You're running too much current on the welder. The discoloration is too extreme.
I guess I need to make 72v 35ah battery pack
- Thread starter biknut
- Start date
docw009
10 MW
I've not had clean folds even with two cell widths. What I have done is solder the two layers together, after they are stacked in place.
hello sir, you are using too much J in your kweld to spot weld. some posts ago you posted a picture of your spot weld, the cables are too long, reduce the cable the most you can and try to use only 55J, I use the same kweld as you and 55J is just perfect.
I don't understand what you trying to fold, usually this battery requires only you to fold from series 10 to series 11. To fold the battery you should join all the battery as one, then you lay the battery on her side (after you protect everything off course) and you fold the battery always keeping the battery on his side so it folds perfectly.
so basically you do all the 2 parts of the battery and protect everything (I recommend also doing the negative and positive of the battery while the parts are disconnected, is easier to solder) after that you spot weld the copper between the 2 packs.
finally with your battery in the position of the photo above, you fold the battery always keeping the side of the battery under support. don't try to bend the Cooper piece by piece.
also remember to use some hard isolation between your packs.
I don't understand what you trying to fold, usually this battery requires only you to fold from series 10 to series 11. To fold the battery you should join all the battery as one, then you lay the battery on her side (after you protect everything off course) and you fold the battery always keeping the battery on his side so it folds perfectly.
so basically you do all the 2 parts of the battery and protect everything (I recommend also doing the negative and positive of the battery while the parts are disconnected, is easier to solder) after that you spot weld the copper between the 2 packs.
finally with your battery in the position of the photo above, you fold the battery always keeping the side of the battery under support. don't try to bend the Cooper piece by piece.
also remember to use some hard isolation between your packs.
If it helps, I have made quite a few of these now with some previous Bomber packs reaching 3.25kwh/45AH+.
For every single one, to fold them I've done it in stages. Starting with them end on end and folding each layer over as it is applied. Works for both copper/nickel sandwich and many nickle layer approaches. I usually use something hard like a plastic tyre lever to push the layer into the right shape as I fold also. They key and important thing to note is that you add thick/multiple layers of insulation (barley paper and/or kapton tape) around the cell top (positive) end where the nickel/copper folds over. As it folds it will want to push down hard into the edge of the cells at the end and can short out if not enough insulation is present.
You will end up with a small amount of excess poking out the end if doing it this way, but this has never been enough for it to be a problem and easily within the length taken up by padding.
I would not recommend the wire/solder method if you can avoid it. It's not a huge issue, but it just takes up space and could place pressure where you don't want it without a lot of padding....then you've got a space issue again.
Hope that helps.
Cheers
For every single one, to fold them I've done it in stages. Starting with them end on end and folding each layer over as it is applied. Works for both copper/nickel sandwich and many nickle layer approaches. I usually use something hard like a plastic tyre lever to push the layer into the right shape as I fold also. They key and important thing to note is that you add thick/multiple layers of insulation (barley paper and/or kapton tape) around the cell top (positive) end where the nickel/copper folds over. As it folds it will want to push down hard into the edge of the cells at the end and can short out if not enough insulation is present.
You will end up with a small amount of excess poking out the end if doing it this way, but this has never been enough for it to be a problem and easily within the length taken up by padding.
I would not recommend the wire/solder method if you can avoid it. It's not a huge issue, but it just takes up space and could place pressure where you don't want it without a lot of padding....then you've got a space issue again.
Hope that helps.
Cheers
Thanks for the reply. I was coming to that same conclusion.
Thanks CD, I appreciate your advise. I would prefer to fold it, but I may have to use wires anyway. This copper is so thick for trying to fold 7 cells at once. Soldering such short wires is tricky too because of the solder wicking into the wire, but Mr EE has a very high level of skill for soldering. If anyone can do it, he can.
When I started out I thought I was smart using 21700 cells, but they're turning out to be a big PIA
Trust me TV, the alternative has it's own drawbacks. Pouch cells work great....at first...then they swell, bloat and can easily puncture or in some cases spontaneously burst and catch fire. They also have no self supporting structure, the tabs can be hard to work with depending on the layout/application, sometimes requiring custom fabrication of bus bars etc, and they often don't last as long as comparable cylindrical cell options, especially when they swell.
I have bikes with both 18650's/21700's and pouch batteries and the preferred custom made option is still cylindrical cans.
