I continue thinking about possible configurations for my e-bike. Due to several "real world" constraints, I am considering going "big" anyway (since having small packages in the end have almost the same constraints, for my personal situation, as big ones).
One possibility is going towards a 50V (14s) / 40A configuration, ie 2kW.
The reasons for this configuration are as follows:
- 100 pieces of good batteries are cheap (I have been quoted $2.07 for a Samsung 22P). This would allow a 14s7p configuration (98 cells plus 2 spare in case there are bad cells)
- A good 14s 40A BMS is available: http://em3ev.com/store/index.php?route=product/product&path=42&product_id=75 and then there are the bestech BMS, too
- em3ev provides good controllers, such as the 12 fet 40A one http://em3ev.com/store/index.php?route=product/product&path=38&product_id=81
Note: 7p of 2.2Ah is about 15.4Ah. Samsung 22P are quoted to give 10A. 7p would theoretically give a max of 70A. I guess assuming a max in the real world of 40A (slightly above 50% of the theoretical maximum) is not irrational
This configuration would require building a tailor-made enclosure. I believe I have found technicians who can do that, anchoring that box to the holes for the water bottle. A box there has a good center of gravity, and the solution can be replicated for any bike, assuming there are holes for the water bottle. The controller could also be put inside the box, making the whole structure safer.
The question is if 2kW is too much. There is little information about max power for Xofo / Bafang CST motors. There is a loose assertion that gears "go" at around 2kW. There is also an assertion that the max power for these motors should be 1.5kW to 2kW. d8veh asserted he briefly tried a Xofo with almost 70V and about 30A (slightly above 2kW) and nothing went wrong, apparently.
I would not be using 2kW constantly. In fact, I believe I would be using much, much less power, say 200W. But maybe some day I would need strong power (on a hurry going home?). And surprisingly, powerful configurations are almost as cheap as 250w ones.
What do you think?
One possibility is going towards a 50V (14s) / 40A configuration, ie 2kW.
The reasons for this configuration are as follows:
- 100 pieces of good batteries are cheap (I have been quoted $2.07 for a Samsung 22P). This would allow a 14s7p configuration (98 cells plus 2 spare in case there are bad cells)
- A good 14s 40A BMS is available: http://em3ev.com/store/index.php?route=product/product&path=42&product_id=75 and then there are the bestech BMS, too
- em3ev provides good controllers, such as the 12 fet 40A one http://em3ev.com/store/index.php?route=product/product&path=38&product_id=81
Note: 7p of 2.2Ah is about 15.4Ah. Samsung 22P are quoted to give 10A. 7p would theoretically give a max of 70A. I guess assuming a max in the real world of 40A (slightly above 50% of the theoretical maximum) is not irrational
This configuration would require building a tailor-made enclosure. I believe I have found technicians who can do that, anchoring that box to the holes for the water bottle. A box there has a good center of gravity, and the solution can be replicated for any bike, assuming there are holes for the water bottle. The controller could also be put inside the box, making the whole structure safer.
The question is if 2kW is too much. There is little information about max power for Xofo / Bafang CST motors. There is a loose assertion that gears "go" at around 2kW. There is also an assertion that the max power for these motors should be 1.5kW to 2kW. d8veh asserted he briefly tried a Xofo with almost 70V and about 30A (slightly above 2kW) and nothing went wrong, apparently.
I would not be using 2kW constantly. In fact, I believe I would be using much, much less power, say 200W. But maybe some day I would need strong power (on a hurry going home?). And surprisingly, powerful configurations are almost as cheap as 250w ones.
What do you think?
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