Aftermarket iMiEV battery upgrade project

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Re: Aftermarket iMiEV battery upgrade project

Post by francisco.shi »

So it means that with 47Ah we should get about 75km right?
I am not going to test down to turtle mode. I am going to stop when the dial starts flashing (I don't want to have to tow)
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Re: Aftermarket iMiEV battery upgrade project

Post by mark_hetho »

A proper 47Ah should give over 100km. On a reported 38Ah we get 75km at highway speeds and an elevation increase of 800 meters, generally without hitting the flashing dial.
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Re: Aftermarket iMiEV battery upgrade project

Post by mikedufty »

Mark is that in a minicab or an i-miev ?
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Re: Aftermarket iMiEV battery upgrade project

Post by francisco.shi »

I found the minicab uses a lot more power. After it gets to 40kph it seems to pull much less and it barely makes 100kph with the foot to the floor and the power meter to the max. The Imiev on the other hand gets to 100kph quite easily and it only needs about half of the meter some times close to the end of the green ECO shade.
The testing I did was mainly 60kph area with a bit of 70 and 80.
I should get a measurement today with a full battery. (Not looking fwd to doing 140km+)
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Re: Aftermarket iMiEV battery upgrade project

Post by mark_hetho »

Ah good point - my reference point is for an i-miev not the minicab.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

An update on the 60Ah cell replacement project.
I decided to take these cells out and put the original LEV50s back in.
There are a number of reasons for doing that.
One of the main reasons are best explained by coulomb's discharge curve overlay

Image

there just is not enough capacity in the voltage range the iMiEV uses between full and what is considered safe as empty.
I may have lived with that if the early promise of resetting some parameters gave me some marginal more range than the old cells.
I took the pack down three more times and connected wires to the most trouble some cells to assist with balancing, it was partly successful that I was able to charge the pack to above 360 V rather than only to 358/359 V, but it proofed that this would have to be an ongoing pain in the butt for very little gain.
It was expected that relatively brand new cells would show some initial degradation.But not as bad as it turned out.
When "new", I could with driving straight after fully charging about about 90 km on a couple occasions,in ideal temperatures and very gentle driving. By now, three months and 2000km later, the degradation has reduced the range to about 70 km (65 km if driven like a normal car without babying). I fear that these cells will badly degrade further, I can see how a bit of load is dropping the voltage much quicker than it did with the LEV50s, I also noticed that when slowing down and regenerating, the RR number goes up, this it did only ever when slowing down on a long,steep hill. RR goes(did go) up and down like a yo-yo with these cells. I assume the RR number is only a symptom of battery volts collapsing under load and ramping up during charging, regenerating current can and does go up to what I believe is a limit set by the EV-ECU or BMS of about 56 A. Load is restricted to about 180 A, I made sure to never have gone above 120 A, but even that may have been too much.
The modules are back in the tray, all connected and ready for the cover to go on.
I play bowls tomorrow so on Wednesday I shall find out if the quality control did miss anything....lol.
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Re: Aftermarket iMiEV battery upgrade project

Post by jonescg »

Sorry to hear this Andreas :( It was always a risk, and a compromise too, but at least now you've learned a lot about your iMiEV and you now have a large home storage battery to use or sell.
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

That's super fast degredation, the cells must really not like over 1C.
Are you still planning on trying to upgrade but by using different cells?
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Re: Aftermarket iMiEV battery upgrade project

Post by coulomb »

brendon_m wrote: Tue, 09 Mar 2021, 06:03 That's super fast degredation, the cells must really not like over 1C.
It could be rapid degradation, but I think it may have been the BMS misunderstanding the nature of the NMC cells, and giving pessimistic range remaining figures, and even turning on the tortoise too early. In other words, the "learned capacity" was artificially low.

@Nuggetgalore, are you sure that when the RR said you had little range left, that this was really true? For example, what was the pack voltage, and voltage of the lowest cell, when idle? My apologies if you've checked this thoroughly.

The other thing is that these cells may be optimised for energy density rather than power density, and with a relatively small battery, they need to be optimised for power. A 60kWh battery might not have to worry about that, since the C rates would be so much lower. Edit: basically agreeing with Brendon here, the cells not liking over 1C.

