The battery builders club

Honestly it hasn’t been the biggest improvement. The major change is overheating. When pulling 80 battery amps on the same setup I never overheat.

At low to medium speeds, 80+80 motor / 80 battery feels pretty much the same as 80+80 motor / 160 battery. Where it shines though is keeping that powerful feel past easy cruising speed. This surprised me, that off the line it felt almost the same.

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Yeah for me my at speed acceleration isn’t super great, and on hills my voltage sag is pretty bad

At lower battery voltages the problems are more apparent


Hey, I have a question for builders using Cooper braid for series, what’s your work process, do you pre-tin the braid and then solder it, go straight away to the PCB/nickel or… ? You get the idea.

You should always pre-tin both sides. Pre-tin nickel, pre-tin braid. Place them, then heat both solder blobs till they melt together fully. It will work without pre-tinning, but you won’t be able to tell as easy if you got a cold solder joint on the pad without yanking or wiggling at it hard. Really melting solder good to the pad first and you can avoid cold joints easier. I’d recommend not pre-tinning the braid with as much solder as the pad because the braid will wick the solder, solidify down the braid, and become inflexible and brittle.

If holding my iron for a while when pre-tinning, I usually spread extra flux on both sides being joined, or at the very least melt a little bit more solder in there so it all flows together.

Also, are you using lead free solder? If I’m doing fat cables or anything requiring a lot of heat, leaded solder melts so much easier- lead free requires substantially higher temps to not get cold joints. I always try to use leaded solder unless I’m soldering in the living room or something and I don’t want bits of lead in the carpet

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If you don’t need your product to pass a health safety rating go for good quality 60/40 solder and throw that lead free garbage in a bin.
I have been doing DIY for many years and if I learned three things it is:

  • Pre-tin both sides
  • Use more flux… the bigger the glob the better the job
  • Don’t ever use lead free solder
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Iv been trying out settings on cheep eBay battery and 0.3mm Nickle strip increasing then pulling it off with pliers. It started to get stronger about the 120j and I can feel the heat building guessing about 40 deg if I toutch it straight after welding heat gone after a second. I’m worried I’m using to much energy. What people’s opinions? More or less?

130j I started to rip a hole in the Nickle when pulling it off on 1 contact. 100j seemed to start to leave a little Nickle behind.

so it seems I need difrent settings from pos and beg terminals. My tests found that using a new batty and Nickle strip I was pulling it off early with pliers.

I think this is a little to much energy but is the strongest join so fare by a long way.

I’m no builder, but usually no one uses anything thicker than 0.2. this is just to thick, for what you’re doing.

thanks think you right

If the welds show burn marks it’s usually a bit much.

I think like @Andy87 is saying, you’re just blasting it with too much energy.

I’m sorry if that’s not a right group to post it but I’m a noobie and I need a little help before I start building .
Just recieved last part needed for my skateboard. I want to start building battery tomorrow using Samsung Q30 and NESE 2s4p modules - to create 10s4p pack. I’m also using DieBieMS with discharge and charge setup. Can you please review my build plan so i dont destroy my BMS or Q30 cells. Thanks a lot!!!

Also that’s my first build so sorry for shitty discription and plan.

I thort that but if you look at the back it’s not leaving behind any nickel I think I need more preset and holes in the nickel to force the current thro the nickel in to the battery as it appears most is tracking thro the Nickle alone with out penetrating in to the battery.

For now iv gone back to 0.15 will reinforce it with flat 10mm by 1mm tined copper braid.

Cool, is that a K Weld? What power source are you using?

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Your diagram looks good to me. Have fun building!

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Hey nice welder. :slight_smile:
I tried .25mm and .30mm nickel, and it could make good welds but I felt there was too much energy going in. Everything got very hot. Seemed better to solder copper wire to the cells at that point. iirc about 60 joules is the most I feel comfortable using on 18650.

Splitting the nickel will probably help, but that is not a convenient operation as far as I can figure.

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Need help with BMS

I’m using this BMS bypassing discharge. It’s a 13s BMS but I’m using it for a 12s3p 30Q pack. I followed the schematic except for the last wire.

My problem is:

B- to B12 = 49.0V
B- to B13 = 0.0V
Main + and Main - = 49.0 V (Bypassing Discharge)
Main + and C- = 43.9 V
Main + and P- = 43.9 V

Anyone know what’s happening here?

why? i’m not even sure that works. there was some anecdotal evidence you can use higher S count bms on lower voltage packs but nothing confirmed.

in your diagram, B13 lead is pack+, but that’s already connected to B12 lead so not sure how you can get around that.

mmm…i’d rather find a 12S bms.

comon brosef, why you gotta make me link this?

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difference is bestech bms balance leads don’t attach to pack+ and pack-.

(diff model but same idea)
image

whereas the one that’s being used here, highest and lowest balance leads DO attach to pack+ and pack-.

also, that post by @scepterr, that’s an initial finding and he said he’s need further confirmation. then that thread digresses into using multiple low S count bms to balance higher S count packs. i was there when that happened.

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