ninepointeight
1 W
- Joined
- Nov 16, 2016
- Messages
- 60
Hello all, having past through my quarter life crisis, I am embarking on another build and to address previous shortcomings. I am planning likely 20s36p pack of Panasonic's NCR18650pf, these still seem to be the best cell for a long lasting chemistry + high discharge(I haven't seen anything that looks like a direct upgrade). The datasheet says you can store these at up to 50C and discharge up to 60C. Obviously these are not the best conditions for a long lasting battery, but just how bad are they? I can't find any data about the cycle life impact other than that the cells have a bit more capacity at 30C than 20C which is to be expected.
Heating the pack is pretty simple with a few resistive pads, the problem is cooling.
The implication of living in Texas is that temperatures are regularly 35C-40C outdoors, and can easily reach 50C inside a garage, and we all know that a ebike spends the majority of its life not moving. The easiest solution to this was to make the battery removable, so I plan to have 2 packs 10s36p that are fairly easy to remove for long term storage/charging inside. This isn't exactly convenient though. The next question is, what if I park my black ebike outside on a hot sunny day, I doubt it would have much trouble reaching garage temperatures in a semi enclosed battery compartment. I thought about forced air cooling through past the 2 packs that could keep the enclosure at least just above air temperature. This seems like the most practical option.
I don't know how much heat these cells put out under load, and could probably write a thesis on it, but I don't think these cells will really see more than a continuous 0.5 C-rate on them so it shouldn't be an issue.
Then I found some neat little compressor units for small refrigerator systems:
https://www.rigidhvac.com/mini-compressor
This combined with a small evaporator in the battery enclosure area and condenser out of it should have no problem maintaining ideal battery temperature in even the worst conditions, and would enable me to just leave it on the charger to run the AC. I am building a custom frame for this bike so it could easily be integrated (only a few pounds).
I'm curious to hear what you all think of this problem and if I am over engineering a solution, and what are electric motorcycle doing about this problem? I think most electric cars have battery cooling systems, is this something worth it for large ebikes? I am pretty much looking for a no compromises solution when compared to gas bikes (except maybe price), I just don't know how negatively these cells are impacting by spending time out in the heat.
Heating the pack is pretty simple with a few resistive pads, the problem is cooling.
The implication of living in Texas is that temperatures are regularly 35C-40C outdoors, and can easily reach 50C inside a garage, and we all know that a ebike spends the majority of its life not moving. The easiest solution to this was to make the battery removable, so I plan to have 2 packs 10s36p that are fairly easy to remove for long term storage/charging inside. This isn't exactly convenient though. The next question is, what if I park my black ebike outside on a hot sunny day, I doubt it would have much trouble reaching garage temperatures in a semi enclosed battery compartment. I thought about forced air cooling through past the 2 packs that could keep the enclosure at least just above air temperature. This seems like the most practical option.
I don't know how much heat these cells put out under load, and could probably write a thesis on it, but I don't think these cells will really see more than a continuous 0.5 C-rate on them so it shouldn't be an issue.
Then I found some neat little compressor units for small refrigerator systems:
https://www.rigidhvac.com/mini-compressor
This combined with a small evaporator in the battery enclosure area and condenser out of it should have no problem maintaining ideal battery temperature in even the worst conditions, and would enable me to just leave it on the charger to run the AC. I am building a custom frame for this bike so it could easily be integrated (only a few pounds).
I'm curious to hear what you all think of this problem and if I am over engineering a solution, and what are electric motorcycle doing about this problem? I think most electric cars have battery cooling systems, is this something worth it for large ebikes? I am pretty much looking for a no compromises solution when compared to gas bikes (except maybe price), I just don't know how negatively these cells are impacting by spending time out in the heat.