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TickTock
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Re: SOC-Meter Improvement Suggestions

Mon Oct 31, 2011 7:56 am

After spending much like looking for a friction inidcator, I realized I was looking in the wrong place. According to the service manual, such a signal does exist, but on the CarCan NOT the EVCan where I was looking. I guess I'll be out gathering some more braking logs using the CarCan mode today.

I think I'd like to revise my feature request #3 a little. Since it is not really safe to keep looking down at the SOC meter, I think a really killer app for it would be to add a small piezo-electric speaker and have it emit a tone whenever friction brakes are being applied (maybe with frequency proporional to amount of hydraulic pressure). Since most of us avoid friction braking all-together, we will only get the beep whenever we screw up so it shouldn't be too annoying and would allow you to keep your eyes on the road.

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garygid
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Re: SOC-Meter Improvement Suggestions

Mon Oct 31, 2011 10:08 am

Amount of Friction Braking? Great, Good Work!

You might look on the 3-CAN Short Drive Log that is posted.
Get the logs at: http://www.wwwsite.com/puzzles/cando/" onclick="window.open(this.href);return false;

As you find things (Ev-CAN or Car-CAN), let me know
so that I can add them to the CAN-Do Recipes, and
consider them for the next SOC-Meter firmware.
See SOC/GID-Meter and CAN-Do Info
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TickTock
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Re: SOC-Meter Improvement Suggestions

Sat Nov 05, 2011 12:59 pm

I took a car can log specifically to find something we could use to give better feedback when you start to engage friction brakes. I think I found three signals indicated in the service manual. Target braking force (1CB:D3<<3+D4>>5), Regen Braking Force (1CB:D1<<3+D4>>5), and Brake Pressure (1CA:D1). Here is a graph of a simple test where I pressed the brake pedal three times at the beginning while I was at a standstill, accellerated, then slowly increase brake pressure until I stopped. I repeated again but more gently.

What is interesting is when you start to engage friction braking, regen is turned off. They do not simply add friction on top of regen. I guess they couldn't get the feel smooth enough. So it tells us it is VERY important to avoid friction braking because you waste *everything* once you go there - not just an incremental amount above the regen capability.

Image

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garygid
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Re: SOC-Meter Improvement Suggestions

Sun Nov 06, 2011 12:55 pm

Regen Braking Force is D1 and D2 (not D1 and D4)?

These are EV not CAR bus readings?

Scale Friction Brake Pressure by about 3.0 ??

GOOD Find, Good Test!!!
See SOC/GID-Meter and CAN-Do Info
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TomT
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Re: SOC-Meter Improvement Suggestions

Sun Nov 06, 2011 12:58 pm

I tried a few tests last night. At about 50-55 mph, I initiated heavy braking. Observing the center display of energy at that point, I was still showing significant regen even though it was clear that I was strongly in to the friction brakes. I would have loved to have a GID meter at that point to see the actual regen power... In any event, it would seem that there is more going on than the logged graph would indicate...
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TickTock
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Re: SOC-Meter Improvement Suggestions

Sun Nov 06, 2011 7:29 pm

garygid wrote:Regen Braking Force is D1 and D2 (not D1 and D4)?

These are EV not CAR bus readings?

Scale Friction Brake Pressure by about 3.0 ??

GOOD Find, Good Test!!!
Oops. Right D1 and D2 (cut and paste error). These are from the car can.

Not sure of the units and they clearly don't line up on the y axis. It looks the the regen braking signal is not the whole picture. I did some more tests today and I did see current into the battery in some cases when this signal was zero. However, the brake pressure signal does look like a good candidate for a friction braking alert.

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TickTock
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Re: SOC-Meter Improvement Suggestions

Sun Nov 06, 2011 7:44 pm

TomT wrote:I tried a few tests last night. At about 50-55 mph, I initiated heavy braking. Observing the center display of energy at that point, I was still showing significant regen even though it was clear that I was strongly in to the friction brakes. I would have loved to have a GID meter at that point to see the actual regen power... In any event, it would seem that there is more going on than the logged graph would indicate...
Yes. It does appear that way. However, the amount of regen does drop dramatically when friction is applied. I will post some more detail in the other thread once I have a nice plot but it looks like there is still some current being put into the battery even though the "regen braking" signal has gone to zero.

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garygid
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Re: SOC-Meter Improvement Suggestions

Thu Nov 10, 2011 1:55 pm

good work guys, wish i could play.
but, not yet.
See SOC/GID-Meter and CAN-Do Info
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vegastar
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Re: SOC-Meter Improvement Suggestions

Sun Nov 13, 2011 4:32 pm

I just assembled my SOC-meter. Thanks Gary for putting everything available for the community. The SOC data and the electrical parameters of the battery are very useful.

If possible I think a third set of data on the EV CANBus should be the battery pack temperature, with the average value and the individual 4 sensors (5 values total). For us outside the US and UK, a degrees Celsius version would be perfect.
2011 Nissan LEAF since 2011-07-07, 151000 km on 2018-03-03, 7 bars, 37.9Ah.

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garygid
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Re: SOC-Meter Improvement Suggestions

Tue Nov 15, 2011 8:01 am

Yes, the Battery Pack Temperature(s) would be very helpful, but they have not yet been identified.

I am not yet convinced that the 4 internal Pack temps actually occur outside the Pack, at least without an active request.
See SOC/GID-Meter and CAN-Do Info
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