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Re: Buying a used 2011 iMiev from Norway

Posted: Sat Dec 14, 2019 10:11 am
by Bilych
Hey guys, thanks for the feedback I really appreciate it! :)
The problem is this car is 1000$ more than the previous one and I have a certain budget I would like to stick to. I am planning to take a look at 2 more iMievs next week. Guys, if the next 2 cars I look at have similar indicators as this last one, should I consider them as a buy signal? They will be around 400$ more than the first one I posted and within my budget. Thanks for the advice.

Re: Buying a used 2011 iMiev from Norway

Posted: Sat Dec 14, 2019 3:09 pm
by Don
There are times when trying to save $1,000 is not the way to go in the long run . . . . and this is one of those times. Considering the health of the battery in the first car and all other things being equal, the second car is easily worth $1K more, IMO

Don

Re: Buying a used 2011 iMiev from Norway

Posted: Sun Dec 15, 2019 12:50 am
by Bilych
Don, I understand your thinking and agree in regards to not being cheap when in comes to such things as the health of the battery. However, as I mentioned I will take a look at 2 more cars next week which will be about 400$ more and may be just as healthy as this second car. The thing is these models are exotics in Ukraine right now so the people bringing them in have no knowledge of the state of the battery health which is a great bargaining factor for me.

Re: Buying a used 2011 iMiev from Norway

Posted: Sun Dec 15, 2019 4:32 am
by kiev
In my way of thinking the most important item for an EV is the battery pack.

There are no commercial aftermarket solutions available, so it is not economically feasible nor possible to repair or replace a pack. The estimated cost for Mits to replace the pack is more than the car is worth.

So a car with a degraded low-capacity pack would need to be discounted heavily and would still not be considered a bargain.

With 4 cars available in your area it is a buyer's market for you, so hopefully you can sort thru them to get the best one.

Re: Buying a used 2011 iMiev from Norway

Posted: Tue Dec 17, 2019 2:09 am
by DBMandrake
kiev wrote:The internal resistance of 2.8 mOhms is good and shows slightly higher than the first car due to the colder temperature.

I have a strong suspicion that the BMU doesn't actually measure the internal cell resistance of individual cells (even though it could) and that this figure is purely calculated from a lookup table based on cell temperature sensor readings. In other words it assumes the cell resistance based on how the cell should perform at a given temperature.

I've monitored this figure a lot and it only seems to correlate with differences in cell temperature. Prior to replacing some cells in my pack I had three cells that had obviously higher than normal internal resistance due to them going to maximum voltage well before other cells during a rapid charge, (reaching 4.105 volts even at 20% SoC after less than a minute charging) and yet there was never any spread indicated between minimum and maximum resistance, with warm cell resistance being 1.5mO.

After replacing the suspect cells the "new" cells now maintain a significantly lower voltage than others during rapid charging (suggesting they actually have lower internal resistance than the remaining original cells) and yet the minimum and maximum resistance values quoted by the BMU have not changed and still just relate to cell temperature.

So I don't think any useful information about the true health of the cells can be gleaned from the internal resistance figures if they are just derived from cell temperature with a lookup table.

There are only three useful stats for looking at the condition of the battery pack in my opinion:

1) Reported overall Ah figure.
2) The voltage balance between cells at 10-30% SoC after a full balancing charge can be used to identify weak cells with low capacity. (The voltage balance above 40% is more or less meaningless, and no inference should be taken from a good balance at a high SoC)
3) The voltage balance between cells at a low SoC a couple of minutes into a Chademo rapid charging session can be used to identify cells with high internal resistance as these will quickly go to the maximum 4.105 volts at high charge current long before other cells that are healthy.

Re: Buying a used 2011 iMiev from Norway

Posted: Tue Dec 17, 2019 2:16 am
by DBMandrake
kiev wrote:In my way of thinking the most important item for an EV is the battery pack.

There are no commercial aftermarket solutions available, so it is not economically feasible nor possible to repair or replace a pack. The estimated cost for Mits to replace the pack is more than the car is worth.

So a car with a degraded low-capacity pack would need to be discounted heavily and would still not be considered a bargain.

With 4 cars available in your area it is a buyer's market for you, so hopefully you can sort thru them to get the best one.

Totally agree.

Don't buy a car with an unusually degraded battery pack. I'd rather avoid buying one at all if I couldn't afford the cost of one with a reasonable battery pack. 34Ah is reasonable, 27Ah is not - the 27Ah pack is well into the range where rapid degradation will be occurring if not outright cell failures.

Another thing to consider is how much yearly mileage will you be doing and how long do you want to keep the car. You need to think about how the battery will be at the end of your anticipated ownership after the mileage you're expecting to do and whether the range will still be sufficient for your needs.

I'm actually strongly considering selling mine and moving on to something a bit better with a bit more range next year (a year earlier than I originally planed) as I do a high mileage and the battery has unfortunately degraded a lot more than I was expecting to the point where I can't make my 35 mile commute in winter without a brief rapid charge on the way home...and that's with the current 33.5Ah. 2 1/2 years ago when the battery was at 39.9Ah I could make the winter journey without stopping to charge.

Buying something with a known poor battery at any price is folly in my opinion. Once the battery is unusable and cannot be repaired by swapping one or just a few individual cells it is not economic to repair. Get the best battery you can afford or don't bother and look for a different kind of car altogether.

