Author Topic: Battery bus design  (Read 10013 times)

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Offline ksouers

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Battery bus design
« on: April 28, 2012, 07:27:07 AM »
My little bank is growing and it's time to start thinking about hooking up to a bus. My criteria are fairly simple. As my bank is growing I need room for expansion. I will be switching from 12 volt to 24 volt in about 6 months or so. I also need to reduce the chances of shorting. I really don't want to drop a wrench and have it weld itself to the bus.

So, how has everyone laid out their bus? Did you put the bars end to end or parallel? How much separation between the bars?

I know brass would be the preferred material, but steel and aluminum are readily available. Brass would have to be ordered, not a problem, just extra cost and hassle. Are steel and aluminum acceptable materials with proper corrosion protection?

How did you protect the connections from inadvertent shorting? Did you mount them in a box? Put them in separate boxes for each pole?


Thanks,
Kevin
As far from the city as I can get but still keep my job.

Offline bj

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Re: Battery bus design
« Reply #1 on: April 28, 2012, 08:29:29 AM »
  I will be interested in the replies as well Kevin, as I am at that point.
  At this point, I can only tell you that all incoming (solar/wind someday) will be in a box.
  I suspect my buss will be copper, as I have a large free piece.  Copper is pricey these days.
  As building a box is fairly easy for me, (and cheap) I am leaning towards putting the buss's in
one.
  If you use aluminum for a buss, put the anti-oxident grease on all connections, and it should be fine.
"Even a blind squirrel will find an acorn once in a while"
bj

Offline ghurd

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Re: Battery bus design
« Reply #2 on: April 28, 2012, 08:38:12 AM »
I would not use steel.

Actually, I personally would not use AL either, but I think it would be better than steel.

Bus bars may be one of those items that is cheaper to buy than make, depending on the requirements.
G-

Offline tomw

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Re: Battery bus design
« Reply #3 on: April 28, 2012, 08:59:10 AM »
Kevin;

Avoid Aluminum like the plague. I think Stainless Steel is OK but higher resistance than other options. Among the common, affordable metals copper is where I would go for low resistance.

I do not use a bus as you think of it. I have 2 big boy traction batteries with 2 heavy cables each and factory interconnects on each for the cells within the individual "battery". One is copper cables with ends the other is tinned copper straps. The batteries tie together through a breaker and ginormous terminal blocks with 500 MCM connections.

I had access to a decent industrial salvage outlet and collected a few copper bars from electrical boxes 1 inch wide and a quarter inch thick and various lengths to build a "bus" but never needed to.

It seems that any decent metal dealer in a largish city should have copper bar stock available. I think copper is the best bang for the buck for conductors whether wire or bar stock. I use Aluminum triplex with 3 conductors the size of your pinky to feed from my turbines but that is an availability issue and weight consideration being overhead lines. I got 2 150 foot rolls of it for $90 each used. It never wears out and can move 200 amps all day without issues.

I guess I am saying Aluminum has its uses but NOT for a bus and certainly not near possible acid vapors.

Just from here.

Tom

EDIT:

I meant to add you could split PVC tube to cover your bus bars. My 810 AH GNB set uses a formed plastic strip to snap over the interconnect bars. PVC pipe split with zip ties be an easy way to duplicate that out of any hardware store.

Tom
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Offline ChrisOlson

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Re: Battery bus design
« Reply #4 on: April 28, 2012, 10:18:52 AM »
I got a four bar 2,000 amp DC bus (for two inverters) from SquareD, rated 250 volts.  It has 6061 aluminum bars in it.  Seems to me that most all of the commercially made power panels use aluminum bus bars, including the DC Conduit Box for Xantrex inverters.

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Offline tomw

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Re: Battery bus design
« Reply #5 on: April 28, 2012, 11:10:31 AM »
I got a four bar 2,000 amp DC bus (for two inverters) from SquareD, rated 250 volts.  It has 6061 aluminum bars in it.  Seems to me that most all of the commercially made power panels use aluminum bus bars, including the DC Conduit Box for Xantrex inverters.

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Chris

I guess I need to preface comments with "In my Day"..

Anyway, I have personally had bad luck trying Al for battery interconnects. All the power boxes I salvaged had copper bars in them but being a dinosaur my experience is dated. Not all aluminum is created equal, either.

