Hidden battery in the DownTube replacements hard to find?

[endi67]

am i missing something here, or is that i don't understand the battery technology. most of the batteries i have looked at on line; china aliexpress and bafang in tube models (bt f040.b360.c) all have a 2 wire dc output (+ and -) based on the voltage of the battery, say 36, 52, or 72 volts. the battery output wire plugs into the controller which is specific to the motor electronics. The controller voltage has to match or be capable of handling a higher voltage.

 

[gromike]

On some ebikes the whole thing is a propriety system. The battery communicates with the controller.
Makes things complicated, from what I understand.

 

[harryS]

am i missing something here, or is that i don't understand the battery technology. most of the batteries i have looked at on line; china aliexpress and bafang in tube models (bt f040.b360.c) all have a 2 wire dc output (+ and -) based on the voltage of the battery, say 36, 52, or 72 volts.

I don't see anything like the BT F040.B360.C tubular battery on aliexpress. Maybe you can post a link?


.

 

[tomjasz]

For us kit builders there are controllers that read the battery voltage and adapt to 24v.36v.48v and 52v. 24v options are almost if not already unubtanium

 

[lnanek]

am i missing something here, or is that i don't understand the battery technology. most of the batteries i have looked at on line; china aliexpress and bafang in tube models (bt f040.b360.c) all have a 2 wire dc output (+ and -) based on the voltage of the battery, say 36, 52, or 72 volts. the battery output wire plugs into the controller which is specific to the motor electronics. The controller voltage has to match or be capable of handling a higher voltage.

Expensive proprietary bikes with motors like from Bosch don't just have positive and negative lines coming out of the battery, but also CAN bus high and CAN bus low:


The BMS in the battery pack has an extra driver chip to support this. The motor will refuse to work with a pack that doesn't communicate with it correctly over CAN bus.