[Frank Neuperger]

Thanks for the reply.

The original question was driven by trying to determine what motor performance I will have at various states of discharge. . i.e. what voltage would I have to derate the motor to to determine rpm and tourque when the battery is under load in a partially discharged state. In our applicaton, our robot lift operates at the end of the match (poorest battery state) and this is going to be a high current effort to liftanother bot in say 5 sec.

I thought the internal resistance inceased as it discharged and hence you got a greater load vs no load sag for a given current when the battery was partly depleted.

The other series losses are the victor or spike and wiring.

I asked the question of Victor and spike on resistance in another thread and have not yet seen the replies. . Victor data sheet does not give an on-resitance spec but the FET they use is 0.012 to 0.16 ohms. There ar 3 FETS in each leg of the H bridge and thus the series/par effective resistance is .008 to .0102 ohms for the Victor.

Stil wondering however if SLA battery has increasing internal resistance as it discharges and what is the curve. i.e on-resistance vs voltage or
on-resistance vs remaining charge. Near total discharge, Iknow the internal resitance gets hisgh as i have seen this. The question is wht is the curve that intoerpoaltes between .01 ohms at full charge to ?? 1 ohm ?? or more at near total discharge.

Regards
Frank