i have a t4 with cc5700 combo. i find it is perfect on a 2s lipo. well i have a 3s lipo that has been sitting and i decided to plug it in and set the throttle endpoint low so it acts more like a 2s. my thoughts are that it will last a little longer too beings im not using all the voltage. but my question is can it harm the battery by limiting its usage all the time?

Nope. Your battery won't care at all.

The ESC may run pretty hot though because it's constantly operating in its range where it is most stressed. It's really best to just use a lot smaller pinion gear if you can. I'm not sure if you can go small enough or not, but that's technically the "right" way to do it.

If the ESC doesn't overheat though, you should be good to go!

-Eric

thanks, i will just keep an eye on temps.