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Discussion Starter · #1 ·
This may have been asked before but can't find a post on the topic.

When I start the morning with a fresh full charge the distance remaining is 44 miles. The power flow screen displays all green bars/full charge. The next 5 miles are down hill so I gain 7 miles... so now there are 51 miles remaining. The power flow screen shows there is minus one green bar or one less green bar.

Is there a good explanation for that? Do the extra miles get placed in a reserve portion of the battery?

Thanks!
 

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I use my OBD2 meter to measure capacity and can see the battery capacity drop even though my commute is down hill
You actually use some battery (hence the missing bar) but were driving so efficently that its also increasing your range estimate.

In my case since its uphill at night, the car has pessimistic estimate (thinking I'll be driving up hill again).. when I head to work its mostly down hill with some flat spots so it uses very little (but does use some) power but the range will stay pegged at 50 (or if at 48 will increase to 50).. for a few miles. I get to work, after 17miles, with 43-47 miles showing but will 2or 3 bars missing.
 

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The estimate if based on your recent driving style (or in other words the recent average KWhr/mi). I believe the green bars depict the state of charge. It is normal for the two to deviate.
 

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Discussion Starter · #4 · (Edited)
Thanks, tboult. That makes perfect sense especially as it relates to "range estimates." It makes me wonder if there is such thing as the term "regen" though. Is the battery regenerating (charging) or is driving efficiency causing the range to display higher?

Sounds like your commute is similar to mine only I usually get to work with 42 miles remaining after 15 miles.
 

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Also, the algorthym estimating range probably, at least, partially resets for each new drive. If you start a drive regenerating, it may (falsely) estimate what your range will be. I think many cars do this. Our diesel does the same thing.
 

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Looking at the "kWh Used" on the center stack display will be more informative than looking at the estimated range display and number of bars.

Idk if it's capable of going into negative territory or not. But it does display the net energy usage -- e.g., if you're doing a lot of regen down a long slope, you should see it go backwards.
 

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From what I've read in other threads here: when the battery is full, the car will dissipate any regen energy as heat, through the generator and traction motor cooling systems, and accessory use. If you want to see how much a given very long down hill segment will regenerate, you have to start it with a partially consumed battery and see what happens. When plug in charging is complete, there most likely will not be any "reserve" battery storage capacity, because the charging system uses the end of charge time to balance cell voltages, which is very important to battery life, but doesn't add much total stored energy on any one charge. rechargable lithium batteries don't like to have power stuffed into them after the reach a specific voltage, bad things happen. As I poke around the old threads, here, which don't search really well, and aren't organzied well, I think that I've found discussion of devices that can be plugged into the OBD2 port and will record lots of details about discharging and regen power flows. every day I try to read a handfull of old threads to understand more of this.
 

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Thanks, tboult. That makes perfect sense especially as it relates to "range estimates." It makes me wonder if there is such thing as the term "regen" though. Is the battery regenerating (charging) or is driving efficiency causing the range to display higher?

Sounds like your commute is similar to mine only I usually get to work with 42 miles remaining after 15 miles.

There is absolutely regen.. I've had 0 miles and zero charge at the top of pikes peaks.. had 75% charge and 39 miles when I got down.

Then the battery is full (~86% SOC) you can only add a little regen.. before its full with the two EV motors resisting each other. (Some threads say it leasts to a wierd state counting as ICE miles but no use of the ICE). But regen is part of how you keep it efficient. E.g. it takes power to back out of the garage and drive on the flats. You loose power stopping at the stop sign. The eletroncis are using up power. But the downhill regen keep the total power used much lower than normal which is why the range decays so slowly.
 

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The day after I made my 313 mile EV drive all in one day, my Volt assumed I was going for another 60+ mile EV drive as that was what I had been doing my previous 5 drives. However, this was not the case. As you can see, I lost a bar in my '12 Volt, but I was still pegged at 50 mile range.

 

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Discussion Starter · #10 ·
I think the lights are coming on in my head (<junior member/1162 miles on my Volt)... starting to understand this better. It would be more advantageous if I could charge at work instead of at home so I can get the most out of my downhill commute to work. I am still working on getting the people at work to install a dedicated plug.
 

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If you can get a dedicated plug at work and not need to charge at home, you've hit paydirt!
 
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