Cell smoothing attempt from home

[Steeeeve]

Hi all, as you'll be aware there are 2 battery conditioning operations that can be carried out, a BMU reset and Cell smoothing.
Without expensive kit, I can see no way of doing a bmu reset. This is also not the recommended conditioning as if effectively makes the BMU forget everything it knows about the battery.
The second option, cell smoothing from what I can tell is just a case of bringing the cell pack down to 0% before carrying out a slow charge back to 100%.

I have just done the latter at home by removing the fuel pump fuse and running the air con until the battery is drained. (I know the risks and thought... Why not) my car is now on charge and I will report back at some point tomorrow on if it makes any difference. I managed to flatten the auxiliary battery in the process so had to jump start to even get the thing to start charging the traction battery which was alarming for a second and ended up jump starting off the wife's car before everything came back to life. I wouldn't recommend doing this before we can see if it has the desired effect but thought I'd share my test and the outcome.

Steve

 

[HHL]

How did you determine that the battery was fully discharged? Did you monitor the pack voltage or look at the cell with the lowest?
What voltage is deemed to be fully discharged?
Interesting experiment!

 

[anko]

Sceptical, but very interested in the outcome

Sceptical, because I think there is more to the procedure than what you are doing. First of all, I think the BMU must be put in a specific mode. Second, the lowest you will get to bij running A/C is 22 (or 20?) % SOC. By then the A/C will shut down. The lowest you will get to by driving is 14%. And both are still a long way form empty.

But like I said, I am very interested to lean about your results.

 

[Steeeeve]

I'm sceptical too. I relied on phevwatchdog to confirm 0%. As mentioned there is probably some residual power but I certainly got the reading down to 0%, for the last 10% it took a bit of coaxing, car off, car on heaters up down etc. Pack was showing a voltage of 274v. Average cell voltage was 3.416.
It certainly took the 30% extra charge, I don't know how long it would take for a new SoH tile to be generated. The car was reading a charge of 11kw for a 97% SoC which is higher than the 10.3kw shown as its health so here is hoping!

 

[elm70]

I'm interested in the BMU reset

Anybody knows how to do it with just the obd2 adapter?

 

[Steeeeve]

So this is more of a pre-update update
My car has had 2 charges since my cell smoothing attempt. Both times, my state of health has been 90.5% with 10.3kw capacity which remains as it was for now. However capacity after charge has been around 11kw while at 98% charge. I feel that it has made a difference but need to wait on that card whenever it is generated for confirmation.
The first charge did show 11.3kw as its current charge... Gaining a whole KW would be very nice... But I imagine not likely lol

 

[elm70]

So this is more of a pre-update update
My car has had 2 charges since my cell smoothing attempt. Both times, my state of health has been 90.5% with 10.3kw capacity which remains as it was for now. However capacity after charge has been around 11kw while at 98% charge. I feel that it has made a difference but need to wait on that card whenever it is generated for confirmation.
The first charge did show 11.3kw as its current charge... Gaining a whole KW would be very nice... But I imagine not likely lol

Did the PHEVwatchDog report any difference about the SOH of you battery ?

Else ... another way to see if the battery is better then SOH .. is to drive in EV mode from fully charged down to few KM left in EV ... check the SOC from the "wDog" , let the car rest for over 2h, and check again the SOC ... if the SOC is going up, it means the SOH is better then what is reported by the wDog

 

[Steeeeve]

No change in the dog yet, but I had noticed when parked for a couple of hours I tend to get figures like +1.4Ah whereas before it went down. I'm intrigued to see how things pan out with my car, its a 2014 model and had only 22000 miles ish in the clock when I purchased it. I've done a further 3500 miles on it and the battery has dropped 0.5% in that time. I assumed it would have been a bit higher, but it is what it is. I love the car but I refuse to pay for smoothing etc, I may try to persuade the garage to do a reset in a few months if I pay for them to service it.. Otherwise it won't be getting a dealership service at their cost...

 

[elm70]

No change in the dog yet, but I had noticed when parked for a couple of hours I tend to get figures like +1.4Ah whereas before it went down. I'm intrigued to see how things pan out with my car, its a 2014 model and had only 22000 miles ish in the clock when I purchased it. I've done a further 3500 miles on it and the battery has dropped 0.5% in that time. I assumed it would have been a bit higher, but it is what it is. I love the car but I refuse to pay for smoothing etc, I may try to persuade the garage to do a reset in a few months if I pay for them to service it.. Otherwise it won't be getting a dealership service at their cost...

It will be interesting to know if they will do a reset , since it sounds against the Mitsubishi "design"

1.4Ah plus after rest it is good ... I would expect that soon your SOH should jump up ... my understanding is that the BMU logic is to consider this "delta" in the estimated capacity after a usage, and estimated capacity after usage and rest ... for update the SOH

Anyhow ... your procedure would not make any sense in my "understanding" ... but apparently you got some "results" ...

Is still 3.81v the voltage level consider as 30% of SOC and 0KM of EV left ? Or this has been changed after your procedure ?

PS: Ideally it would be nice to be able to reset the BMU parameters ... like what Mitsubishi did to our PHEV user in Australia ... I soon may go for service my PHEV too ... and I may ask ... but here they see so few PHEV that I bet they have no clue and they may ask extra money for any little extra "servicing" via the diagnostic tools

 

[Steeeeve]

I'll have to keep an eye out on cell voltage, 3.416 was the average when it was down at 0.3% reported by watchdog. I've not had a battery health card on the lower reading since. I got a state of charge card for 97% the day after which showed a higher average cell voltage compared to before the smoothing.. 4.043 v at 103% charge vs 4.09v at. 97% charge post smoothing.

Let's see what happens!
Steve

 

[elm70]

I'll have to keep an eye out on cell voltage, 3.416 was the average when it was down at 0.3% reported by watchdog. I've not had a battery health card on the lower reading since. I got a state of charge card for 97% the day after which showed a higher average cell voltage compared to before the smoothing.. 4.043 v at 103% charge vs 4.09v at. 97% charge post smoothing.

Let's see what happens!
Steve

4.043v at 103% :shock: :shock:

This is looking very wrong ..

Now 4.09 at 97% is about correct .. actually on mine 4.09 is about 100%

If before your battery could only charge up to 4.04v .. this alone explain the low SOH, or the gain you got now in range/SOH

Still a mystery for me how your smoothing could have impacted the max charging voltage

 

[Steeeeve]

I guess let's see how things pan out. Until I get a new card I can only assume things are slightly better than they were. I suppose the inherent risk in doing what I did would probably make it right for me to say... Don't try this at home lol

 

[GreyBigFoot]

Lots of good stuff here.

And happy to see the Dog is helping there

Will follow this post carefully!

 

[Steeeeve]

My Car registered a drop in battery health to 90.3% last night. This is after the car sitting in an airport car park for a week with a depleted (30%) battery. I don't know if that is a direct correlation to what has caused the drop. This means a 1% drop since owning the car equivelant to 0.25% per month. I think its fair to assume this is a failed experiment, well it made no difference lol.

It's great that we have the tools to measure this though

 

[richi]

I think its fair to assume this is a failed experiment, well it made no difference

...or that your BMU already had accurate data about your traction battery?

 

[Steeeeve]

or that your BMU already had accurate data about your traction battery?

That's even more depressing :lol: