The Kweld setup I used for this:
1600w power supply from a Bitcoin mining machine.
Ksuppply set to 8.1v
Kcap
Kwelder
1600w power supply from a Bitcoin mining machine.
Ksuppply set to 8.1v
Kcap
Kwelder
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I guess I need to make 72v 35ah battery pack
- Thread starter biknut
- Start date
Thank you for this post. My bike is the same model as your's. I was wondering, was it necessary to space out your side covers, and where did you fit the BMS?
Hello, no the battery is the exact size of the frame, almost 12cm. You can see no space is needed between covers and frame.
The BMS goes on the top of the battery.
Try to use the outsides of the original pack made from fiberglass to design your battery, I made mine using them as limit and even used them to close and protect the pack. The pack is the exact same width as the original.
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cheeko
100 W
Nice Controller, I have the same on my Futr Beta or Stealth P7 Running 20S7P 105A Mxus 3k, Good Work i built my own battery and whole bike never its still going strong after 5 years.
eMark
100 kW
If you had used plastic cell spacers instead of staggering and gluing the cells together (to save space) would your DIY battery still fit in the frame space of your bike?
If you had used plastic cell spacers instead of staggering and gluing the 140 cells together (to save space) would your DIY battery still fit in your bike frame ?
Sometimes there doesn't seem to be any other option other than staggering the cells and gluing (to save space)) in order to fit your DiY battery pack in the bike frame. With a BMS temperature sensor is there little need to worry about thermal runaway ... correct?
What is the best method to monitor cell pack temperature of a glued staggered cell arrangement in a custom DIY battery pack to hopefully prevent any danger of thermal runaway?
Will plastic holders would not fit the frame.
eMark
100 kW
Do you use an internal temp sensor in the middle of your 20s7p battery pack or does the BMS shut-down the battery should the temp of any of the innermost cells gets too hot (thermal run away?).
Have you run any tests to see how long you can run at MCD before innermost cells of your 20s7p reach ... say 110 F, 43 C) ? What do you consider the maximum inner cells temp to throttle down preventing the danger of thermal runaway (fire).
Hello,
The pack is 21s9p not 20s7p, each cell is rated for 45amps so even if I use 140amps each cell will only be at 15amps, very low for this cells.
But yes the pack have 4 temp sensors never got this pack warm.
cheeko
100 W
Im still rocking the Ant BMS and have the VBMS app it shows all cells and temp also
I'm in a holding pattern right now waiting for the battery cells to arrive. I've been stressing over the bms I bought because it's too big to fit without a lot of extra trouble. I found another one, actually two. One is 100 amp, and a 120 amp. Both are small enough that they should fit on the end of the battery so I bought them both. The 120 amp only has about 1/4 inch clearance so I'm not sure about it. I'll use it if I can but just in case, the 100 amp is definitely small enough. If I end up using the 120 amp that would allow me to install my Nucular controller at a later date, probably next winter. If I use the 100 amp bms then I'll be fine keeping my 80 amp Kelly controller.
I didn't know what ANT bms means, but apparently it's a brand name sold by a lot of different stores in china. I think the first one I bought is made by the same company.
I didn't know what ANT bms means, but apparently it's a brand name sold by a lot of different stores in china. I think the first one I bought is made by the same company.
O have used Ant BMS 300 amps, they are cheap and good, they will fit on the top of the battery no problem.
Here is the link. 24s double layer version (2,5cm)
https://a.aliexpress.com/_EGkZah9
Have Bluetooth, predischarge, 200 MA passive balancer, etc etc
Here is the link. 24s double layer version (2,5cm)
https://a.aliexpress.com/_EGkZah9
Have Bluetooth, predischarge, 200 MA passive balancer, etc etc
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floydr
100 W
According to the link Balance current :200MA which is fine for most batteries.
later floyd
later floyd
Thanks for the info. That's a different store than the one I bought from but the product is exactly the same.
This 100A, ANT BMS came today. Love the small size. 
This should work fine with my 80A controller. It's tempting to plan on upgrading, but my bike has been so satisfying to ride since the last upgrade I think I'll leave it alone for once. I'm already expecting somewhat better performance from a less saggy battery.
This should work fine with my 80A controller. It's tempting to plan on upgrading, but my bike has been so satisfying to ride since the last upgrade I think I'll leave it alone for once. I'm already expecting somewhat better performance from a less saggy battery.I'm planning to make a copper sandwich with this 0.20 32.5 2P copper. It was easy to figure out the correct size for the plastic cell holders I'm using because of the 2 sizes available, I always order the wrong size first. At least the 0.15 nickel I bought will work to make the sandwich.
According to the chart this copper should be able to handle about 25 amp x 7P = 175 amp. I only have an 80amp controller so this should be well overbuilt. I hope if this is incorrect someone will let me know.
According to the chart this copper should be able to handle about 25 amp x 7P = 175 amp. I only have an 80amp controller so this should be well overbuilt. I hope if this is incorrect someone will let me know.
I did some testing of my design layout, and it looks good. I just need to trim the excess plastic off the ends. The reason it ended up that way is because it allows me to separate the battery into two equal halves, 7p 10s each, that will be folded over to be 5 cells wide.. I'm thinking 7 parallels would be easier to fold at a time than all 14 at once. The overall fit looks pretty good too. This is all 140 cells.
Attachments
The plastic holders I'm using don't snap together or connect in any way. They're 5x4. I'm guessing the pack will need to be supported on some kind of base foundation? Can anyone elaborate a little about this. I do have on order a fiberglass board material that battery suppliers sell, but I'm not sure if this is what it's used for.
Attachments
Looks almost like the original BMS from stealth.
How will you layout the nickel on this battery?
I'm planning to use 0.20 mm copper which I'm waiting on.. The layout will be like this.
Attachments
I'm thinking about something like this as an alternative design. I could fit 20s 8p 40ah in my frame. There seems to be more advantages than disadvantages to this kind of design. A battery made like this running a 80 amp controller is probably not going to ever get very hot. It would have potentially 200 amp discharge capability.
you can even fit 21s9p in your frame, im doing one with this size next week and will be posting the photo here.
samsung 50s are not the best ones with in terms of temperature, but for 80amps only you have no problem at all, 40ah is very very good, the most I got in this space was 37,8ah.
My opinion, if it's mostly fiberglass base supporting the weight you'll want 1mm or greater, and the thicker you can fit/afford the better. You'll also want a sturdy frame/armature/case, and if that's robust enough you can probably go as slim as .5mm thickness. Pack weight being a critical factor. Others probably have some useful perspective on this too.
The link photo looks like what is typically sold for isolating individual prismatic cells and/or module grouping of cells, not necessarily for load supporting, so be sure to check the items listed thickness and adjust accordingly.
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DCMotorworks
10 W
- Joined
- Jun 23, 2010
- Messages
- 75
I just purchased a bomber with no battery. I have 2 older 72v 11ah packs that I have been using to ride it around but I will need to build a new pack. I will probably go with a 20s configuration but I’m still deciding on which cells to buy. Theodore, where did you end up purchasing your cells from?
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