This is something important to consider when buying an EV car which does not have like 400km of range!!!

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This is something important to consider when buying an EV car which does not have like 400km of range!!!

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1) Charge up to a known exact percentage (e.g. 100%).

2) Reset trip & average consumption logs.

3) Drive & use up the battery, the more the better.

4) Calculate kWh like so:

(Miles Driven in Step 3) / (Average miles per kWh efficiency in Step 3) * 100 / (Percent Battery Used from Step 1) = Estimated Battery Remaining

For example, I drove ~12.7 miles starting from 90% charge in my eGolf, and the battery went down to 78% @ 4.4 mi/kWh efficiency:

https://www.google.com/#q=12.7+miles/+(4.4+miles+/+kWh)+*+100/12+to+kwh&*

= 24.05 kWh. Pretty good for ~16k miles on the odometer. However, driving further will provide a more accurate result.

Can someone do the same with their Ioniq Electric to get a more objective reading on degradation? Also note the car's mileage?

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[(Miles Driven in Step 3) / (Average miles per kWh efficiency in Step 3) ] * 100 / (Percent Battery Used from Step 1) = Estimated Battery Remaining

Assuming that the efficiency indication of the car is correct, the charge percentage indication is correct, and the battery will always indicate 100% for a full charge, even after years of degradation, I think this estimation may make sense.

But when the battery gives a lower percentage than 100 for a full charge, then you have to put that percentage instead of the 100. In fact you can also start this with a non-full battery by using the initial charge percentage minus the final charge percentage as (Percent Battery Used from Step 1).

You will always use the 100 in the equation, because you are trying to calculate 100% of the remaining battery. You put the % of battery used in the denominator. In my example, I started at 90% battery & went down to 78%, so I put in 100 / (90 - 78), or 100 / 12 for the last part of the equation.

[(Miles Driven in Step 3) / (Average miles per kWh efficiency in Step 3) ] * 100 / (Percent Battery Used from Step 1) = Estimated Battery Remaining

Assuming that the efficiency indication of the car is correct, the charge percentage indication is correct, and the battery will always indicate 100% for a full charge, even after years of degradation, I think this estimation may make sense.

But when the battery gives a lower percentage than 100 for a full charge, then you have to put that percentage instead of the 100. In fact you can also start this with a non-full battery by using the initial charge percentage minus the final charge percentage as (Percent Battery Used from Step 1).

Gotcha. A better way to write the equation is:I meant if after some years you start with a full battery, but that fullness is indicated only by 98% (which happens for some BEV's), then you have to take that 98% into account in some way, as the 2% loss is already in that number.

[(Miles Driven in Trip) / (Average miles per kWh efficiency in Trip) ] * 100 / (Before Trip Battery % - After Trip Battery %) = Estimated Available Battery Capacity Remaining in kWh

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You are assuming a degraded battery will stop @ 50%, thinking it is fully charged. If a battery degrades about 2% - 3% a year, are we seeing Ioniq's stopping at 97.5% now? I've driven my eGolf for almost 2 years, and it still says it charges to 100%.

I expect a heavily degraded battery will just take more battery to do the same trip. In my example, with a highly degraded battery, I'd expect the same trip would take the battery from 90% to let's say... 60%. Crunching the numbers:

[(12.7 miles) / (4.4 mi/kWh) ] * 100 / (90 - 60) = 9.621 kWh

Now... would a heavily degraded battery change the reported efficiency numbers? That I don't know...

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If the "fully charged" percentage goes down over the years, you won't have to calculate anything. If it stops at 70%, your battery is at 70% capacity.

It should be easy to tell if the Ioniq is doing this, since people should start seeing it not charge to 100% already.

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Yes, that could be the case if they exactly do that system, but still I would like to be sure it is not a mix of the two systems. And you rely on the figures generated by the car anyway, so there will always be a doubt whether these figures are correct.If the "fully charged" percentage goes down over the years, you won't have to calculate anything. If it stops at 70%, your battery is at 70% capacity.

Personally, I used Google Maps to get a better "miles driven for trip". In respect to efficiency & state of charge... we kinda have to assume it isn't lying to us. There is no way to calculate battery capacity if we can't trust the numbers the car provides.Yes, that could be the case if they exactly do that system, but still I would like to be sure it is not a mix of the two systems. And you rely on the figures generated by the car anyway, so there will always be a doubt whether these figures are correct.

Can someone do this with their Ioniq? I'd love to see some calculated numbers on remaining capacity vs miles on the odometer. I still may be interested in an Ioniq if the battery appears to hold up really well.

((25.6 miles) / (5.0 * (miles / kwh))) * (100 / (90 - 66)) = 21.3333333 kilowatt hours

That actually sounds much more accurate, since the eGolf has a 24.2 kWh battery, and approximately a little over 21kWh available. No signs of degradation yet... I'll keep taking numbers. I'm presuming degradation in the Ioniq won't be worse than my eGolf.

I am driving a 2015 eGolf, which has a 24.2kWh battery, with a little over 21kWh usable. I'm very interested in an Ioniq, if the battery looks like it will hold up (since I prefer to own my cars for a long time). I expect the degradation can't be any worse than my eGolf, which has no thermal management. I'm running new numbers today, since I'll have to average out a few readings to get an accurate number.This is a bad outcome if you find an estimate of 21 kWh for the battery for which the usable part is 28 kWh. This would make this method not usable to find differences such as 2 or 5%. Are you sure the input numbers were correct?

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