My Car is Only Charging Up to 12 Bars

[ed5000]

Hello Everyone. For the last three days my car only charges up to 3/4 of a "tank", i.e. it only charges up to 12 bars. From what I've read here it could be a cell going bad in the traction battery so I checked my Canion ap and found cell #75 low at 3.880 volts while all the rest are at 4.010 volts.

I have an appointment at the local Mitsu dealer for next Monday but in the meantime, I've been taking it easy and driving the car in only "eco" mode on my 32 mile round trip commute to work. When I get home I have only 12 miles/3 bars remaining each day. If need be I can charge at work but I'm wondering if I should park the car until the Monday appointment.

 

[zzcoopej]

I'm wondering if I should park the car until the Monday appointment.

I'm no expert however I've done a lot of reading on battery degradation & cell failure and have a keen interest in understanding it further.
I don't think continuing to drive before the dealer sees it will further damage the battery as the dealer doesn't have any way of reversing the damage to the faulty cell (if that is infact your issue). All the deailer can really do is a full cycle with balancing after resetting the BMU as you would when a battery or faulty cell is replaced.
I now know of 2 owners who have successfully replaced faulty cells so it doesn't sound like the damage spreads by stressing out other cells, as the BMU limits the cycling to the level of the most damaged cell (although "only charging to 12bars" is new to me). I thought from the others who have had damaged cells that the battery still charges to 16 bars and just the RR and range actually achieved diminishes.
How recently have you driven to <2 bars and then done a full charge, and after that left the car on for a while after 16 bars was reached (which triggers cell balancing)? It is also possible if you are using an off-peak dedicated circuit that is on for only 6 or 8 hours that the final balancing stage is not getting a chance to run to completion.

 

[PV1]

Failing to charge to 16 bars has always been the telltale sign of a faulty cell. Capacity degradation, on the other hand, will only show by a decrease in RR but will still charge to 16 bars. The more the faulty cell discharges, the less and less the battery will charge. You are correct that the car will adjust the pack's SoC based on the faulty cell's voltage, so no cell will be driven outside of its specified voltage range. However much charge the pack can take before a cell reaches 4.11 volts is all the more charge the car will put into the pack.

I would continue to drive the car as long as possible, as even when it sits, the bad cell continues to discharge, which has left at least one member with a bricked car. Eventually, if the cell continues to lose charge, you'll get to a point where the MCU warning light will start coming on. But, if your appointment is Monday, you should be able to continue using the car for the rest of this week (but Friday's commute will be pretty close ). Keep your cord with you.

Using CaniOn, it might be a good idea to track the charged %SoC. My hunch is that the percentage of a "full" charge will continue to decrease (my car got to the point where I only had about 10-15 miles of charge available), however one member managed to bring their pack back into balance with repeated driving and charging.

 

[kiev]

A failing cell is an Unknown Quantity--there is no predictable response or future life estimates available.

How much hassle would you suffer if the cell runs out on the way to work or on the way home?

It seems that you were lucky that it failed gracefully and didn't (yet) leave you stranded, and maybe not press your luck too far--unless you feel really lucky, then go for it and share the adventure...

 

[ed5000]

How recently have you driven to <2 bars and then done a full charge, and after that left the car on for a while after 16 bars was reached (which triggers cell balancing)? It is also possible if you are using an off-peak dedicated circuit that is on for only 6 or 8 hours that the final balancing stage is not getting a chance to run to completion.

That is a good point. I have been using the car's delay timer which is set for 5 hours of charging. That seems fine for charging up a half full battery but it may need more time now. I went ahead and plugged it in without the delay.

Failing to charge to 16 bars has always been the telltale sign of a faulty cell. Capacity degradation, on the other hand, will only show by a decrease in RR but will still charge to 16 bars. The more the faulty cell discharges, the less and less the battery will charge. You are correct that the car will adjust the pack's SoC based on the faulty cell's voltage, so no cell will be driven outside of its specified voltage range. However much charge the pack can take before a cell reaches 4.11 volts is all the more charge the car will put into the pack.

I would continue to drive the car as long as possible, as even when it sits, the bad cell continues to discharge, which has left at least one member with a bricked car. Eventually, if the cell continues to lose charge, you'll get to a point where the MCU warning light will start coming on. But, if your appointment is Monday, you should be able to continue using the car for the rest of this week (but Friday's commute will be pretty close ). Keep your cord with you.

Using CaniOn, it might be a good idea to track the charged %SoC. My hunch is that the percentage of a "full" charge will continue to decrease (my car got to the point where I only had about 10-15 miles of charge available), however one member managed to bring their pack back into balance with repeated driving and charging.

Thanks, PV1. Maybe I can exercise the bad cell back to life? I'll bring the cord for sure.

How much hassle would you suffer if the cell runs out on the way to work or on the way home?

It seems that you were lucky that it failed gracefully and didn't (yet) leave you stranded, and maybe not press your luck too far--unless you feel really lucky, then go for it and share the adventure...

