Newbie with some questions

[ManxViking]

Hi everyone,

I am a total and complete newbie to all of this and so I want to ask some questions and hope someone might be able to offer some advice on where to buy bits in the UK or even what I should be getting.
I have bought a complete battery pack from a 2020 Hyundai Ioniq. It consists of 2 large 72v packs, 3 48v packs and a weird flat pack of 48V ( 4 x 12v ).
These are the NCM 622 cells. After researching these are ok cells apparently? So long as you don't over stretch them from 0 to 100% constantly.

Anyway, my issues are as follows.

The 2 x 72v packs need to be made into 3 x 48v packs. The weird flat 4 x 12v pack needs to be reconfigured to match the other 3 48v packs. Thus giving me 7 packs at 48v. I thought having everything 48v would be a better solution than trying to understand how to build a bank with all these different voltage packs.
From research, the nominal minimum voltage should be 3v? and a fully charged cell should be 4v?

As I have stripped the metalwork from around the packs, I cannot actually see how to separate the cells? Can anyone advise please?

There are the cooling / heating channels/flat tubes are still attached. Are the pouches somehow glued to this cooling channel?

Can someone explain to me briefly what BMS I need to find for each of the 48V packs. I dont know how many individual cells are in each pack but would it be 13?
I am guessing that I will need an individual BMS for each pack? Id like to be able to see them on my phone or PC. Is this possible??

Lastly after fitting BMS's then I need to understand what type of charger I need?

In the new year i'm moving across to a cheap overnight electric rate so would be nice to make use of that as well as my 11kwh solar for a battery top up etc. as it barely does 3kwh per day with our current overcast dull days here. But that will be a while away yet.

ANY help would be really appreciated or a point in the right direction to speak to someone about this.

Many thanks,

David

 

[ManxViking]

These are the photos of the packs and some close up shots

 

[Oberfail]

It would be really nice, if you can disassemble the pack down to having each cell individual, so you can better work with them. You should have something between 96 and 104 cells (common for EV's).

When you got all cells individualised, you can put 7 or 8 in parallel (7p) and put those 7p packs in 13 or 14 series connections (14s) to get a 14s7p pack. Then you'll only need a single BMS for all and the capacity of all parallel strings are nearly the same, so you have as much capacity as possible.

Stuarts DIY BMS is a very great choice, but the parts are hard to come by during the chip shortage. Alternativly a JKBMS is a good option. Batrium is super expensive and their support is rather bad, but its not a bad BMS either, just not worth the price.

Also the nominal voltage is 3.6v or 3.7v, the minimum 3v and the maximum 4.2v. But i reccomend to keep them between 3.95v & 3.4v as higher & lower states stress them much more and decrease the cycle count.

 

[ManxViking]

Hi Oberfail.
I have 3 packs already at 48v that I won't have to mess with. It's the 2 that are 72v that need splitting to make 2 X 48v and the 'leftovers' will combine to make another 48v pack.
Just NO idea how the packs are held together?? I've taken one packs front and back metal plate off but each cell is still together..... I was wondering if they used a mastic or even double sided tape or something. I will take some more pics now.
Cheers,
David

 

[ManxViking]

A few pictures of the 3 X 48v packs. 1 of the 72v and several of the long flat 4 X 12v pack

 

[Oberfail]

There is barely any information on how to handle those batteries, i only saw a video where one used a flex saw to take them apart

 

[OffGridInTheCity]

From research, the nominal minimum voltage should be 3v? and a fully charged cell should be 4v?

Looks like they are lithium-ion from this link - https://pushevs.com/2020/05/13/volkswagen-meb-details/ which shows:

because of the "Voltage: 3.65 V" bullet. So 4.2v max, 2.8-3.0vmin with 3.5v/cell discharge curve knee - e.g. standard lithium-ion voltage ranges.

As I have stripped the metalwork from around the packs, I cannot actually see how to separate the cells? Can anyone advise please?

There are the cooling / heating channels/flat tubes are still attached. Are the pouches somehow glued to this cooling channel?

Agree with @Oberfail - if you can separate these out you can do capacity tests on each individual cell and then arrange them in a balanced way.

From above they may be 78ah each. From your description you may have 56 cells so perhaps 14s4p or 14s3p if some cells don't test as well. 14s4p 48v (nominal) @ 312ah = ~ 16kwh potential.

Can someone explain to me briefly what BMS I need to find for each of the 48V packs. I dont know how many individual cells are in each pack but would it be 13?
I am guessing that I will need an individual BMS for each pack? Id like to be able to see them on my phone or PC. Is this possible??

14s is highly recommended for a really good match with all 48v equipment. You 'can' do 13s or 15s but it will limit compatible equipment choices. NOTE: This is based on my believe (above) that these are lithium-ion

The Batrium (www.batrium.com) BMS system could do 14s4p 312ah/cell (or any combination) but it's expensive.

Alternately you could do 4 separate batteries of 14s1p and parallel them - with a BMS on each one - and use more common (cheaper) BMSs on each battery.

Lastly after fitting BMS's then I need to understand what type of charger I need?

BMS has nothing to do with charging - except it may have limits on max amps for charging.

