Having been in a similar situation in early December of last year - considering a used PHEV and wondering about the HV battery, I'll share what I learned (long).
It's not uncommon for manufacturers to show 100% charge, when the actual charge is lower. Many sources say that an 80% charge is an optimal limit for extending the life of a lithium ion battery. Constantly charging 100%, or discharging below 20% are both bad. All batteries degrade over time; how they are treated has some effect on how fast this degradation occurs.
Omg thanks so much for your time and help, that makes a lot of sense I’ll try doing that thanks again very helpful 👍Having been in a similar situation in early December of last year - considering a used PHEV and wondering about the HV battery, I'll share what I learned (long).
Without driving: first charge it to 100% on preferably a level 2 (3.5 kW @ 240V for this car) charger. Power on the car, turn off the HVAC if possible and note the estimated EV miles. Up through 2022, at 99-100% charge it should say 26. With HVAC on - even just the fan, it will show 24. That's a basic indication the HV battery is in good shape. If it doesn't charge to an indicated 26 miles, it's probably degraded some.
Second and better, a drive test: charge it fully and reset the trip meter. Then go drive it around in the default EV mode - don't floor the accelerator either, until the car switches into HEV mode. The engine may not immediately start if you're going relatively slow, like 20 mph or so. Note the trip meter miles traveled when "HEV" displays in the car mode. In mine that's usually 16-18% HV charge level, and 0 miles EV range remaining. For many or most people the miles traveled at this point exceeds 26. On an early test drive mine made 25 on a metro 65-70 mph highway with many small hills - not super, but enough for me to buy it. After a couple level 2 charge cycles at home and on a combo of in town stop-and-go + some 55 mph highway driving, it now reliably goes 29-31 miles on EV. I've read of other people getting more than this, perhaps with a stronger battery. If it goes at least 26 miles on anything but a high speed highway run, I'd say your HV battery is in good shape.
Third, when I posed this question of a dealer's service manager - how to know/test, they only offered: if the HV gauge on the left consistently charges to 100% and doesn't ever go much below the white 20% or so bottom range, all is good. I don't trust that answer much. Perhaps they've seen cars with a failing HV battery and e.g. they wouldn't charge to 100%.
Last, when attaching a bluetooth ELM reader and phone app (I use Torque Pro) to the OBD port and a Kia plugin for Torque, quite a bit more battery detail became available. It does seem to have some degradation info. I saw 20 or 25% degradation level appearing to be the level when the car would throw a "hybrid battery weak" error... but not what the current degradation was. There was also a curious state of charge percentage showing 95-96% when indicated as 100% on the dash. I don't know exactly what that meant. Anyway, I poked around with this at first, and haven't spent any more time on it because I'm satisfied my HV battery is in decent shape.
One other thing I forgot, though haven't quantified what it means: when discharging to the lower limit of no less than 15% or so... and putting on a level 2 charger... it usually consumes almost exactly 8.9 kWh to take it to 100%. I interpret that as another indication the battery is basically OK. I'm aware of charging losses - meaning not that much actually made it into the battery, though even close to that much usable is a pleasant surprise - given Kia's published capacity is the same 8.9 kWh.
Thanks I’ll keep that in mind 👍
Just don't obsess. If you need to make a trip that requires a 100% charge, just do it. I have a Google Pixel 6a phone, and routinely charge it to 80%; after 15 hours, it usually still has 50-60% charge remaining before I plug it in for overnight "adaptive" charging, which limits the charge to 80%. If I expect to be doing something that is more demanding than my normal use, such as shooting photos or videos, I either give it a little extra, or top it off if the charge drops below 40%.
The PHEV can be charged to "100%" at all times as it has battery management that does not allow overcharging and also does not allow battery level to reach below a safe point as well.
What the car reports as 100% isn't necessarily 100% of design capacity. It would be an interesting experiment to compare the battery's design capacity with the actual capacity measured by a test instrument at full charge. This would reveal the state of health of the battery, which gradually degrades over time. At least in phones and laptops, new batteries usually test a few percent higher than rated capacity, and started dropping off over time.
Over Charged Degradation 😉
I don't believe there is and I don't know why you would want to do that.
No, the PHEV has no ability to limit the max charge. But in a PHEV it's really not necessary, as they have already programmed buffers into the battery to protect the battery life. The battery is treated differently in a PHEV compared to a BEV vehicle.
That's indeed how Kia Connect appears to behave today, allowing one to try - incorrectly presenting both DC and AC limits. It then returns an error implying the request itself was incorrectly formatted. The raw API vehicle info responses do point to the AC limit being settable, and I plan to soon test the corresponding request format.
Another angle: tossing say 20% of the PHEV's already-few EV miles in the long term is a lot of EV miles in total. Is giving those up worth the tradeoff of only possibly, slightly slowing the HV battery degradation over the time you own the car?
Yup, sure is because I don't think there will be any greater degradation than if charging to 80%
