Mitsubishi Outlander PHEV Forum

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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Mon Dec 03, 2018 7:17 am 
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Location: Netherlands, Utrecht area
elm70 wrote:
How accurate you can monitor the charging current via OBD2 ?
Amps: 0,01. Volts: 0,1.

elm70 wrote:
The DOG, apparently can't report anything below 1Amp ... so even monitoring the full charging process, there will be too much error if the charging current is integrated over the time
In theory, the Dog has access to the same granularity. But the number of readings per second (if any ;-)) will be far less.

elm70 wrote:
But, if you can monitor the charging current at 0.1A accuracy ... then you should be able to integrate this current and have a precise number of Ah which get push into the battery while charging.

Only in this way you can know if the SOC above 100%, is due to the fact that the battery got more Ah then expected by the SOC % delta + SOH .. or for some different type of estimation error.
I have no reason to think the Ah count is wrong. I think either SoH is wrong or SoC at beginning of charge is wrong. If we calculate Ah ourselves, there are two outcomes.
- We get the same Ah value and still have no answer to my question
- We get a different Ah value and the answer to my question MAY BE neither. But we may also still have no ansewr.
still The SoC number we see is not a result of integration done by the Dog or myself. It comes directly from the BMU.

elm70 wrote:
PS: In my case, today, I got the SOC above the real (similar to how reported time ago) ... the DOG reported my morning trip to be started with 33.1Ah and 4.05v max (97.9% SOC) .. after a 10min pre-heat via keyfob hack ... since car was not charging while pre-heating at best the SOC should have been 31.6Ah ... but I also doubt that the car got charged up to 35.3Ah .. so ... it must be that sometime the SOC don't count in the pre-heating ... sometime .. since sometime it is looking it is properly counted inside the SOC (even when this is activated by keyfob hack)
I have done three FOB initiated pre heats yesterday, and the end result was the beginning of the charge in the next post.


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Mon Dec 03, 2018 7:21 am 
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Joined: Mon Dec 01, 2014 11:30 am
Posts: 3364
Location: Netherlands, Utrecht area
You see Remaining Ah and SoC follow exact same path. So, i think SoC is calculated by dividing Current Capacity (SoH) by Remaining Capacity or Remaining Capacity is calcultated by multiplying Current? Capacity (SoH) by SoC

Image


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Mon Dec 03, 2018 11:56 pm 
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Joined: Mon Sep 26, 2016 11:18 pm
Posts: 1014
Location: Poland
Very interesting graph Anko.

It is not very clear why the charging process did stop for few minutes (5?) ... and while the charging process was pause the SOC got raised by 5%

This rise of 5% (actually a bit more then 5% right ?) then cause to have the end of SOC 105% ... so not only the pausing of the charging process is a mystery, but as well it is looking wrong the decision to rise the SOC

Anyhow ... with all approximation from reading a graph (XLS would give more precise info) .. it is looking that the charging process did need a bit less current then expected, but due to the overshot on SOC, the end SOC number was massively wrong.

Based only on this charging info .. apparently the SOH of your battery is a bit less then what is known by the BMU

PS: The only reason for pause a charging process would be to unbalance or if one of the cell is above 4.10v (again unbalance) ... while the charging process stop with an unbalance of 0.06v .. and resume with 0.04v .. still it did not stop later on when same unbalance was present ... so it is quite a mystery why it did pause


PPS: The rise of SOC, must be due to the mapping between voltage and SOC which the car has inbuild ... still it is "odd" that 2 or 3 minutes of rest from charging, it is consider a safe time for read the voltage level and consider this voltage equal to a rest voltage


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Tue Dec 04, 2018 11:57 am 
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Joined: Mon Dec 01, 2014 11:30 am
Posts: 3364
Location: Netherlands, Utrecht area
I thought this pauze would be the cell balancing phase? It appears quite often exactly at 80%, so I think it is planned and not ad-hoc.

