hour
Observer
Oh yea, some additional testing last night... I was charging through the MPPT @ 15 amps (210w) with a 24v power supply - how I've been charging this thing during testing lately. I was down almost 60ah when I started charging so the process took about 4 hours.
Started at 70*F BMS (atop the cells) and 68*F from the BMS probe, dangling on the edge of cells and towards the bottom of the can. Put the lid on.
When charging ended the BMS was reading 82*F and the probe was 77*F. The MPPT was way hotter than 82*F but didn't reduce output at all, so I'm guessing beneath 104*F (think Victron says that's when output decreases)
This will not work at all in the summer (even though I'll never see 15a in from 200w solar), the bed of my truck in July was frequently 110*F. I have one vent directly behind the MPPT but may need to add another next summer, or an intake fan. I just don't want to cut any more holes in the box right now since the objective for the next 6 months will be keeping it warm. If the other incubator heater works out then I could leverage the separate wiring for fan vs heater and use it as a bit of an intake, gapped about 1/4" off the wall of the ammo can with a plastic louver vent through can. For summer mode I could adjust params in software and set the thermostat to an impossibly high temperature (or disconnect it entirely) and pull in a little air from outside the can. In winter just throw a square of reflectix over the vent and change settings back + re-enable thermostat.
What a pain in the ass all of this is... and for pretty much no reason. I don't venture far from camp in the winter and could have easily heated the truck bed with my portable diesel heater on morning 3 of a trip to kick start it in to accepting charge. Otherwise it'd take me being in the hospital for a month to drain the battery, assuming it was below charge temp that entire time. That's assuming the fridge wouldn't cycle much/ever in those temps, and given a < 4 watt continuous draw from the router and particle photon + arduino nano (peak of 4 when downloading large files on two wireless clients)... ~7ah/day.
FWIW I'm aware that I'm TL;DR boss, I just type myself through tasks since dogs don't offer much in terms of conversation. Not trying to continuously bounce ideas off people, but it helps me and in the future maybe this thread will help someone else planning a build. Hell of a lot better than OP ghosting with no resolution.
Started at 70*F BMS (atop the cells) and 68*F from the BMS probe, dangling on the edge of cells and towards the bottom of the can. Put the lid on.
When charging ended the BMS was reading 82*F and the probe was 77*F. The MPPT was way hotter than 82*F but didn't reduce output at all, so I'm guessing beneath 104*F (think Victron says that's when output decreases)
This will not work at all in the summer (even though I'll never see 15a in from 200w solar), the bed of my truck in July was frequently 110*F. I have one vent directly behind the MPPT but may need to add another next summer, or an intake fan. I just don't want to cut any more holes in the box right now since the objective for the next 6 months will be keeping it warm. If the other incubator heater works out then I could leverage the separate wiring for fan vs heater and use it as a bit of an intake, gapped about 1/4" off the wall of the ammo can with a plastic louver vent through can. For summer mode I could adjust params in software and set the thermostat to an impossibly high temperature (or disconnect it entirely) and pull in a little air from outside the can. In winter just throw a square of reflectix over the vent and change settings back + re-enable thermostat.
What a pain in the ass all of this is... and for pretty much no reason. I don't venture far from camp in the winter and could have easily heated the truck bed with my portable diesel heater on morning 3 of a trip to kick start it in to accepting charge. Otherwise it'd take me being in the hospital for a month to drain the battery, assuming it was below charge temp that entire time. That's assuming the fridge wouldn't cycle much/ever in those temps, and given a < 4 watt continuous draw from the router and particle photon + arduino nano (peak of 4 when downloading large files on two wireless clients)... ~7ah/day.
FWIW I'm aware that I'm TL;DR boss, I just type myself through tasks since dogs don't offer much in terms of conversation. Not trying to continuously bounce ideas off people, but it helps me and in the future maybe this thread will help someone else planning a build. Hell of a lot better than OP ghosting with no resolution.