Roomba battery 3300 li-ion cell replacement error

[ziemniaczenka]

Hi, I've replaced 18650 cells in the original Roomba 3300 battery for the Roomba 980 with Sanyo UR18650ZM2 2470mAh - 8A.
The problem is that Roomba doesn't want to work with it.
The charger gives 20V when the roomba is connected.
Roomba only turns on when on a charger:
 - when trying to start, it says "please charge the battery"
 - in the app, it says "Unable to start; battery is too low"
 - when left for a few hours on a charger, I got "charging error 9" the second time, after like 12 hours, "charging error
7". The voltage on the cells stayed the same as when building the pack.
Here are some measurements on the BMS where the problem probably lies:

Did anyone encounter a similar problem? Any help is really appreciated.

[CodaCM]

http://www.robotreviews.com/chat/viewtopic.php?t=3773
This may help.
Even though it's not for a 980 it still talks about charging issues.
I hope you can get your Roomba working.

[matofill]

This will never work, Roomba BMS with stronger cell..... forgot !

[ne0tekk]

I was reading about how the BMS board will disable itself if it reads 0v along any of the cells. Take a look at the board, there should be a blue fuse that is blown out, you can try soldering a piece of wire to bypass it to see if the roomba will start again.

I think the only way around this in the future is to clamp another 4s battery to the roomba in parallel. I'm not sure if there is a variance in voltage that'll shut down the bms in roomba packs but the Dyson packs will have the BMS board disable itself if there is greater than a 300mv variance between any of the cells.