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The "steady state" with ignition on (after the car settled down with whatever initial stuff is coming on line) was pulling ~0.34 to 0.45 kW ...
...
I'm not sure the AC can't pull more than 3 kW ... I'll have to test that. I could set the temp as low as it would go (instead of 72) and put the fan on high ... based on the pretty easy test I did this afternoon, it wouldn't take much more to move it above 3 kW consumption.

Just ran out and re-tested the car in the garage. This is interesting... the power consumption seems to tract the PID labeled "Batt Coolant Pump RPM(RPM)". Not sure if this is really the coolant pump for the battery or related to the variable compressor for the AC...


Also, the steady state power consumption with ignition on after shutting off the AC and after all the electronics in the car were stabilized (and turning off the headlights) was only 0.11-0.23 kW.


I'll have to log the Batt Coolant Pump RPM(RPM) parameter next time I do a longish drive using AC and see how that behaves.
 

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GJETSON said:
I'd love to get one, just as soon as it is plug and play. I am no computer geek. I am terrified of screwing something up, playing with the OBD, and software. That is like a baby with a hand grenade.
It really is pretty much plug-and-play.
 

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The "steady state" with ignition on (after the car settled down with whatever initial stuff is coming on line) was pulling ~0.34 to 0.45 kW (the DIC only shows 0.5 kW resolution which is much more coarse than the OBD shows), so ramping up to 2.82 kW is ~2.82/0.4=7.05 times as much energy. I consider a 7000% increase "considerable" :)
Um, I'm no mathematician, nor do I play one on TV, but...
If you use 7 times as much energy as before, that's a 600% increase, no?
The original 100% + an additional 600% = 700% so not 7,000, not 6,000, but 600.

Now 700% is a big number, but to paraphrase Mssr. Jetson, 700% of very little is still very little.
 

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Um, I'm no mathematician, nor do I play one on TV, but...
If you use 7 times as much energy as before, that's a 600% increase, no?
The original 100% + an additional 600% = 700% so not 7,000, not 6,000, but 600.

Now 700% is a big number, but to paraphrase Mssr. Jetson, 700% of very little is still very little.
Ha! Yes, my bad. 7.05 would equate to 705%. Just an order of magnitude off :) And the use of the term "increase" would indicate the ~605% as you indicate.

The thing I was trying to get across was some actual measured data of AC energy utilization, which had been speculated about in this thread, but not quantified precisely. However, I made a mistake with posting too fast and not double checking my post before submitting.

However, the measured data shows that the peak energy consumption from the AC use can be VERY high (good grief, the peak #'s if converted to kWh would be roughly 1/2 my normal kWh usage for a normal commute). So YES, without any doubt, that is a significant energy consumption figure.

But I also know, from results for a long round trip in very warm conditions with AC use that I posted earlier, that the peak consumption I was measuring from today's test MUST reduce once the cabin temperature is stabilized, as the full trip consumption figures, even at 70-75mph in 102F temps was close to the EPA range rating even when using AC. And the measured data from today showed a rapid tailing off of consumption as the cabin temperature came closer to the desired set point. But I expect the exact energy consumption from AC to depend on a combination of factors (ambient temps, cabin temp, length of time of trip, etc.)...
 

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Just ran out and re-tested the car in the garage. This is interesting... the power consumption seems to tract the PID labeled "Batt Coolant Pump RPM(RPM)". Not sure if this is really the coolant pump for the battery or related to the variable compressor for the AC...


Also, the steady state power consumption with ignition on after shutting off the AC and after all the electronics in the car were stabilized (and turning off the headlights) was only 0.11-0.23 kW.


I'll have to log the Batt Coolant Pump RPM(RPM) parameter next time I do a longish drive using AC and see how that behaves.
Yeah. I'd be really surprised if those little 12 volt, 10 amp fused coolant pumps were variable speed. If you put your hand on one of the reservoirs while its pump is running, you can feel slight vibration, and hear a little hum. But I don't think they are turning anything like 6K rpm. The 400 volt compressor motor though is definitely varying speed, and sounds like a jet engine winding up.
 

