New user query: how to interpret battery statistics output

[arinbasu]

Hi All,

I am writing from New Zealand.

Last weekend I purchased a used Mitsubishi Outlander PHEV 2014 XLS model with 62000 kilometres on it. Following the advice on purchasing used PHEV I learned in this forum, I asked the dealership to provide me with an SOH of the battery before purchase, but they said they would be able to provide me with those stats following purchase as they would need to keep the car overnight and run tests on the battery. The car is tidy, and on test run, it was such a pleasure to ride (eerily silent in the city traffic); it was love at first sight, . So, I went ahead and exchanged it for an old Mitsubishi Colt and paid the difference.

Yesterday, the dealership returned me the battery test results. They said the SoH = 70%, and returned the following statistics:

- Battery current capacity: 28.6 Ah
- Battery remaining capacity: 28.1 Ah
- Battery maximum input power: 19.75 KW
- Battery maximum output power: 63.5 kW
- BAT cell voltage difference MAX: 0.004 V
- Target cell voltage: 4.089 V

I drove the car practically everyday this week (Monday to Friday). I live about 70 kilometres out of the city so 140K drive every day, plus additional 50K to drive for various errands). I started with a full tank of petrol on Saturday, and after 790 kilometres of travel (I have verified it through the trip meter, plus my own jotting down of the distance through google map), there is still about 40% petrol in the tank. I have charged the car to full every night, and it shows 48 kilometres on full charge when I start out in the morning. I have driven it slowly mostly about 90 k/h on a back country highway (did not use any of the B settings, did not use Eco mode, left it as D mode and charge/save) and between 50-60 k/h in the city.

The car is deafeningly silent to drive in city streets (a very mild hum, like a cat purring as it starts off a traffic block). Handles the highway remarkably; all in all, I find driving this car a beautiful experience! It's a tad slow to take off at the lights (compared with my old petrol vehicle, but barely noticeable). I have found that driving on the highway at about 80-85 kilometres/hour with "save" mode on adds rapidly to the battery distance (I used to think that save mode will preserve the battery kilometres but it seems to add; for example, I activated this morning the "save" mode at 29 kilometres on the battery as I entered the highway but when I reached the city, it registered 34 kilometres).

Overall must say a fantastic experience to drive this car and thank you forum members for your wisdom and incredible knowledge that gave me the confidence to buy this, .

Question: how do I interpret the battery stats? Is there a manual/guide for that you can advise?

Best,
Arin

 

[jaapv]

That is good for a car of this age, just leave it as it is and drive it like you do. Treat the distance prediction for what it is: just a guess by the car based on your driving before.

 

[arinbasu]

Thank you @jaapv! Greatly appreciate.

 

[greendwarf]

I don't understand why you find it slow to pull away - in EV mode (like all electric cars) it can beat any petrol vehicle for initial acceleration

 

[arinbasu]

Possibly it would be no different if I were to floor the accelarator. , with this car, i do not feel any urge to rush at all.

 

[jaapv]

I don't understand why you find it slow to pull away - in EV mode (like all electric cars) it can beat any petrol vehicle for initial acceleration

I can understand - it is that hesitation before the ICE comes in in parallel hybrid.

 

[zzcoopej]

- Battery current capacity: 28.6 Ah
- Battery remaining capacity: 28.1 Ah
- Battery maximum input power: 19.75 KW
- Battery maximum output power: 63.5 kW
- BAT cell voltage difference MAX: 0.004 V
- Target cell voltage: 4.089 V

Question: how do I interpret the battery stats? Is there a manual/guide for that you can advise?

The 2014 PHEV battery is 40Ah, however it is often considered to be at best 38Ah as it degrades from the minute it is manufactured, just like all batteries. The SOH of your PHEV is calculated based on a degradation model along with previous driving and the model adjusted, hence the current and remaining capacity calculations being different. Both are just estimates, see the red line in this http://evpositive.com/battery-history.html graph where the calculated capacity of my PHEV's battery is dropping then jumping up again as the calculation does its thing (sometimes well, other times not so well). The blue dots are other vehicles which show the variation in the calculated capacity for a given odometer reading. Its all just guess work as lithium chemistry is not 100% predictable.

Max input power is the amount of power entering the battery via charging (regen or plugged in)
Max out is usually the cap of around 60kW which the battery can deliver to drive the PHEV (if it needs more the ICE is powered up)
There are 80 cells (think like you might have 4 AA cells in a torch) making up the PHEV battery. Battery cell voltage difference is the voltage of the cell which is highest compared to the cell that is lowest voltage. This should be a very small amount for a healthy battery just after it has been fully charged and balanced (all cells are charged, then individual cells adjusted to attempt to make cell voltage difference = 0). So if there is a significant difference after balancing, one of more cells in the battery is unhealthy as the battery SOH is only as good as the weakest cell. When the battery is drained, again a large difference in voltages between highest and lowest is a sign of a weaker cell.

Target cell voltage is just the voltage used to determine when the battery is considered fully charged.

 

[arinbasu]

Thanks a million @ zzcoopej for this detailed information! EV positive webpage in particular is excellent!