Re: Buying a used 2011 iMiev from Norway

Posted: Wed Dec 18, 2019 12:28 am
by Bilych
DBMandrake wrote:
kiev wrote:In my way of thinking the most important item for an EV is the battery pack.

There are no commercial aftermarket solutions available, so it is not economically feasible nor possible to repair or replace a pack. The estimated cost for Mits to replace the pack is more than the car is worth.

So a car with a degraded low-capacity pack would need to be discounted heavily and would still not be considered a bargain.

With 4 cars available in your area it is a buyer's market for you, so hopefully you can sort thru them to get the best one.

Totally agree.

Don't buy a car with an unusually degraded battery pack. I'd rather avoid buying one at all if I couldn't afford the cost of one with a reasonable battery pack. 34Ah is reasonable, 27Ah is not - the 27Ah pack is well into the range where rapid degradation will be occurring if not outright cell failures.

Another thing to consider is how much yearly mileage will you be doing and how long do you want to keep the car. You need to think about how the battery will be at the end of your anticipated ownership after the mileage you're expecting to do and whether the range will still be sufficient for your needs.

I'm actually strongly considering selling mine and moving on to something a bit better with a bit more range next year (a year earlier than I originally planed) as I do a high mileage and the battery has unfortunately degraded a lot more than I was expecting to the point where I can't make my 35 mile commute in winter without a brief rapid charge on the way home...and that's with the current 33.5Ah. 2 1/2 years ago when the battery was at 39.9Ah I could make the winter journey without stopping to charge.

Buying something with a known poor battery at any price is folly in my opinion. Once the battery is unusable and cannot be repaired by swapping one or just a few individual cells it is not economic to repair. Get the best battery you can afford or don't bother and look for a different kind of car altogether.


Hey DBMandrake,

Thanks for the input. My expected commute will be around 20-30 miles round trip at most, I plan to put on around 7-8 thousand miles on the car and hoping to have the car for 3-4 years. Is this a feasible plan to have and not have the battery die on me in the process? I also have a private warm garage and will only charge at home.

Re: Buying a used 2011 iMiev from Norway

Posted: Wed Dec 18, 2019 1:55 am
by DBMandrake
Hey DBMandrake,

Thanks for the input. My expected commute will be around 20-30 miles round trip at most, I plan to put on around 7-8 thousand miles on the car and hoping to have the car for 3-4 years. Is this a feasible plan to have and not have the battery die on me in the process? I also have a private warm garage and will only charge at home.

7-8 thousand miles in total or per year ?

I bought mine at 28k miles, at that time the battery health was 39.9Ah and it would do about 63 miles in summer and 43 miles in winter.

It's now at 58k miles so I've done about 30k miles, the battery is now down to around 33.5Ah and can now only do 55 miles in summer and about 37 miles in winter. As my daily commute is 35 miles at minimum this has become a problem for me, so I'm now having to charge on the way home in winter every day...

For a bit of a reality check, the 27Ah car you were originally considering would not even make your 30 mile journey in winter if my experience is anything to go by.

Is your commute slow city roads or motorway driving ?

Re: Buying a used 2011 iMiev from Norway

Posted: Wed Dec 18, 2019 12:00 pm
by Bilych
DBMandrake wrote:
Hey DBMandrake,

Thanks for the input. My expected commute will be around 20-30 miles round trip at most, I plan to put on around 7-8 thousand miles on the car and hoping to have the car for 3-4 years. Is this a feasible plan to have and not have the battery die on me in the process? I also have a private warm garage and will only charge at home.

7-8 thousand miles in total or per year ?

I bought mine at 28k miles, at that time the battery health was 39.9Ah and it would do about 63 miles in summer and 43 miles in winter.

It's now at 58k miles so I've done about 30k miles, the battery is now down to around 33.5Ah and can now only do 55 miles in summer and about 37 miles in winter. As my daily commute is 35 miles at minimum this has become a problem for me, so I'm now having to charge on the way home in winter every day...

For a bit of a reality check, the 27Ah car you were originally considering would not even make your 30 mile journey in winter if my experience is anything to go by.

Is your commute slow city roads or motorway driving ?


Sorry I didn’t clarify. I will be doing 7-8 thousand miles per year. Looking to put on about 30K miles on it in 4 years. My commute will be either 90% highway or I can do a shorter route which will be 90% city. Which is better recommended?

Re: Buying a used 2011 iMiev from Norway

Posted: Thu Dec 19, 2019 8:55 am
by WReed82
Hi Bilych,

Since 1971 I've been driving on the slow side as an environmentally sensible choice.

For me, choosing a highway or city route is based on multiple factors.

The I-MiEV has a fair amount of wind drag, which really affects energy use at high speed.

Generally speaking, cars go farther at slower speeds.
This is often more obvious with electric cars than gas/diesel.

A highway trip at modest speeds can take less energy than a
city trip with lots of stopping and getting back up to speed.
A plus for electrics is no engine idling at stoplights.
A negative can be energy drawn for the heater or AC while sitting at a long light.
(We mostly just use the heated seats. And the defroster some as needed.)

Then there's the hassle factor - is a bunch of stopping and turning worth saving a couple hundred watts-hours?

If one route consistently takes seven bars and another eight bars, I'll
mostly take the seven bar route.

Thanks and good health, Weogo