man getting the tandem wired for two batteries is a bit crazy.

[fooferdoggie]

even though Gepedia offered the tandem back in 2019 with two batteries its seems they did not have the wiring or the motor setup for it. I bought it from a importer and thats what he told me. He had an extra battery holder and I traded him the charger for it and he installed it. but to get that second battery wired up it looks like my mechanic will have to splice and solder the wire as they wont fit through the opening. so its like what the hell? now Gepedia includes the tandem with two batteries installed and its twice the price. There is a place somewhat close that does this conversion so he called and asked them.
I will also have it changed over to the new nyon I like the old one but it sometimes reboots when it boots up and every time I open my phone I get the message it wants to connect and I have to ok then it opens the ebike connect app. Plus I have to open the app and change between the new and old nyon every-time I change bikes. So one anyone swapped between my bikes with a extra nyon for backup.

 

[wildtrak]

Those Gepida tandems were always a pain to get the chain and gears adjusted. And if the battery mounts are not close enough to each other, you will have to cut and extend the battery cable anyway to get it all connected on the Gepida.
I would have spent the extra $ for the Moustache tandem which is way more fun and much better setup.

 

[fooferdoggie]

Those Gepida tandems were always a pain to get the chain and gears adjusted. And if the battery mounts are not close enough to each other, you will have to cut and extend the battery cable anyway to get it all connected on the Gepida.
I would have spent the extra $ for the Moustache tandem which is way more fun and much better setup.

at the time it was over twice the price we got the Gepida for 3700.00 in 2019 and we had to struggle for that. the gearing has been totally changed and much better brakes put on it too. Plus we had never ridden a tandem and we could test ride it and it was local.

 

[mjp_hyi]

Which generation of Bosch drive unit does your Gepida have? Post a photo of the left side of the drive unit.

 

[fooferdoggie]

second gen perfomance. I guess they did not make a opening large enough for the plug ends.

 

[mjp_hyi]

I don't know why you would want to even think about splicing cables, aspecially as you keep saying warranty is a concern to you.
AS you know from your Trek dual battery setup, you need your original battery to Drive unit cable, and also a Dual Battery cable, and a Frame Battery cable, as well as a Frame battery and the mounting system. All of these are Bosch parts. The Dual Battery Y cables don't have much variety of lengths but the Frame battery cables do. They are available in lengths of approximately 200mm, 310mm, 520mm, 840mm and 1100mm IIRC. If you take off the left side cover of your Drive Unit, you'll see something like this picture, which shows the original battey cable going into the DU. So you unplug that being careful with the plastic retaining tab, and you plug the removed plug into the shorter side of your Y cable, the common plug of the Y cable goes into the Drive Unit, and you lead the long side of the Y cable out of the bottom of the DU plastic cover and zip tie it to the horizontal frame tube, leading it back towards your second battery. Then you'll need a Frame battery cable of a suitable length to come out of the bottom of the 2nd battery mount and meet up with the longer side of the Y cable. Then you need the parts to block off one of the charging sockets to prevent some bright spark thinking it's clever to plug 2 chargers in at once, which the Bosch system doesn't like.

The only reason to fret about lack of holes in the frame is if you were determined to lead the cables through the frame, which most people would say is dumb after they look at your picture which shows cables and wires attached to your tandem frame everywhere. Lots of bikes with a factory 2nd Bosch battery have cables zip tied to the frame. A few don't.

If you're still hung up on your belief that your Tandem DU won't support Dual Batteries, then you could even place your bikes close by each other, disconnect the common DU plug in the Y cable of your Trek and your Thoris, and pluf the Trek Dual Battery system into the Thoris, as well as the Nyon2, check the Nyon 2 on the Thoris handle bar sees the 2 batteries, and if it does, then pull the tandem over on its side stand so the back wheel comes off the ground, and have someone turn the pedals and see if you get electric assist. Or take it to any Bosch dealer for a checkout before you power it up.

Just use all the correct Bosch parts, and don't splice anything and I'd be expecting it to work. The left side cover may need the left pedal to come off; if you don't know how to do that, then get your pro to do it for you.

 

[fooferdoggie]

My mechanic got the ok from the bosch rep and the guy told him how to do it. plus the local shop that had done this on this bike a lot. the bosch rep said it would cause issues if the wires are run on the outside and he told my mechanic how to splice them thats approved by bosch. the run would be pretty long compared to most bikes. so when my mechanic does the work it will nto void the warranty.

 

[fooferdoggie]

we hope to drop the bike off on Sunday and get it Tuesday when we will ride next.

 

[fooferdoggie]

ok got the bike converted to two batteries. also the new nyon so I can use the same nyon on all my bikes.
the Mechanic ended up running the battery cable outside the bike it was a nightmare to try to do it inside as the connectors would have been in the middle of the tube. He made a sleeve to protect it. he has to call his bosch rep to program the motor for two batteries. but we got the bike and only one battery worked. he found he did not push the plug in all the way. no biggie.
once the 98% battery reached 71% they both kept really close t[less then 5% the times I checked.

 

[wildtrak]

he has to call his bosch rep to program the motor for two batteries.

All motors from 2016 or later support dual battery. But it is always good to do a software update (no need to call Bosch for that though).
Also the batteries require a software from 2016 or later to support dual battery setup.

once the 98% battery reached 71% they both kept really close t[less then 5% the times I checked.

The one with the higher charge is the active one when turning the bike on. It will stay active until it is 5% below the passive one. Then they switch and the now active one will discharge 10% until it is 5% below the passive one. Only at below 20% they will be true parallel to keep the current on each battery low to keep the voltage from breaking down. And you will be able to discharge them to 2% instead of 4% (if they are 500Wh, 400Wh are 3% / 5%) to keep the reserve for the light.

 

[fooferdoggie]

Just because the motor supports duel batteries does not mean the factory set it up for duel batteries. the motor needed setup for it by the bosch rep and that just took a phone call and he connected to the mechanics computer and set it up. the motor was already updated. . Hell the bike builder did not even put a large enough hole in the frame for the wire ends so it makes you wonder why they offered it with two batteries? they must have had some arrangement.

 

[wildtrak]

Just because the motor supports duel batteries does not mean the factory set it up for duel batteries. the motor needed setup for it by the bosch rep and that just took a phone call and he connected to the mechanics computer and set it up.

We have done the dual battery setup on countless motors and there is definitely nothing the Bosch rep has to configure (or even can configure - I have configured motors with them). However, the most important part is that it works.
My easiest dual battery conversion is to connect a second battery just to the charging port. So even if one of my riding buddies forgot his key, I can just hook up my or his second battery to his bike just using that cable. This only works with the 6A charging ports as they have all 5 wires connected (second battery only needs the 36V and CAN-BUS, does not require the 5V charging signal).
My trunk box has a 1kWh battery with a Bosch BMS and Bosch battery port. Pretty good range with that (60 cells 21700).
Beside the battery, the box still fits all necessary tools and spare tube etc. Needed the spare tube on the last 9 days trip as I had a big cut in the sidewall. Still the blue sealant all over the bike.

Only too bad they restricted it to two batteries. The diagnostic software supports up to 5 batteries parallel (noticed that when I checked the source code).
Older motor software could even display more than two batteries but did not like it.