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My homemade battery bank, what do you think? (Pictures)

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Rockyriver

· Ham Extra Class
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Discussion starter · #1 ·
Well been board today so I decided to put this together for part of my backup power supply. I went way over budget on this one. I tried to make it as safe as possible for inside my house use.
I bought a lot more expensive batteries than I wanted, however I think I will be happier in the long run. I now have to take the wood back off and round the corners and paint it. I also have to tidy up a few of the wires.This is a work in progress project, so I will be making improvements over the next few weeks. I can't wait to see how long the batteries will last running my fridge,TV and lights around the house.
When charging I plan on taking the tops off the boxes so to let the batteries be cooler. I also placed a small amount of space between the batteries so as to have cooling room.
The inverter is a 3000 watt continuous and 5000 surge (Wish I had spent the extra on a pure sine inverter).
The batteries are four 12 volt 105 AH AGM batteries, giving me a total of 420AH.
I used 2 Guage wire.
I made the unit mobile so I can roll it where I want with ease.
I placed 2 very large power switches on the unit to cut power to the inverter when not in use, The inverter still draws ampage even when off, the switches prevent this.
I placed a 175 amp fuse on each battery in case of a short.
Check out post # 22 for newest pictures.

My mobile battery bank.
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My battery bank and battery charger.
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The interter i'm using, wish I had a pure sine now.
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The battery top off one of the AGM batteries, notice the large 2 gage wire connecting the batteries.
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My mobile battery bank. I use the wood to keep the batteries in position and stop them from shifting, I got to paint it.
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A close up of the 175 amp fuses i'm using.
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Large high amp marine on off switches to prevent battery drain when not in use.
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#5 ·
Nice job. Question for you though. Where do the positive and negative leads come off of the pack? Are they one one battery or two batteries or do you have then even spaced from all of them to a central point? The reason I ask is because when you get into a large parallel configuration like you have, it is easy to get the bank unbalanced due to charging and discharging. If one battery is closer to the loads and the charging source than the others, it will see more wear than the others because it is doing more work than the others.

Another question. What size wire do you have going to your inverter? 2ga is kind of small for a 3000w inverter, even for a short run.
 
#6 ·
About $1100 by my best guess. Very expensive in one sense but extremely valuable should you need silent power. I am not well versed on electrical applications but I know a good thing when I see it. Please keep the board informed on this project. I would like to know how long this will run the items that you select to use it on and how long that power generation unit takes to fully recharge.

Have you thought about a small auxiliary solar trickle charger for maintaining the charge?
 
#7 ·
Just to add to the discussion:

I make battery cables for some of my clients. They have serious demands and I saw the results when my brother in law tried to save a few bucks and go low dollar on his homemade cables. His rig burned to the ground.

Here is the stuff I use.

2 ga welding wire [I like welding wire as it handles a lot more amps, handles overloads a lot better for the same size as auto grade and its far more flexible.

I use solid copper terminals and solid copper/silver plated connectors. I SOLDER everything using specialty solder bullets that you drop into the connector that match the size of your cable. It is electrical grade and is enough solder to to properly make the connection. I use solid copper/silver plated 'YELLOW' grade [500 amp] quick connects.

I shrink wrap all connections

Point being go for the copper and do it right the first time. You are slinging some amperage and some chance of major surges and overloads and you must have the cushion to absorb these loads.

A typical set of battery cables complete runs about $50 - $100 bucks my cost. Silver plated copper is not cheap but if put together correctly its generally a one shot deal that is gonna last near forever if properly maintained.

In the first pic is a cable I made as compared to a OEM cable.

The second pic is a comparo of oem vs my cables on a dual battery setup.

As you can tell one set is marginal and the ones I build are for the really long haul.

Most of the battery issues I see on HD rigs are a result of bad OEM cabling, don't let it happen to you.
 

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#9 ·
Can someone give me an idea of what a rig like that can power and for how long?

If it were to be recharged via solar power what sort of a setup would that require?

Thanks! I'm still trying to get a feel on understanding DC.
 
#10 ·
LEPER said:
Do you have a good source for 4/0 cable?
Click to expand...
I was getting my stuff from Dell City, then I found a big welding supply house local (Praxair) that was supplying me at better prices as that is where I was getting all my welding supplies for my shop. Dell City has good enough pricing but by the time I added shipping it was not profitable at all for my shop unless I was doing other work. The stuff is heavy and copper is expensive.

For the cable, for sure I would go to a welding shop and use that over auto grade.
 
#14 ·
Very nice. I'm no electrical genius. I'm wondering what all you can run with this.

And did you use Optima Batts? I see you said you used AGM batteries.
 
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Discussion starter · #15 ·
LEPER said:
Nice job. Question for you though. Where do the positive and negative leads come off of the pack? Are they one one battery or two batteries or do you have then even spaced from all of them to a central point? The reason I ask is because when you get into a large parallel configuration like you have, it is easy to get the bank unbalanced due to charging and discharging. If one battery is closer to the loads and the charging source than the others, it will see more wear than the others because it is doing more work than the others.

Another question. What size wire do you have going to your inverter? 2ga is kind of small for a 3000w inverter, even for a short run.
Click to expand...
I was going to run all the batteries to one central point and then run one wire to the switch and then inverter, however I am going to rotate the batteries ever so often. Each battery does have a connector so as I can charge that battery directly, however they are still in parallel. I am still learning, and this is a work in progress, thanks for the tips. The inverter has 2 positive input wires and 2 negative input wires, all four wires are 2 ga. This was suppied by the maker of the inverter.


Pangea said:
About $1100 by my best guess. Very expensive in one sense but extremely valuable should you need silent power. I am not well versed on electrical applications but I know a good thing when I see it. Please keep the board informed on this project. I would like to know how long this will run the items that you select to use it on and how long that power generation unit takes to fully recharge.

Have you thought about a small auxiliary solar trickle charger for maintaining the charge?
Click to expand...
I have a solar charger and it is about 300 watts, the amount it charges them depends on how much they are drained. It does enough to keep me going over night and run the fridge,TV,a few lights. If fully charged I can get about 2 1/2 nights use out of the battery bank. Then it needs to charge about 2 to 3 hours on my homemade charger. To top off the batteries all the way it needs a slow charge of a few hours more, however if the SHTF, the slow charge would get skipped.

txflyboy said:
Very nice. I'm no electrical genius. I'm wondering what all you can run with this.

And did you use Optima Batts? I see you said you used AGM batteries.
Click to expand...
I am running a AGM battery that are Generic, I will have to find the manufacturer, I think its Johnston controls (They make optima also).
But no they are not Optimas. I can run my fridge,TV, a few lights, my clock radios, a few other low watt things for about 2 nights without chargeing. It really depends on how many times I open the fridge and how much TV I watch.
 
Discussion starter · #20 ·
Pangea said:
So, are you charging all the batteries at once or one at a time? Are all the batteries running through the inverter at the same time?

Just so you know, I think you have an outstanding setup.:thumb:
Click to expand...

Yes I charge the batteries all at once, and yes I use all four batteries at once.
They are all hooked up and running the inverter.
I ran a few electrical items thru the setup all last night (showed 350 watts on the meter) and the battery bank is still going strong this morning.
I am thinking now that maybe with my fingers crossed I can get 3 nights use between charges. I am still testing, got to take it apart today and paint the bare wood.
 
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