Range Testing

[David Towle]

Looks like I can no longer track the battery amp degradation of my 2018 with 118k miles. On May 8 it was at 42.76 amps, but since I brought the car in for replacing the coolants 3000 miles ago it was reset and has not budged from 54.98 amps reading. (It doesn't seem worth hassling with the dealer to try and figure out what is wrong I doubt they could determine anything)
So the only way I see to track future battery degradation is by monitoring maximum range. I just did a 100% to 0% battery test with my normal around town driving (mostly 35-50 mph), no AC/windows open, using my best technique, and was at 59.6 miles when the engine came on. The GOM initially read 75.2 miles. For hahas I repeated the test using AC the whole time and got only 31.4 miles! Looks like I'll continue to minimize the AC use except on highways where its pretty much a necessity.

 

[Robert_Alabama]

Run the battery all the way to zero (until the gas engine kicks on). Then plug it in to charge. The number of kWh needed to fully recharge the battery will give you a good measurement of the Ah. I think you can assume about 14.65 kWh to fully recharge the battery when new at 55 Ah. So, for example, if you need 11.2 kWh to fully recharge, then 11.2/14.65 x 55 = 42.05 Ah. This should be pretty accurate.

 

[Conelite]

Didn't think the AC used that much power. That's wild. I'm at 125k miles and on average I get 35-40miles from 100-0%.

My car usually reads around 44-46ah. Max. The most power I have been able to charge into the battery was around 10kwh. Average is 9-9.5kwh

 

[David Towle]

Run the battery all the way to zero (until the gas engine kicks on). Then plug it in to charge. The number of kWh needed to fully recharge the battery will give you a good measurement of the Ah. I think you can assume about 14.65 kWh to fully recharge the battery when new at 55 Ah. So, for example, if you need 11.2 kWh to fully recharge, then 11.2/14.65 x 55 = 42.05 Ah. This should be pretty accurate.

Why didn't I think of that, sheesh. Will try soon. Thanks!

 

[David Towle]

Didn't think the AC used that much power. That's wild. I'm at 125k miles and on average I get 35-40miles from 100-0%.

My car usually reads around 44-46ah. Max. The most power I have been able to charge into the battery was around 10kwh. Average is 9-9.5kwh

Realize how slow I'm going, with lights and stop signs probably an average of 25 mph, so almost 1.5 hours of AC. Versus on the highway using up the battery in 35 miles or less than a half an hour, so I'm using the AC 3 times as long as I would on the highway. That's why the difference is so big.

 

[Jim1960]

My 2018 Clarity has 80K on it, and on some summer days, when I have done no highway driving, the GOM has reached 60.1 miles. That is, of course not real, but I have seen very little degradation on the highest GOM numbers. I'm not enough of an engineer to know if this is actually a sign of a robust battery.

 

[Landshark]

For those who may have forgotten, the EV Range Estimate has been dubbed the Guess-O-Meter (GOM) for good reason. It is a spectacularly useless number for determining anything other than how far the car might travel in EV Mode if it is driven similarly to how it was previously driven. Other than that it does seem to generate a fair amount of drivel on this forum.

 

[Conelite]

Just did a test this morning on my 4am commute to work to see how much Air conditioning effects range.

Typical condition:
AC on entire time set to LOW, Fan speed 2
All highway 60-65mph entire way (no Traffic)
37-40miles of range in the trip meter @ Zero on GOM

This morning:
No AC at all
All highway 60-65mph entire way (no Traffic)
47.9 miles of range in the trip meter @ Zero on the GOM

Around 10miles extra range not using the AC. Impressive. I knew the heater is the worse consumer of electrons, but that AC is pretty bad too. I don't have LRR tires (cheap China tires) and have 125k miles on the car.

I'm going to test my commute home with no AC. I usually get 30-35mile range on the way home, but AC is CRANKIN! I'll suffer a bit for scientific purposes.