Edit 2: the RR changing with regen does suggest excessive cell internal resistance, which suggests degradation, or at least the cells not being suitable for the loads, which could lead to rapid degradation.
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Re: Aftermarket iMiEV battery upgrade project

Post by francisco.shi »

I am not sure what cells you are using.
Have you asked Grahame from Suzie Auto what cells he used?
The cells he put in the minicab were 94Ah which gave almost double the range and they seemed to hold the voltage under load just fine.
Obviously the BMS would say the battery was empty after 50Ah but if you cycle the power to the BMS at that time it would adjust it's guess to about 50% SOC.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

brendon_m wrote: Tue, 09 Mar 2021, 06:03 That's super fast degredation, the cells must really not like over 1C.
Are you still planning on trying to upgrade but by using different cells?
No.
I only did this project because I (like a lot other people) wanted it completed to find out
all the "ifs" and "hows". I probably should not have attempted it, as I only have enough knowledge to be dangerous, the theoretical, electronic side is way above my paygrade, the physical,practical engineering side I am quite good at though.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

coulomb wrote: Tue, 09 Mar 2021, 07:05
brendon_m wrote: Tue, 09 Mar 2021, 06:03 That's super fast degredation, the cells must really not like over 1C.
It could be rapid degradation, but I think it may have been the BMS misunderstanding the nature of the NMC cells, and giving pessimistic range remaining figures, and even turning on the tortoise too early. In other words, the "learned capacity" was artificially low.
In guesstimating capacity I compared the voltage range of the original(LMO) cells with the voltage range of the NMC replacements.(see page 13 this thread, where I posted some V data on the LMO cell, with the battery degraded to about 66.88%).
LMO Pack 360.1V ; 98.5% SoC {31.7 of 32 Ah} max cell 4.1 V min cell 4.09 V { all data
LMO pack 327.1 V; 15.5% SoC { 5.0 of 32 Ah} max cell 3.78 V min cell 3.72 V { at rest
NMC pack 359.9 V; 79.6 % SoC {36.3 of 45.6 Ah} max cell 4.11 V min cell 4.07 V { vary slighly
NMC pack 322.6 V; 8.3 % SoC { 3.8 of 45.6 Ah} max cell 3.70 V min cell 3.66 V { from charge
{to charge
So yes,the BMS is confused, but the real energy in and out of the pack is what matters and for that I have real world data (from the electricity meter at the wall and the kilometers driven (and confirmed with the CanIon app that the car is not in any way using more watt-hours per kilometer now than before (about 125 uphill , less than 100 same road back down, pretty good actually).
coulomb wrote: Tue, 09 Mar 2021, 07:05 @Nuggetgalore, are you sure that when the RR said you had little range left, that this was really true? For example, what was the pack voltage, and voltage of the lowest cell, when idle? My apologies if you've checked this thoroughly.
At idle (rest) when the fuel gauge and RR go to zero (just before the tortoise sticks its neck out),
the difference between the highest and lowest cell is about 0.04 V on both packs, but the new NMC cells are about 0.06V lower than the original LEV50s.
coulomb wrote: Tue, 09 Mar 2021, 07:05 The other thing is that these cells may be optimised for energy density rather than power density, and with a relatively small battery, they need to be optimised for power. A 60kWh battery might not have to worry about that, since the C rates would be so much lower. Edit: basically agreeing with Brendon here, the cells not liking over 1C.
Yes I agree, rating is 3C, but I never trusted that.
coulomb wrote: Tue, 09 Mar 2021, 07:05 Edit 2: the RR changing with regen does suggest excessive cell internal resistance, which suggests degradation, or at least the cells not being suitable for the loads, which could lead to rapid degradation.
I can read the internal max and min resistance with both the i909 and the Vident scanners,it has not changed from the old pack to the new one ,1.50mΩ, consistent with the reading on an 2012/13 iMiEV. My non scientific theory is the cell is not as bulky, weighs only 1kg compared with the 1,7 kg of the LEV50, so in addition to the different chemistry the voltage goes up and down much faster due to less material to absorb the stress. Interestingly though, my observation of low cell volt under load is not much lower on the new cells (about 2.85V) compared with the degraded LMO cells (about 2.95V)
Even just shortly before tortoise, the car runs with no obvious lack of power with the pack V down to 290 V. The discrepancy between high and low cell V is on both packs increasing drastically under load as the SoC reduces to very low.But changes back quickly to "normal" with a bit of regen or reducing the force on the "gas pedal".
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Re: Aftermarket iMiEV battery upgrade project

Post by adoepner »

Any updates on the Suzi Auto work by Graeme? Watching with keen interest.
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Re: Aftermarket iMiEV battery upgrade project

Post by francisco.shi »

He has changed the cells on the Imiev but one of the cell boards has a problem and is getting repaired. Once he gets that done he will send the car back and I will continue working on it. I got most of the algorithm sorted. I just need to do motors testing to make sure I haven't left anything out. I also need to make a board instead of using the Arduino. It is progressing but I have had a few other (higher paying) jobs to sort out in the last few weeks.
I will keep an update on this thread. I also want to add one pedal driving while I am at it.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

Oops, in trouble again.
I reinstalled the battery and turned the car on. All things looked ok, the READY light came on.
But after about 20 or so seconds the READY light went off and the high voltage alarm light( yellow car with exclamation mark) and the red auxiliary battery warning light came back on.
I also tried to charge, but that is also not working, the charge icon on the dash is on but flashing but no handshake commences.
My scanner informs me that it is fault P1A44 (leak detection BMU) + a couple of stored faults.


