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thetick
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# Posted: 29 Mar 2015 09:22pm
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I'm upgrading/expanding my batteries (replacing 8 agm's) with 16 new batteries. It is a 24 volt system and the batteries will be 6 volts. Instead fs wiring 4 series/parallel strings, and avoid imbalances with charging and or discharge of this size bank is there a better solution? I have read some on using bus bars but not sure if they are a good choice and how best to implement.
As usual thanks for the help!
-Mark
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Nirky
Member
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# Posted: 29 Mar 2015 10:58pm
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If you require heavy duty, can make your own bus bars from copper pipe. Flatten & drill as needed.
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creeky
Member
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# Posted: 30 Mar 2015 02:22pm
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yes. get a lithium iron phosphate battery pack.
take a look at how long your last pack lasted. then look at lfp. minimum 10 year life span. and lfp goes 70% dod not 20%. So your battery pack can be far smaller. lighter. not toxic. no outgassing.
and you'll save all that bus bar money. 
how long did those agms last?
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FishHog
Member
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# Posted: 30 Mar 2015 03:03pm
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Quoting: Nirky If you require heavy duty, can make your own bus bars from copper pipe. Flatten & drill as needed.
Good idea.
Creeky should get commission from the LFP producers
LFP's look great, if it wasn't for the can't charge below freezing part. Warmer climates, they seem like a great solution. Not so much for a place that gets cold more than I'll have it warm.
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creeky
Member
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# Posted: 30 Mar 2015 07:37pm
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Commission. ya ... thanks for the recommendation.
Nope. the reason I keep pointing to lfp ... I've been four years and counting with a lead acid battery pack (1200 amp hr at 12v) that I rely on for power. 24/7. 365. no run back to the city.
FH, I know you're a solar newb. so lead acid has to be kept warm too. Wait till your batteries get cold and you lose 50% of your usable power. or the watering. or the need for constant charging. or managing the off gassing or the indescribable inefficiency ...
What are you going to do with a lead acid battery pack? The maintenance is way higher than just a little heat.
thetick is talking about 16 batteries. in series/parallel. if he needs that much power it's time to get off the lead acid train. FLA is terrible tech and its day is done. nuff said.
For heavy duty bus bars go to an electrical shop for the pros. They'ze a bit pricey. but you can get 'em where they are wrapped in rubber and you just screw and unscrew the connections. see my build for a pic of what I'm talking aboot. i'm a fan of city electric. dang. still no commission.
And I think I saw blue sea bus bars wuz it? on amazon.
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thetick
Member
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# Posted: 30 Mar 2015 09:57pm
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I've done the research on them creeky and the one thing I cannot overcome at the moment is the cost. These storage systems are still to much, considering all the other things I need to get done to the cabin (never ends...but that's part of the fun...).
The agm's have been in service for about 8 months now and don't want to add new to old as they say.
So decided to go the FLA route for the cost and availability (for now).
I'm adding on a 12x14 utility room/laundry room in 2 weeks and will have a section for a battery box (vented outside) so temp extremes will not be much issue, especially being in N. Georgia. My wife is happy as I will also finally have ALL the solar stuff out of the hallway (was the only place to put it until now).
So i hope the prices for the Li-ion packs are more reasonable choice in a few years, and hope the release of Tesla's system helps in that direction!
One question still creeky! How are the batteries wired? 2 bus bars for each string (one for + and one for -)? Forgive the ignorance, but I did not see the details for it in your build.
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creeky
Member
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# Posted: 31 Mar 2015 08:28am
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geez tick. it's been so long. lessee. i have two batts in series so 6v for 12v. and three parallel strings. 6 batteries.
there was guy online who had the three ways to wire these things with diagrams. basically the best way that I remember is
a) all cables for the batteries must be the exact same length
b) all three battery groups should each have its own cables to the bus bars and the charge line and the line to the inverter also are going into the same bus bars.
2 bus bars. one positive one neg. of course.
at the time this was the "best" method. with each battery series as a stand alone you reduce the travel distance so you don't get isolated batteries doing less work. plus the multiple cables distribute the load reducing the amperage going through the lines.
c) I have learned since that it's also considered "best" to have the charge in and power out cable beside each other on the bus bar. apparently it has something to do with when the suns out and you're using power ...
i know some people even occasionally move their cables so battery a becomes battery c etc to balance any load effects... but i dunno about the utility of that.
I have my fingers crossed with Telsa too. Lot of players in the market now. I do wish Balqon would get their act together. Not just here, but they've lost sales all over. Lack of support.
The long term cost is considerably lower with LFP tho. Not to mention time, safety, and my commission. 
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thetick
Member
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# Posted: 31 Mar 2015 09:04am
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Thanks creeky. Ok, based on that I did find this
URL
Thinking option 3...
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creeky
Member
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# Posted: 31 Mar 2015 10:24am
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ah. you found it. nice.
yup. what i did is #3. the difference in the diagram is that his model is using 12v batteries. my "battery" is two batteries in series, so I still go from one + and one -. but the + from series battery 1 and the - from series battery 2.
Why 16 batteries tho? What amp are those batteries and would you be better off going to a higher amperage battery?
Crown makes a 395 and surrette's 550 is 400 amps as well.
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thetick
Member
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# Posted: 31 Mar 2015 05:18pm
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Well, my thought is not what me needs are today but next year. I can get Crown cr-220's for $65 each plus core (from a local guy). I will be building a shop and my sons cabin and will then breakup these 16 batteries into 2 smaller systems. So having more batteries gives me more flexibility later on how many AH I want and where, and that's when I get the really good stuff for the main cabin.
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creeky
Member
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# Posted: 31 Mar 2015 07:05pm
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dagnabit i hate living in canada. (kidding). but that's 1/2 the price of batteries here. heck. it's half the price of buying from wind and sun in Arizona.
you've got some kind of special mojo going on there for sure.
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thetick
Member
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# Posted: 31 Mar 2015 08:50pm
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That's why i'm getting as many as I can afford. Not sure how long he will have them for. They're "factory blemishes" but come with a full warranty, just may have a scratch or bad label or something. You said before ou can be here in a couple days, so lets load you down for the return drive!
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creeky
Member
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# Posted: 31 Mar 2015 09:19pm
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You know me. I love a bargain. And that is a good one. Calculating gas costs now.
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