A key thing to figure out is discharge/charge amps per cell. Let's say it's 20a/cell - then a 14s1p would be 48v @ 20a = ~ 1000w per battery. If you had 4 of them you'd have 4000w of discharge/charge. **Need to find the specs for these cells and then you can figure the correct numbers.

In the new year i'm moving across to a cheap overnight electric rate so would be nice to make use of that as well as my 11kwh solar for a battery top up etc. as it barely does 3kwh per day with our current overcast dull days here. But that will be a while away yet.

ANY help would be really appreciated or a point in the right direction to speak to someone about this.

Many thanks,

David

Happy to answer more questions - but maybe see
1) If you plan to separate and test - *Highly recommended* - and this decision will lead to the next steps.
2) If you can confirm the spec above and/or find some specs and share. We might even be able to take the total battery charge/discharge info on the number of cells extrapolate to individual cell level charge/discharge specs.

 

[ManxViking]

Thank you OffGridInTheCity.
In 1 response I've got more specific info than my trawling of the web.
3 of the packs are already configured to 48v but I am not sure about capacity but as a whole 336 volts with a total pack capacity of 44kw of which the manufacturer states 39kw usable?
I guess for stability my idea of making all the packs the same size as the 3x48v that are already made up, as are already configured, would be best.
I need to understand how many cells are in the 48v packs. How they need to be wired up, the 14s?p which I still can't get my thick head around As I cannot see the sides till the packs are split.
Maybe they a glued or double sided tape? Am a little hesitant to force apart without knowing how they're held in case I damage something.
The cooling sections are integrated into the packs, these will not be needed in our UK climate.
Merry Christmas and thank you for your help. I will add photos for reference as I go along.
David

 

[Oberfail]

36 volts with a total pack capacity of 44kw of which the manufacturer states 39kw usable?

That means, that when each cell is fully charged to 4.2 volts, you'd have a capacity of 44kWh, but the manufacturer only charges the cell to a lower voltage (probably 4.1v max) which results in a longer life-span of the battery but a slightly reduced capacity.

Am a little hesitant to force apart without knowing how they're held in case I damage something.

You could start on the little 12v packs and have a big bucket of sand nearby in case something goes wrong.

 

[ManxViking]

Right. That makes sense, 40 to 80% for longer lasting life. But that was why I didn't go for a forklift battery because that was only 40% of usable power..... Would like to get 10 years out of them if I can. Going to take a hammering in winter and no use in the summer. If I can figure this out I will buy another pack in the next couple of years to increase capacity. I'm wondering if somehow the cooling channels are glued to the cells but surely that wouldn't be EVERY cell but they are all solid...
So each 48v pack is actually 52v right? So 14 individual cells or pouches...
When I can see how the sides are mounted and how to split them then should be easy to reconfigure.....I hope

 

[floydR]

I think if you used a heat gun and gently heat the cooling plates and a very flexible plastic putty knife you might be able to separate the packs.

later floyd
ps don't try to separate the individual cells just yet .

 

[ManxViking]

Thanks floyd.
I'll have a look tomorrow and try on the smaller pack first. I have a heat gun but does anyone think that I need to remove the plastic ends where I guess the pouch connections to the bms would be?
Cheers,
David

 

[floydR]

Yes remove the plastic ends, access to the individual cells would be good. If they are like many of the LG Chem pouch cell packs the ends may be held on with plastic clips molded into the covers. I am just guessing on using the heat gun and plastic putty knife to remove the cooling plate i would proceed with caution. The plate be integrated into the battery pack more than the photos showed.
Later floyd

 

[ManxViking]

Ok. I'll see how they come apart. I couldn't find any videos with any info on how these ends come away.
If I can get any of these end caps off I will try to get the heat gun in to split each pack apart and will take some pics for here

 

[Oberfail]

Thats the only video somewhat related that i found:
I dont think I have to say, if you're going to do what they are doing in the video, be *very* cautious. Cutting Lithium Cells is very dangerous.

View: https://www.youtube.com/watch?v=HStjs4xuEJc

 

[ManxViking]

Ok, not alot further today as too much on. But at least I understand how these are held together and am hopeful through this week I will spend a little time each day working on them.
Any more thoughts please feel free to write as I will take any and all advice.
Many thanks for your help so far.
David

 

[ManxViking]

The putty like paste must be for effective heat transfer but I still can't get this pack broken down any further. The sections still seem solid so there must be another lock somewhere I haven't come across yet. Bloody tedious....

 

[ManxViking]

Am so nervous about stripping this to make the packs because I cannot find ANY information on how to safely deal with them. I need to charge the packs, bms etc. No idea what to do or how to do it. Till I can figure that out I can't do much unfortunately.
Thanks for the advice so far

 

[Oberfail]

If you want to, i could try to help you remotely via videochat. You can use your phone to show me the battery and i could give some advise on what to do. I'd prefer to use discord for that.

 

[ManxViking]

Thanks Oberfail. I don't mind what app to use. Whatever you suggest. At least I may be able to show you in more detail because I can't believe it's this difficult to split the cells. Let me know what I need to do and I'll get on it.