Mitsubishi Imiev Electric Vehicle Forum

The question on the table is: what is the maximum regeneration in the iMiEV relative to the maximum power draw?



This gauge seems to be nothing more than a damped analog ammeter with a pretty background, showing colors instead of numbers.

Maximum power draw has the needle all the way to the right (white zone "Power"); maximum regeneration has the needle pegged all the way to the left (blue zone "Charge"). Mitsubishi calls it the Energy Usage Indicator, and I had previously suggested that we call it a Power Gauge, ... maybe Eco Gauge is a cutsier title.

Anyway, if the display is linear, then it would appear that maximum regeneration shown is only 1/3 of the maximum that can be drawn. I don't think this is correct, as my impression is that there is more retardation (e.g., when lightly touching the brakes and thus adding even more regen) even when the needle is pegged all the way to the left in the blue zone.

Does anyone have any data on this?

Probably the only way to find out is to clamp a CT (current transformer) onto one of the battery wires...

The reason for bringing this up is my attempt to quantify energy usage as part of the hypermiling discussions...

Edit 7/15/12: added "and Consumption" to thread title.

Joe, I sure wish you were in the hood, we could do one heckuva garage and track day for the i. I've got the equipment to log these values, but haven't had the time yet. Since you've brought it up, makes me want to deploy them dataloggers! In related news, there's a dandy new option to wirelessly monitor and log your DMM through an Android device. Here's hoping it makes the jump to iPhone/iPad soon.
http://www.engineeringtv.com/video/In-Bluetooth-Adapter-Android-Me

Way cool! Yes, would also like to see the app migration to iOS/OSX. Datalogging would sure be nice.

Back on topic: would like to find a nice place to clamp the CT onto a battery cable and run the (small) wires into the cockpit where I can place a nice 12v-driven digital ammeter display good for either 200A or 500A.

Y'know, it's tempting to get an extra service plug from the parts counter and modify it to accept a shunt! Old school metering simplicity, and would also enable one to track the total amp-hrs in and out of the battery, if using an old reliable device like the E-Meter or Link10. Not many new options at 300+ volts, unless you can afford the awesome offerings from http://www.metricmind.com/category/ev-instrumentation/.

OK, I have a Hall-effect clamp-on 200A ammeter with a a six-foot cord which enables me to read amps while driving. Put the clamp on one of the wires going from the battery pack to the controller, and took our iMiEV for a drive.

Here are the ammeter readings correlating to the Power Gauge markings:
(usual disclaimer as I'm using an uncalibrated instrument - but it's close)

Power ON, needle midway between blue and green: 0.0A
(this is an update as I had previously said 0.3A - that was simple instrument offset error)
First Tick Mark 45A
Second Tick Mark 95A
Max Tick Mark 154A (when briefly floored at about 60mph); otherwise I was getting 152.6A at lower speeds.

Regeneration (blue zone):

Seems to be linear, with max tick mark reading ~50A
Regen continues on up despite the needle being pegged, with a maximum reading seen of 104A when letting off the go pedal in "B" at around 65mph. I didn't try also applying the brakes to see if it would further increase.

This is really good news, as it means that our iMiEV indeed has quite powerful regeneration.

Dang, liking this car even more as time goes on...

Update 4/18/12: corrected "zero" reading

JoeS; Good information, Thanks


EcoGauge by JJLINK, on Flickr

Joe,

It sounds like you are saying that we can regen back in at a rate of 2/3 of the power we can send out? That sounds pretty great to me, at least much better than I expected.

Jenn

jjlink: that's a cute graphic!

jenn: you're right - the iMiEV regen appears to be 2/3 of max power, which I consider really good! No wonder both the Fuel Gauge and RR came up on the long downhills to/from Santa Cruz!

Now that we have a rough idea of the calibration of that power gauge, what's needed is a windless perfectly level road to compare power consumption at various speeds. I've been unsuccessful in all my attempts, as there are no perfectly level traffic-free roads around my house. Four data points should be enough: halfway to the first tick mark (22.5A), first tick mark (45A), halfway to the second tick mark (70A), and second tick mark (95A). Post your results here of the speed you measured at these points, and we'll see what we can make of the numbers. Maybe this will allow us to quantify the iMiEV's range-robbing aerodynamic drag effects (or maybe not...)

Joe,

How do you get your ammeter display into the car, where do you thread the wire in?

Thanks,

Jenn

Joe's using a clamp-on inductive meter that doesn't require any conductive connections. Here's an example of the tool with good explanation of how it works.
http://www.powerstream.com/DC-clamp.htm