HV and HV charge - TPMS quirk.

[insightman]

I agree, been back and forth from 1,000’ to 5,000+ feet numerous times and never had the low tire pressure warning. Like David says, as long as the altitude or temperature or both affect all 4 tires equally, there’s no reason for the system to detect one wheel rotating at a different speed than the others, which is what triggers the alert.

I'm sure the problem arises only when the pressures of the tires are close, but not equal, when the ascent begins.

 

[Whisper]

In my particular case, when I get to the top of the hill and there is like a 10 mile or more downslope (I-15 from LA to Vegas), I turn off HV and ACC, just letting the car go down on EV mode and regulating speed with the regeneration pads, avoiding hitting the brakes as much as possible. The "EV range" (GOM) would go incredibly high (almost to the 80-90s) and I won't spend a drop of gas. This wouldn't work if I leave the ACC on, it would keep the engine on for some arcane reason. Next time I will use the CarScanner ODBII app to monitor what happens with the different parameters.

In my experience (more limited given I don't normally get a several mile downslope), I have seen regen on significant downgrades adding miles of EV range back much faster than our level 2 charger (especially when on HV Charge). Somewhere around a mile added per minute. When not using HV Charge, I still see plenty of regen. Given that I seldom use HV Charge I have to wonder if having used HV Charge and hit the "set point" and going to "regular" HV mode is what leaves it set and in place. Have you tried manually switching to EV mode, then going back to HV?

Can you send your 10 mile downslope over for testing ?

 

[coutinpe]

Just came back from a road trip on a slightly different scenario, through the hilly 93 from LV to Phoenix AZ and back, so I didn't have the LONG downslope on the 15, but still some pretty ones, especially returning to LV. I just let the car run on HV/Sport mode and ACC on. Only a small improvement on charging when "coasting" downhill. For some reason the car ACC kept the engine on almost all the time, even when going on a heavy downslope and the indicator was way down the green "recharging zone". SOC fluctuated between 56-58%, never increased from there, and EV GOM range almost didn't change. Of course, with SOC > 50% HV charge didn't want to work, so I couldn't test that. Hence, my impression is that switching off ACC and HV down hill and controlling with the paddles would maximize the recharging. Otherwise the mechanism would only act to preserve the previous charge level. That, of course, if you're in the mood to play with the car. Otherwise just let it do its stuff, relax and just keep watching the fuel gauge just in case you need to stop by the nearest pump.

 

[Reyn]

BUT - I have never seen the EV range go higher than the HV set-point.,

In the past few months I have driven from a coastal town (elevation 100' above MSL) up to Big Bear (7100' above MSL) and back 3 times. Since this is a long journey that is well beyond the EV range, i start with a fully charged battery from the lower elevation, and run on HV mode. As I climb the hill I frequently reset the set point to progressively lower numbers to help reduce the stain on the engine. I usually reach the higher elevation destination with about 70% SOC. On the way down I run on HV mode (starting with SOC around 70%) and as I descend the SOC% increases to much higher numbers - high 80s, low 90s until I reach the foothills and then the SOC% starts dropping to the set point. SOC% observed using the OBDII reader.

Edited to add: 2021 Clarity PHEV - in case the model year makes a difference in the software logic used.

 

[ClarityBill]

W

In the past few months I have driven from a coastal town (elevation 100' above MSL) up to Big Bear (7100' above MSL) and back 3 times. Since this is a long journey that is well beyond the EV range, i start with a fully charged battery from the lower elevation, and run on HV mode. As I climb the hill I frequently reset the set point to progressively lower numbers to help reduce the stain on the engine. I usually reach the higher elevation destination with about 70% SOC. On the way down I run on HV mode (starting with SOC around 70%) and as I descend the SOC% increases to much higher numbers - high 80s, low 90s until I reach the foothills and then the SOC% starts dropping to the set point. SOC% observed using the OBDII reader.

Edited to add: 2021 Clarity PHEV - in case the model year makes a difference in the software logic used.

What does the EV range do while the SOC is increasing in HV mode?

 

[Reyn]

W

What does the EV range do while the SOC is increasing in HV mode?

The EV range keeps increasing as the SOC increases. From what i recall, the maximum EV range i saw when coming downhill was 85 miles. What I did not pay attention to was whether the engine was running (despite being in HV mode) and if so at what RPM. I don't know when i will next go up to Big Bear, but when I do I will request my wife to do some screenshots of the CarScanner app screen on our way back.