Effect on LiFePO4 battery stability when wired in series

[Ocracoke]

That is also the reason for the rule to use dedicated chargers/balancers for those packs.

Thanks, I do understand that - I wasn't planning to have both batteries on charge when wired up in this manner (though having re-read my original post, it does look as if I was asking about charging them at the same time as well), just when inside the robot (i.e. whilst in use). From the sounds of it, would be OK to do.