jray3 wrote:The procedure was based upon a UK owner who threaded 30 cm sections of allthread (12MM, 1.25 pitch) in place of four of the eight mounting bolts. I chose those bolts immediately fore and aft of center, and put wheel ramps under all four wheels as my tallest unmodified jacking option. I threaded a nut up the shaft till finger-tight, and then locked two nuts together at the bottom of each shaft to provide a 'bolt head' to hold and prevent the shaft from turning. Turns out that it would take forever to lower the pack by backing down the nuts, even with a ratcheting box end wrench due to only getting perhaps 20 degrees of rotation per turn due to the surrounding structure. I then realized that we could let a jack support one end of the pack, spin the nut down a couple of inches by hand, and then lower the pack and repeat at the other end. This was methodical enough to prevent any scraping or cable-snagging, but greatly sped up the process while preserving safety, lowering the pack gently onto a mover's dolly.
In the next couple of months I'm going to do much the same thing to swap 4 cells. My plan is to use the M12 x 1.25mm threaded rod method (you say 30cm was enough length ?) and like you use a jack to support it while the nuts are spun quickly then lower the jack a bit more. Should work quite well I think.
I was originally going to use a dolly (made of 4 caster wheels and some 25mm plywood) to support it all the way down - in other words put the jack under the middle of it and jack the dolly right up in the air under the pack to support it from the middle and lower it down from there, however your description of simply supporting one end of the other alternatively with the jack sounds like it would be easier still and just require the dolly to wait at the ground.
In short, the salvaged pack woke up on the first try, displaying 64% SOC on my MUTIII clone, with only .06 V difference between the highest and lowest cell. We immediately took a spirited 20 mile test drive down to a displayed 1 bar, and plugged into L2 for a full recharge to recalibrate the BMS. Now after 3 full L2 recharges and two DC fast charges, the MUTIII is still reporting the same capacity of 28.6 Ah, and I haven't seen higher than 50 miles RR, after a typical 38 to 41 miles RR in recent weeks on the old pack.
If you see another thread I posted in not long ago you'll see that the BMU won't make large changes to the Ah capacity by itself in any reasonable amount of time. I reset mine to the factory default (which is 45.8Ah) using the "battery replacement" service operation in Diagbox and drove the car for several days and several hundred miles and it did not budge even though I ran the car right down to the point where it nearly shut down on one occasion.
If you swap the battery pack you must either do the "battery replacement" diagnostic process (not sure what it is called in MUT-III) or do the "battery calibration" diagnostic process. The battery replacement procedure simply resets the capacity to a factory new 45.8Ah and does not
measure the true capacity of the battery - in the diagnostic tool it says this should only be used if the battery pack is verified to be less than 6 months old from date of manufacture - clearly not true in your case!
So instead you need to run the battery calibration process - whatever it is called in MUT-III. Set aside a whole day to do it, it takes a long time as you have to both discharge to about 20% then fully charge to 100% on Level 1/2, but it will accurately measure the performance of your replacement battery and update the usable Ah capacity figure accordingly.
After this you will see increased range, assuming the replacement battery actually does have better capacity.
Full power acceptance is another issue, however. The first DCFC was on a brand new Electrify America station that delivered 125a, 50 kW to a buddy's SOUL EV the day before, but my session started at 11 kW and quickly tapered to 9 and then a measly 6 kW. The second DCFC, 24 miles and 30 minutes later, was on a BLINK DCFC, which started at 100 amps, 35 kW, but then tapered down similarly.
Early and excessive throttling of DC rapid charging speeds suggests one or more high resistance cells. My car has 3 cells which have developed higher than normal internal resistance over the time I've had the car and the symptoms of this are rapid charging speeds starting to throttle much sooner and at low SoC and also reduced regenerative braking strength. This high resistance is one reason why I am going to replace these cells. (They also have low Ah capacity)
It's relatively easy to diagnose high internal resistance cells by rule of thumb using Canion and DC rapid charger. Monitor the cell voltage page on Canion before starting rapid charging, if soon after you start rapid charging certain cells go much higher in voltage than others (say more than about 15-20mV) and they were equal or lower voltage than others before charging they have high resistance.
When the highest voltage cell hits 4.105 volts the rapid charge rate is throttled back to keep it exceeding this voltage. If even one cells has high internal resistance it can dramatically slow down rapid charging as the BMU attempts to keep the cell going over voltage.
You can see this in the following post I made where the cells highlighted in red have gone to a higher voltage than the rest during rapid charging:viewtopic.php?f=23&t=4014&start=50#p39013
Before jumping to conclusions I would perform the battery calibration though and make sure the BMU has a correct figure for the Ah of the battery.
I removed the lids on both packs for inspection, and found that though both contained LEV50 cells, not LEV50N, my originals were yellow and the replacements are aqua blue in color.
The cells I just bought are aqua blue, I don't know what cells are in my car though. Purple is another colour of cell for these as well.
Since the temperature sender is enclosed in the rear portion of the pack lid, I simply transplanted the lid rather than extracting the sensor.
What temperature sender is this ? There are 66 temperature sensors on the CMU PCB's to monitor cell temperatures but I am not aware of any other temperature sensors inside the battery enclosure ? Are you sure that cable wasn't for the extractor fan ?
jray3 wrote:Thank you Bjorn,
There was no VIN lock, so no brain transplants required.
Correct, there is no VIN coding of the CMU boards in the pack.
I got a definite sign of trouble this morning. I had noticed that the first bar didn't last very long in driving, and last night it only charged up to 15 bars, 48 miles RR.
The datastream says only 88% state of charge. So I pulled the trouble codes, which I hadn't done before on this battery, as there were no warning lights. I got P1AC6- Each Cell Volt diff (Hi side) and P1A4D, IGCT line voltage. The voltage difference between hi and low is 0.05V (4.10V on cell 19 and 4.05V on cell 38). Cell 38 has been the lowest every time I've scanned. We'll see if #38 gets better or worse with some 8A L1 TLC over the next few days.
P1A4D according to this
means that the 12v supply voltage to the EV-ECU is below 8 volts or above 16 volts with the car in the READY mode.
Check the health and charge of your 12v battery! Has it been replaced in the time you've had the car ?
P1AC6 according to this
is due to a difference in voltage between the cells of more than 0.05v. However a difference of this magnitude is perfectly normal, and shouldn't result in a fault.
So what I think this fault really means is the consistency check it does where it measures the entire string of 8 or 4 cells in a module and compares that to the sum of the individual measurements has failed.
In short, you might have a faulty CMU board. So don't throw away that old pack yet! You might need to salvage a CMU off it and swap it over.
If you look at the realtime voltage data for each CMU in the MUT you should see individual cell voltages for each cell in the module and one overall module voltage which is 31 volts for an 8 cell module - this overall voltage is not simply the sum of the individual measurements but a separately taken measurement.