I’m building up a BMC TM01, with Di2 9070 and opted for the external battery so I can use the frame’s internal storage… I got both the external charger sm-btr1 for charging and the internal charger sm-btr2 so I can use the e-tube project software .
My question is, why doesnt the external battery charge when using the internal sm-btr2 charger? Aren’t the batteries just batteries or is there more to it? Thanks.