CZeroOwner
Gold Member
Posts: 34
Joined: Mon Jan 15, 2018 1:47 am
Location: Denmark

Re: Is my battery dying ?

Wed Sep 25, 2019 7:20 am

My battery was tested in the car. I wasn’t there but the procedure they told me they followed sounded very much like the one you described for the Diagbox.

Could it be that the Diagbox knows that 3.63 volts is equal to a SoC of 10% and that the Ah it measures between 3.63 and 4.1 is 90% of the battery’s true capacity? The number it gives you is in fact an estimate of the capacity between 2.75 and 4.1 based on this 90% number. I don’t see how we can compare capacities if all the measurements depend on different voltages.

David

DBMandrake
Posts: 223
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: Is my battery dying ?

Wed Sep 25, 2019 8:47 am

CZeroOwner wrote:My battery was tested in the car. I wasn’t there but the procedure they told me they followed sounded very much like the one you described for the Diagbox.

Could it be that the Diagbox knows that 3.63 volts is equal to a SoC of 10% and that the Ah it measures between 3.63 and 4.1 is 90% of the battery’s true capacity? The number it gives you is in fact an estimate of the capacity between 2.75 and 4.1 based on this 90% number. I don’t see how we can compare capacities if all the measurements depend on different voltages.

Yes exactly. The car (and Canion) will report 0% SoC at about 3.63v per cell and shut off the car when the cells really have about 10% capacity left, if they were to be discharged down to below 3.0 volts. However that bottom 10% can't be used because the cells would go under voltage under heavy load, eg when you accelerate and this would damage them.

To use that last 10% of capacity you have to progressively limit the current drawn to a lower and lower level to remain at a safe voltage, which is not useful in a car. Instead of doing this the car just uses a higher shutoff voltage - at 3.63 volts (no load) even under full acceleration the voltage doesn't go below about 3.0 volts.

By the way I'm not sure if you read in another post of mine, but I discovered that there are two different triggers for turtle mode. One is if the SoC drops below about 10% (as reported in Canion) which is in reality close to 20% left in raw capacity, the other is any cell going below 3.0 volts even instantaneously during acceleration will also turn on the turtle lamp on the dashboard and limit acceleration.

Normally the 10% SoC threshold for turtle mode comes first however if the Ah figure in the BMS was way too optimistic for some reason, you might hit the 3.0v safety limit. This happened in my testing when I reset the Ah capacity to factory default and the battery ran out "sooner" than the BMS was expecting causing it to run the battery right down to 3.0 volts...
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

CZeroOwner
Gold Member
Posts: 34
Joined: Mon Jan 15, 2018 1:47 am
Location: Denmark

Re: Is my battery dying ?

Wed Sep 25, 2019 11:17 am

My car shows 8% SoC when the voltage is 3,63.

David

DBMandrake
Posts: 223
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: Is my battery dying ?

Fri Nov 01, 2019 3:26 am

After many other unrelated delays (other car breaking down and needing repairs first, house renovation, family commitments, illness, bad weather etc...) I'm almost ready to drop the battery pack out of my car to swap four cells. I built the following trolley/dolly specifically matched to the size of the battery pack, and designed to be as low as possible to minimise the height I need to raise the car:

Image

Image

It's sized to allow the battery pack frame to overhang the trolley enough to let the threaded rods clear the trolley, also to allow jacks to get under the edge of the battery frame while it's still resting on the trolley:

Image

That means I can get a jack under the edge of the overhanging battery pack frame and lift it up off the trolley onto the threaded support rods if necessary. The eye hooks are to attach 4 ropes to allow me to pull the battery sideways out from under the car (with a bit of help!) and also into my garage for disassembly then back again. At an alleged 240Kg it hopefully won't be too difficult to move on 4 castor wheels!

So, just waiting for a fine weekend now - a tall order at this time of year as I was originally planning to do this job more than 2 months ago... :roll:
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

DBMandrake
Posts: 223
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: Is my battery dying ?

Mon Nov 11, 2019 3:07 am

I spent this weekend removing the traction battery from my Ion and it is currently sitting in my (slightly less freezing than outside) garage. Plan is to actually disassemble the pack starting on Wednesday (my body needs a rest after two hard days working on it in the freezing cold) to swap cells and then refit it next weekend.

Will post a full write up with picture and results once its back in and tested however I wondered if anyone wanted any specific photos taken of the insides, dimensional measurements, tracing of wiring and so on while I have it all apart to add to the available knowledge on these traction battery assemblies ?

I will take a few photos of course but I know some things would have helped me make the removal easier if I'd known them before hand - such as the height of the pack from the bottom chassis to the top of the plastic cover.... (I ended up having the car higher off the ground than I needed which increased the time to lower the battery on the threaded rods!)

Oh, and it's very rusty down there. Large parts of the under body of the car are seriously rusted as there is no underseal to be seen anywhere... including the bottom side of the traction battery itself whose cross members have a couple of places where I can poke my finger through the rust! :shock: Nothing that will cause imminent structural integrity problems but disappointing none the less.

