Fast Charging in Winter Experience

[sandange]

My first cold weather -13 C ( 8 F) fast charging was disappointing

I'll be using fast charging only for emergency in the winter

My Charging report
I just drove 85 km ( 53 miles ) so the battery was warm.
I waited 15 minutes for an I 3 to finish charging
There were 12 km ( 7.5 miles )on the RR gauge
Charged to 77 km ( 48 miles )

It is in French but the main details are understandable
Keep in mind that here our residential electricity cost
are less than .10 kwh

My Circuit Electric charging session

Nom du parc: Centre de services communautaires du Monastère
Nom de la borne: CEC-00002
Date de début de session: 2014-12-30 10:03:55
Date de fin de session: 2014-12-30 10:53:31
Énergie consommée: 8.6 kWh
Durée de la session: 00:49:35 sec.
Coût de la session: 7.19 $
TPS/GST 5%#813762895RT0001 0.36 $
TVQ/QST 9.975%#1215530678TQ0001 0.72 $
Coût total: 8.27 $

 

[RobertC]

My first cold weather -13 C ( 8 F) fast charging was disappointing.

You paid $10/hour (Canadian), for a total of $8.27 (Canadian) for 49 minutes and 35 seconds and 8.6kWh.
In US dollars you would have paid $7.14 for your session, or $0.83/kWh.
Member JoeS was charged $0.59/kWh recently. At that rate you would have paid $5.07 (US).

I just drove 85 km ( 53 miles ) so the battery was warm.

The battery temperature only increases a little from driving. If when you started out your battery was at ambient outside temperature, and it was cold outside, then your battery was still cold. Judging that it took almost 50 minutes for your battery to charge only 8.6kWh, I would guess that it was still cold.

I'll be using fast charging only for emergency in the winter.

Thank you for this informative post. We can see that fast charging isn't so fast when the battery is cold. DC fast charging rates are expensive compared to what we pay when we charge at home. Do you have a heated garage that you could park you MiEV in overnight before the next time you use a DC fast charger? It would be interesting to see if your charging time was reduced.

 

[peterdambier]

Just for comparing, Mitsu Europe Ruesselsheim (Germany) have a public e8enery CHAdeMO charging. It is not far from the autobahn and it is free.

It happened to be almost middle of our trip and back home. The charger can only do 20 kilowatts. Close to the charger we dared meeting the metal with the pedal. Not enough to heat our batteries but it still took only 15 minutes to fully charge to 80%. Maximum power our batteries took was 16 kilowatts. I guess our batteries were about 40% before charging.

To bad we rarely come close to Ruesselsheim and Mitsu is the only "supercharger" close enough to our home.

At RV parks we pay Euro 0.50 per kWh. At home it comes close 0.33 or less. Public charging is either free or expensive here. Mostly it is kind of flat rate with membership fee 45 Euros per year for a single group and you need more than one of them.

We have very few fast chargers but all I know are free.

Happy new year
Peter and Karin

 

[sandange]

You paid $10/hour (Canadian), for a total of $8.27 (Canadian) for 49 minutes and 35 seconds and 8.6kWh.
In US dollars you would have paid $7.14 for your session, or $0.83/kWh.
Member JoeS was charged $0.59/kWh recently. At that rate you would have paid $5.07 (US).

Just to add Bluey is parked outside.
The temperature the night before was down to -22 C ( -7.5 F ) & I had timed a 6 hr L2 charge to end prior to departure.
I also did preheat for 30 minutes

A Fast charger competitor nearby is planning to start operating in Jan and their rate will be $ 5 CAD/hour. This will make it much more reasonable.
Sorry- correction $5 for 1/2Hour = same rate $ 10/hr

 

[DonDakin]

Hi sandy,

I think it would be a good idea for you to get canion setup. You can then see the battery temp. If you use the dh to heat the battery on your way to the fast charger perhaps you could get a faster charge rate.

Its easy to remove the servo and manually direct warm air to the battery. You can direct the warm air to the battery and to the cabin at the same time so you dont freeze on the way down to the quick charger.

But i think HQ should bill all chargers fast as well as L2 on a per KWH basis. Its the most reasonable thing to do.

It looks like you paid close to a dollar per khw which is 20 times my residential rate in summer with a heat pump and about 6.5 time the high rate when its below -12 deg c and my heat pump switches over to natural gas. Kind of expensive if you ask me.

In general people pay a premium to get a fast 50 kw charge but if thats reduced to a 10 kwh rate then its not really. A quick charge anymore is it. But still much faster then a 3kw imiev l2 charge.

