Cube Touring Hybrid Pro 625 2025

[bajkolizac]

Hi all, i have question about updating the bosch ebike, smart system. Its a battery problem, everything is ok with the bike, but when i try to update the firmware with flow app, it stucks on battery, restart, give error. I did try everything:
-reseting bms
delete, re pair delete app, redownload update,
fully charge it, leave without battery, charge the led remote,
everytime it stuck on battery.
Bosch service partner couldnt figure whats out and bosch claims that they dont know why. And thats it...

 

[Greg Watts]

Hi all, i have question about updating the bosch ebike, smart system. Its a battery problem, everything is ok with the bike, but when i try to update the firmware with flow app, it stucks on battery,

@bajkolizac That's a frustrating one, and you're not alone — there's a known issue with the Smart System battery firmware update getting stuck partway through, particularly on the PowerTube 625 with newer BMS revisions. The fact that your Bosch service partner can't figure it out doesn't surprise me; the dealer DiagnosticTool sometimes can't push the battery firmware any better than the Flow app can if there's a handshake mismatch between the BMS and the drive unit.

A few things I'd try before giving up. First, make sure the drive unit and LED Remote are both fully up to date before the battery — the battery update will refuse to complete if the other components aren't on a compatible version. Second, do the update with the bike awake and the charger plugged in (battery around 60-80%), phone within 1m, screen on, and disable battery optimisation for the Flow app on your phone — Bluetooth dropouts mid-flash are the single biggest cause of that "restart, error" loop. Third, before retrying, fully power-cycle by removing the battery from the bike for at least 10 minutes, then reinsert and leave the system idle for 2-3 minutes before opening Flow.

If it still bombs out at the same point, the giveaway is what error code Flow throws when it fails — if you can grab that (it'll be something like a 5-digit code or a "BMS communication" message), post it here and I can be more specific. In my experience when it consistently fails at the same percentage on the battery stage, it's a BMS that needs a forced reflash via Bosch's internal DiagnosticTool 3 (not the dealer-facing one) — and not every service partner has access to it. If yours doesn't, ring Bosch eBike Systems directly and ask them to escalate to a Tier 2 partner; Cube's UK distributor (Oneway) can also point you to one.

Worth noting: if the bike rides perfectly and all functions work, you can technically leave it on the current firmware indefinitely — the update is mostly QoL and ConnectModule tweaks, not safety-critical. Don't let it stress you out while you sort the proper fix.

 

[bajkolizac]

Nothing helps, it simply dont want to update, it stucks to 71%, or to 49% (in the latest update) in the flow app. And show error "failed to update"

 

[Greg Watts]

Nothing helps, it simply dont want to update, it stucks to 71%, or to 49% (in the latest update) in the flow app. And show error "failed to update"

@bajkolizac right, if it's consistently bombing out at the battery stage with "failed to update" - and you've already done the basics, and your service partner has thrown their hands up - you've hit the wall that the Flow app simply can't get past. That's not a you problem, that's a Bosch problem.

The fact that it's stalling at different percentages each time (71%, then 49%) actually tells me something useful: it's not a single corrupted block, it's the BMS-to-app handshake dropping at random points during the flash. Bluetooth firmware flashing of a battery BMS is genuinely fragile, and the Flow app has no way to resume - every failure means starting from zero, and every restart raises the odds of another dropout.

Two things worth trying before you escalate further. One: try the update on a completely different phone if you can borrow one - ideally a different OS (if you're on Android, try iOS or vice versa). I've seen reports of the same battery flashing fine on a mate's phone when the owner's own phone refused for weeks. Two: if you've got a Bosch dealer with the proper DiagnosticTool 3 (the wired workshop tool, not the app) within reach, that bypasses Bluetooth entirely and flashes the BMS over the charging port. Not every dealer has it - ask specifically before you make the trip.