DonDakin
Posts: 387
Joined: Wed Aug 15, 2012 7:10 pm
Location: Montreal Quebec.....

Canion Battery Readings

Thu Sep 26, 2013 12:08 pm

Well canion has really been an eye opener.

There are a few things that I have learned.

First:

I use to think that the OEM L1 EVSE was about 900 watts going into the battery less the charger overhead. But it looks more like it's 500 watts. It also looks like the car overhead is about 300 watts give or take.

When the car is powered up and not moving it seems to draw about 1 battery amp.
That's just the basics no lights or ancillary equipment.

Second:

But more surprising is that when you select Preheat on L1 it actually draw about
2 amps from the battery. This is a surprise to me. I thought Preheat was free heat but not on level 1. Shame on you Mitsu..... All the more reason they should have provided a 12 amp L1 or a 120/240 L1/L2 capable EVSE. Very disappointing to think I was draining away the battery last winter during L1 preheat.

Now for L2

L2 charge battery current is 7 amps or about 2.5 KW. Where did the other .8 KW go ? Even if there is 300 watts of overhead required to power ancilary stuff we are still missing 500 Watts of power (that's a whole L1 OEM for god sakes......)
Hmmmmm.....

oh yeah wait a sec 90 % effeciency in the charger would explain that, Well that's good news.

As for preheat on L2 1 amp for the battery and the rest for the heater. That's reasonable.


Third:

That battery heats up on L1 charging. I am guessing all those little bypass mini heator resistors in there are heating up the battery chamber. After
9 hours of L1 charging I saw about 5 deg C above ambient. I was surprised because I expected with such a low current no heat to be generated but I'm thinking the heat is generated in the shunts.

Siai47 is right it's better to charge on L2 then L1. Charge time is faster/equalization/shunting time is shorter and I guess less heat is generated in the battery chamber with the faster times.

Fourth:

There is a hot spot in the battery, at least on my imiev. Its the third bar from the right on the battery temp display, always above the others when the battery is working.

Fifth:

Our little battery has a ton of thermal inertia.

Even with 16 Deg C of temp difference ( battery 24 deg C /ambient 8 Deg C) on a 15 Km gentle ride to work (30 minutes with traffic) the battery temp dropped only .2 deg on average. Maybe I should be thinking about how to extract heat from the battery and vent it into the cabin while I am on the road in winter.

I suppose the reverse is also true that a cold battery will tend to stay cold on those return trips from work in the winter. It will be interesting to check this out this winter.


All of this came from Canion and reading siai47's posts.

Anyways canion is a great app and wonderfull tool. It's like a step in the direction
of the Tesla instrumentation.....

Don.....

offgridQLD
Posts: 101
Joined: Wed Jul 17, 2013 4:13 am

Re: Canion

Thu Sep 26, 2013 2:45 pm

I have measured every charge at the plug. I know when using stock 240v 10A charger it consumes 2200w from the plug so just under 10A. Once a week I do a long trip that takes the Imiev down to two bars (I just hit 2 bars as I pull up home consistently) Measuring KWH from the chargers plug and doing a full charge and balance I always return 14.5kwh give or take 0.1kwh. So I am only loosing 3.5 - 4.5% when charging and balancing. No heating or cooling of the battery.

Most Lithium battery's perform best around 30C. They also create heat while being discharged. (even if you think your taking it easy on them) EV's are hard on battery's so even strolling along they will at least maintain there temp. Granted there is a big chunk of thermal mass there to as you mentioned.

I question the accuracy of the Canion application or at least the data its receiving. Who is to say it's accurate especially at low power consumption/return . Trying to measure say 300w (car idle) accurately on a instrument that also has to measure 50,000w- (inverter powering the motor at full load) is a big ask. You might find the car only consumes 100w at idle its just not accurate at that low consumption. Easy to test place a 100w load on the 12v accessory socket and see if the reading jumps to 400w? (remembering there will be some loss in the DC/DC converter.

I have my android tablet but it looks like my Bluetooth scanner is going to be week or so away in shipping . I'm am keen to have a play and cross check the accuracy of the apps data with a 2nd reference measurement.

Kurt

DonDakin
Posts: 387
Joined: Wed Aug 15, 2012 7:10 pm
Location: Montreal Quebec.....

Re: Canion Battery Readings

Thu Sep 26, 2013 3:14 pm

Hi

It would be great to have some samples from other owners also. I only did this once there maybe some cases that I didn't see.

It is strange to see 500 watts on OEM L1. I mean a 15.2 kWh battery should take longer then 22 hours at 500 watts no ?

Please post and let's find out....

Don....

RobertC
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Location: Winter Garden, FL

Re: Canion Battery Readings

Thu Sep 26, 2013 4:52 pm

DonDakin wrote:It would be great to have some samples from other owners also. I only did this once there maybe some cases that I didn't see.
It is strange to see 500 watts on OEM L1. I mean a 15.2 kWh battery should take longer then 22 hours at 500 watts no ?
I charged last night starting at 7:20PM at Level 1 starting at 46%. This morning at 6:10AM (10 hours 50 minutes later) I was at 97%.
My L1 EVSE was using 7.5 amps at 124 volts AC or 930 watts.

10.83 hours. 51% of 16kWh is 8.16kWh.
8.16kWh/10.83 hours equals 753 watts.

