What 282 kWh CATL LFP look like

[OffGridForGood]

I am wondering if you could have just stood the pack up-right instead of cutting. Like a Tesla power wall set up, so it doesn't take up much floor space.
Can those cells be that orientation? Then: Cut the bus bars that you need to and make new ones to create the 16s-6p arrangement you wanted.

If I start driving tomorrow early I can be in Quebec City by Tuesday afternoon to pick up two of those original (un-cut) packs and get them out of your way!
From the dimensions, two packs will fit side by side in a truck box, 2,000 lbs is fine for my 1-ton for the trip home!

 

[yabert]

Well I guess the biggest difference is you're using true automotive grade cells ... only one BMS and it fails, well now you're out everything (unless you have a spare BMS just sitting on standby).

I totally agree. I only play with OEM cells from scrap yard or new old stock.
Also, if I was completely off grid I would prefer to have back up, so 2 BMS / 2 batteries.

 

[yabert]

I am wondering if you could have just stood the pack up-right instead of cutting. Like a Tesla power wall set up, so it doesn't take up much floor space.
Can those cells be that orientation?

Only 2x1 ft at the floor when up-right. Cells can be on the side no problem.

Then: Cut the bus bars that you need to and make new ones to create the 16s-6p arrangement you wanted.

This is the part I'm not interested to play with. If the busbars was bolted instead of welded that had been a solution, but it's not the case.

If I start driving tomorrow early I can be in Quebec City by Tuesday afternoon to pick up two of those original (un-cut) packs and get them out of your way!

Sure. I will keep them for you. I'm near Montréal, so remove 2 hours of road to your trip ?

 

[yabert]

I would never think this possible few days ago, but I have now a 16S and 11.7 kWh battery in stock.
It's a good amount of job. The aluminum go out of the way fairly easily, but the green glue is hard to broke and impossible to remove.
One of my fear was this green glue to damage the insulating blue wrap of the cells during the separation of the module.
Effectively the green glue stick a lot on everything and rip the blue wrap on the cells... But I'm so lucky, there is more than one layer of blue wrap on the cells ?

Thanks Skypower for the idea of the saw. That work well.

 

[oglark]

Hey I am still interested in the 16S battery.

 

[yabert]

Things go forward. It's clearly a DIY LifePo4 battery banks ?

 

[yabert]

That is, in less than a week I've sold 211 kWh (3 batteries).
Ok, so the title isn't accurate anymore as there is only my 70 kWh battery left.
I will still continue to update the modification / installation of my 35 kWh or 47 kWh or 58 kwh or 70 kWh battery in my house (really not sure of the end capacity installed).

 

[OffGridForGood]

Can we get any more of these packs?
How much did these cost?

 

[yabert]

Clearly it's was a one shot deal. It's not every day that you can find new old stock destinate to big trucks.
Since 10 years I find used EV battery pack at very good price (50-100$ / kWh).
And I think the future is bright for reusers like some of us. LFP packs start to be popular (Tesla model 3, Mercedes Sprinter, Ram promaster, some Ford EV and others) so the low cost LFP packs will be available at the scrap yard soon.

It's simple, more and more texting/driving morons will drive EV, OEM build their EV to protect occupants and battery, insurances declare total most EV when there is deploy airbags... conclusion: More and more perfectly working/high quality battery pack will end at the scrap yard.

 

[electric]

@yabert Those are very nice 16S blocks, perfect for a 48v house battery. You got very lucky with this purchase.
You can easily parallel your blocks at the cell level by drilling and tapping those busbars in the raised center sections, then connecting in parallel with 10 or 8 gauge wires with crimped ring terminals. With normal use I don't expect more than a few amps of "balancing" current between cells, as long as your main pos/neg connections are symmetrical between all blocks and your C rate is low, which it will be on such huge battery.

Good to see you are still around playing with batteries, I randomly stumbled on your post and instantly recognized your writing style and your forum handle. We go way back from early days of DIY EV forum, I'm the miniBMS guy if you remember

 

[yabert]

Those are very nice 16S blocks, perfect for a 48v house battery. You got very lucky with this purchase.
You can easily parallel your blocks at the cell level by drilling and tapping those busbars in the raised center sections, then connecting in parallel with 10 or 8 gauge wires with crimped ring terminals. With normal use I don't expect more than a few amps of "balancing" current between cells, as long as your main pos/neg connections are symmetrical between all blocks and your C rate is low, which it will be on such huge battery.

