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Re: Weird Charging Curve

Posted: Tue Oct 17, 2017 10:04 pm
by derminghsieh
JoeS, I checked into the owner's manual for "Regular Charging is discontinued" and there are 5 possible causes listed. The one that, I think, most reasonable for my case is "The temperature of the main drive lithium ion battery is too high or too cold to charge". Well, I think you have reminded me a more compelling cause "excessive voltage sag between cells" and it really gets to my nerve because it means " I have bad cells."

I do electric biking like you do and I remember one time while charging my 36V LiFePO4 pack, one bad cell popped and charging stopped. I did not use BMS because I considered it too tedious to use. But I use two metal wires to line up positive and negative terminals respectively after charging to balance out any differences between cells, no more BMS.

I am really interested in your suggestion of using CaniOn to have a real-time monitoring at individual cell voltage while charging to see how serious the sagging is. I am checking into CaniOn section of this forum. Maybe the super-smart on-board charger is saving my bad cells.

I sign in chargepoint website and key in USN and PSW, then I get to see the charging curve.

I am adding new charging curves recording the whole charging process, performed by Chargepoint EVSE, orchestrated by my imiev on-board charger for everyone to see.

This one is from the beginning to the time I unplugged the charger:
Image

This one I started a new charging session until the end:
Image

Total Energy into my battery pack is 8.835 KWh
Total elapse time is 2 hours 30 minutes

Re: Weird Charging Curve

Posted: Tue Oct 17, 2017 10:16 pm
by derminghsieh
Sorry there is a typo. The total elapse of time is 4 hours 30 minutes.; not 2 hours 30 minutes. It really talke a long time to charge.

Re: Weird Charging Curve

Posted: Wed Oct 18, 2017 3:22 am
by rnlcarlov
derminghsieh wrote:Wow, I do not not even know that much detail about stopping of the charge. Thank you for sharing. I thought the stop was due to too high or low a temperature in the battery or on-board charger. I will certainly ask the technician of the dealership if this is the way the on-board charger is programmed when I arrive there next week. Hopefully I can get some definite answer.


It happens to all triplets I know. It was first described by Malm.
In the summer, when the cells are hotter, the 70% pause happens very rarely. No idea why.

phb10186 wrote:Makes perfect sense... clearly the man who devised the Portuguese EVSE pubic charging network knew nothing about how EVs charge, and rather worked on the current-drawing model of an electric kettle.</span>

Your workaround is quite inspired.


To be fair, the portuguese public charging network is one of the first in the world. We already had hundreds of charging points before there were barely any electric cars at all. The problem is that is has remained in pilot phase for all these years and only now are they little by little updating the software. In the new version this problem seems to be resolved.

derminghsieh wrote:JoeS, I checked into the owner's manual for "Regular Charging is discontinued" and there are 5 possible causes listed. The one that, I think, most reasonable for my case is "The temperature of the main drive lithium ion battery is too high or too cold to charge". Well, I think you have reminded me a more compelling cause "excessive voltage sag between cells" and it really gets to my nerve because it means " I have bad cells."

I am really interested in your suggestion of using CaniOn to have a real-time monitoring at individual cell voltage while charging to see how serious the sagging is. I am checking into CaniOn section of this forum. Maybe the super-smart on-board charger is saving my bad cells.


There isn't any big voltage sagging in my car and it stops all the same. Actually, there was a study made with the fleet of electric cars (peugeot ion) of my city's town hall, and the charging data showed this as well in all cars. Like I said, with hot cell temperatures the 70% pause may not happen, but the 30% stops always does, no matter how hot or how cold it is.

Re: Weird Charging Curve

Posted: Tue Oct 24, 2017 7:17 pm
by derminghsieh
Hi all,

I went checked my car at the dealership and no error code was found on my car. Now it is becoming more difficult to pinpoint the problem of charging not able to restore to level 2 at 240 V after time out dropping. I am lucky, the technician I met did not stop in telling me the car is fine. Instead, he takes this matter into his own hand and contacts the Mitsubishi chief engineer to resolve this issue. I have provided all the information I have to the technician. Hopefully, there is a software update to rectify the problem.

I suspect this weird charging behavior is not unique to my car even though JoeS says otherwise. If you happen to charge your imieve using Chargepoint Dual , would you please check your charging curve to see if it shows similar characteristics to mine ? I would really appreciate your help.

Re: Weird Charging Curve

Posted: Mon Feb 25, 2019 7:23 pm
by kevin1956murray
I am seeing the charging reduction to 1.1 kW after the pause. I believe this must be some 'handshake' issue, where the station does not recognize that the car should get 240V again. I think maybe Chargepoint software/firmware is interpreting the i-MiEV's pause as an error, and they play it safe (hedge the bet) by only sending out 120V after that. I am trying to get Chargepoint to address this issue/problem, but it has taken 3 weeks to get replies to each of my 'opened tickets', so my hope for a fix is kind of fading.

The thread that I have been posting on is here: viewtopic.php?f=24&t=3977&start=20

Re: Weird Charging Curve

Posted: Mon Feb 25, 2019 10:13 pm
by coulomb
kevin1956murray wrote: I think maybe Chargepoint software/firmware is interpreting the i-MiEV's pause as an error, and they play it safe (hedge the bet) by only sending out 120V after that.

I find it hard to believe that an EVSE, which already has a mechanism for controlling load (the pilot signal), would go to the trouble of adding another contactor, and interlocking with another contactor, to provide 120 V. Do you have evidence that it is doing this?

I suppose that providing 120 V would be a way to force a non-complying vehicle to take less load, while still allowing some charging. That would imply that the vehicle was ignoring the pilot signal, or at least there would have to be some disagreement between the EVSE logic and the vehicle's logic. But it still seems unlikely to me.

I note that per the last post on 2019/Feb/07 on the other thread, @ChrisEV is actually talking about a non-Chargepoint EVSE that is partnering with Chargepoint to use their card facilities. Is that the case for you too? If so, perhaps it's better to attempt to talk to them directly, rather than have Chargepoint talk to their partner.

Re: Weird Charging Curve

Posted: Tue Feb 26, 2019 10:38 am
by kevin1956murray
I have no evidence of 120V. The reduced charge rate of 1.1kW equates to just about 4 miles gained per hour, down from the 12 miles gained per hour that I want (for the whole charge). 4 miles gained per hour is what my 120V cord can do.

The station is Chargepoint, with no third party involved.

Re: Weird Charging Curve

Posted: Wed Feb 27, 2019 11:01 am
by jray3
Thanks Kevin1956Murray, I have this same issue with ChargePoint public EVSE, whether the unit is new or old, weather is warm or cold.
It's meant that I now only use ChargePoint L2 if I have several hours to stop there, otherwise I'll hit a DCFC.

Re: Weird Charging Curve

Posted: Thu Mar 14, 2019 10:58 am
by kevin1956murray
When a ChargePoint station charges at just 1.1kW after a MiEV induced pause, I have found that calling ChargePoint and asking them to reboot that station will get the rate to return to 3kW, without having to physically go to the car to start a new session.

Re: Weird Charging Curve

Posted: Thu Mar 14, 2019 12:59 pm
by JoeS
kevin1956murray wrote:When a ChargePoint station charges at just 1.1kW after a MiEV induced pause, I have found that calling ChargePoint and asking them to reboot that station will get the rate to return to 3kW, without having to physically go to the car to start a new session.
Wow! Good information. Guess we'll have to be paying attention from now on...