i have a Hyundai Ioniq5, 100% EV. it is recommended to charge to 100% at least once a month. all other times, charge to 80%.
my Emporia charger has a switch button with Entity ID of “switch.home”
my HA can read my car’s SOC via the WiCAN device with Entity ID of “sensor.battery_soc”
how can i write the automation via GUI or yml for this automation to auto charge the car to 100% once a month? for other times, when “sensor.battery_soc” = 80% send the switch stop command to “switch.home”
Hi tung,
I would pick the day, say the first of the month. If you are charging that day, do 100% otherwise do 80%. If the car doesn’t get plugged in that day, then it will miss it. Not a big deal, right? If it is pick 2 days in a month.
I’m sure that can be done. Also having someone or something writing it for you means the second it misbehaves, you will be struggling back to find someone to fix it for you.
The best way to learn is to just try. Run thru the docs on getting started with the automation editor. If you get stuck, come back with what you have done.
i charge approx 10 times per month.
so i think it would be easier to charge the 10th to 100%. all other charge will be 80%.
how do i set up this count? if 1 to 9, charge to 80%?
thanks!
Set up a counter:
Then check it each charge, incrementing or resetting as needed.
To my knowledge, the traction battery used in Hyundai/Kia EVs that are based on their 800V E-GMP architecture, like the Ioniq 5, use NMC lithium ion technology. Owing to that battery chemistry’s voltage vs charge curve (approximately a linear 30 degree slope) determining its current charge level based on voltage is reasonably accurate.
In contrast, an LFP lithium ion battery has a flatter voltage vs charge curve thereby making it more challenging to accurately determine its current charge based on its voltage. Accuracy is improved by periodically charging it to 100% in order to reset the charge-level calculation (i.e. start from a known, definitive point). This procedure is not needed for NMC batteries.
Engineering Explained has two good videos explaining NMC and LFP batteries (and best practices to extend their lifespan).
This first one contains a chart showing the charging curves for both battery types and explains why it’s recommended to periodically change an LFP battery to 100% (not NMC).
LFP
This one’s all about NMC batteries. Ideally, you charge an NMC battery to 100% only for a long trip in order to get maximum range. Long-term storage of the battery charged to 100% isn’t recommended. Its lifespan is extended by normally keeping it in the 50-75% range (i.e. performing small frequent charges, not to 100%, as opposed to large infrequent ones).
NMC
EDIT
According to the Ioniq 5 Wikipedia page, it uses an NMC battery, so monthly charging to 100% isn’t required (or advisable).
Set a datetime helper to a date 30 days ahead, when now is larger than this datetime move it 30 days again and charge to 100%
oh. i see. thank you!
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The whole topic of EV max charging is a mess of over-hyped and oft-repeated urban myths.
Simple rule: don’t leave the car at, or near to, 100% for prolonged periods. Other than that, just use it as you want. The battery will outlive the rest of the car.
A lot of these “recommendations” come from the Mk1 LEAF, which had a small, old-tech and non-cooled battery. These are now showing significant degradation, and most were regularly charged to 100% due to short range.
More modern EVs are showing much less deterioration independent of charging regimes.
Could it be a warranty issue if you don’t charge it to 100% every month?
Currently, EV batteries employ two different chemistries (NMC, LFP). The best practices to extend their lifespan (i.e. minimize loss of charge capacity) aren’t identical. That makes it easy to confuse which best practice is best for which technology.
It can become especially confusing when a manufacturer can employ either NMC or LFP in the same car model. In that case, you may have to check its VIN against a reference to know what’s in your EV (unless its documented in the owner’s manual)
I know our Kia EV uses NMC (clearly indicated in its owners manual). It’s mostly used for urban driving so we never bother to charge it to 100% (usually just from 50 to 80%).
In addition, EVs have distinctive charging curves (varying from one manufacturer/model to another) which means as the battery’s state-of-charge approaches 100%, the charging rate decreases. That means the last 20% to charge may take as long as the first 50%.
The charging behavior depends on how the manufacturer configured it. For example, our Kia charges at a high rate until ~50%, decreases a bit until ~75%, then really slows down until 100%. Thermal management is a concern because high heat (ambient and that produced by charging) degrades battery life.
FWIW, the best practices I mentioned are for maximizing battery life. Even if one has no intention of keeping their EV beyond the manufacturer’s battery warranty, the vehicle is more useful (and its trade-in/resale value will be better) if its battery can still retain 80-90% of its original capacity.
If the EV is leased, or one cannot conveniently charge it at home, then one might not be concerned with, or able to, maximize its battery’s charge capacity.
If it’s an LFP battery, the way they calculate the state-of-charge requires a periodic ‘reset’ by way of charging to 100%. If you don’t do that, the calculation (based on the constant measurement of current leaving/entering the battery) eventually gets out of sync with the battery’s true state-of-charge. Worst case, it can indicate more than is actually available.
An NMC battery doesn’t need periodic 100% charging, neither for computing its state-of-charge or for its health.
I understand that, but I’m assuming the car manufacturer also have the charge level data and in the event of a battery warranty they might hold this against you even if it’s not the best for the battery.
They know people can’t meet that demand, so they set this as a requirement and makes them slip through the warranty claims.
Before we spend time discussing potential warranty infractions, it might be helpful if the OP posted the exact statement from Hyundai that requires monthly charging to 100%. Moreover, any statement indicating a failure to comply will void the battery warranty.
Otherwise, we’re wasting our time discussing hypotheticals.
FWIW, it’s the exact same paragraph, word for word, as for our 2024 Kia Niro EV (which is not based on the E-GMP platform; it’s a 400V system with an NMC battery).
Paragraph summary is:
If charge is < 20%, you can maintain optimal performance by charging to 100% monthly.
Which begs the question, why does that paragraph begin with the qualifier “If the high voltage battery charge amount is below 20%”. What if it’s rarely ever below 20%?
You would assume that if the advice is to simply charge to 100% monthly, it would state that without qualifications. Or perhaps they’re suggesting that at least once a month the battery should undergo an extensive charge from under 20% to 100%. 
At best, the paragraph is open to interpretation. If you think it means to charge to 100% monthly, by all means go ahead. Don’t let me, an Internet stranger, dissuade you with technical information that isn’t from Hyundai.
In my case, I lean towards the subject matter experts like Dr. Jeff Dahn (pioneer in the development of lithium-ion batteries).
