derminghsieh
Posts: 19
Joined: Mon Sep 10, 2012 10:10 pm
Location: Bellevue, Washington

Re: Weird Charging Curve

Tue Oct 17, 2017 10:04 pm

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

derminghsieh
Posts: 19
Joined: Mon Sep 10, 2012 10:10 pm
Location: Bellevue, Washington

Re: Weird Charging Curve

Tue Oct 17, 2017 10:16 pm

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.

rnlcarlov
Posts: 80
Joined: Wed Apr 13, 2016 8:30 am

Re: Weird Charging Curve

Wed Oct 18, 2017 3:22 am

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.

derminghsieh
Posts: 19
Joined: Mon Sep 10, 2012 10:10 pm
Location: Bellevue, Washington

Re: Weird Charging Curve

Tue Oct 24, 2017 7:17 pm

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.

Return to “Batteries and Battery Management”