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Battery Building Questions.


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Well, not so much as a question. but well seeking a better way of connecting wires to battery cells.

 

I hate soldering.  Is there any type of connector that I can clamp the wire on the connector and then spot weld the darn thing on the cell?  I can't seem to find anything of such a thing.  Seem like there would be something as such.  I mean they got every other connector under the sujn. . .

 

Why not a nickled wire conntor?  I got this BMS that I'll never use, a 48v big sucker, and on the main leads its got what looks like blades connector on the end of them and I've not try to see if its any kind that can be spot welded, but really, do they even make a nickle wire connecotr by chance?

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  • 2 months later...

Was wondering, what would be  good to use.  two 14 awg capper wires per cell moudle or 3?  for 100a 12v battery.  I just got where I can solder and solder wires directly onto the batts. and was wondering if two 14 awg would hold up useing two per side.  I even solder the darn bms wires directly to the battery this time.  no more rigging :P.

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3 hours ago, Sid Genetry Solar said:

Only 14 AWG for 100A??  2x 14AWG gives you 11AWG, 3x 14AWG is 9AWG.   https://www.wirebarn.com/Combined-Wire-Gauge-Calculator_ep_42.html

6x 14AWG wires would roll in at 6AWG combined, and with 90C insulation, that could be good for 75A.  Only.  http://wiresizecalculator.net/calculators/wireampacity.htm

Uhm, even bettween the cells? not the combin output.  the conbin output I would use more stronger wire, but between wouldn't that be less amprage?

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12 minutes ago, TheButcher said:

How many cells in parallel are you talking about?  I'm assuming this is a build using cylindrical cells.

Yes, LP4 make 12v battery 100ah rateing. k26650 cells.  there is no way you going to use 10 awg wire between the cell modules.  I was useing nickle strip which works fine normal useing 3 2p nickle spot welded betweeent he moduls, but I'm doing these new ones with wire instead so I can shrink wrap them and make it look better.  they are 30 cell moduals with all them spot welded.  on my 18650 which Im' readowing there is no way you going to solder on 10 awg wire to a battery. you would short it out in a heart hbeat.

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@The Blind WolfNow I understand; was under the impression that it was a single 100Ah cell that we were talking about.  Yes, you can easily use 14AWG wire on a battery bank.  Actually, on my DIY 12kwh battery (using Tenergy 32650 LFP cells), I used 12 or 14 AWG wire on each cell string to a common binding post--but I've got 22 parallel strings.  (Cells rated 5.5Ah ~1C anyhow.)

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37 minutes ago, Sid Genetry Solar said:

@The Blind WolfNow I understand; was under the impression that it was a single 100Ah cell that we were talking about.  Yes, you can easily use 14AWG wire on a battery bank.  Actually, on my DIY 12kwh battery (using Tenergy 32650 LFP cells), I used 12 or 14 AWG wire on each cell string to a common binding post--but I've got 22 parallel strings.  (Cells rated 5.5Ah ~1C anyhow.)

huh?  22 parleele strings?  48v would be 16 moduals.  Oh never mine you mean you got 22cells in each modual I'm guessing.  Yeah my neg and pos ends will have four 14awg wires going to the terminal.  2 14awg between each modual.  That solder 60/37 flux wire works perfect, just wrap it around the bear wire, then take another wire about 6 inchs and ball it up, lay it on top of the battery cell put the pro iron gun on top of it, let it melt, then take the wire and lay it on top of that and do the same and the soler melts into the wire onto the cell and if need more just repeat with some eaxtra wire on top.  the only way I figured out how to solder with a dang two hand thing. I can't hold both wire and gun at same time since I can't see my tip. but the way I'm doing it, I can litterly take the 30 cell modual and dangel it in the air from the soder joint, so I'm thinking its good :P.

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For the most part I have never had issues soldering cells the key is doing it fast with a big iron and lots of flux and a wet rag but if you have a spot welder available that is the better option.  I know when I built my 5x5 26650 packs I used nickel strip on the negative side of the cells and then used either 3 pieces of 14AWG equally distributed or in later packs one single 8AWG bus across the nickel strips.  On the positive side I used a piece  of 8 AWG bent into a loop that would fit in the cell holder between cells and soldered a 5A fast-blow glass fuse from each positive to the 8AWG busbar.

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36 minutes ago, kuhrd said:

For the most part I have never had issues soldering cells the key is doing it fast with a big iron and lots of flux and a wet rag but if you have a spot welder available that is the better option.  I know when I built my 5x5 26650 packs I used nickel strip on the negative side of the cells and then used either 3 pieces of 14AWG equally distributed or in later packs one single 8AWG bus across the nickel strips.  On the positive side I used a piece  of 8 AWG bent into a loop that would fit in the cell holder between cells and soldered a 5A fast-blow glass fuse from each positive to the 8AWG busbar.

Well after figuring that useing Lead Free soldder doesn't work and switching to a 60/37 with flux solder, I haveing no issue soldering all wires to my battery.  I'm hopeing this time when I put it under a big load that I don't run into the issue I did with my big pack, that flash vap a nickle strip like it was never there due to over amp. also putting a bussmann 150a breaker on the battery will prevent that over spike happening again.  I found out that in my BMS programming its set to 100a for 35s before it triggers a shut down of the battery.  hence why it spiked to 279a and never shut off cause of the time, which 279a going trhough a strip of nickle spot welded to a battery then to a bulk connector with a wire to the terminal well, the nickle vap, the bulk connector disformed and the wire, didn't even flinch about it.

 

So, breaker, solder wires to cells, and reprogramming of my bms to shut off if over 100a for 10s should do the trick.  since AI will have over 5 batytery strings I should be good on not tripping that setup.

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  • 2 weeks later...

Okay, here is a weird sictuation on one of my batteries. and I don't know what else to do.

 

its a 216ah 12v 56 cells in a  modual.  All now wired solder together.  On the testing meter it shows 13.36Vdc before the bms.  On the bms five wire, its reading all correctly.  however, when I plug the bms and check from postive to negtive on terminal I'm getting 12.89Vdc.  It will not take a charge, nor give a charge.  unplug the balance calbe and the bms cuts off as it should.  I've even got another brand new bms same kind out of the box and got the same exact results.

 

I know this battery had a major 275A before it litterly smoke the nickle strips that was holding the postive wires.  I've tooken it out of the case, to solder on the bottem and checked all the nickle strips all the spot welds are fine.

 

I'm at a lost, and I need this battery since its a big one for my system.

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3 hours ago, The Blind Wolf said:

however, when I plug the bms and check from postive to negtive on terminal I'm getting 12.89Vdc.  It will not take a charge, nor give a charge.  unplug the balance calbe and the bms cuts off as it should.  I've even got another brand new bms same kind out of the box and got the same exact results.

Could you elaborate on the make/model of the BMS unit?

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30 minutes ago, Sid Genetry Solar said:

Could you elaborate on the make/model of the BMS unit?

Yep the Dayly 100a BMS from battery hook up. 12v.  all my other batts got the same kind and they all work fine. but even when I tried a brand new one never used on this battery its giveing the same results.  I check the wire coming from the negative to the bms and it shows the correct voltage.

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