Tried a few times to disconnect the auxiliary battery and start again, but no joy.
Tried to clear the fault but it fails to clear. The Vident scanner does clear some faults, I caused one on purpose (removed the service plug, checked the fault, put the service plug back in, checked that fault was still showing, then successfully cleared it).

Now I have to try to find any information on that error, any suggestion greatly appreciated.
I hope there is something in the the Mitsubishi iMiEV forum on that topic.
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

Sounds to me like a ground fault from the HV battery.
No water got in anywhere while it was apart?
Or something touching? like a bus bar installed wrong?
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Re: Aftermarket iMiEV battery upgrade project

Post by brendon_m »

As always the Russians are here to help
http://mmc-manuals.ru/manuals/i-miev/on ... 300ENG.HTM
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

brendon_m wrote: Wed, 10 Mar 2021, 20:18 As always the Russians are here to help
http://mmc-manuals.ru/manuals/i-miev/on ... 300ENG.HTM
Yes, thanks for the hint, I also got a good reply here:
http://myimiev.com/forum/viewtopic.php? ... 527#p42527
The fault is probably in the battery, but I have to check a few things before I take the battery out again.
From the manual:
STEP 1. M.U.T.-III diagnosis code.

Electric motor switch: 20 seconds elapse after ON
Select lever position: P range

Q. Is the diagnosis code set?
If the diagnosis code is stored during the electric motor switch ON, the ground fault could occur inside the traction battery. Replace the traction battery


Replacing the battery is no option, replacing the iMiEV more likely!
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Re: Aftermarket iMiEV battery upgrade project

Post by francisco.shi »

It sounds like there is an insulation problem between the battery and the chassis.
You can start by unplugging the high voltage plugs from the AC compressor, motor controller and charger. If the fault persists then he problem may be inside the battery.
If you have changed the cells there is some chance you may have accidentally damaged some insulation.
You can try to do an insulation test by connecting a 1M resistor across your multimeter probes and then checking for voltage between chassis and the cell terminals. You should get either zero or a very low value and the value.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

francisco.shi wrote: Thu, 11 Mar 2021, 05:33 It sounds like there is an insulation problem between the battery and the chassis.
You can start by unplugging the high voltage plugs from the AC compressor, motor controller and charger. If the fault persists then he problem may be inside the battery.
Yes ,thanks, I will do these checks first.
francisco.shi wrote: Thu, 11 Mar 2021, 05:33 If you have changed the cells there is some chance you may have accidentally damaged some insulation.
You can try to do an insulation test by connecting a 1M resistor across your multimeter probes and then checking for voltage between chassis and the cell terminals. You should get either zero or a very low value and the value.
There is a ref to ground fault checking the BMU in the manual.
http://mmc-manuals.ru/manuals/i-miev/on ... dex_M1.htm
CHECK AT THE BMU TERMINALS

35 Main battery ground fault detector Electric motor switch:
"LOCK" (OFF) → ON More than 8 V → less than 1.3 V (after several seconds elapse)
46 Main battery ground fault detector pre-check signal Electric motor switch:
"LOCK" (OFF) → ON More than 5.3 V → less than 1 V (after several seconds elapse)

Now before I do this test, I need to know exactly how to check the voltage on
pins 35 & 46 at C-109 .
I can see on the circuit diagram (MAIN BATTERY MANAGEMENT SYSTEM) that these wires go to
5 & 7 on D-21 on the MAIN GROUND FAULT DETECTOR on the battery, but the I cannot get a clear view to read the wire colour, some of the circuit diagrams are very blurry.
Do I unplug C-109 ?
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Re: Aftermarket iMiEV battery upgrade project

Post by coulomb »

Another possibility is that you didn't re-connect the "battery detector" (really a battery leakage detector) properly. I have a post on it here. There is an orange lead that connects to the battery somewhere, and a white connector with ELV wires off to the BMU.
some of the circuit diagrams are very blurry.
If you click on the blurry diagrams, you get a nice PDF that can be zoomed, and is quite clear. At least, that's how it works with my browser, Chrome.
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Re: Aftermarket iMiEV battery upgrade project

