I have purchased and installed two ofthese 13S cheap (US$46) BMS units on my and my partner's electric pushbikes and thought they may be of use for people building their own powerwalls.
As far as I can see they work well and I haven't managed to blow anything up.
They are based around the Texas Instruments BQ76940 Li-ion battery monitor chip with an Atmel Mega32P microcontroller providing the smarts and coms.
The big plus with these units is that the can be connected either via the USB dongle provided to a computer and programmed and calibrated via software provided. There is also a bluetooth dongle which allows the BMS to be connected to an Android app on an Android phone.
The BMS has a 30A MOSFET switch to disconnect the battery from the outside world in the event of overvoltage/undervoltage, over current and temperature out of range.
If the 30A is not enough there are 100A units or you could tap into the separate Charge Disable and Discharge Disable signals that drive the charge and discharge switching FETS. I have done a really rough sketch of the FET driving circuitry.
If anyone is interested I might look at writing some code in my BMS software to link in with this unit which would allow one to log the data and display it on the Internet.
Simon
As far as I can see they work well and I haven't managed to blow anything up.
They are based around the Texas Instruments BQ76940 Li-ion battery monitor chip with an Atmel Mega32P microcontroller providing the smarts and coms.
The big plus with these units is that the can be connected either via the USB dongle provided to a computer and programmed and calibrated via software provided. There is also a bluetooth dongle which allows the BMS to be connected to an Android app on an Android phone.
The BMS has a 30A MOSFET switch to disconnect the battery from the outside world in the event of overvoltage/undervoltage, over current and temperature out of range.
If the 30A is not enough there are 100A units or you could tap into the separate Charge Disable and Discharge Disable signals that drive the charge and discharge switching FETS. I have done a really rough sketch of the FET driving circuitry.
If anyone is interested I might look at writing some code in my BMS software to link in with this unit which would allow one to log the data and display it on the Internet.
Simon