10s 3p cell battery for scooter long term storage?

[semiroundel]

Hi all, I leave a couple of M365 scooters abroad for holiday use. My brother in law who lives there allegedly scoots about with them occasionally and recharges etc to keep them cycled, but each year I go visit him, one of the packs has dead cells and needs replacing.
I'm familiar with lithium from RC plane use, and have cells that I've stored for years without use and they continue to be good, so I'm suspecting that the BMS that's still connected to the scooter battery is draining them beyond 3v and making the pack useless.
Short of bringing the packs back home with me to monitor them, is there a way of keeping them in good shape by disconnecting the BMS multi connector so that they are in effect connected to nothing at all?
TIA

 

[OleP]

I myself have an M365 that is 4-5 years old and is now only used a few times a year.
It has the original battery and is stored with approx. 50% SOC and only loses 1-2% per month. I turn on the scooter 1-2 times a month to check the charging status and charge for approx. 50% if the level has fallen below approx. 30% The battery and the state of the cells can be easily read via the "m365 Tools" app.