I have 2 ESC R3 with 2 T200 connected parallel to 1 Lipo Zippy 4000mAh 40C 5S 18.5V battery. They are working fine. But the battery does not last long enough. I bought another Lipo battery 6000mAH 50C 5S 18.5V. I would like to connect this battery parallel to my existing circuit to provide longer power. Can anyone please advise me if this is fine or it may have a chance to blow up my ESC? I dont know how to do the calculation for all those amperes and voltage. Thank you very much!
When connecting batteries in parallel, the voltage does not change. The capacity and current discharge capability of the batteries will add, so it will increase your run time without affecting anything else. This is perfectly fine to do and will not harm the ESC.
However, I would strongly recommend against running the batteries you have in parallel. In general, you should only run batteries identical in voltage and capacity (ideally fully identical in all aspects) together in parallel, otherwise problems with uneven discharge and heating can occur. One of your batteries has a 4000mAh capacity and the other a 6000mAh capacity, you should not run them in parallel.