Update: I made the drive home yesterday in 90f+ weather no A/C and barely got 30miles range in traffic..... So much for that. Ill crank the A/C home. lol

 

[David Towle]

Run the battery all the way to zero (until the gas engine kicks on). Then plug it in to charge. The number of kWh needed to fully recharge the battery will give you a good measurement of the Ah. I think you can assume about 14.65 kWh to fully recharge the battery when new at 55 Ah. So, for example, if you need 11.2 kWh to fully recharge, then 11.2/14.65 x 55 = 42.05 Ah. This should be pretty accurate.

I followed your recommended calculation and didn't like the answer haha. The last time I was able to get a real AH reading from the car was 3000 miles ago it was 42.76. When I charged the car (with my admittedly cheap Chinese charger that may not be accurate) it showed 10.82 kwh. 10.82/14.65 * 55 = 40.62, which is a huge drop for 3000 miles. I did a quick AI search and I found that your 14.65 is accurate, it comes from posts on this forum in 2018 where users were seeing how many kwh their brand new Clarities could take. But the drop of 2 AH seems impossible, maybe there is something else the car calculation takes into account?
Robert did you compare your calculation to the reading from your OBD port? Or has anyone else done this?
Maybe I should just back calculate it to line up with my previous data. Typical previous AH drops in 3000 miles averaged around .2
55/42.56*10.82= 13.98 kwh.
I don't want to go to a public charger for a possible more accurate kwh reading, my view is that high charge rates are not good for a small battery like this one, I never go over 12amp/220v anymore.

 

[Robert_Alabama]

@David Towle , in January of 2025, my Ah reading with the VGate was 46.02 Ah. Sometime in mid to late 2025, my Ah reset to 55. Like many here, it has been very slow to recover to a reasonable reading. It was 51.58 in December of 2025, and 50.08 on Jan 31, 2026. I just checked it and it said 46.2 Ah, so it is settling in, but is probably still high. Last week I used a chargepoint 32A charger at work and it said I used 10.8283 kWh to charge. I had 2 miles left on the GOM when I plugged it in, so probably add 0.5 kWh had the car been fully discharged. So that is roughly 11.3 kWh.
11.3/14.65 x 55 = 42.43 Ah. If it is possible to further discharge the battery a little to get it "fully discharged" (it will run on zero miles without starting the engine if you are really easy on it) then maybe my full charging would have moved up to 11.8 kWh. That would give an Ah measurement of 44.3 Ah. I would bet that is probably pretty close to where I really am. I have a 2018 with 77k miles with 2/3 of the miles in electric, 1/3 on gasoline.
So if you could have possibly depleted your battery another 0.5 kWh by gently driving it at the end of your charging cycle, you might have also made it to the 11.3 kWh range, yielding an approximation of 42.4 Ah. There may also be a little approximation in the 14.65 kWh for full charge when new. If that was softened even to 14.5, it would make a significant difference.
Bottom line, though, it really doesn't matter what our Ah measurements are as long as they are above the 36 Ah level and we aren't throwing any error codes. All we can really do is drive the cars until they fail. If we are relatively confident that when under warranty the Ah reading is above 36, then that is the relevant information....

 

[Landshark]

I don't want to go to a public charger for a possible more accurate kwh reading, my view is that high charge rates are not good for a small battery like this one, I never go over 12amp/220v anymore.

The Clarity isn’t capable of charging at a “high” rate by any reasonable definition. At 2.5 hours for a full charge using a L2 device, we’re looking at a charge rate of 0.4C. For a lithium battery of any size a charge and discharge rate of 1.0C is the standard by which manufacturers determine battery longevity. You guys can’t harm this battery by charging it, even if you let it charge fully, which is really about 90%.

 

[Conelite]

I don't want to go to a public charger for a possible more accurate kwh reading, my view is that high charge rates are not good for a small battery like this one, I never go over 12amp/220v anymore.

I have heard that some people get error messages when using the 50a+ chargers. I fast charge my car 5 days a week at work at 6.6kw/h. Charges from 0% to 100% in just over an hour. 6.6kw at 240v= 27.5amps.