What I still don't understand is this: if SoC is derived from cell / pack voltage, how is it possible that neither of these changes a bit after SoC reaches approx. 92%. Maybe I am to blond, but I don't get that bit.


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Thu Dec 06, 2018 5:08 am 
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Joined: Mon Sep 26, 2016 11:18 pm
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Location: Poland
A "programmed" pause at 80% while charging .... very strange indeed

Maybe they use the 80% rest Voltage level as one of the many error accumulated parameter for their SOH logic

Still ... strange logic

On the parallel world ... I saw an interesting card from you:

SOC 14.8% / 3.9Ah
301.5v (3.77v per cell)

You must have been play hard with the per-heating function :ugeek:

Anyhow ... It sounds quite pessimistic only 14.8% left at an healthy level of 3.77v

Based on LEV50N specs ... nominal voltage is 3.75v ... and the operating voltage is reported to be 2.75v to 4.10v
Also discharge graph from producer of LEV50 do show a discharge from 4.1 to 2.75 ... till 3.5v there is plenty of capacity left .. per the graphs ...

I don't understand this maniac from Mitsubishi to protect the battery on low SOC , and have zero protection over max SOC

I would have assumed to block the battery cycle between 4.00v down to 3.70v ... it is way better then between 4.10v and 3.82v as it implemented by Mitsubishi ... but possibly/hopefully ... they did their homework :mrgreen:

PS: Possibly old PHEV don't have the LEV50N battery shrink to 40Ah version ... in the new(er) LEV50N , I see it is granted 80% SOH after 5500 cycles ... which even with two cycle a day .. it is still over 80% SOH after 7y (in theory ... since battery decline in performance with by when unused , even if kept in the ideal storage voltage)

PPS: New Outlander PHEV I think, should have much better SOH when ageing, since GS Yuasa, made apparently significant progress in the last years ... I'm wondering it the BMU firmware has been tuned for the different chemistry which have been used in different version of our PHEV in the last 5 years ...


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Fri Dec 14, 2018 9:09 am 
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Joined: Fri Dec 14, 2018 9:04 am
Posts: 2
Prospective buyer here.
I read like 5-6 pages from this thread, and cant understand what is the conclusion?

I am comparing to the Tesla Model X, their batteries have very negligible degradation, people say 5, max 10% or so.

Are you guys saying here you see 20-30% degradation, and having to fight to get warranty service (just to see it degrade severely again in a few years)?
If so, that sounds like a turn off, despite the much better pricing compared to the X...


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Sun Dec 16, 2018 2:28 pm 
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Joined: Wed Jul 11, 2018 4:35 pm
Posts: 155
Location: Saratoga, CA
Carmageddon wrote:
Prospective buyer here.
I read like 5-6 pages from this thread, and cant understand what is the conclusion?

I am comparing to the Tesla Model X, their batteries have very negligible degradation, people say 5, max 10% or so.

Are you guys saying here you see 20-30% degradation, and having to fight to get warranty service (just to see it degrade severely again in a few years)?
If so, that sounds like a turn off, despite the much better pricing compared to the X...


Well you have to realize what you're dealing with in a PHEV. Batteries are generally good for around 500-2000 cycles (discharging to 0% and charging to 100% is 1 "cycle"; discharging to 50% and charging to 100% TWICE is also 1 "cycle"), depending on a number of factors. https://batteryuniversity.com/learn/art ... _batteries

1. Cutoff voltage (lower is better). The lower the charge voltage, the more cycles you get.
2. Depth of discharge (lower is better). Going between say 50% and 75% repeatedly is way better than going between 100% and 0% and gets you many more cycles.
3. Temperature (li-ion batteries like the same temperatures we humans do. Elevated temperatures that make humans sweat are especially bad for them).
4. C rate (how quickly you discharge or charge a battery relative to its capacity). Lower is better. Discharging at something like 1C (discharges or charges battery completely in 1 hour) is generally okay. Anything way over that, say 3C (would charge or discharge the entire battery in 1/3 of an hour or 20 minutes) is really bad for the batteries. https://batteryuniversity.com/index.php ... ristics_li

