklift battery. Either way it's going to cost far more than I can afford right now (or in the foreseeable future) and the time needed to recover the investment would be many years.

The point of this thread is to discuss how you (the off gridder, any of you) are doing it. What kind of batteries are you using? How many? What have you had to do to live on your bank and solar setup? Do you miss anything? How much is your bank rated for? How much do you really get out of it? How many and what kind of solar charge controllers do you have? Any brands or types suggested? How did you arrive to where you are now concerning the size of your battery bank? How much did it cost you? So on and so forth.

I want this thread to be all about battery banks and only battery banks. I have created another thread to cover solar panels and everything solar panels.

techman
Site Admin
Posts: 1323
Joined: Thu Dec 22, 2011 11:49 am

Re: Battery banks and bank size calculations?

Post by techman » Tue Oct 20, 2015 1:47 pm

I miss my rice cooker. Really. That is the one thing I miss the most about living off the grid. I used that thing a lot. And a bread machine. Those are so nice and save you so much money and/or time.

You know most of the other details of my solar power battery bank so I wont waste your time.

I do think that forklift batteries are the way to go. But you can start with golf cart batteries and keep adding to the system as finances allow. This may be the easier way for you to go.

DumbAssMusician
Posts: 5
Joined: Wed Nov 04, 2015 4:07 am

Re: Battery banks and bank size calculations?

Post by DumbAssMusician » Wed Nov 04, 2015 5:03 am

We live off grid, have upgraded as we could afford. I scored a really good deal on some agm rack mount batteries when we started, 8 x 100ah new in box out of a telco tower but wasn't really happy with them after 6 or so months so we sold them and got 8 x Trojan T-105 and they served us well. I scored a few weeks back a 750ah forklift battery bank that was 12 x 2 volt for scrap value and they are a different league to the trojans, they are sitting at 25.6v and we run a fair amount of gear off it daily, impressive. I was going to keep the system 12v but 1. didn't feel comfortable using oxy acetylene to cut the bar on the battery to make 2 banks of 12v and 2. I was exceptionally lucky that the service agent for Victron energy took pity on us as sold me a second hand multiplus 24/3000/70 cheap, I sold my 12v victron multiplus for the amount of the 24v upgrade. I have trial and error our system with much nagging from the boss (could of put mains on, paid years of power blah blah) but since we have the forklift battery bank sorted she has become very quiet. The only down side is that they are 430kg and were hard to move into position.

techman
Site Admin
Posts: 1323
Joined: Thu Dec 22, 2011 11:49 am

Re: Battery banks and bank size calculations?

Post by techman » Wed Nov 04, 2015 5:59 pm

The forklift batteries are heavy. That is a huge problem.

I cut my battery bars with a simple reciprocating saw. No problem if you vent the battery cells first and then do the cutting outside.

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