Is it okay to throw the car on the charger each night even if you haven’t used the entire battery each night? Some days I am projected to have 25-30 miles left on electric. Will I diminish the battery’s life by charging it each night. Please forgive my ignorance, I’m quite the noob with this stuff. Thanks in advance.
I really don't think it makes a whole lot of difference. If you are leaving the car for days (like if you go on vacation), it probably is best not to leave it fully charged or fully discharged, maybe leave it more like 50-80% charged, but I doubt even that makes much difference over the life of the battery.
The manual says to fully charge the battery prior to each use. There are as many theories on charging protocols and preserving battery longevity as there are owners of electric vehicles.
If Honda, like Tesla, wanted owners to charge to only 80% to protect the battery, the Clarity PHEV would have an 80% charging option.
Charging to 80% is the most it will let you do. (13.5 kWh out of the 17 kWh capacity is 80%). So technically it isn't really an "option" I guess.
To elaborate just a bit on your charging question: the battery is comprised of 168 individual cells that have a nominal voltage of 3.7V. These cells are considered to be fully charged (100%) at 4.2V. At 4.1V they are considered to be 90% charged. Honda has established a charging protocol that targets a cell voltage of 4.092V, approximately 90% State of Charge (SOC). Simply plugging in the car to charge, will charge the battery to ~90%, despite what Hondalink or some other diagnostic device may tell you. SOC is determined by measuring the resting voltage of a battery. The Battery Maintenance System (BMS) also protects the battery from becoming completely discharged. When it reaches ~10% SOC, the ICE will start and attempt to maintain the battery at that level. In a nutshell, if you utilize all of the available battery capacity, you will be operating with the battery between 10%-90% SOC. This is, in my opinion, a reasonable range in which to operate a Lithium battery and should provide several thousand charge cycles (100-0-100) while maintaining 70-80% of the batteries original capacity.
Calendar aging of a Li ion battery in general increases with state of charge. In other words, the higher the SOC the faster it degrades, especially at higher temperatures. For the best longevity, charge the car right before you use it as Honda recommends.
