RSC wrote: ↑
Wed Apr 10, 2019 4:12 pm
MrDRMorgan wrote: ↑
Wed Apr 10, 2019 11:37 am
I just began a new series of tests where I will only charge the car to 80 - 85% SoC. I want to see if not fully charging the HV battery will slow down or stop the degradation.
Currently I'm using rate and departure time charging. I don't have any experience with departure time charging, but I'm thinking about trying your approach. Let's say you set departure time to 10am, and disconnect at 8am before charging is complete. Then if you reconnect at 11am, will the car immediately resume charging, or will it delay charging, thinking that departure time is 10am tomorrow.
I'm a little reluctant to the leave the car disconnected in the heat of the day. Living in Sonora, it gets pretty hot in my garage in the summer. I got the car in September, so it hasn't yet been through hot weather. So far I've insulated a southwest facing wall that gets pretty hot in the afternoon and the northwest facing garage door that gets some late afternoon sun. I'll probably add reflective bubble wrap type insulation on the rafters and/or a gable vent.
If you have your car set for a departure time of 11:00 am, disconnect before 11:00 am and then reconnect before 11:00 am, I think the car will charge until 11:00 am and then shut off. If you go past 11:00 am, a new charging cycle will start and charging will not start until the time is reached to start charging so it will be fully charged at 11:00 am the next day. I have never tried this.
I have both of my Spark EVs set for departure time charging and both cars are disconnected at 8:00 am each morning. My 2014 departure time is set to 11:30 am. Unfortunately, Each day, I have to manually reset the charging rate to 12 amps as I am using my L1 EVSE which delivers 1.4 kWh to the car at 12 amps. I also plan to test the default 8 amp charging rate so I do not have to reset the charging rate each day. My 2016 departure time is set to 9:15 am as I am using my L2 EVSE which delivers 3.3 kWh power to the car. My target for both cars is to have an SoC of 80 to 85% when I disconnect at 8:00 am. The 2016 is dialed in but the SoC in my 2014 is a bit high. I am seeing about 88% SoC at disconnect time so I moved my departure time from 11:00 am to 11:30 am. I will see if that works when I check the SoC tomorrow morning.
One thing to keep in mind is how long it takes to recharge your car at different charging rates. 8 amps will give you about 0.75 kWh per hour into the battery. 12 amps will give you about 1.0 amp per hour into the battery. If the capacity of your battery is 16 kWh and you need to add 60% to get to 80% you will need to add about 10 kWh. That equates to about 13.3 hours at an 8 amp charge rate and 10 hours at a 10 amp charge rate. My L2 EVSE will add about 2.8 kWh per hour into the battery. This equates to about 3.57 hours of charging.
I live in Manteca which is about 90 miles West of Sonora so I see some of the same summer heat. My garage easily hits temperatures over 100 deg. F during really hot summer days. If you have access to TorquePro, you can measure the battery temperature to see how hot it gets during the hot summer months. I do not know if battery cooling is active if your car is set to departure time. If it is, I would keep the car plugged in. I also do not know if the L1 EVSE can supply enough power to run the battery cooling circuit.