If you have to solder, they key is keeping things cool. I wrap wet wipes around the cells being soldered and have a fan blowing on them while soldering. Get the iron as hot as possible, and apply for as short a time as possible to avoid heat soaking into the cells.
Cheers
I have bikes with both 18650's/21700's and pouch batteries and the preferred custom made option is still cylindrical cans.
If you have to solder, they key is keeping things cool. I wrap wet wipes around the cells being soldered and have a fan blowing on them while soldering. Get the iron as hot as possible, and apply for as short a time as possible to avoid heat soaking into the cells.
Cheers
I actually think you made the correct choice.
I throttled the Kweld back to 94j, and started welding today. I only did one side. The composite seems easy to weld. So far so good. Next MrEE is going to solder the 5th, and 6th, and 15th, and 16th rows together. That's where both haves will be folded eventually.
Chalo
100 TW
Rectangular, okay. Would have been way easier to use 35Ah cells, yeah? And just as rectangular.
Sondors guy, though. Must learn the hard way, or not learn at all perhaps.
Sondors guy, though. Must learn the hard way, or not learn at all perhaps.
Would recommend adding kaptop tape as you go. Dropping a metal tool on top of that is the last thing you will see happen!
Cheers
Cheers
j bjork
1 MW
Are you welding with 94J ?!
Are your cells surviving that? I welded the first battery with 45J, but I got a little hissing sound on two cells. Not sure if they got punctured, but I am afraid that they did. I welded the second with 40J, and it seems like it went well.
Wellgo bus plates with the same style of weld inserts.
Are your cells surviving that? I welded the first battery with 45J, but I got a little hissing sound on two cells. Not sure if they got punctured, but I am afraid that they did. I welded the second with 40J, and it seems like it went well.
Wellgo bus plates with the same style of weld inserts.
Yes 94. I tested 90, but some of the welds were easy to pull apart. 100 seemed pretty severe. I'm using a 12v truck battery as a power source.
Very very good congratulations. Is not the layout I would use and 90J seems to much to me, but looks very very good.
Thanks I appreciate it. So far so good.
I ordered some insulating double sided heat tape to help hold this thing together after folding.
Can anyone give me tips on how to get the right size of shrink tube I'm going to need for this pack? The measurements are approx 340mm L x 120mm W x 160mm H
Can anyone give me tips on how to get the right size of shrink tube I'm going to need for this pack? The measurements are approx 340mm L x 120mm W x 160mm H
Search for PVC heatshrink on aliexpress. Get a size above and below what you think you need and order twice as long as you think you need.
If you use a hair dryer it will be slower but less likely to tear. A heat gun is much faster but can heat through if not careful and you'll have a hole to patch....that's why you order twice as long as you think you need.
Cheers
docw009
10 MW
The perimeter of the battery would be 120 +160 for 280 mm. Anything above that will work, and I rather not use the 2:1 shrink that they advertise. Ten percent is good.
I'd probably look for 320mm wide heat shrink, but I prefer to use the rubber heat shrink, It takes more heat to work with, but is a lot tougher. I'm not aware of any rubber heat shrink that is that wide enough for a 280mm perimeter, I've seen 290mm at batteryspace.com, which has expensive shipping.
I'd probably look for 320mm wide heat shrink, but I prefer to use the rubber heat shrink, It takes more heat to work with, but is a lot tougher. I'm not aware of any rubber heat shrink that is that wide enough for a 280mm perimeter, I've seen 290mm at batteryspace.com, which has expensive shipping.
Oh yeah, should have clarified.....you'll want to put padding on before heatshrink.
I like to use single sided stick on specific battery battery padding. Not cheap and hard to find, but worth it IMO. Leave gaps for hot area's like the BMS and build up padding nearby to give a good buffer.
Just don't use any open cell foam or reuse any packaging....that will compress permanently and not do a good job.
Cheers
I like to use single sided stick on specific battery battery padding. Not cheap and hard to find, but worth it IMO. Leave gaps for hot area's like the BMS and build up padding nearby to give a good buffer.
Just don't use any open cell foam or reuse any packaging....that will compress permanently and not do a good job.
Cheers
Thanks doc that's very helpful.
Thanks CD. I'm not familiar with padding, this is new to me. What I have so far is fiberglass sheet, fish paper, and heat tape, and soon double sided heat tape.