Tesla carefully controls all 4 factors to ensure battery longevity. Consider:
1. Tesla allows the user to tell the vehicle to only charge the car to a certain level for daily driving (typical values people select are between 60%-90%). The batteries are then only charged to 100% just before a long trip, when the capacity is needed.
2. Teslas have huge batteries. Not many people drive > 300 miles in a day. Thus, the % of power used before they reach a charge station is low, and depth of discharge is low.
3. Teslas keep their batteries cooled on hot days, even when they aren't plugged in, unless the power level drops below a certain threshold.
4. Teslas have large batteries. When you have a 100 kWh battery but it only takes 25 kW to cruise down the freeway, you are only discharging that battery at 0.25C

Also, let's say that battery is good for 2000 cycles. In a Model 3 or Model S with 310 miles of range, this means the battery is good for 310*2000 = 620000 miles. The darn car isn't going to last this long. Something else is going to break before the battery does!

Now on a PHEV, the situation is basically the opposite.
1. Many PHEVs, the Outlander included, don't allow the user to limit the charge level. The thinking is probably that the range is so short, the users need all of it on every trip. I've figured out a way to manually cut off the charge when it reaches a certain point by calculating how many kWh per bar on the gauge, and telling the EVSE to stop charging when it reaches a certain number of kWh, but this is the exception rather than the norm.
2. PHEVs have small batteries. Most people drive more than the range of the battery in a day, and thus, put the battery through a lot of cycles in a short amount of time.
3. PHEVs don't have the spare power in their batteries to cool their own batteries when parked outside on a hot day. The Outlander DOES have a battery cooling system, but it only operates when the vehicle is switched on.
4. When you accelerate in the Outlander PHEV, it often takes 30-50 kW of power. It's for a brief moment, but you're discharging that battery at around 3-4C when you do this. In order to discharge a Tesla's battery at 4C, you're basically talking launching the car in ludicrous mode (which needs 300-500 kW of power). How often do you typically do that? Yeah, I thought so. If you are cruising down the freeway and you're not in Save mode, you're consuming way more than 12 kWh of power. I mean, the battery is a 22-28 mile battery and you're doing 50-80 mph typically. That means you're draining the whole battery in under 30 minutes, which is an over 2C discharge rate.

All of these factors combined mean that your PHEV battery likely isn't going to last the life of the vehicle, while a Model X battery IS likely to last the life of the vehicle. Even if we assume that the PHEV battery lasts for the same number of cycles as the Model X battery (which is unlikely because of the above 4 factors), we're talking 2000 * 25 = 50000 miles.


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Mon Dec 17, 2018 9:24 am 
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Joined: Mon Dec 03, 2018 8:04 pm
Posts: 7
Hold on, 50,000 miles? I thought the forum had folks way over that nark that maybe have seen significant deterioration but certainly don't have useless batteries...


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Mon Dec 17, 2018 9:25 am 
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Joined: Mon Dec 03, 2018 8:04 pm
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Ok, I think I'm following now. You're talking 50,000 miles of all electric.


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 Post subject: Re: Drive battery degradation . Houston, do we have a proble
PostPosted: Mon Dec 17, 2018 11:23 am 
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Joined: Wed Jul 11, 2018 4:35 pm
Posts: 155
Location: Saratoga, CA
blweeden wrote:
Ok, I think I'm following now. You're talking 50,000 miles of all electric.

Yep. I'm pretty sure most manufacturers do whatever it takes to make sure that you get about 2000 cycles out of your batteries. But 3000-4000 cycles is pretty rare. On a Tesla, it doesn't matter, because the darn car is going to break down before you get that many cycles on it. On a PHEV...expect to have to replace the batteries.


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