jjeff wrote: ↑
Sat Feb 13, 2021 6:27 am
LeftieBiker wrote: ↑
Fri Feb 12, 2021 11:46 am
IIRC, the battery heater can use about 20% charge per day if running constantly. 20% in 8 hours does seem a bit high, as the warmer only draws 300 watts. That would be 50-60% SOC used in one 24 hour period!
OK I did an accurate test. At 4pm yesterday I checked the SOC on my '12SL and it was 84%. It just sat in one place outside in negative single digits and when I approached the car at 7am this morning(15h later) the blue battery warmer was on and when I checked SOC it had dropped to 65%
a 19% drop in 15h just sitting, again only in single-digit temps. It's supposed to get even colder tonight, approaching -20F and today's high is only supposed to be in the low(or would it be high, single digits below, approaching 0F). Sunday's high is supposed to be -4F while Sunday night/Monday morning we'll be greeted by -15F.
It won't be driven this weekend at all and I think I'm going to leave it unplugged until Sunday morning, take a SOC reading and see how low it dropped. Then I'll plug it in and charge it up to full(somewhere close to 90% I hope at a time of 10am I'd think) and take the final SOC reading and leave it plugged it. I'm then going to check the SOC Monday morning. What I'm trying to verify is if the EVSE/car will keep waking up to charge the traction battery even after it's fully charged. I don't know for sure but do you think it will? I'm wondering if once the battery is full and stops the charging it might require a cycle of the J1772 connector to start the charging again. If this is the case that would be BAD as what would happen if someone were to be gone for weeks in sub-zero temp, the battery could go almost flat even if plugged in, or at least as low as it would get before the battery heater stops working, somewhere around 20%??
More testing to come....
Well, last I left my 12SL at 7am yesterday it was at 65% SOC, the battery warmer was on basically all day yesterday and for sure all last night, this morning at 8am(25hrs later) SOC was 57% for an 8% drop, less than half the drop of the 15hr period before that when I'd assume it was even a bit warmer outside.......
I plugged it in at 8am and will note the SOC% when it stops charging, I'll leave it plugged in and then recheck the SOC% tomorrow morning to make sure the SOC% is the same and hasn't dropped due to the battery heater which I'm guessing will be on all day today and tonight(-18F tomorrow morning forecast and high -4F today).
On another note, I plugged in my '13S yesterday evening and it charged to 100% and stopped charging, I left the EVSE hooked up and like my '12SL I'm guessing the battery heater ran all night long. When I checked it's SOC at 8am this morning it was still 100% which tells me the car must have started charging again last night as otherwise it would have dropped SOC, that's a good thing.
On another note, I'm wondering what would be the best strategy for long term outside storage of an EV in an extremely cold(for an extended period of time) climate, lots of places worse than MN. If you leave it plugged in it seems like the vehicle will be near constantly drawing 300w for the battery, in sub-zero temps I've noted the battery warmer really never goes off. 300w 24x7 is nothing to sneeze at, seems like a real waste of electricity to me. I wonder if it might not just be better to not plug it in, in which case the battery would get down to 20% SOC and then stop the 300w heater, it would stay at this roughly 20% until you plugged it back in. This would eliminate the 300w 24x7 constant draw but I wonder at what harm to the battery? I've read it's not good to let the battery get too cold and it's also probably not the best to leave it at a relatively low 20% SOC? Now I know it might be different but I've always stored my single-use batteries, mostly alkaline but also lithium button batteries in the freezer for long term storage, I've read in the past it helps extend their shelf life. Other than the fact that these batteries will be stored at near 100% SOC what's different about these batteries compared to our Leaf batteries, is it that the Leaf batteries is rechargeable vs single-use alkaline and Li button batteries?
I don't have to worry about any of this with my ICE vehicles, they can sit outside in all kinds of weather and once it warms up, they just fire up. Note I do generally put a small 10w? battery tender on their 12v battery but that's peanuts to a 300w Leaf battery heater.
Personally, I really think a Leaf should be garaged in sub-zero temps, just makes things easier all around. It's not like you have to really heat the garage, just keep it from getting sub-zero, if indeed leaving it at sub-zero temps for an extended period of time is harmful to the battery.