What counts is accuracy.

Tom

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Offline ksouers

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Re: Battery bus design
« Reply #6 on: April 28, 2012, 01:03:01 PM »
Thanks for the replies, everyone.

I'm not keen on the idea of using aluminum. I grew up with the stories of house fires started because of aluminum wiring. My personal experience is that it usually reacts badly when in contact with other metals. During trips to Home Despot and others it seems that all the commercial bus bars are aluminum. Copper or brass is not available anymore. They also seemed too small and only accepted #10 or #8 wire. I'd prefer #4. The price of copper has just gotten obscene the past couple years. A 100 foot coil of 10/2 wire is almost $200!

The scrap dealers here are a funny lot. There are only a couple and I think they are all related somehow. They really don't want to deal with walk-in traffic and small lots and will always try to rip you off. Even after haggling the price is not really any better than some of the online retailers. Since they are a long drive and out of my way to go there I'd just as soon save the aggravation and order it.

I have 6061 aluminum billet in the shop I can use, but that's a last resort. I'm not desperate, yet. I like the idea of using PVC for covers. I'll have to think about that one.

Thanks again,

Kevin
As far from the city as I can get but still keep my job.

Offline ChrisOlson

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Re: Battery bus design
« Reply #7 on: April 28, 2012, 09:04:49 PM »
During trips to Home Despot and others it seems that all the commercial bus bars are aluminum. Copper or brass is not available anymore. They also seemed too small and only accepted #10 or #8 wire.

Whoa - don't use those.  Those are for ground strips in AC service panels.  The bars in my SquareD bus are about 1/2" thick and 1 1/2" wide.  They got a big screw lug on the top that accepts 4/0 cable and the rest of the bar is drilled and tapped for 5/16" NF bolts.

Anything you find at Home Depot is going to be a toy for DC.
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Offline ksouers

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Re: Battery bus design
« Reply #8 on: April 28, 2012, 10:12:53 PM »
During trips to Home Despot and others it seems that all the commercial bus bars are aluminum. Copper or brass is not available anymore. They also seemed too small and only accepted #10 or #8 wire.

Whoa - don't use those.
--
Chris

Had no intention to. Way too small. I've looked several times and they have no other bus bars of any kind.

I checked current prices with one of the online vendors I use for metal stock. Copper is a bloody fortune, brass is a little more than 2/3rd that price.
A two foot piece is about the price of a tank of gas.  :o  Both are quite ridiculous.


Kevin
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Offline ghurd

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Re: Battery bus design
« Reply #9 on: April 29, 2012, 12:35:07 AM »
It has 6061 aluminum bars in it.

Why do you believe it is 6061?
That's kind of a generic type of AL considering all the types made.  Seems like with all the different types, someone must make something special.

I'm not keen on the idea of using aluminum....
Home Despot and others...

Me too, about the AL.

600W and 1000W inverter, and a couple hundred watts of solar?
I was thinking more along the lines of parts for those obnoxious car stereos.  Retailers like best buy, or "stereo parts to PO your neighbors at 2:30AM with crappy music and rattling windows dot com".

I like ebay because of the photos, but.... here is a quick copy/paste with some pricing, they all have a cover, and these were all on the 1st page of my search.

STINGER SPD5210. SKU: SPD5210. Fused Distribution: ANL. Input Gauge (s): 0 Gauge. Inputs: 1. Output Gauge (s): 4 Gauge. Outputs: 2. ($30)

AudioPipe PB-1448. 1 in 4 out configuration. 4/6/8 gauge compatible (IN). 8/10/12 gauge compatible (OUT) . ($13)

AUDIOBAHN ADB48 CAR AUDIO STEREO WIRE DISTRIBUTION BLOCK (1) 4GA IN (4) 8GA OUT ($12)

Platinum Car Stereo Distribution Block. One 4 Gauge Input. Four 8 Gauge Outputs. Works with Power or Ground Wires. Platinum Finish with Gold Hardware. ($8)

All prices were "Buy Now" and included 'free S&H'.

Be hard pressed to find a metal retailer who would SHIP enough material to make a bus bar for $8 in S&H?
That's how I was thinking,
G-

Offline ChrisOlson

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Re: Battery bus design
« Reply #10 on: April 29, 2012, 08:35:47 AM »
It has 6061 aluminum bars in it.

