Two Batteries with steps 8000?

[Hugh-Jazz]

I'm building up a custom mtb tandem frame with a steps 8000 motor. My current plan is to hold two 504WH motors external on the frame, with one being wired to the motor and other only mounted. We will swap batteries when the first one is used up. The Bosch system on the Moustache tandem can switch between two battery packs automatically to use both without having to swap. Does Shimano support a similar mulit-battery setup?

 

[MassDeduction]

I've never seen a dual-battery set-up with a Shimano motor, it doesn't seem to be something that Shimano has been targeting. A shame, as I'd be interested in an option like that.

 

[Hugh-Jazz]

I'm probably going to end up with two Shimano batteries, one hooked up and other in a dummy mount. The other option would be to use YT Decoy battery if we decide on a custom boom tube. That option may be more trouble than it's worth.

 

[steve_sordy]

The Shimano Steps 8000 motored Focus has this as standard. It has a 378Whr battery in the frame and the same capacity TEC pack. The TEC pack slots onto a rail on the downtube and is connected to the charging point with a short cable. If the cable is connected, the motor takes power from the TEC pack. If disconnected, it takes power from the frame battery. You choose which is used. You can swap between them whenever you like. You can also swap as often as you like (although why would you want to?)

The idea was to make the bike as light as possible for most rides and then add extra battery for the longer rides. It works. If the frame battery was 504Whr, the total of 882Whr would be something else!

 

[Hugh-Jazz]

The Focus bike must have a transfer switch to sense voltage and switch. I wonder if that is available as a spare/replacement part? The Shimano motor connector has a pair of pins in addition to the normal battery terminals.