Re-Build ande Re-Cell of Shimano Batteries

[serden28a]

@Darmanin Nice battery! Could you please let me know what cells did you use (~5300mAh 32650?) and from where did you buy them? Thanks.

 

[Darmanin]

@Darmanin Nice battery! Could you please let me know what cells did you use (~5300mAh 32650?) and from where did you buy them? Thanks.

We used the 21700 Samsung 58E (pack of 40cells)

 

[Paco_Loco]

Would it be possible to reduce the battery size/capacity during this process?
i.e. by rebuilding it using less cells.
Or is there some reason to do with the BMS why that wouldn’t work?

 

[serden28a]

Would it be possible to reduce the battery size/capacity during this process?
i.e. by rebuilding it using less cells.
Or is there some reason to do with the BMS why that wouldn’t work?

As far as I know, the BMS is not concerned with the type or number of cells per bank. You need at least ten identical cells in series to reach a nominal voltage of 36V. Additionally, the engine's power requirements must be met, meaning the pack must be able to deliver 500–600W in boost mode. From there, we can calculate the maximum current per cell: 600W ÷ 36V = 16.66A. Rounding up, we conclude that we need at least 10 cells, each capable of 20A. The smallest cylindrical cells capable of 20A are probably the 18650 type. They usually weigh 45-50g each, so 10 of them weigh less than 500 g. The wiring, BMS, and minimal case add at least another 200 g. In theory, you could build a 3Ah (108Wh) battery weighing 700 g. With 10 21700 cells you can build a 5Ah (180Wh) battery weighing 10x70g+200g=900g.

 

[Paco_Loco]

As far as I know, the BMS is not concerned with the type or number of cells per bank. You need at least ten identical cells in series to reach a nominal voltage of 36V. Additionally, the engine's power requirements must be met, meaning the pack must be able to deliver 500–600W in boost mode. From there, we can calculate the maximum current per cell: 600W ÷ 36V = 16.66A. Rounding up, we conclude that we need at least 10 cells, each capable of 20A. The smallest cylindrical cells capable of 20A are probably the 18650 type. They usually weigh 45-50g each, so 10 of them weigh less than 500 g. The wiring, BMS, and minimal case add at least another 200 g. In theory, you could build a 3Ah (108Wh) battery weighing 700 g. With 10 21700 cells you can build a 5Ah (180Wh) battery weighing 10x70g+200g=900g.

Awesome - thanks for the comprehensive reply! Super helpful

 

[Toomanybikesnotenoughlegs]

The wife’s Vitus has developed a problem with its BT8010 …..it’ll take a charge and the charger comes up with no faults ..
But the battery won’t turn on without having to REALLY press the on button and then it’ll show five lights , but waggle the battery and they’ll flicker …..what’s loose or is it rebuild time …
I’ve opened the battery and there’s a clip that goes to the back of the power button that seems to be disconnected or just slots in?!!?

 

[Toomanybikesnotenoughlegs]

What’s this and is it supposed to be loose ?!

 

[Toomanybikesnotenoughlegs]

Soooo update , tried a few things and touched a few bits , but I’m not brave enough to mess with it …but discovered if I push and hold on the corner of the front board near the connector ribbon the lights come on and stay on, take pressure off , lights go out ….simple fix or

 

[Ogorek]

What kind of plates did you use to connect the cells? 0.15 or 0.2 mm?