Measuring battery temperature before and after flight I have found this:

4 ea. 25C batteries (30-40 cycles): rise is 23 - 35°C (73 - 95°F)
1 ea. 65C battery (9 cycles): rise is 14°  (57°F)

All batteries of the same type 2600/5S, recharged at 1.5C  approx. by 2'000 mAh (77%). All load defining parameters unchanged.

The 25C batteries begin to show signs of fatigue, i.e. puffing, no-load end of flight cell voltage around 3.6 V and much (+50%) longer balanced-charge time. The batterie with the highest rise has triggered the low voltage cut-off after the clover and was retired.

The 65C battery remains significantly cooler and I now wonder whether this may contribute to longer cycle life? If so, does anybody have cycle numbers of the ThunderPower G6 Pro Power 2700/5S battery?

Thank you, Peter Germann

Peter, I am sure all you say is true.  Battery heating would be a function of C rate.  The C rateing is a measure of battery internal resistance.  The higher the C rateing the lower the battery's internal resistance.  With a lower internal resistance less heat is generated, (IR losses). And heat is what kills a battery.  All battries have some water in them (even so called dry battries).  When you over heat a battrey and boil out some of the water you reduce the battery capacity.

When I worked on military hardware we derated every thing by 50%.  So a part in a 5V circuit had to have at least a 10V rateing.  So using this reasoning if you are pulling 25 amps you need a battery that will deliver 50 amps.  A 2200 mah battry would need a minimum of a 23 C rateing.  For this to be enough it depends on the amount of cooling air flow, Air temperature and other things.  Also don't forget the center cells of a multi cell pack run hotter than the rest.

The above is a lot of words to say a higher C rateing is a good thing. That's why they cost more!

 

Peter
165+ cycles on my 3each 5S2700's still going strong.
Norm

Peter
165+ cycles on my 3each 5S2700's still going strong.
Norm

Thanks and good to hear from you, Norm.Just two questions:
How much do you put in when charging?
What is your charge current?
rgds Peter