Jump to content
Genetry Solar Forums

Battery Building Questions.


Recommended Posts

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?

Link to comment
Share on other sites

  • 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.

Link to comment
Share on other sites

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

@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.)

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

  • 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.

Link to comment
Share on other sites

Also I can put a charger on the battery it self before the bms and it starts charging the batts, but if I try with the bms in the system it won't do jack, in the app it shows the bms is fine. and shows the correct voltage as well, but not on the pysical output.

Link to comment
Share on other sites

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?

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Just had one of my Le Ion go up in flames.  Luckly I was awake in smell sometrhing burning, wnet into the power room and there was heat coming from one of the batts I made, grab the wire cutters , and snipped the wires off the bus bar and ran outside and place in the middle of the drive way.

 

luckly it was one pack in a pack of 16 that went up, snipped it out and left it while keeping the ammo box on the porch checking each of the other 15 packs makeing sure there wasn't any heat or melted eletrical tape lol.

 

 

 

These were 4.4 3.7 le ion flat cells that was used in scanners, and I paird 7 of them to make a 24v.   16 of them made 70ah.  These had built in bms, but, for some reason one of them decide to say the heck with it, my other batts bms didn't even shut down I got some floating at 15.73vdc and they are set to cut off at 14.40  Looks like I'm going to have to find a cut off switch to have from the charger to the batts. any suggestion?  I got one of those 100a victron, but from what I heard those things are junk.

Link to comment
Share on other sites

Yikes.  Glad you caught it before it got out of hand.

Did you test the cells before building the pack - ie, full cycle capacity test, temperature rise during charging, resting voltage after charging, impedance test etc?  Personally I'd never reuse any of the lithium chemistries that are prone to thermal run away unless I knew their full use history.  Even experienced people can get caught out with cells randomly turning into glow plugs.

  • Like 1
Link to comment
Share on other sites

1 hour ago, TheButcher said:

Yikes.  Glad you caught it before it got out of hand.

Did you test the cells before building the pack - ie, full cycle capacity test, temperature rise during charging, resting voltage after charging, impedance test etc?  Personally I'd never reuse any of the lithium chemistries that are prone to thermal run away unless I knew their full use history.  Even experienced people can get caught out with cells randomly turning into glow plugs.

Nope, I check to make sure they were working as far as voltage, as these supposed to have built in bms per 3.7 cell.  and they was new never used flat cells for scanners, battery hook up still sell them.

 

What happen was they were the first on the bus bar after the charger, so they get all the power before my main bank of regular Lipa4, and they reached 29.2, if I had a regulator I could have prevented it from reaching that high of a battery power. I only want my system to go up to 28V nor more better at 27.8v.  since I got a skyblue that is not wifi running my charging I can't program it so its pushing I'm guessing to 29.4 before it floats.   I'm probley going to switch it out to the other blue since I know it works now, and I have it set to not go pass 28.8 I've been letting my bank recover from a full discharge which I wasn't trying to do, and well I see what happens now, and odd, two of my 12v built batts the BMS were hot, and when I log into them to see what was going on they was over 15v range, however, as soon as I got rid of the le ion out of the system and ran a shop vac to suck the power down the master GS stop beeping and I went back into the bms and it was at normal 13.89V makes me not trust those daily bms and one of them was the overkill bms which is a modified daily bms it was hot as well.  That is why I'm looking for something that I can clamp down on the chargers when they hit that level and don't back off.

Link to comment
Share on other sites

Also I'm really, really considering on moveing the batts outside in a shed, keep the inverter where it is but move the batts on the outside in some kind of shed against the house where the power room is.  soon as I find a job where I can afford to buy a shed.

  • Like 1
Link to comment
Share on other sites

The Victron Battery Protect works well, but you have to keep within it's own specs.  The BP is not intended to switch very high loads.  People were hooking up inverters and the inrush current from the capacitors in the inverter charging up grossly exceeds the ratings of the transistors in the BP, and pretty much all FET (transistor) based protectors for that matter, and kills them.  The FETs either go open, so no power, or short, so impossible to turn power off.  Victron even advises that loads like inverters should not be connected to the BP, but it doesn't stop people doing it, and then blaming the BP when they kill it.

Ideally the battery's own BMS should protect the cells rather than relying on something external turning the current off.  Some solar chargers, such as Victron's blue / smart series, can be remotely turned off by pulling a pin on the VE.direct interface ... to +12v or 0v, can't remember which, but also with hex commands set via the serial lines on the VE.direct port.  The problem with non-lifepo4/lto cells is that once thermal run away starts disconnecting the load makes no difference.  It's all self sustaining.  All it takes is one defective cell in a pack that draws current from its neighbouring cells, not necessarily enough to blow it's own fuse to the pack bus wire.  The heat from that cell raises the  temperature of its neighbours to the point where they run away, and all hell breaks loose.

Watch this ...  it started when just one cell failed.

 

FYI, it's not just things like the BP that get destroyed with extreme current from inverter capacitors etc.  BMSes that use FETs to switch the battery output can also be damaged.  Even contactors degrade if subjected to another high current cycles.  Precharging is mandatory IMO.

 

  • Like 1
Link to comment
Share on other sites

well, then I can use the bp to cut off if the voltage gets higher then I like, will do that. I've siwtching everything to those mega vuse, but thats not going to stop the over chargeing.  nah, I don't put the bp in line to the inverter, its a BP not a power giver lol. cause 100a it would trip just turning on the gs inverter lol.

Link to comment
Share on other sites

You really should adjust the voltage your chargers are set at rather than using the BP to disconnect them even if it means calling in a friend / relative / etc.  Using the BP to terminate  charging is like using a hammer to put a screw in.  It'll work but it's not really the right tool for the job.

  • Like 1
Link to comment
Share on other sites

9 hours ago, TheButcher said:

You really should adjust the voltage your chargers are set at rather than using the BP to disconnect them even if it means calling in a friend / relative / etc.  Using the BP to terminate  charging is like using a hammer to put a screw in.  It'll work but it's not really the right tool for the job.

*laughs* last time I had somebody try to program a solar charger, they justr didn't understand what to do. lol.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...