Post by coulomb »

nuggetgalore wrote: Thu, 11 Mar 2021, 08:57 There is a ref to ground fault checking the BMU in the manual.
http://mmc-manuals.ru/manuals/i-miev/on ... dex_M1.htm
CHECK AT THE BMU TERMINALS

35 Main battery ground fault detector Electric motor switch:
"LOCK" (OFF) → ON More than 8 V → less than 1.3 V (after several seconds elapse)
46 Main battery ground fault detector pre-check signal Electric motor switch:
"LOCK" (OFF) → ON More than 5.3 V → less than 1 V (after several seconds elapse)
That sounds like 46 is a signal from the BMU to the battery ground fault detector.
Now before I do this test, I need to know exactly how to check the voltage on
pins 35 & 46 at C-109 .
I can see on the circuit diagram (MAIN BATTERY MANAGEMENT SYSTEM) that these wires go to
5 & 7 on D-21 on the MAIN GROUND FAULT DETECTOR on the battery, but the I cannot get a clear view to read the wire colour, some of the circuit diagrams are very blurry.
Do I unplug C-109 ?
You could try unplugging C-109 from the BMU first, since that's probably more convenient, but if that doesn't seem to work, I'd say you're supposed to leave it plugged in, with 46 providing the prompt to the detector to start detecting.

35 and 46 seem to be SB (Sky Blue) and L (bLue) respectively.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

coulomb wrote: Thu, 11 Mar 2021, 09:08
If you click on the blurry diagrams, you get a nice PDF that can be zoomed, and is quite clear. At least, that's how it works with my browser, Chrome.
Thanks ,yes that works perfect, I can read it clearly now as you say below 35 is SB (skyblue) and
46 is L (blue).
Since many wires on my 2010 car are of different colour than the manual (and other 2012models)
I hope these are standard and in the same slot.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

francisco.shi wrote: Thu, 11 Mar 2021, 05:33 It sounds like there is an insulation problem between the battery and the chassis.
You can start by unplugging the high voltage plugs from the AC compressor, motor controller and charger. If the fault persists then he problem may be inside the battery.
If you have changed the cells there is some chance you may have accidentally damaged some insulation.
You can try to do an insulation test by connecting a 1M resistor across your multimeter probes and then checking for voltage between chassis and the cell terminals. You should get either zero or a very low value and the value.
I disconnected the HV cables ,no change to the leakage fault. It of course indicated the disconnect faults, but I could clear these.
I removed the battery, it gets easier every time I do it,ha ha ha.
I took out the leak detector unit, no obvious signs of any thing wrong,but this is a fancy piece of equipment way above my paygrade to test it. Coulomb and I have posted about this detector on this forum:http://myimiev.com/forum/viewtopic.php? ... 511#p41511
I can't see any obvious things wrong yet, I will try your suggestion for testing the cell terminals tomorrow.
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Re: Aftermarket iMiEV battery upgrade project

Post by nuggetgalore »

nuggetgalore wrote: Thu, 11 Mar 2021, 09:34
coulomb wrote: Thu, 11 Mar 2021, 09:08
If you click on the blurry diagrams, you get a nice PDF that can be zoomed, and is quite clear. At least, that's how it works with my browser, Chrome.
Thanks ,yes that works perfect, I can read it clearly now as you say below 35 is SB (skyblue) and
46 is L (blue).
Since many wires on my 2010 car are of different colour than the manual (and other 2012models)
I hope these are standard and in the same slot.
Ok, so the wires of pins 35 & 46 are as per the diagram ( to make sure I'm at the correct connector I double checked wire colours on pins 31,32 and 33, yes they are red, white and green.
I did the test:
CHECK AT THE BMU TERMINALS and found the following wrong:

35 Main battery ground fault detector Electric motor switch:
"LOCK" (OFF) → ON More than 8 V{ reads 0 V} → less than 1.3 V {reads 10.5V} (after several seconds elapse)
46 Main battery ground fault detector pre-check signal Electric motor switch:
"LOCK" (OFF) → ON More than 5.3 V {0V}→ less than 1 V {0V} (after several seconds elapse)
So there is something amiss that the ground leak detector sees.
No voltage with the motor switch off,could it mean a broken wire (or fuse) supplying current to the leak detector?
I had the aux bat disconnected o/night, so all the caps must have properly emptied. Turning on to READY, it again looked fine for some seconds until the READY light went out and the warning lights lit. Turning off and on again, no READY, just the warnings.
Any body has an opinion whether it would be safe to connect the aux battery and turn the car on without the traction battery ? I just wonder what fault codes would be on, or could it mess up some data?
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