Hello from South East England

[Rusty911]

As I've just posted up a question, it's only polite I belatedly say hello.

Three years ago I installed solar here and naturally wanted something with a battery to drive around in. Sadly in the UK a combination of Covid aftermath, Brexit and appalling working conditions had led to a tanker driver, and so petrol, shortage. As a result, anything EV sold out and those that remained were overpriced, broken or both. Ever on the hunt for a bargain I bought an Outlander Phev with engine failure (timing chain), but healthy electrics. I fitted a lovely low miles engine and this was all good. I was now officially hooked on the EV experience.

Just under two years ago the Phev was joined by a 2012 Peugeot Ion, which I love. Just so handy size-wise and a bucketful of fun. As per the norm, its range was about 45 miles tops in the summer, much less in the winter. I'm in a hilly bit of Sussex which doesn't help.

Last year I finished putting a Land Rover Discovery Webasto diesel heater into the Ion with my own fuel tank (3 litres, so way more potential energy than the Ion's battery!). This, coupled with a cheap e-Bay heated seat pad, has transformed winter driving. I turn it and the car's own heater to full and literally within one minute it's getting warm, five mins is roasting hot air. Uses very little diesel and the electric element of the heating dials itself back very quickly as the diesel takes over. Barely touches the range.

It was a busy year as the 2015 Phev's battery had a cell failure, so the battery was rebuilt here with late 2019 low mileage LEV46's but retaining everything else from the 2015 pack. Car now transformed with no issues and no programming.

Anyway, now Mr Turtle / Tortoise is becoming less and less shy on the Ion, so next project is to try and use half a Stellantis / CATL 50KWh pack to do a modest battery rebuild, hopefully to simply reinstate slightly better than new performance to the car.

I shall report back, naturally.

All best wishes, Barry

 

[MickeyS70]

Hello and welcome to the forum

Anyway, now Mr Turtle / Tortoise is becoming less and less shy on the Ion, so next project is to try and use half a Stellantis / CATL 50KWh pack to do a modest battery rebuild, hopefully to simply reinstate slightly better than new performance to the car.

Replacing LEV50x cells with something else poses two fundamental challenges:

1. Physically fitting replacement cells and connecting them to the OEM CMU boards
2. Getting the BMU to properly recognise the capacity of the ‘new’ cells

Below discussion will give you a good idea what is involved:

https://myimiev.com/threads/main-traction-battery-upgrade-i-miev.5458/

 

[Rusty911]

Thank you, I've read that thread at length.

I believe that as I'm not overly concerned at having more capacity than the original, and I think I've gathered the BMS might allow a little over with repeated use, I'm not super concerned about it seeing extra KWh's. The car should be a little lighter anyway, so range can't help to be an improvement over original regardless. If it can do a real 60 miles, that's fine for what I need.

The CATL's have welded tags, but they overhang from the welded portion quite a bit. I need to get hold of a dead cell (and Ion module dimensions, as per my other thread) to see if I can do something with this overhang in terms of bending it up at 90 degrees and using this to attach the bus bar and modified CMU connections.

My gut is that I can, but early days. I'll chip away at the research before taking the Ion apart. Generally in life I find it's best to read, read, read then do do do: give it a go and if it fails, well there will have been some interesting lessons learnt along the way probably. It's better than chucking it away and buying (another) i3! Equally, I'm absolutely not going to throw £3-4000 at a 90K mile local-journey car that will still be worth almost nothing in real terms.

Oh yes, I have a friend / customer that has hacked the same CATL / Stellantis modules / CMU's to work with a late Leaf drivetrain (to go in a Range Rover Classic project that never happened) and then hooked all that up to a tablet display. Hopefully I won't need to bother him, but it might be an avenue should I get stuck!

 

[MickeyS70]

I believe that as I'm not overly concerned at having more capacity than the original, and I think I've gathered the BMS might allow a little over with repeated use, I'm not super concerned about it seeing extra KWh's. The car should be a little lighter anyway, so range can't help to be an improvement over original regardless. If it can do a real 60 miles, that's fine for what I need.

Tests have shown that the native BMU can recognise around half the capacity of an NMC cell, fine if you use 93Ah cells but anything lower might not bring back even original range.

The ‘auto learn’ capacity adjustment only works when replacing LEV50 cells with higher capacity LEV50.

Oh yes, I have a friend / customer that has hacked the same CATL / Stellantis modules / CMU's to work with a late Leaf drivetrain (to go in a Range Rover Classic project that never happened) and then hooked all that up to a tablet display. Hopefully I won't need to bother him, but it might be an avenue should I get stuck!

Better stay on his good side then…

 

[Rusty911]

I assume this is why you see overlays of discharge cycles? In that the BMU sees what it takes to be a well discharged battery when reality is the NMC drops off steeper a bit earlier, then levels off in later stages of discharge compared to the LEV50's?