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It really is pretty much plug-and-play.
OK. I am looking at this spreadsheet from Telek. It doesn't look like plug-and-play to me.

http://bit.ly/ChevyBoltPIDs

I figure I'd go for the high end OBD2 unit? Low battery draw is good, given how poorly the 12 volt batteries are maintained in EVs, and high sample rate sounds good too, I imagine?

[ame]https://www.amazon.com/ScanTool-427201-OBDLink-Bluetooth-Professional/dp/B00H9S71LW/ref=sr_1_2?s=automotive&ie=UTF8&qid=1522253582&sr=1-2&keywords=obdlink+lx[/ame]

It comes with Android software so it should communicate with my LG VS501 K20 phone? Think the Tesla nut, kid at my Verizon store could load up/setup the app and PIDs for me?
 

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The Bjorn guy posted a video this afternoon of a similar AC power consumption test on a Tesla. Once the cabin was down to temp, over a 2 hr period the car was using ~950 W an hour to keep it cool, compared to 1500-2000W for a heating test in winter conditions.



 

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...
I figure I'd go for the high end OBD2 unit? Low battery draw is good, given how poorly the 12 volt batteries are maintained in EVs, and high sample rate sounds good too, I imagine?...

That looks like a nice unit. I've been using Torque Pro on multiple vehicles with a couple cheap $10 obd2 bluetooth dongles from Amazon for the last 7 years and both dongles keep working. You can always just pull it off the OBD connector when you're not using it to make sure there's 0 current draw, but neither of my units have had issues with draining batteries from remaining plugged in (although my experience of 2 cheap units is a small sample size).


If you go with Torque Pro and want to use those custom PIDs and need help with installing them, post on the thread the PIDs came from and I'll try to help with the install/setup if you have issues.
 

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If you go with Torque Pro and want to use those custom PIDs and need help with installing them, post on the thread the PIDs came from and I'll try to help with the install/setup if you have issues.
Thanks. I will definitely need lots of hand holding.
 

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GJETSON9 said:
OK. I am looking at this spreadsheet from Telek. It doesn't look like plug-and-play to me.
Once Torque Pro is loaded onto your phone, you just input the indiviual PIDs that you want to use right into the app. I couldn't get the file to load to have all of 'em available, so I just put them in one at a time.
I'm using a BAFX OBDII bluetooth unit that I got on Amazon for 18 bucks. Works great.
I leave mine plugged in all the time, but you can always unplug it if you're worried about battery draw.
 

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the measured data shows that the peak energy consumption from the AC use can be VERY high (good grief, the peak #'s if converted to kWh would be roughly 1/2 my normal kWh usage for a normal commute). So YES, without any doubt, that is a significant energy consumption figure.

But I also know, from results for a long round trip in very warm conditions with AC use that I posted earlier, that the peak consumption I was measuring from today's test MUST reduce once the cabin temperature is stabilized, as the full trip consumption figures, even at 70-75mph in 102F temps was close to the EPA range rating even when using AC. And the measured data from today showed a rapid tailing off of consumption as the cabin temperature came closer to the desired set point.
You measured a peak of about 2 kWh of AC consumption, right? That highlights the importance of conditioning the cabin while still plugged in.

As pointed out in another thread by Zoomit, it takes about 25 kW to travel at 75 MPH. 1 kW AC maintenance cooling is 4% of total consumption at that speed.

However, at 50 MPH, only 10 kW is needed to maintain speed, and that same 1 kW cooling would account for 10% of consumption.

There is 746 Watts in a HP, so AC is consuming roughly 1.34 HP.



Speed vs Energy consumption thread:

http://www.chevybolt.org/forum/9-2017-chevy-bolt-ev-general-discussion-forum/5866-speed-vs-energy-efficiency.html

OK. I am looking at this spreadsheet from Telek. It doesn't look like plug-and-play to me.

http://bit.ly/ChevyBoltPIDs

I figure I'd go for the high end OBD2 unit? Low battery draw is good, given how poorly the 12 volt batteries are maintained in EVs, and high sample rate sounds good too, I imagine?
I've been running a $10 unit for about 7 years now. I measured 38 mA draw, which is about 1 Ah per day. It has an off button that doesn't do anything. As long as the car is run every few days, keeping the adapter plugged in is no big deal.

