I have one big 10% average one mile long hill to climb, and when I first got this battery, on that hill, the FET's on the BMS would get quite hot, but the battery felt basically room temp. i didn't have a temperature gauge to measure. What I did is lay a couple pieces of 12 guage solid copper wire across the tops of the FETS and wrap them around some 3/8 inch copper tubing and soldered it all up to get a nice thick heat sink. I also encased the battery in lexan acrylic sheets I got from Home Depot, separate from the BMS, so the BMS sits on top of the lexan panel, and is open to the air. I also ran a sheet of aluminum foil from the copper pipe down the length of the battery for further heat dissipation. I don't know how good this heatsink really is for instantaneous heatsinking, but it does a good job of cooling the FETS down, once the power is off. I did monitor it once by putting a thermocouple right on top of the FET. When I went up the steepest hill at maximum current of 35A, the temp rose as high as 57 deg C. That is acceptable, since most consumer grade electronics are designed to run up to 70 deg C, so I'm satisfied it is keeping within a safe range.
When I said there is no heating I'm talking about the battery itself, not the BMS. I think some people feel a hot BMS, and consider that to be the battery heating up. I do notice a small warmth from the battery after charging, but is so close to room temp, I don't believe it is an issue. If you are only seeing a 10 deg rise, I don't believe that is a concern at all.
As far as cooking, when you charge higher, I found the thing that cooks the most is the resistors on the BMS. They are there to keep each cell at or below 3.8V. I think for longevity, 3.6V is better, but at the expense of maybe 5% loss of capacity. The difference may not be that much of an issue. I don't think there is enough published data out there to support it. I'm just going on a gut feeling based on my knowledge of electronics, and the fact that higher voltages and/or temp, typically reduce life. The way most electronics companies test long term reliability is they run parts or systems at higher than normal temps and higher than normal voltages until they break, and then extrapolate the expected lifespan when run at normal temps and voltages.
It would be nice to be able to run different scenarios to see what strategy gets the maximum life, but I'm not interested in pushing limits to prove or disprove a point. I just want to get the most for my $. I think if you just use the charger as is, you should easily get the 1000 cycles out of it, and still have 85% capacity. According to most websites, even after 3000 cycles, these lifpo4's should still have 70% of original capacity. For me, that is over 10 years. I think shelf life may kill me before I ever use up this battery. I think now the weak link is the charger. I popped a capacitor on my charger twice already.
The capacitor was rated 50V, so I'm looking for a higher volt, maybe 63V. I can't go too high because of a lack of space (bigger capacitor).