 

[MickeyS70]

I assume this is why you see overlays of discharge cycles? In that the BMU sees what it takes to be a well discharged battery when reality is the NMC drops off steeper a bit earlier, then levels off in later stages of discharge compared to the LEV50's?

Yes, differences in charge/discharge curves will confuse the BMU, more on this topic below:

https://www.goingelectric.de/forum/viewtopic.php?t=82690&start=80

 

[Rusty911]

Yes, differences in charge/discharge curves will confuse the BMU, more on this topic below:

https://www.goingelectric.de/forum/viewtopic.php?t=82690&start=80

Super, many thanks: I shall engage translate and have a good read. I'd like to avoid getting my friend involved since this is a one-off, so it would be nice to avoid some sort of man in the middle affair and keep it stock where possible.

In real terms I wonder if the above merely affects range predictions and SOC reading (fuel gauge) and whether actually, the car just keeps going all the time the battery voltage is above the bottom limit for the LEV50's? I.e. the last two or three bars then last much longer than expected?

Again, this isn't project-perfection (other than cell safety), this is 'it's better than it was and will probably stay like this for a few years now,' For me it's a likeable little local runaround with just me using it.

 

[MickeyS70]

In real terms I wonder if the above merely affects range predictions and SOC reading (fuel gauge) and whether actually, the car just keeps going all the time the battery voltage is above the bottom limit for the LEV50's? I.e. the last two or three bars then last much longer than expected?

Unfortunately not, the car uses the SoC as a baseline for various calculations; the tortoise light will come on as a warning around 10%, power reduces between 1-2% and the car shuts down under 1%, regardless of what’s left in the tank.

SoC is based on the actual battery capacity value (45Ah * SoH)

 

[kiev]

It's counting Coulombs with the current sensor. Here is a simple example without regard to cell degradation:

So if the BMU thinks you have "new" or reset to, 45Ah capacity cells, then it counts down from Full to 45Ahrs worth of Coulombs and that's the end. Even if you started with 93Ah and are only at half-empty for both voltage and capacity remaining, the car won't drive further.

 

[Rusty911]

I'm not sure that Coulomb counting worries me as I'm not intending on exceeding the original battery size particularly. The discharge curves I can see could be an issue, depending on just where those curves lie and at what point the BMS says the new cells are flat.

Ultimately though, the thing that would kill this stone dead is if the cells can't be made to fit in the hole with the existing CMUs. Then next thing is the welded tabs. I.e. split the whole thing into two: physical and software. If the physical isn't happening, I don't need to worry about the software.

Also, I assume if I can make the cells fit, hook them up to the existing CMUs and deal with the temperature sensing, the battery can go back in the car and I can simply try it. If it needs software, man in the middle or whatever, I take it that'll all be external to the battery? I.e. the battery can stay in place whilst other stuff is sorted?

 

[MickeyS70]

Also, I assume if I can make the cells fit, hook them up to the existing CMUs and deal with the temperature sensing, the battery can go back in the car and I can simply try it. If it needs software, man in the middle or whatever, I take it that'll all be external to the battery? I.e. the battery can stay in place whilst other stuff is sorted?

Yes, the BMU of a 2012 iOn is easily accessible under the rear seat bench.

What is the rated capacity of the ‘new’ cells?

 

[Rusty911]

The whole Stellantis pack is a little over 50KWh total, which is made of 18x12 cell modules: so 216 cells. Each cell therefore 0.23KWh. Using 88 x 0.23 gives a fraction over 20KWh. Minus 10% or so, so about 18KWh usable.

So you can see why Coulomb counting doesn't keep me up at night. The discharge curves might, but as above, the whole thing becomes moot if I can't squeeze the cells in height-wise. They will easily go in width-wise (and indeed I could shift the CMU's there if needed). They are comically smaller in depth, so they'd have a ton of air around them: probably not a terrible thing.

 

[MickeyS70]

The whole Stellantis pack is a little over 50KWh total, which is made of 18x12 cell modules: so 216 cells. Each cell therefore 0.23KWh. Using 88 x 0.23 gives a fraction over 20KWh. Minus 10% or so, so about 18KWh usable.

The stock BMU will recognise about 10kWh without modifications but you can cross that bridge when it comes to it…

the whole thing becomes moot if I can't squeeze the cells in height-wise. They will easily go in width-wise (and indeed I could shift the CMU's there if needed). They are comically smaller in depth, so they'd have a ton of air around them: probably not a terrible thing.

There is another thread that explores various other possible cell replacement solutions:
https://myimiev.com/threads/making-a-custom-battery-pack-for-miev.5459/