It's exactly the plan. 51.2V nominal and 684Ah (3x 228Ah).
It's not that simple to build this 35 kWh battery, so I start to cad a 3D model. I have to flip the center module and design main busbars (red/black) and of course the parallel busbars (yellow).
I need to measure more things and finish the structural part of this battery and I will send this to laser cut.



I have hard time to find any pertinent informations about cells orientation, so I stick with the old tundersky tips to convince myself that cells on the side is ok:

https://gwl-power.tumblr.com%2Fpost%2F136176357111

Good to see you are still around playing with batteries, I randomly stumbled on your post and instantly recognized your writing style and your forum handle. We go way back from early days of DIY EV forum, I'm the miniBMS guy if you remember

Still playing... of course. 15 years after has paid 600$/kWh for my first LFP cells (Headway 38120), it's now my job to design EV, since 6 years ?
I perfectly remember you. I play with solar and 40-50$/kWh cells since 2 years now and I'm seriously surprised by all those Fet's BMS everywhere.
On cheap batteries, on costly batteries, on big batteries, everywhere. I still stick to contactor BMS for my build, but I'm always surprised to see everyone happy and suggest Fet BMS.
From what I know every car OEM use contactor BMS in EV and I can't believe car OEM will start to use Fet BMS for their vehicle soon
Do you have other experiment?

 

[electric]

Do you have other experiment?

I plan to build a similar home battery to yours, 51V 1320AH, 67kWh, so I can be completely energy independent, using solar/battery to power my home and 2 EVs. But first I need to build the home where this system will go into.

 

[Ampster]

We go way back from early days of DIY EV forum, I'm the miniBMS guy if you remember

And I remember the photo of Yabert;s Smart Car conversion doing wheelies from that forum. I did a VW conversion in 2012 and learned a lot from that forum.

 

[yabert]

I plan to build a similar home battery to yours, 51V 1320AH, 67kWh, so I can be completely energy independent, using solar/battery to power my home and 2 EVs. But first I need to build the home where this system will go into.

Awesome! Build a efficient home completely energy independent is a dream.
When I asked do you have other experiment, I would mean, based on your experiment of BMS designer/seller, do you have any comment about Fet BMS vs contactor BMS?

 

[AntronX]

We got diyelectriccar.com reunion over here. Member since 2009. Never did my own EV conversion because I bought Nissan Leaf. Did buy 7 Tesla Model S modules in 2015 to convert my gas car. Using them for offgrid solar now.

 

[electric]

do you have any comment about Fet BMS vs contactor BMS?

Every decision is a trade-off, sometimes FETs work well, but in larger, more powerful systems contactor is simpler, cheaper and arguably more reliable, depending on application needs. Since those old days of DIY EV I have evolved BMS designs to pass strict UL safety and reliability testing, where redundancy and fail safe modes are required to pass the UL tests. I have 12V 4kWh batteries with FET based BMS in my RV, but a 67kWh 51V battery will definitely use a contactor based BMS.

 

[yabert]

That it for the 3D model. I decided 35 kWh will be enough for me.
You can see the 3 modules 11.7 kWh each. They will be fix with the 3 green channels in the rear.
Modules and channels will be fix together with M6 screws. The purple parts will have M6 nut weld on it and will be slide in the cooling openings of the cooling plate.
I just receive my 120$ quote for those steel and aluminum laser cut parts ?
Not too tough on the wallet.

 

[yabert]

I'm still waiting for my 48V inverter (Luxpower 6kW aka EG4 6000XP) so I work slowly on the battery.
I've cut another time three modules in 3 parts to been able to flip the module in center. That manner all the similar polarity are the same side.
So I connect all the busbars and I have now a 51.2V and 684Ah battery.

Next step is to dismantle this assembly, enter each module in the house, reassemble and add the BMS, fuse, cables, cover.

 

[yabert]

The 35 kWh stack of 3 modules is now inside.
Here a good view of the first modules with supports for the two others.
I can't wait to receive my 6 kW inverter to use this battery.

 

[740GLE]

Looks very clean!