Also of the multitude of M6 bolts that hold the bottom plastic covers on approximately half of them snapped off at the head of the bolt even after using rust penetrant and after they were already turning. And I was only using a tiny 5" long ratchet! Soft as butter steel springs to mind... :roll:

Anyone have any tips on drilling out a large number of broken M6 bolt remains other than the obvious one of using a correctly sized small drill ? (I have a new, sharp 4.2mm drill bought just for this which I think will be about right)

To add to the knowledge base I did confirm one theory - Canion can still read all the cell voltages even when the high voltage safety link plug under the seat is removed. I thought this would be the case. Turning on the key with the link plug removed (or the entire traction battery removed, heh heh) does of course set the high voltage orange warning light on the dash, (as there is a small low voltage "sense" connector in the link plug as well that the ECU can read) but I'm sure it's nothing I can't clear with the diagnostic tool.
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

JoeS
Site Moderator
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Location: Silicon Valley, California

Re: Is my battery dying ?

Mon Nov 11, 2019 8:58 am

DBMandrake, thank you for the update. Pity about the rust (here in California, my 1967 Saab is still rust-free so I'm clueless) and the bolts breaking are just a PIA to drill out and remove. Looking forward to the photos and your writeup of the process!
EVs: 2 Wht/Blu SE Prem., '13 Tesla MS85, 3 156v CorbinSparrows (2 Li-ion), 24v EcoScoot(LiFePO4)
EV Conv: 156v '86 Ram PU, 144v '65 Saab 96
Hybrids: 48v1kW bike
ICE: '88 Isuzu Trooper. Mothballed: '67 Saab (orig.owner), '76 MBZ L206D RHD RV

jray3
Posts: 1662
Joined: Tue Dec 06, 2011 1:05 am
Location: Tacoma area, WA
Contact: Website

Re: Is my battery dying ?

Mon Nov 11, 2019 3:56 pm

Yes, sorry to hear of all the rust and broken bolts. Minimal salting here in the Pac NW for salmon recovery, so minimal rust down below.

The threaded rods area really just needed for safety and alignment purposes. I swapped my pack by jacking each end of the pack down/up 5 cm at a time and then finger-spinning the nut down the shaft before releasing the jack and moving to the other end. Wrenching on those nuts while they carry the load is a real drag... When properly aligned, I didn't even need to hold a wrench on the two locked nuts I had installed on the end of the shaft to act as a bolt head. I just held the shaft with one hand and spun the nut with my other hand. Gotta make sure not to unscrew the rod while backing off the nut.
2012 i-SE "MR BEAN" 105,400 miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh
1965 Karmann Ghia Cabriolet

DBMandrake
Posts: 223
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: Is my battery dying ?

Fri Nov 22, 2019 5:37 am

That's my four cell swap completed and the car back on the road on Tuesday. :)

I took loads of pictures but posting them here is a real PITA as it's the only forum I use that doesn't support uploading attachments, and uploading them elsewhere and linking is a bit of a pain for lots of photos to be honest. :x

Apart from things like rusty bolts everything went fine except for one mistake I made - I matched the Voltage/SoC of the replacement cells at 20% SoC rather than 100%.

So as they charged up the newer higher capacity cells "fell behind" as they would need more charging to reach 100%. So at full charge they ended up 50mV lower than the other cells. (4.05 v instead of 4.1 volts)

Of course the cell balancing system valiantly spent 3 hours trying to balance the cells at the end of the normal charge cycle but finally had to give up after making little headway. 50mV less is approximately 5% of the entire capacity of the battery so assuming about 40Ah that is a 2Ah error in cell balancing between original and replacement cells.

With 100mA capable balance resistors it is going to take at least 20 hours of balancing time to correct this mistake! :roll: I tried using the "Voltage equalisation" procedure in Diagbox (which I believe is the same as the Cell Smoothing feature in MUT-III) however it aborted after less than an hour so the only option seems to be to simply let the balancing system pick away at it bit by bit at the end of every charge cycle, and it seems to be willing to do about an extra two hours of balancing after reaching 100% before timing out and ending the charge session without achieving balance.

The car is working fine but due to this the usable capacity will be limited by the imbalance so I'm probably not going to attempt the battery calibration procedure until after adequate balance has been established, which make take around a month.

Meanwhile the BMU has made a small Ah adjustment itself. The day after I refitted the battery it went down from 33.0Ah to 32.9Ah - which will just be modelled degradation, but then this morning after three days commuting totalling about 100 miles driving it bumped the figure up to 33.9Ah which is higher than it was when I removed the battery. :)

This seems to align with what happened during jray3's battery swap where the BMU would gradually bump the Ah up by 1Ah every few hundred miles, so it will be interesting to see where it gets to by the time I'm ready to do the battery calibration.

For those of you who have had your battery packs out before I have a piece of advice - check the rubber grommet/seal for the battery air intake is properly engaged in the bodywork!

It might not be immediately apparent but when you jack the battery up into place again it's impossible to properly engage the air intake grommet simply by raising the battery - the grommet will be partially crushed against the body and not sealing.

You must lift the carpet and remove the air duct from the grommet to the AC system to get access to pull the grommet through and engage its slot into the bodywork hole properly then refit the air vent. I have pictures detailing this.

If this is not done road spray may be able to enter the battery pack through the air vent.
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

DBMandrake
Posts: 223
Joined: Mon Mar 20, 2017 4:57 am
Location: Scotland

Re: Is my battery dying ?

Mon Nov 25, 2019 2:58 am

By the way does anyone know the significance of the colour of the LEV50 cells ? Or is there no significance ?

My original cells are an olive green colour, my replacements are blue.... however online I have also seen purple and yellow!
- Simon

EV: 2011 Peugeot Ion
ICE: 1997 Citroen Xantia V6

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