80% or 100% Re: Charging the battery

[keithr]

Note what Volkswagen say in their Owner's Manual for the ID.3 concerning good maintenance of the battery pack (taken from the YouTube video referenced earlier in this discussion):

Three golden rules for greater autonomy

It is relatively easy to maintain your high voltage battery. If you follow these three golden rules then you have already done the most important thing to maintain the high range of your car.

1. Please do not load your car, on average, with more than 80% of its capacity when using it over short distances.

2. If the car is not used for more than 12 hours, it must be loaded between 30 and 80% of its capacity.

3. To fully charge your car (100%), use a charge time gauge found in the charge manager and and then start immediately after the car is charged.

[Reuben80]

In short, as keithr is saying, there is no fixed % when the battery degrades. But the higher the percentage the higher the degradation. Same for the lower %. Best is around 50%. So if your daily use is 20% charge, charge up to 60% till 40%. If you use 40% charge to 70% till 30% and so on. Charging to 100% is not going to kill the battery but keep charging to high % everyday expect a shorter life of your battery.
I never heard that Honda/Panasonic found a new battery formula so don't follow the manual. They are using Lithium-ion cells.

[keithr]

it also means that you can have regen available even when the car indicates 100% charge.

No it doesn't, because the BMS won't let you charge to more than 100% indicated charge. So at an indicated 100% SOC there will be no regen available.

Just to try and confirm that, on page 503 of the Owner's Manual it says, "When the high voltage battery has fully recharged regenerative braking may not be possible", and on page 20 it says, "When the High Voltage battery is fully charged or its temperature is too cold/hot, or another factor or factors are affecting the condition of the battery, the regenerative braking system may not be activated".

[SwissChris]

This week, I discovered something interesting. I have set the max. charging level to 80% and left the car plugged in for two days without driving it. When I checked the SOC, the system showed 82% (coming from 40% or so). Could it be that the BMS started to balance the battery and the optimisation gained the additional 2%?

[londiniumperson]

This week, I discovered something interesting. I have set the max. charging level to 80% and left the car plugged in for two days without driving it. When I checked the SOC, the system showed 82% (coming from 40% or so). Could it be that the BMS started to balance the battery and the optimisation gained the additional 2%?

I've found that it charges a 1 or 2% above the max set level.

[londiniumperson]

This week, I discovered something interesting. I have set the max. charging level to 80% and left the car plugged in for two days without driving it. When I checked the SOC, the system showed 82% (coming from 40% or so). Could it be that the BMS started to balance the battery and the optimisation gained the additional 2%?

I've found that it charges a 1 or 2% above the max set level.
Battery balancing will only occur at/near 100%.

[grayw]

This is all based on the assumption that 100% is 100%. Since it’s been calculated that the “usable capacity” is only 28.5 kWh, 28.5/35.5 means that 100% indicated charge may well be only 80% of the actual battery capacity anyway.

While this is annoying, as the car could potentially have a greater range, it does mean that Honda can issue their 5-year battery warranty without too much risk, and it also means that you can have regen available even when the car indicates 100% charge.

I believe the warranty on the honda E battery is 8yrs, 100,000 miles.

[ZoeDave]

This week, I discovered something interesting. I have set the max. charging level to 80% and left the car plugged in for two days without driving it. When I checked the SOC, the system showed 82% (coming from 40% or so). Could it be that the BMS started to balance the battery and the optimisation gained the additional 2%?

I've regularly seen 81%, and always thought that it might be down to temperature fluctuations between when it stopped and when getting in the car. Then again it just might be the car being generous and giving a few hundred extra meters to coast to a standstill when the driver (me) has made some 'bad decisions'. I do think that Londiniumperson is right in stating that balancing usually happens at the top, but can happen at empty as well, but I'm not aware of any car that does the latter, and can't see how that would work in the real world. Then again, what I know about battery tech would fit on a post-it note and probably have room to spare...

I find it a bit odd that the more we rely on digital tech, the more we are also relying on batteries which seem to me to be almost the exact opposite - they degrade over time, the charge is affected by temperature, the voltage jumps up and down with load, and they consist of basically a bath of electrolyte and some anodes and cathodes. Pretty far from the 'it works until it doesn't' nature of most of the things they power.

[milligoon]

I get percentage increase even when not plugged in, normally when the weather is warmer than the previous day when I parked up.