The other day I drove down a mountain -- here.... Here's the google link It took me about 6 minutes. I was on highest level of regen and I still had to apply the brakes here and there. After getting to the bottom I had gained 11 miles of range. Thinking of it, that was a helluva lot of kWhs going into that battery quickly. About 4x as fast as a 240 volt charge. Makes me wonder what is the upper level of charge rate that this car's batteries can accept.
You're probably seeing a combination of two factors... the batteries are getting charged, but the range estimation algorithm is also seeing that you are using a negative amount of energy to go X miles. So it thinks, "Wow, this guy is super efficient! I'm going to increase my range estimate, because clearly he can go way further than I originally thought!" I'd imagine if you drove on level ground afterwards, you'd see the range estimate fall quicker than normal for a while.
It isn't unusual for a FWD car to be able to regen at a rate of 50+ kW. It is like DC quick charging. In short bursts, even on a mountain pass like that, it really isn't a big deal. Most DC quick charging sessions are more like 30 minutes, and the car can help cool the battery too.
I had a long downhill stretch coming out of Mt Rainier National Park, my range said 67 miles. Once I got to level ground it started coming off pretty quickly. After charging it again showed the range as abnormally high, but again it came off pretty quickly. After a couple of charges it came back down to a normal range with normal rate of use. My first charge still showed around 14kwh, so it would appear that the numbers I was seeing were bogus, just an estimate with numbers not based on reality, and there was no real "extra" charge.
I wouldn’t necessarily call that estimated EV range number bogus even though it doesn’t reflect what your “normal” driving yields. It’s just saying that if you took that trip or one similar to it that you could expect approximately that much range. It’s only an estimate and can’t see into the future. Just giving the Clarity some loving!
Drove to the top of Pikes Peak today. Had zero EV range at the top. By the time we got back to Colorado Springs on regen, EV range was up to 80 miles and about 3/4 charge back in battery.
Similar experience for me on a long hill in Washington State on I-90 (going down into Vantage eastbound). At first I was super excited to get 10 miles of EV for "free", but then noticed that my battery gauge only went up a bar or two and as soon as I hit flat ground, the EV "guesstimate" started falling quickly. I think Emanuel Green hit the nail on the head.
Wow, how long do you think it took you to complete that drive down? Just wondering what the rate of charge is, basically if it's charging faster than a level 2 charging rate is, or in other words, if the charge rate is so high that it might be damaging to the battery. Pretty sure with everything else about the charging system we know, it's probably limited to prevent that from happening.
A FWD car like the Clarity can probably regen up to 50 kW (educated guess, could calculate this but haven't). So it is like DCFC charge rate. It will protect the battery, you will notice there is no regen when battery is full (85% SoC approx) and adds in regen as the charge drops (usually safe to fast charge up to 85%, depending battery). Also, the generator on the engine can probably generate 30 kW or more, so it also acts like DCFC. An important thing to note is that the car always works to protect the battery, so you don't have to worry about this. These short bursts of regen are not harmful to battery, and even longer ones are just like fast charging. My only warning is relying on regen: always assume that it could cancel regen at any time (overheating, loss of traction, etc). I actually haven't seen this as much with Clarity as Volt, but Clarity limits regen unless you are on brake pedal, likely for this reason (max regen is with brake lightly applied, so if it cancels you are already on the brake pedal).
Most of the way down Pikes Peak is about 25 miles per hour for about 19 miles of distance. Then maybe another 10 miles back to Colorado Springs at about 40 miles per hour. Elevation drop is about 8000 feet. It took at least 1 hour to maybe 1 1/2 hours to go down. Faster charging than my home charger. Here is a picture wife took just getting back to Colorado Springs. The battery is about 3/4 recharged.