If you look at the reviews on the expensive one, the biggest complaint is that low power mode doesn't work. I've got no experience with the units, so I'm not able to substantiate those claims. I'm sure the sample rate is faster than my unit, but I have a ridiculous amount of gauges on my app and it's still fast enough for my liking.

Once Torque Pro is loaded onto your phone, you just input the indiviual PIDs that you want to use right into the app. I couldn't get the file to load to have all of 'em available, so I just put them in one at a time.
Not sure if this was your problem, but I had run into this myself. From the PID Spreadsheet:

2c) navigate to .torque (this is a hidden directory)
2d) navigate to extendedpids (if this directory doesn't exist, either create it, or do steps 3,4 and return here)
2e) you should be in /internal storage/.torque/extendedpids/
I had copied the file into the external SD card folder instead of the internal device folder. Both folder locations exist, but only 1 is used by Torque.
 

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You measured a peak of about 2 kWh of AC consumption, right? That highlights the importance of conditioning the cabin while still plugged in.

As pointed out in another thread by Zoomit, it takes about 25 kW to travel at 75 MPH. 1 kW AC maintenance cooling is 4% of total consumption at that speed.

However, at 50 MPH, only 10 kW is needed to maintain speed, and that same 1 kW cooling would account for 10% of consumption.

There is 746 Watts in a HP, so AC is consuming roughly 1.34 HP.
...
Not quite.

3.72 kW was the peak power for the min temp/max fan speed test. And the baseline steady state "Ignition On" vehicle draw after turning off the AC was bouncing between 0.11 and 0.23 kW (min resolution seems to be ~.115 kW), so I'd average it at ~0.17'ish kW . So the AC system was able to consume at least 3.72-0.17 = 3.55 kW at the max level I recorded for this test. 3.55 kW is ~4.76 HP, and my daily commute has an average speed of ~43 mph, and based on round trip summer energy consumption figures, that 3.55 kW is roughly 1/2 of my average energy rate utilization without AC. That peak energy draw capability is substantial.

However, as previously mentioned, that peak AC power usage drops substantially once the cabin gets close to the set point. But how hard it needs to work to maintain a setpoint will have a lot of variables involved, but it will definitely stay WAY below the peak power consumption figures (based on my 102F 85 mile trip at interstate speeds with AC).

Also, my measured data for 75mph in 0 wind on level ground shows less than 25 kW (http://www.chevybolt.org/forum/12-wheels-tires-brakes-suspension/8714-improving-drag-lowering-under-car-aero-6.html). Averaging the flat sections shows ~ 22.5-23 kW. And my measured 50 mph consumption is also less than Zoomit's calculations predict. Wonder if he was using the pre-production Cd estimate which was higher than the final production Cd (0.308)?
 

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In general cruise control is going to be detrimental to efficiency because the system makes too frequent and too severe throttle adjustments in an effort to maintain speed as close as possible, this is especially true when going up even slight hills where the car will apply quite a bit of throttle to maintain the set speed when usually you would try to maintain a set throttle position and allow yourself to slow a bit or maybe only apply a little additional throttle to keep your speed from dropping too much on longer hills. I stopped using it years ago in my ICE vehicles because I can drive much more efficiently modulating the throttle myself. I do use it for brief periods on hours long drives to allow me to "stretch" my legs a bit and hive my calf muscle a brief respite.

Now of course it's certainly possible for a car company to design their cruise control to operate with economy in mind, but based on my limited experience testing it in the Bolt and other reports I've heard it does not seem that GM did so for the Bolt.
So, you are one of the guys that I pass going up a hill that then passes me on the down-slope... An ICE car in general is aggressive on throttle and overshoots, then undershoots and then steadies out on a speed with each extreme changes in grade, but the Bolt EV (and the Volt before it) maintain speed exactly as set even on steep down grades if you have it in L.

Keith
 

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Got some good comparison data for energy consumption impact for an afternoon "return from work" commute of 14.1 miles. Almost exact ambient weather conditions (temp, wind and even the battery temp was <2 deg F different) Tue/Thurs afternoons when I took the Bolt (bicycle commuted M/W) and was able to compare the impact of AC usage versus driving with the driver window down (and rear passenger cracked a little to keep an unpleasant wind resonance from occurring). The use of AC was MUCH more comfortable at these temps/conditions than using the window...

