Bosch Powertube, can you charge at the same time as discharging ?

[Waynemarlow]

Hi, on the Bosch Powertube 625 battery, when its being charged does it require a specific charger to send it a CAN command to allow charging ?

The reason I ask this is that we want to fit a " bottle battery " as a range extender ( simple 10S1P ) the 625Wh is just a tad short on range at times. A theoretical plan would be to limit the bottle battery to say 5A and then just plug the battery into the charge port. As the main battery becomes depleted the bottle battery will charge at 5A's. That may not be enough to maintain the main the battery, but enough to charge some extra range if say you stop for a coffee or whilst using less then 5A's which maybe more often than you think.

OK thats in theory but I know Fazua needs a CAN signal to allow charging, has Bosch done the same ? Also what are the effects on the BMS if you are charging whilst also discharging ? Lots of unknowns here I think but hoping someone will know.

 

[amberwolf]

Well, to limit a battery to a certain current, you'd have to put a DC-DC converter on it's output that is current limited the same way a charger or LED PSU is, so that it lowers the voltage of the output until the current drops to the desired amount. This is going to waste a fair bit of the battery capacity as heat in the conversion process, and you will probably have to have a higher voltage battery than the system uses, to run the DC-DC from (depends on the DC-DC). But the bigger the difference between the two packs, the worse the conversion efficiency may be, depending on the converter design.

As for Bosch's proprietariness, I don't know for certain, but based on some of the posts about the Powertubes around here, I wouldn't be surprised. If the charger port has more than two pins, it's a near-certainty that it requires some enabling signal, whether that's actual communication or simply some voltage or resistance across the extra pin(s). If you can clone that signal and use an MCU (arduino, etc) to play it back when needed, you could use your own charging method, if it's a simple handshake. If it's more complex, such as the battery actually commanding the charger with a specific current or voltage, and if it doesn't get the right response or detects a different current or voltage and shuts off (or bricks itself!), it would be harder and/or not possible.

A BMS can be designed to disable discharge while charging, but as long as that's not done, then it would probably work, if you can get past all the other challenges. It's easy to test, by plugging in your charger, waiting till charge has started, then turn the bike on and engage the motor (with the wheel offground).

 

[leffex]

There´s information already out there on the youtube in german english or if it was italian already.

It needs special care. Best and easiest bet will be to remove battery and use a fast charger.

A way to hack it easier is to use the charge port as a shared port (requirement two bosch charge connectors) or drill and drag some wires out there connecting another bosch branded battery. (one charge connector required) Intuvia display will in one info menu show two battieries and their charge level. With the purion display I don´t know how it looks like.

Maybe this gets you some ideas

When I want stuff I usually have to make them myself.