smallexis Posted October 1, 2016 Share Posted October 1, 2016 2 months ago, a friend of mine has asked for my help because his 9B1 battery did not work anymore. So I ve started to check output voltage : 25V!!! that's not a good new and I have to remove blue PVC protection in order to make more controls : Confirm the problem by directly measuring the BMS output voltage between V+ & V- : again the result is 25V. But good news, cells are not damaged. Because when measuring output voltage between V+ & B-, total voltage is close to the max with 62.4V. I've soldered a wire between V- & B- to solve the output problem. But now I need to know if there is no problem during a load. I've reduced the output voltage (under 62V) in order to allow a load starting. But nothing happen. The load will not start. So the challenge was to replace NINEBOT 15S BMS, soldered on the small face of the battery (14 cells), by a "noname" 16S BMS which is bigger and need to be soldered on the bigger face (16 cells). 1st step : remove 15S BMS in order to separate both blocks of cells. And cuting all tabs. 2nd step : put new tabs on the first block and put it on the new BMS (very easy to do) 3rd step : the second block can't be soldered directly (as it is) to the new BMS. I should make some change before to put it on the BMS. I've cut the last cell (with green mark) which need to be in parallel with the first block. The first pair of cells (with orange mark) is cut in order to be soldered at the end of the block. And finaly, the last cell is soldered to the end of the block (be careful to respect polarity). After laying the tabs the second block is ready to be assembled. You have to think that there needs 2 wires to put on parallel the 2 cells that remain. And don't forget to isolate both blocks. After have checked the battery takes to load and its output voltage was nice, I put a new skin on it. The battery works perfectly (more than 100 km done since the change) with its 16S BMS and my Friend is very happy to have avoided to pay for a new battery. Link to comment Share on other sites More sharing options...
Rotator Posted October 4, 2016 Share Posted October 4, 2016 Great Job!!! Link to comment Share on other sites More sharing options...
smallexis Posted October 4, 2016 Author Share Posted October 4, 2016 5 hours ago, Rotator said: Great Job!!! Many thanks. I just add a picture to compare the battery (without protect skin) before and after the change : Link to comment Share on other sites More sharing options...
MrScruff Posted October 13, 2016 Share Posted October 13, 2016 Looks great. I'm planning to build a new battery for my NB1 e as the original battery is down on range. I'm planning to use the same bms you have pictured here with some NCR18650GA cells. Did you have any problems fitting the new battery configuration in the NB1? How does the new bms handle the missing cell? Link to comment Share on other sites More sharing options...
smallexis Posted October 13, 2016 Author Share Posted October 13, 2016 12 hours ago, MrScruff said: Looks great. I'm planning to build a new battery for my NB1 e as the original battery is down on range. I'm planning to use the same bms you have pictured here with some NCR18650GA cells. Did you have any problems fitting the new battery configuration in the NB1? How does the new bms handle the missing cell? BMS 16s means there are 16 balancing tracks and each track is independent. That's why the place where a cell is missing don't affect the BMS to play is fonction. In my exemple : Now if you want to have a model for making your own battery, maybe this link will help you : https://forum.urban360.com/index.php?/topic/223-fabriquer-ou-plutôt-assembler-sa-propre-batterie-pour-9b1/&page=1 It's a subject I have put on a french forum (so language is in french too, but you can use a translator) in which you can see many pictures to follow step by step the way I have used to make my DIY 9B1 battery. (And after more than 1400 km riding, my DIY battery still work very nice). Link to comment Share on other sites More sharing options...
MrScruff Posted October 17, 2016 Share Posted October 17, 2016 I understand the balance circuits are all independent, but the protection circuits are not. I don't understand why the under voltage protection doesn't trip as its seeing zero volts across its missing cell. Having looked at a few of the Seiko datasheets I know some of there protection ICs have the option for 3 or 4 cells. Have you had to change any pull up/down resistors on the SEL pin to change this option. As you've said, you've been using this setup without any problems so the protection ICs must be happy. Do you know which IC they use out of interest? Thanks for the extra information. Its nice to see a build with some nice high res pictures. Link to comment Share on other sites More sharing options...
smallexis Posted October 17, 2016 Author Share Posted October 17, 2016 11 hours ago, MrScruff said: Have you had to change any pull up/down resistors on the SEL pin to change this option. As you've said, you've been using this setup without any problems so the protection ICs must be happy. Do you know which IC they use out of interest? I'm not sure to have the answer but you can see on following link and pictures that this kind of BMS is able to be used from 3S to 16S : https://fr.aliexpress.com/item/12S-60A-lipo-lithium-Polymer-unicycle-BMS-PCM-PCB-battery-protection-board-for-12-Packs-18650/32709456444.html?spm=2114.13010608.0.49.j5gxQj picture from aliexpress You can see on product description this BMS is sold as a 12S BMS but it have 16 tracks, to use it as a 12S BMS you have to fix cells like that : In this case, overcharge protection is OK and discharge protection is switched (for more security) Link to comment Share on other sites More sharing options...
MrScruff Posted October 19, 2016 Share Posted October 19, 2016 I've ordered most of the bits I need for the battery and I've started work on a spot welder. To make sure i build it correctly (as its really hard to unspot weld it) I've done the below model in sketchup. Thanks for your help. Link to comment Share on other sites More sharing options...
Hunka Hunka Burning Love Posted October 19, 2016 Share Posted October 19, 2016 @Battling did some great work with his spot welder and custom battery pack build. You might search for his thread about it. Found it! Link to comment Share on other sites More sharing options...
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