The logged parameter "Batt Coolant Pump RPM(RPM)" is definitely related to the AC variable compressor, and tracks extremely well with its power consumption, and it did trail off as the trip home went on and seemed to level out at ~ 1800 rpm range when traveling at ~57 mph.

Interestingly, even with ambient afternoon temps in the low 90's the logged "Batt Temp" parameter increased about 1.8F (which seems to be the resolution limit on that sensor) on both return trips. There did not appear to be any effort to reduce the battery temp when the battery is in the mid 80's F. Does anyone know at what temp the "thermal management" kicks in and starts cooling the batteries in hot environments?

Using AC for my 14.1 mile afternoon commute caused an extra energy consumption of ~ 0.51 kWh (~ 3.38 kWh - 2.868 kWh), or comparing with/without AC, a ratio of 117.8%.

I'd rather use the AC and pay the extra kWh cost in electricity/pollution and be comfortable in hot/humid wxr and not be sweating in my work clothes...
 

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Definitely speed. If I charge the car 100% every day I can drive two full days and I still have about 50km left. Yesterday I was not paying attention on speed and i drove very fast and stepped on the pedal harder than usual. it was the first time I arrived home on a red gauge.
 

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I wouldn't even assume that it rounds. It could well simply truncate - meaning that a reading of "1 kW" could be anywhere from 1 to 1.9 kW. We simply don't know, or at least I personally haven't seen anything to tell me.
I agree. I hope it rounds because it is a very simple calculation to round correctly (even when considering negative numbers). But a lazier programmer could have simply truncated.:nerd:
 

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In general cruise control is going to be detrimental to efficiency because the system makes too frequent and too severe throttle adjustments in an effort to maintain speed as close as possible, this is especially true when going up even slight hills where the car will apply quite a bit of throttle to maintain the set speed when usually you would try to maintain a set throttle position and allow yourself to slow a bit or maybe only apply a little additional throttle to keep your speed from dropping too much on longer hills. I stopped using it years ago in my ICE vehicles because I can drive much more efficiently modulating the throttle myself. I do use it for brief periods on hours long drives to allow me to "stretch" my legs a bit and hive my calf muscle a brief respite.

Now of course it's certainly possible for a car company to design their cruise control to operate with economy in mind, but based on my limited experience testing it in the Bolt and other reports I've heard it does not seem that GM did so for the Bolt.

If we focus strictly on fuel efficiency, you have a point. But I think your focus is flawed on two dimensions.


1. You are describing a skill that places you well above average. The average driver is not above average. Decades ago, the only way we could drive at a constant speed was do what you describe. I thought I did pretty well. I thought a few other drivers did pretty well. In my experience, it was beyond the skill or desire of the vast majority of the other drivers on the road. My point is, you are not other drivers and they are not you. In recent years, my observation (granted I see only a small part of the world) is that drivers are doing better holding speed and my guess is that this improvement is due to cruise control.

2. The main purpose of fuel efficiency is financial. In every driver's ed course I've taken, the instructor has stressed the important of "driving with traffic (flow)." When in moderate traffic a reliable way to stay with traffic flow when others are using cruise control, is to also use cruise control and adjust to whatever the others are doing. Another safety advantage is that if I'm not using the "gas" pedal, I can prepare for a quicker stop by positioning my foot over the brake pedal. I do this when I'm closing on another car or approaching a stale green light at highway speeds. (My commute has 3 such lights, each way.) Anyway, an advantage to cruise control is safety (in moderate traffic at highway speed) and getting into a crash is extremely inefficient.



My overall point is we should look at the bigger pictures.
 

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I'd rather use the AC and pay the extra kWh cost in electricity/pollution and be comfortable in hot/humid wxr and not be sweating in my work clothes...

I agree. Also, when I'm comfortable and happy at work, I'm far more effective at my job. The cost of A/C is dwarfed by what my job is worth.
 

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I agree. I hope it rounds because it is a very simple calculation to round correctly (even when considering negative numbers). But a lazier programmer could have simply truncated.:nerd:
Boy, you'd have to be *really* lazy to not test for sign and add positive or negative .5 before truncating!


I'm a hardware guy (but did my share of coding), and even *I* know how to do that! :eek:
 
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