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Discussion Starter · #1 ·
I am planning a mini Cooper conversion and I was hoping to get a 130 mile range on one charge. I was aiming for a 40kwh battery capacity but this would be very expensive using new lithium batteries. What would be the best way to get a battery pack of that capacity for as little money as possible. I was thinking maybe I could find salvage electric cars at my local junk yard? Used batteries online are still pretty expensive. Any way to Source cheaper lithium batteries?
 

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I was aiming for a 40kwh battery capacity but this would be very expensive using new lithium batteries. What would be the best way to get a battery pack of that capacity for as little money as possible. I was thinking maybe I could find salvage electric cars at my local junk yard?
That seems to be the popular solution... although I think you should check online listings from used part brokers covering a large area, rather than expecting to find something suitable at the nearest location.
 

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I would not bother with scrapped cells these days

unless I had the ability to test capacity before paying

and the price was 30% or less compared to buying new.
 

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Sometimes cheaper to just buy a whole EV secondhand, at high miles they do go cheap, just a few grand.

Deals on decent big matched packs sometimes do come up, but demand currently outstrips supply, so unless you are in a position to test State of Health before paying, very much a crapshoot.

Figure the battery pack should cost maybe half the total vehicle cost / value, under a third would be unrealistic IMO.

Of course cheaping out just to get started can be an option, then once the whole build is complete, be ready to pay full boat for a new pack, maybe will be cheaper then, or give you timee to hunt at leisure for a good deal.

How many kWh you talking?
 

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Discussion Starter · #6 ·
Probably around 40kwh. Would diy 18650 modules be cheaper? I understand that they are time consuming to make but at the moment I have way more time on my hands then money...
 

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Probably not, and way crazy troubleshooting

target voltage?

Figure the range is USD $200-500 per kWh ?

so many variables

Do you need to maximize energy density

that's a very big pack, was it a truck or bus?
 

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yes I think just setting yourself up to be a victim believing that, likely if real, to be QA rejects

and of course that price is per 3.2V unit only

What is your target voltage?

Finally, as much as I love the longevity and safety of LFP, your energy density will be much lower than if you use the 3.6-3.7 LI chemistries with well designed thermal management system.

As I stated, a 40kWh pack just won't fit in such a small vehicle, going with LFP you would need to tow a trailer

or go with a van or pickup truck rather than a Mini.
 

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Hey there,
I did an EV conversion of a 2003 Mini Cooper back in 2014. I had a 15 kilowatt battery pack that I put in the area where the back seats are. I cut the back seat floor out and had a box welded in that held 48 100AH Calb lithium battery packs. That was 350 lb of batteries. You are trying to Triple that so it sounds like you're going to have about a thousand pounds of batteries have you considered that weight in your conversion plan?

Here is a link to my photo album
 

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Discussion Starter · #12 ·
Hi! The energy density of the cells I am looking at seem to be much better than the ones you used. I am looking at the Boston power swing 5300 cells, which have a density of 207Wh/kg, compared to the CALB 100ah 3.2v with a density of 94Wh/kg. I am also thinking of putting as much weight as possible in the engine bay, because that was where a lot of weight was with the ICE. I am planning on putting the lightweight component somewhere inside the car. Thank you soooo much for the photos!!!! I am sure they will be very handy!!!!!
 

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Discussion Starter · #14 ·
Hey there,
I did an EV conversion of a 2003 Mini Cooper back in 2014. I had a 15 kilowatt battery pack that I put in the area where the back seats are. I cut the back seat floor out and had a box welded in that held 48 100AH Calb lithium battery packs. That was 350 lb of batteries. You are trying to Triple that so it sounds like you're going to have about a thousand pounds of batteries have you considered that weight in your conversion plan?

Here is a link to my photo album
How much range are you getting out of 15kwh?
 

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How much range are you getting out of 15kwh?
I was able to get 45-50 miles with the 15kwh rolling on Michelin Primacy tires.
Looking at some data i collected, i averaged 372W/miles mostly commuting on a freeway.
Best was 307 ,worst was 499 (hauling butt for an emergency)
 

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New Lithium cells are a bad combination
Really really expensive AND bloody unreliable

You best bet BY FAR is cells from a crashed production EV

Lots of people have used "New" lithium cells and the failure rate is high - over 5% in the first few month and another 5% in the next year
And they cost a fortune

I'm using Chevy Volt modules - $1800US for 16 kwh
 

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You are over-generalizing, talking about new LI bought based on the price, made by shoddy manufacturers or bought from vendors that pass QA rejects off as Grade A.

Product from top-notch makers bought through reputable channels will not have QA problems like that. Or at least very rarely.

But of course usually lots more expensive than secondhand packs from scrapped cars.

For the latter, you need to be able to test them before paying, or longevity will be a real roll of the dice.

And demand is rising fast in many places, prices charged double or triple compared to a few years ago.
 

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New Lithium cells are a bad combination
Really really expensive AND bloody unreliable
...
Lots of people have used "New" lithium cells and the failure rate is high - over 5% in the first few month and another 5% in the next year
And they cost a fortune
I assume that in this remark you are referring specifically (and only) to new LiFePO4 prismatics, such as those from CALB.
 

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I doubt it, who uses LFP for EV anymore in he west?

Quality grade A CALB bought new via trustworthy channels have less than .001 return rate.

Same or similar for A123 GBS, Winston Thundersky, Sinopoly

CATL must have upped their game supplying Tesla at their China factories
 

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The energy density of the cells I am looking at seem to be much better than the ones you used. I am looking at the Boston power swing 5300 cells, which have a density of 207Wh/kg, compared to the CALB 100ah 3.2v with a density of 94Wh/kg.
Any other lithium-ion cell chemistry will typically have a higher energy density than LFP, and any other cell format will have a higher energy density than prismatics. About 200 Wh/kg is pretty typical of current EV batteries.

Keep in mind that these Boston Power cells are just cells, and packaging them into modules will add weight; when you compare to salvaged modules from EVs, those are already in modules. How do you connect to these cells - ultrasonically weld tabs to each end?
 
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