[thetoad]

So I'm new to my volt (got my lease a bit over a week ago). I can't charge at home, but there's free level2 charging near work so I generally try to fill it up as much as I can there.

So today I filled it up from "empty" and according to chargepoint receipt it filled up 16.365 kWh (and both got the onstar text saying it was filled and following the charging status on the chargepoint app showed that it wasn't pulling any more power), I then drove it about 50 miles and it conked out after about 41-42 on electricity and when I finally got home and looked at the info screen it showed me that it used about 14something kwh to go those miles (which sort of fits with the chagepoint numbers if one assumes a 10+% energy loss)

what am I missing about battery capacity that I should have thought was closer to 18.4kwh?

 

[edk-austin]

Volt will only use 14-ish KWHrs. To prevent battery wear, it never fully tops off, and never fully discharges. Gen 1 only used 10-ish of 16.5KWHrs. The 53 mile EPA all electric mileage IS based on the 14 KWHr use, and many people do get well over that. Common actual battery use is about 14.4KWHr.

 

[thetoad]

ok, that explains it. I sort of figured that, but its sort of the inverse of what Tesla does, they advertise a kwh battery but that's actually how much usable battery you get, the internal battery is actually bigger.

in the past I've done better than the 53 miles as well, but that was driving very conservatively, this was going 70+ for the majority of my trip home.

 

[freshcut]

Keep in mind too that Tesla, like other BEV vehicles (Bolt, Leaf, etc) only have the battery as their power source and as such they dip into far more of the battery total capacity than the Volt does. It would be like having a vehicle with a 20 gallon tank, but only able to use 15 of those gallons. Fortunately in the case of the volt, those extra "5 gallons" are available for use under VERY EXTREME conditions.

With the BEV's using nearly their entire battery capacity, they usually don't lend themselves to any sort of emergency reserve power, however the Volt actually does. The bottom ~15% is normally untouched even when the battery meter is exhausted since it starts the ICE and generates power. The Volt however has an ace up it's sleeve and after the main part of battery has been depleted and even after the gas has been depleted that extra 15% or so is utilized as an emergency backup giving you up to about 3 miles of reduced propulsion power to get immediately to a gas station or charging location.

 

[llninja]

Don't worry, years down the road you'll be happy GM designed it this way while other vehicles which charge all they way up and drain all the way down will start losing their charge bars. Early leafs have this problem. It's possible this will also happen to Tesla's (though it's harder to tell with such a big battery), BMW i3's and Leafs.

 

[flyingsherpa]

ok, that explains it. I sort of figured that, but its sort of the inverse of what Tesla does, they advertise a kwh battery but that's actually how much usable battery you get, the internal battery is actually bigger.

in the past I've done better than the 53 miles as well, but that was driving very conservatively, this was going 70+ for the majority of my trip home.

That's not what Tesla does, according to this article. Restricting usage like this is often called a "state of charge" (SoC) usage window. Original Volt allowed about 65% SoC usage, gen2 is around 75%. Pure BEVs like Leaf, Tesla, etc tend to use higher SoC windows, like 90-95%, to maximize range. But battery longevity is highly dependent on SoC window used (among other things like temperature of course). So you would expect a Tesla to have more battery degradation than a Volt over time... though note that one cycle of a Volt battery might be 40 miles, while one cycle on a Model S might be 250 miles, so it would take over 6 cycles of a Volt pack to cover the same mileage. This can make comparisons tricky...

 

[thetoad]

you are correct, GM advertises it correctly when they advertise it. i.e.

https://media.gm.com/content/dam/Media/microsites/product/Volt_2016/doc/VOLT_BATTERY.pdf

I was going off of info I saw elsewhere, so telling me that hte battery capacity is 18.4kwh is relatively irrelevant. it's 14+'ish and the chargepoint numbers make sense with a 10-15% loss in charging.

that also makes the back of the envelope calculations I was doing in terms of the equivalent cost of gas more favorable to the volt. i.e. should be multiply kwh cost by 16.365 (or thereabouts) instead of 18.4.

 

[llninja]

you are correct, GM advertises it correctly when they advertise it. i.e.

https://media.gm.com/content/dam/Media/microsites/product/Volt_2016/doc/VOLT_BATTERY.pdf

I was going off of info I saw elsewhere, so telling me that hte battery capacity is 18.4kwh is relatively irrelevant. it's 14+'ish and the chargepoint numbers make sense with a 10-15% loss in charging.

that also makes the back of the envelope calculations I was doing in terms of the equivalent cost of gas more favorable to the volt. i.e. should be multiply kwh cost by 16.365 (or thereabouts) instead of 18.4.

Your Newb is showing. Although it's fun to try to figure out how your new vehicle is performing, eventually it will wear off and you can just enjoy driving the car. Resist the urge to constantly look at the telemetry on the dash and center console and pay attention to the road. Otherwise you might find a sudden stop sign materialization out of thin air or a kamikaze deer ruining your grill, front hood, side panels, roof, and radiator.... followed by multiple trips to the body shop.

 

[timoshev]

For gaging electric performance I like to calculate mi./kWh.(from the leaf screen and you can get a pretty good approximation by inspection) 4-5 mi. is "normal" Slow and go in summer may get you over 5 and cold winters or 70 mph+ can yield below 4.
Enjoy the ride.

 

[Rampage_Rick]

what am I missing about battery capacity that I should have thought was closer to 18.4kwh?

Further to what everybody else has said, the charger in the Volt is about 86% efficient in converting AC to DC. 86% of 16.365 kWh is 14.074 kWh.

http://gm-volt.com/forum/showthread.php?100681-What-is-the-charging-overhead/page2

 

[tony604]

Keep in mind too that Tesla, like other BEV vehicles (Bolt, Leaf, etc) only have the battery as their power source and as such they dip into far more of the battery total capacity than the Volt does. It would be like having a vehicle with a 20 gallon tank, but only able to use 15 of those gallons. Fortunately in the case of the volt, those extra "5 gallons" are available for use under VERY EXTREME conditions.

With the BEV's using nearly their entire battery capacity, they usually don't lend themselves to any sort of emergency reserve power, however the Volt actually does. The bottom ~15% is normally untouched even when the battery meter is exhausted since it starts the ICE and generates power. The Volt however has an ace up it's sleeve and after the main part of battery has been depleted and even after the gas has been depleted that extra 15% or so is utilized as an emergency backup giving you up to about 3 miles of reduced propulsion power to get immediately to a gas station or charging location.

This is true. There are youtube clips of people testing this if you don't want to risk trying yourself