The hassle factor wouldn't be too bad. I commute on a busy freeway but, right now I'm only in the slow lane and there's a breakdown lane all the way to work. I just need to have a cord and a cell phone with me. I'll let you know if any of this changes.

 

[zzcoopej]

That is a good point. I have been using the car's delay timer which is set for 5 hours of charging. That seems fine for charging up a half full battery but it may need more time now.

Remember it is only after you drop to <2bars (ie flashing) that the BMU will trigger cell balancing when the battery is subsequently fully charged. If what you say has been going on for many months, cell balancing may not have happened to your battery in a LONG time and could easily explain a cell drifting well out of balance.
The letter from "Mitsubishi Motors North America, Inc" which describes this procedure also mentions to ensure ambient temps between 50 and 122 degrees Fahrenheit, and only using a level 1 or 2 charger (ie not fast charge). They recommend the procedure is done once in the first year and every 2 years after that, however I would think it would depend significantly on your driving and charging patterns.

 

[ed5000]

Remember it is only after you drop to <2bars (ie flashing) that the BMU will trigger cell balancing when the battery is subsequently fully charged. If what you say has been going on for many months, cell balancing may not have happened to your battery in a LONG time and could easily explain a cell drifting well out of balance.

Wow, good to know. My car actually did go to 2 bars flashing today for the first time in some time. The freeway jambed up 5 miles from home today and I took a detour. The car just barely went to the 2 bars when I got home.

 

[zzcoopej]

My car actually did go to 2 bars flashing today for the first time in some time.

How long would you say (in Time and Km) since you did a full charge from <2 bars, including enough time to balance considering I doubt 5 hours is enough)? Are we talking months or years, and 10,000km or more?

 

[ed5000]

How long would you say (in Time and Km) since you did a full charge from <2 bars, including enough time to balance considering I doubt 5 hours is enough)? Are we talking months or years, and 10,000km or more?

The last week of January I took a road trip and got it down to one bar.

 

[zzcoopej]

The last week of January I took a road trip and got it down to one bar.

That's pretty recent. Did it get more than 5 hours of charging before you drove it again?

 

[ed5000]

That's pretty recent. Did it get more than 5 hours of charging before you drove it again?

I'm pretty sure I used the time delay. It's been a habit for me to do this.

 

[ed5000]

Well, it charged up to 11 bars this morning :?

 

[ed5000]

The car drove just fine today. Arrived home with 15 miles remaining and with 3 bars. Maybe I'm getting better at eco mode. Then I took the car out for an errand and to get down to 2 bars for balance charging later on.

Then I connected to CaniOn and this time cell #75 (the low cell) is 3.745 volts and the rest are at 3.920 volts. SoC% is 21.5, volts 344. Btw: I have 21,355 miles (34,368 km).

Then I connected EvBatMon and Battery capacity is 41.1Ah, Battery condition is 85.62 pmc, battery soc 8.9 Ah, volts 344.4, and soc real 21.5%. I know 2 months ago battery capacity read 42.1Ah.

 

[JoeS]

ed5000, so what happened after you fully fully balance-charged?

 

[Don]

Then I connected to CaniOn and this time cell #75 (the low cell) is 3.745 volts and the rest are at 3.920 volts.

I think we all know where this is headed . . . . likely sooner rather than later

Don

 

[ed5000]

ed5000, so what happened after you fully fully balance-charged?

This morning I found the car with 11 bars again and 52 miles of range remaining. Still a very functional car.

The #75 cell however was at 3.965 volts while the rest were at 4.105 volts.

 

[ed5000]

I think we all know where this is headed . . . . likely sooner rather than later

Don

I'm just wondering what the Mitsu dealer will do. Do they have some battery recovery routine they can try? I'm also wondering how long they'll need to keep the car.

 

[PV1]

For my dealer, to diagnose, test, and replace the battery, took 3 weeks.

Hmm, the voltage difference was reduced after balance charging. Can you do another balance charge and post the results?

 

[Don]

I think we all know where this is headed . . . . likely sooner rather than later

I'm just wondering what the Mitsu dealer will do. Do they have some battery recovery routine they can try? I'm also wondering how long they'll need to keep the car.

I think your bad cell will eventually fail and you'll get a whole new battery pack with zero miles on it. It may take a couple weeks, but worse things could happen. Nothing like having a brand new battery!

Don

 

[ed5000]

For my dealer, to diagnose, test, and replace the battery, took 3 weeks.

Hmm, the voltage difference was reduced after balance charging. Can you do another balance charge and post the results?

Hmm, 3 weeks could be an eternity for me. :lol: :? In the meantime I'll try for a balance charge tomorrow.

I think your bad cell will eventually fail and you'll get a whole new battery pack with zero miles on it. It may take a couple weeks, but worse things could happen. Nothing like having a brand new battery!

If it comes to that and they replace, I sure can't complain.