I agree with robert that if it was -22 deg c then the battery may have been at about -10 deg c max perhaps lower even with the driving. For sure the computer would lower the charge rate to protect the battery. Only way to know for sure is with canion.


Cheers

Don.....

 

[RobertC]

If you use the diesel heater to heat the battery on your way to the fast charger perhaps you could get a faster charge rate.
Its easy to remove the servo and manually direct warm air to the battery. You can direct the warm air to the battery and to the cabin at the same time so you don't freeze on the way down to the quick charger.

If you direct heat into the battery compartment you will quickly heat the battery temperature sensors located on the outside of the batteries, but you will not heat the batteries themselves. The car's computer will falsely think that the batteries are warm and will allow the DC quick charger to pump high amps into your cold batteries, potentially damaging them.

As an analogy, consider baking a turkey. After a while the turkey will be hot and tasty on the outside, but cold and uncooked on the inside. Heat transfer from air to a solid takes a considerable amount of time.

The opposite, heat transfer from a solid to air, can be accomplished rather quickly with a heat sink with fins and constantly moving air. Unfortunately, the MiEV battery is not constructed with heat sinks and fins to remove heat from the battery either.

For the few degrees of temperature change (confirmed with Canion) your battery will get from blowing hot or cold air into the battery compartment by manually opening the vent to the battery compartment, you risk damaging the battery management circuit boards with dust and dirt accumulation from the outside and cabin air. I have seen many circuit boards fail from corrosion and dirt. I would not recommend manually opening the vent to the battery compartment.

But i think HQ should bill all chargers fast as well as L2 on a per KWH basis. Its the most reasonable thing to do.

Per kWh billing would have definitely saved Sandy some money. Because Sandy's battery was cold, an 8.6kWh charge that should have taken about 20 minutes took close to 50 minutes. The same charge in the summer would have cost Sandy $3.31 instead of $8.27.

 

[sandange]

Hi Don
Is our battery management suppose to kick in at certain temp to keep the battery from freezing (prior the point where it will not accept a charge). Apparently the cold still greatly affects the fast charge rate as you approach that temperature.
Even if I used the Diesel Heater to heat the battery, I wonder how long it would take to warm up the battery mass to make any significant difference.
The canion set up would help to monitor, and record but I don't think the temp sensors are measuring at the core of the battery, - real world testing would give solid results.

I agree with you - the costs should be a per/kw rate.
One member on the Quebec forum (AVEQ) shared his cold weather charging experience with his Spark and had much better results.

BRCC( Fast Charger) Trois-Rivières, Drove 92km @ 90km / h,
temperature -11C / -12C ( 12 F )
Battery Level beginning- 25%
End Level 80%
12.5kwh energy consumed,
16min39sec Time
Cost $ 2.78
continuous up to 78% 392V 121A (47.4kw), then reduced to 80% @ 390V 80A (31.2kw). Voluntary shut down of BRCC (fast charger)

Now that was Fast


Robert -we must have posted with in minutes of each other - pretty much the same line of thought.

 

[DonDakin]

Thats a good point about the temp sensors heating up before the batteries do. Perhaps there is some room to help the battery in winter by heating it but perhaps not for quick charging. Considering the slow L1 rate I'm not sure if there is a need to heat the battery or if there is a benefit.

It is true that it takes time for the battery to change temperature. It does have a lot of thermal mass. This is one of the first things i noticed when i got canion set up.

It makes you wonder why mitsubishi is running the ac for a few minutes when quick charging. Presumably where would be no real benefit to doing this as the battery would not really cool down in a 15 minute period only the sensors would.

I just drove outside in - 15 deg C temps starting out with a battery at an ave temp of -1 deg as the car was in the garage for a few hours. The 40 minute run (half on the highway) brought the ave batt temp up to 3 deg C. So there is a reasonable increase of temp despite the very cold ambient temp. This took about 40 % of the battery. So I would guess that you might be able to raise the battery temp 4-10 deg c average running the car with a roughly .5 to 1C discharge rate.

So it looks like the best way to raise the battery temp is to run the car or charge it. Maybe adding some heat to the battery compartment along the way would help but I would want to know that the battery would be above or near freezing just from the drive. So I would guess that if the battery was at - 8 deg C and you ran it on the highway for an hour you should be above 0 deg c or close.

Maybe I'm wrong but i think to quick charge safely at the high currents the battery needs to be above zero deg c.

If you started at -22 deg c ambient even after L2 charging you might be at -18 deg C and perhaps get to -8 deg C after an hour on the highway. If you added heat along the way for sure the sensors would climb and give a false reading. The question is how long would you need to bake the battery to get it above freezing. Maybe adding some heat along the way would be a good idea but not enough to drive the sensors to far from the real battery temp. Perhaps adding heat for 20 minutes per hour of drive time is reasonable and would help bring the actual battery core temp up.

