[DonRotolo]

OK, 0.9 A x 3.7 hours x 0.9 (charge efficiency) = 3 Ah. So, the max it should take for a fully discharged battery is 3.7 hours.

10 seconds of use - let's call it 2 minutes just to be sure - relieves the battery of 0.033 hours * 8 A (2 Tetrix motors at full steam) = 0.266 Ah. You can put in that amount of energy in perhaps 20 minutes.

I don't think it'll be much of a problem, particularly if you have 2 batteries.