Canion showed L1 charging -1.3 amps at 342 volts DC at 46% (444 watts) and -1.2 amps at 359 volts DC at 97% (431 watts).
If the battery was charging at 440 watts I would have only gained about 4.8kWh in a little under 11 hours.

I'm thinking that the cars ammeter that measures over 100 amps is probably not as accurate when measuring only about an amp, which makes me wonder if the car overhead is really 300 watts?

An interesting test would be to leave the car on for 12 or 24 hours at a starting state of charge at 80%. Turn off the radio, and the heat/AC, and see what the state of charge is 12 or 24 hours later.
Last edited by RobertC on Thu Sep 26, 2013 5:32 pm, edited 1 time in total.
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RobertC
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Re: Canion Battery Readings

Thu Sep 26, 2013 5:31 pm

Preheating Level 1 vs. Level 2 Charging.

With Level 1 charging I started at 97% state of charge and after a little less than 30 minutes of preheating I ended at 95.5%.
My Level 1 EVSE was drawing about 7.5 amps at 124 volts or 930 watts.

Level 1 preheating does use some of the battery charge.

But not much.

Image

With Level 2 charging I started at 99.5% state of charge and after a little less than 30 minutes of preheating I ended at 100%.
My Level 2 EVSE was drawing about 9 or 10 amps at 248 volts or 2350 watts.

Level 2 preheating does not use the battery charge, and can still charge the battery when preheating.

My Level 2 EVSE normally draws 13 amps when charging, and would have charged the battery more if I weren't already almost fully charged.

Image

Comparing the two Amps History screens and the power the EVSE's were drawing, Level 2 preheating heats at more kW than Level 1 preheating.

I would say the heater draws about 1kW at Level 1 and 2kW at Level 2. The heater can draw as much as 5kW.
I have two i-MiEVs and let them sit outside last night. It was about 50 degrees this morning when I preheated. I did not measure the temperature inside the cars, but it seemed that the i-MiEV preheated at Level 2 was warmer than the i-MiEV preheated at Level 1.
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Don
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Re: Canion Battery Readings

Fri Sep 27, 2013 5:32 am

DonDakin wrote:Well canion has really been an eye opener.

There are a few things that I have learned.

First:

I use to think that the OEM L1 EVSE was about 900 watts going into the battery less the charger overhead. But it looks more like it's 500 watts. It also looks like the car overhead is about 300 watts give or take.
Something doesn't add up correctly. If the OEM EVSE was only supplying 500 watts to the battery, a 16 KWH pack would take over 32 hours to recharge and balance
When the car is powered up and not moving it seems to draw about 1 battery amp.
That's just the basics no lights or ancillary equipment.
That doesn't surprise me - There are lots of things running and most of them use 12 volts, so the DC to DC converter is definitely drawing some power off the traction pack. Should it be 330 watts? Hard to say. The converter keeps the 12 volt battery recharged also, so it's hard to pinpoint exactly what's going on there

Don
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siai47
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Re: Canion Battery Readings

Fri Sep 27, 2013 5:44 am

The energy hog when using the factory EVSE is the EV coolant pump. It draws about 300 watts however, it cycles on and off. If it ran all the time, it would take a lot longer to charge but it doesn't therefore the discrepancy in calculated vs. actual charge times. You can watch the battery charge current changing as the pump cycles.

RobertC
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Location: Winter Garden, FL

Re: Canion Battery Readings

Sat Sep 28, 2013 1:25 pm

How much energy does the i-MiEV use when it is turned on just sitting there?

I started the i-MiEV and turned off the radio and the heat/AC, and took a Canion reading at 5PM and the battery was at 62.5% state of charge.

Image

I left the car on overnight and took another Canion reading at 7AM (14 hours later) and the battery was at 51.5%.

Image

16kWh times 11% equals 1.76kWH divided by 14 hours equals 126 watts.

At a DC battery voltage of 346 volts the actual amps should be 0.36 amps, not 1.0 amps. There are two current sensors in the main traction battery, a high and a low. We may be getting the output of the high current sensor on Canion, and not the low current sensor. The output of the high current sensor would not be accurate at low currents.

My i-MiEV was outside and the temperature was in the 50's and 60's, so I am not sure how much the water pump ran. I'm also not sure how much the water pump draws, but it is a tiny thing that is fed from a 15 amp fuse. If it drew 10 amps that would only be 120 watts at 12 volts.

The coolant starts at the radiator condenser tank and runs to the water pump, the on board charger/dc-dc converter, the inverter, the electric traction motor, the radiator, and back to the radiator condenser tank. I would think that the pump circulates the coolant at regular intervals, plus whenever the water temperature sensor (located on the inverter) calls for circulation, or the the three temperature sensors in the on board charger call for circulation. I'm not sure at what temperature the radiator cooling fan (that is on a 40 amp fusible link) runs. When driving the car, the inverter and electric traction motor are creating heat and would probably also call for more cooling.
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peterdambier
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Re: Canion Battery Readings

Sat Sep 28, 2013 1:54 pm

Robert, dont forget the tip for the turtle. She wants her due. We dont get 16 kWh but more likely 80% or some 13 kWh. That gets us down to some 100 watts. How much are the mandatory lights that are on when "the engine is"?

Cheers
Peter and Karin
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PV1
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Re: Canion Battery Readings

Sun Sep 29, 2013 7:38 am

Robert, on the Trip Timer screen, it'll tell you how many Wh were consumed. It would be good to cross check them.

I noticed the same hotspot on the third bar from the right. My battery temperatures are all over the place.
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