I guess it would be ok to heat the battery if you were only going to do a L1 or L2 charge. Maybe there would be some benefit in that case.

Have to think about this a little. But it does seem that air cooling or heating the battery might not be very effective. Given where the temp sensors are in the pack.

Don.....

 

[jsantala]

What did the individual and total voltages look like while charging in the cold? I suspect it's more about the voltages than temperature sensors. I haven't had the "luck" to charge my C-Zero in very cold yet, since I've been elsewhere when the weather has been to worst.

 

[sandange]

Extreme Cold Fast Charging Testing

Car was parked outside overnight , charged L2 for 6 hrs prior to departure and pre-heated two 1/2 hour sessions before leaving home., then driven 67 km ( 42 miles )
Temperature correction - 27C

Thermometer picture removed when accuracy was checked and found to be wrong

Temp 5:15 am, 8 Jan 2015, Ste-Anne-des-Lacs, QC, Canada

Charger start reading - Temp -22C (-8 F) - Charger end reading

Charging Report Recap

Started at: 41% of battery
Charge time: 55:15 minutes
Ended: 81% of battery
Power Drawn: 8.5kw
Cost : $9.21

Videos
https://www.youtube.com/watch?v=SXTmCLOzf7I

 

[DonDakin]

Hi sandy,

Thanks for the post. The numbers show me that quick charging in the extreme cold is slow, expensive and disappointing.

You post shows that hydro quebec should adjust the rate in winter or just switch to a per kwh charge structure.

I don't know if people on the aveq list are complaining about this. The only thing i can think of is if your ev is kept indoors and The battery is above zero deg c then you would get a faster charge i think. But that make the case for an effective battery warming system that allows the car to accept charge faster when it's super cold.

I suppose newer evs have and will have better battery temp management for extreme temps and then charge time in winter will still be relatively quick. which would be bet for everyone.

But to be fair to this generation of ev drivers I think the per kwh fee would be the best way to go.

If we have to pay almost $ 10 for 42 km of range thats pretty pricy. In my opinion that should have been a $2 charge. Its already bad enough that you could be at a quick charger for an hour in very cold conditions, If its that expensive then this will really discourage people from using the quick chargers in very cold conditions.

I think the only way you could have helped this situation would be to park the car indoors and l2 charge. If you are willing to re try this test i think you would see faster charge times with a warmer battery.

Don....

 

[sandange]

Hi Don

I have to agree with you - too expensive for me during cold temps.
It can also be very cold if you have to stay with the car while charging
Pre heating with the remote will not work
The diesel heater will, but the fan will not.
Can't remember but I think the seat heater does not either.

Some of the AVEQ members were complaining .
One guy with a Chevy Spark was very happy with the results.

I'm sure that a warmer battery would charge much faster
I regularly park outside and wanted to experience this test in worst case scenario

 

[jsantala]

Yeah, everything is pretty much disabled while charging with CHAdeMO. If the stations would have a free wall plug I could at least run the electric heater to keep the cabin warm independent of anything else. The paid stations here also charge 0.2€ per minute, which just about kills the whole idea, if you can't charge as fast as usual. Just about does even if you can, but must make several stops. I've decided to take the bus for my next trip. Especially since the return ticket was only 1€ for 250km.

 

[siai47]

This is a little off topic but I need to ask a question. I noticed on the previous page in the picture showing near completion of the QC charge that the pack voltage was 364 and it was still charging at 18 amps. A 364 pack voltage is well above the battery voltage for a 100% charge when using the built in 3.3 KW charger. I have never used a Chademo connection for quick charging as there are none available. I use a 12 KW DC charger connected to the pack through the original Chademo cables. When I do, the charger cuts off on high battery voltage at around 80% charge (according to the dash mounted SOC gauge). When using the CANION to monitor the current going into the pack, an error between the actual current being supplied by the charger vs. what the CANION says occurs. That error, which shows less current on the CANION then actual, increases as the charging current increases. I am assuming the error on the SOC gauge is due to the way I have connected my charger and that the hall effect transducer doesn't compensate for the connection properly. However, if I let the car sit for some period of time after completing the charge in this manner, the SOC gauge corrects itself and will show a 100% charge :?:. So, (winter or summer) has anyone been able to do a QC charge with the CANION connected and see if the KW input (or DC current input) from the QC charger agrees with what the CANION reports? Even if you don't have a CANION, in normal driving after a QC does it seem that you have more actual range then you would normally expect from a 80% charge?

