Measuring Regen

[eplantz]

I would like to measure how much regen energy I'm getting for my commute. I drive 33 miles one-way..... charge at work and return over the EXACT SAME route. My electric range can vary by as much as 10 miles (same weather temp).

I suspect the difference is due to traffic patterns and regen. The morning drive is at 9AM and the return is at 2PM. It is a lot slower in the morning with more stop-and-go traffic (driving in L).

I have a DASHDAQ but don't see any counter for regen energy. Can anyone think of an indirect way to calculate the regen energy on a drive??? I can see AMP HOURS.....which generally is used up during driving but is added to during regen/braking. So, I might get a total at the end of 21 amp hours but that does not really tell me anything about the regen contribution.

[Cap'n Crunch]

Only thing I can think of is to drive the circuit but put the car in neutral when you brake. This will give you a zero regen measurment right?

[cnicholson]

I don't have a direct answer to your Q, but I would also be curious about it.

It sounds like you are thinking that maximizing regen will maximize range. At some level, the opposite is true. Physics being what it is, you can never round-trip energy and gain anything (in the real world you always lose *something*). So max range (round trip) would be constant speed on a flat road.

The only regen variables within your control are (i) minimize friction braking and (ii) minimize excess speed followed by coast-down regen. Note that (ii) is where you want to REDUCE regen to INCREASE efficiency.

Unless you are a lead foot some days, apart from weather I have found that the biggest variable is average speed. With zero traffic and cruising at 70-75, you are burning a lot of power pushing air out of the way. With light traffic that slows the flow down to 30-50mph, I get the best range. Second best is a mix of slow and stop and go. In the stop and go case, regen is definitely your friend, but can never beat a constant moderate speed.

[scottf200]

"Similar Threads" at the end of this thread (and all) as well as a site:gm-volt.com search shows this thread where techtom did it.

Amount-of-Regen-from-Volt-using-DashDaq
http://gm-volt.com/forum/showthread....-using-DashDaq

[Codyozz]

I have two things you should try that might help you estimate kw gained:
No.1 - find the exact elevation for both home and work. I have an iPhone app that tells me.(Current elevation) from this you can determine a if route is actually similar.
No2 - drive your route in middle of night in lightest of traffic and don't use the brakes, or Low. When u get to work you can see the amount of energy used. It should be lower, and range should be similar. From this you might extrapolate an estimate on "real kw used in driving, vs what I use in stop n go traffic, aided by regen)

I also wonder if you can delay charge the car just so, so that you can interrupt the charge before its complete (@95%). Then try and drive to work and see if their is much difference between full charge and almost full charge. Then, for your return home you can do the same thing. find a combo that gives you best results.

I'm also curious what your average speed is for both directions, do u get more range for lower average speed due to regen stops? Or is 37mph steady better?

[Recoil]

I would like to measure how much regen energy I'm getting for my commute. I drive 33 miles one-way..... charge at work and return over the EXACT SAME route. My electric range can vary by as much as 10 miles (same weather temp).

I suspect the difference is due to traffic patterns and regen. The morning drive is at 9AM and the return is at 2PM. It is a lot slower in the morning with more stop-and-go traffic (driving in L).

I have a DASHDAQ but don't see any counter for regen energy. Can anyone think of an indirect way to calculate the regen energy on a drive??? I can see AMP HOURS.....which generally is used up during driving but is added to during regen/braking. So, I might get a total at the end of 21 amp hours but that does not really tell me anything about the regen contribution.

Have you taken the wind into account? Living in Texas I usually get winds out of the South and when they get over 25 mph with my commute out of the North I can lose up to 4 miles of range on a 25.2 mile commute that is about 60% freeway. The way I figured it even though I am driving at 58mph the drag on the car thinks it is going 83mph which uses a lot more energy to overcome.

The worst part is as a pilot I am gone for a couple days and when I return the wind has usually died down so I get no help on the return trip home.

[eplantz]

I'm also curious what your average speed is for both directions, do u get more range for lower average speed due to regen stops? Or is 37mph steady better?

I have experimented by using cruise control set to 67 and found it DOES increaser my range. Driving a steady 37mph is not an option…. if I'm not doing 80, I'll get run over by all the other traffic. The commute involves tollway driving driving for about 20 miles and then city expressway which can be highly variable from 65 to 2mph.

[eplantz]

Have you taken the wind into account?

Not really a factor. I'm basing my comments on one year of driving this route…. winter and summer,etc. I believe all the variability in range is due to traffic conditions (other than the obvious effect by ambient temperatures).

[eplantz]

No2 - drive your route in middle of night in lightest of traffic and don't use the brakes, or Low. When u get to work you can see the amount of energy used. It should be lower, and range should be similar. From this you might extrapolate an estimate on "real kw used in driving, vs what I use in stop n go traffic, aided by regen)

well, this would provide a nice baseline but I'm not about to drive downtown and back in the middle of the night just to prove this.

[DonC]

If you don't have to heat or cool the car nothing increases EV range like slow stop and go traffic on the freeway. The slower it is the better the range. Makes a huge difference.