2 off 850 Mah 3S Batteries, being charged in parallel

at 8.5 Amps

This is a 5C charge rate

Am I right

Thankyou<br type="_moz" />

8.5A is correct at 5C,
I'd prefer 1C 90% of the time. Or if I was in a hurry I'd use a charge rate of 0.8 of the max C rating which is 6.8A

Yes.

Thanks amazing

My batteries last at the 5C , charging

The thing that kills them for me is over discharge

I wish my ESC could give a pulsing throttle mode at 3.75 Volts per cell

That would be the ultimate weapon in battery health for me <br type="_moz" />

I have seen a device advertised to allow old no LVC esc to be used with lipos. It would do as you wish. You can set a voltage that when reached it only allows half throttle. When this situation results you know to bring her home.<div>Alternatively there are many telemetry options available.</div>

If your transmitter has a timer, set it and use that. If not buy an inexpnsive digital timer and either wear it or clip it to the transmitter. If your average run time is 8min ,set it for 7:50 and land before the lipos reach low voltage. It's better for the lipos if you don't push them to low voltage constantly,