Nuff Longboard Experiences and Repairs

ouuuu, every professional battery freak in here warns about that. I wouldn’t do it this way.

I don’t think anyone selling their pack should do it, but I also don’t think it is worth $100+ if you already have a good soldering iron and know what you are doing.

I’d ruin a bunch of cells just trying to figure out how to use the arc welder…

I guess lots of people in the forum are in SF have a spot welder maybe I can get their help…

Original onan battery pack is 89 dollars hahahaha, but anyways, its your decision. But let me give you the only advice i can give you: if you need 20 cells order a bit more, but it is always possible to get a dead cell right out of the box. I read it many times in here:wink: OH, you’re from San francisco?:wink: thought you were an australian but maybe i confound you with someone else.

This was an original onan pack! from ebay anyways.

Weird after a few hours these are the results. It kind of looks like maybe the first two cells are lower capacity than the rest, so they get fully charged before the others… stopping the charge and then it balances out to 40.8?

  1. 4.22
  2. 4.22
  3. 4.18
  4. 4.16
  5. 4.16
  6. 4.17
  7. 4.19
  8. 4.19
  9. 4.19
  10. 4.17

Doesn’t seem right, is the BMS just fucked?

Reset the bms again and charged it for about another hour…

cell before difference from max after difference from max change change in difference from max
1 4.22 0 4.26 0 0.04 0
2 4.22 0 4.26 0 0.04 0
3 4.18 0.04 4.2 0.06 0.02 0.02
4 4.16 0.06 4.18 0.08 0.02 0.02
5 4.16 0.06 4.18 0.08 0.02 0.02
6 4.17 0.05 4.2 0.06 0.03 0.01
7 4.19 0.03 4.22 0.04 0.03 0.01
8 4.19 0.03 4.22 0.04 0.03 0.01
9 4.19 0.03 4.21 0.05 0.02 0.02
10 4.17 0.05 4.21 0.05 0.04 0

It kinda just looks like a poorly matched pack. Cells 1 and 2 appear to be a lower capacity than the rest causing them to get charged first and continue to accept more charge. Or the BMS is broken or just plain sucks.

Is less than .1 volt even something to worry about between packs?

don’t really know if its to worry about, but what could happen in a worst case scenario? It will not blow up anything on the esc or something i guess, the pack just is not as good as it should be.

20190515_161528

Manually balancing cells with a taken apart usb flashlight.

The protection board from the lipo is taken out to prevent over or undervolting. The light turned on discharges the cell (very slowly .5A red 1A white) and then plugging a usb in will charge the cell (very slowly .5A).

Going to get all the cells the same and go through a power cycle and see what happens. I think this BMS doesn’t actually “balance charge” to match cells, it just “balances the charge” while it is charging as best as it can and if one cell hits 4.2 then it stops. But if the cells are out of balance then the pack won’t ever hit 100%

yeah this is crazy, hopefully you get the right result you are looking for. isn’t it possible to skip the bms, like you did, and just use a better balance charger instead to get them cells all the same voltage?

20190515_205121

Hopefully I got it! I manually balanced all the cells to 4.15~4.16 and then charged it up the rest of the way with the 42v through the BMS. I taped it back together and heatshrink put it back together for testing as soon as it stops raining!

So yeah, I think the bms is just a “balance charger”, but not an “active balance” meaning it will try to distribute the charge between the cells but once any one pack reaches 4.2 it stops instead of topping the rest off.

Oh yeah I also cut some of the fiberglass between the cells to make space for the wires, they were getting pinched.

looks good man, maybe you did it…another option is to get just another bms instead to avoid the problems you got with the chinese one.

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Did some experiments and mock ups with parts i have and a totallly diassembled x3…still forced from inside to follow my plans…i want a board with cheap hubs i can treat hard( so wasting and changing them dont needs a bank robbery at all…My first goal is to match it with the onan battery packs( which will be hacked later on). second i want an integrated charger, so i just have to carry a dc conector in my pockets😀 Anyways…this is not a build thread and i think i run out of topic a bit but maybe im in with that, who knows. 20190517_192313 20190517_192402… Edit: these are X2 hubs ( will hack them next, and show up in here, still waiting on parts):grinning:

I bought the original onan batery pack for 89 $ only problem is that the site is a little fishy never got a confirmation thru email or a tracking # despite only 2 day shipping and all there contact info is bogus… not sure if I got scammed or not we will see by Tuesday

Ordered from elecmobileusa.com or w.e I says