 

[DonDakin]

Here is the billing summary of a quick charge i did at the boucherville quick charger in the summer Its the first one in montreal this is a different one then the one sandy used rcently in his post.

Nom de la borne: CE-SBR-001
Date de début de session: 2014-08-01 18:11:16
Date de fin de session: 2014-08-01 18:31:16
Énergie consommée: 7.061 kWh
Durée de la session: 00:20:00 sec.
Coût de la session: 2.17 $
TPS/GST 5%
#813762895RT0001 0.11 $
TVQ/QST 9.975%
#1215530678TQ0001 0.22 $
Coût total: 2.50 $

The good old days when it cost 2.50


The video of the charge is here:http://youtu.be/-Bao2JLag3E

Need to skip thru till the end.

The total kwh regen as per canion was 6.954 very close to the billing above.

Perhaps the 364 volts on the sandys post was the driving voltage of the charger and not the setteled voltage of the pack. My pack was at 358 at 80 %

One thing i found funny in sandys post was the 8.5 kwh for 40% of the battery. Does not compute for me. That makes a 21 khw imiev pack. congratulations sandy.....

Perhaps the ah counter on the charger is wrong. I hesitate to point to charger efficiency i assume the kwh out is what is delivered.

Anyways numbers seem a little fishy...

Don.....

 

[mixmike6]

I too used a QC recently and was disappointed with the result and it was only -1C when I used it.
What I found most disappointing is they continued to bill even after an 80% charge was reached.. I was under the impression it would just terminate the session once my car got to 80%.

8.99$ for 9.1kWh is ridiculous given the residential rate would be 0.67$!

I've been charging at with the stock EVSE at 8amps (not 12amps) cause I read extensively that when temps drop to below freezing its best to charge at low current.

 

[DonDakin]

Hi Mike,

Do you mind posting the charging summary for that quick charge that you did ?

You should have got an Email with all the info. I would like to see the time and KWH's for that charge at -1 Deg C.

As for charging beyond 80% I have not seen that. My car stops the charge at 80-81%. I have not used any of the newer QC's only the first one in Boucherville.

If that happened then you should call HQ and complain. They may credit you some of the money back. I think they are used to charging problems and they seem to be pretty good at refunding you if there is some kind of problem.

Don.....

 

[JoeS]

This is a little off topic but I need to ask a question. I noticed on the previous page in the picture showing near completion of the QC charge that the pack voltage was 364 and it was still charging at 18 amps. A 364 pack voltage is well above the battery voltage for a 100% charge when using the built in 3.3 KW charger. I have never used a Chademo connection for quick charging as there are none available. I use a 12 KW DC charger connected to the pack through the original Chademo cables. When I do, the charger cuts off on high battery voltage at around 80% charge (according to the dash mounted SOC gauge). When using the CANION to monitor the current going into the pack, an error between the actual current being supplied by the charger vs. what the CANION says occurs. That error, which shows less current on the CANION then actual, increases as the charging current increases. I am assuming the error on the SOC gauge is due to the way I have connected my charger and that the hall effect transducer doesn't compensate for the connection properly. However, if I let the car sit for some period of time after completing the charge in this manner, the SOC gauge corrects itself and will show a 100% charge :?:. So, (winter or summer) has anyone been able to do a QC charge with the CANION connected and see if the KW input (or DC current input) from the QC charger agrees with what the CANION reports? Even if you don't have a CANION, in normal driving after a QC does it seem that you have more actual range then you would normally expect from a 80% charge?

siai47, I was hoping someone would answer your question, as I haven't done any DCQC since my December trip.

The voltage being provided by the DCQC was held at a constant 360v-361v indicated on the EVSE, with the current decaying as the vehicle charged. When it shut off at 80%SoC, both the EVSE and CaniOn agreed on that percentage. 80%SoC occurs at the transition of 12-13 bars, and would drop to 12 bars almost immediately once I started driving - if anything, I experienced less actual range than I would normally expect, but that trip was very biased by the strong headwinds.

Next time I do a DCQC I'll take some notes on the current being supplied by the EVSE and as measured by CaniOn.

 

[jsantala]

Personally I wouldn't trust anything the QC station reports. For example, it's quite common for them to report 0.0 kW charged, even when you clearly have charged 10 kW or so. Luckily the charge is actually controlled by the car, so it doesn't really matter what the QC thinks.

 

[mixmike6]

Do you mind posting the charging summary for that quick charge that you did ?
You should have got an Email with all the info. I would like to see the time and KWH's for that charge at -1 Deg C.

Hey Don, Here's the email I received right after my session. There isn't much more info on it.
I sent an email to the company to explain the situation and they refused to credit me.
I wont use their service anymore.