Because that's what all the commercially made panels use for aluminum bus bars.
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Offline ksouers

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Re: Battery bus design
« Reply #11 on: April 29, 2012, 08:47:57 AM »
Thanks G. Good suggestions. I hadn't thought about how much power those obnoxious rattle-traps need.

600W and 1000W inverter, and a couple hundred watts of solar?

G-

That's only TODAY. This is a growing system. I have more panels arriving in a couple days. I will be adding more panels and batteries throughout the year. Think more along the lines of a 2500-3500 watt inverter, that's the goal.
We budgeted 6000-9000 USD for a standby generator. I thought spending that money on solar made more sense. The genny is just a lump of iron until those days we need it. If the RE can be used to help mitigate the electric bill a little and feed my sense of independence, then even better. Made more sense to me. I'll never be off grid here, not in this house, but I'll put up as much solar as I can to keep the wife happy when the rest of the neighborhood goes dark.

We have really nasty storms here where the straight line winds can easily be 60-70 MPH, sometimes reaching 100. Then we also get those twisty ones that send little girls from Kansas to far off lands. Wintertime is subject to ice storms that also take down trees and powerlines. Time without electricity here is measured in days and weeks (yes, weeks!) not just hours after one of these storms. I'm on the edge of civilization*, it's a mix of family farms and subdivisions. It takes awhile before the power company comes out here to repair the damage.


Kevin

* "civilization" being as far away from the city and 'burbs as I can possibly get and still keep my day job.
As far from the city as I can get but still keep my job.

Offline ghurd

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Re: Battery bus design
« Reply #12 on: April 29, 2012, 09:50:36 AM »

We budgeted 6000-9000 USD for a standby generator. I thought spending that money on solar made more sense.

Time without electricity here is measured in days and weeks (yes, weeks!)


Agreed.
Should be able to get by with a $500 genny?

My Bro-in-laws place had the power poles behind the houses, instead of on the road.  60 years of tree growth made it impossible to get to the lines quickly with trucks.
Ice storm took down lines all over everywhere.  Power was out for like 2 weeks?
He got by with a burrowed (from guess who?)1200W inverter, 2 times a day, connected to an idling Chevy Cavalier.
Inverter by the car, long extension cord to the fridge.  Once the fridge started running (would usually trip the inverter a couple times before it got running), he could charge the laptops and cell phones and hand held video games at the same time.
Seems like he only had to connect it to the furnace a time or 2, but the house was not very warm most of the time!
If he got by with a 1200W inverter, not sure how bad he would need a $9,000 back-up genny!  ;)

BTW- That was in the densely populated burbs of Pittsburgh, PA.
G-

Offline ksouers

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Re: Battery bus design
« Reply #13 on: April 29, 2012, 10:29:49 AM »
I already have a 5500 watt portable genny. But it's a finicky pull start and noisy and still needs to be fed. The last ice storm we had blocked all the roads out of here (3 escape routes) with lots of trees and powerlines down and we couldn't get out for a couple days. All the gas cans were empty by time I got out to fill them up again. We went through 20 gallons of gas in two days. That last night I was running a 300 watt inverter off the car to power a light (as much for heat as light) and a radio for news. The next morning they had one of the roads open and I was able to get gas, we were back in bidness.

It was a pretty bad disaster and a total CF by the county. The cops wouldn't let anybody cut up the trees blocking the roads until the utility company had untangled the power lines and cleared the snapped poles.

$9000 was the high estimate we got for a small genny with autostart, installation, natural gas service upgrade and transfer panel.


Kevin
As far from the city as I can get but still keep my job.

Offline Rover

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Re: Battery bus design
« Reply #14 on: April 29, 2012, 11:21:01 AM »
As far as bus bars... I just order copper bar from Speedy Metals (speedymetals.com), price isn't that bad. I usually get 1" x 1/8" . Right now I have just wrapped with electrical tape (red and black) for a small piece of mind. The PVC is a good idea.

Cut and drill etc as needed. Obviously size your bars for the intended voltage and current.

I'm a little concerned you are planning on continuously growing your bank. It can be done, but you're typically better off starting with a larger bank, rather than having an arrangement of young and older batteries.

Rover
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