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Discussion Starter #1
Attached are some photos of some A123 modules that are for sale... the price is good (<140$ / kWh) but the seller can't provide any documentation proving the claim that these are new 11/2017 production or that they aren't factory rejects of some kind...

Does anyone recognize these modules, or know how to decode the label to determine a manufacturing date?
 

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It is true, is it not, that **any** A123 pack will be LFP?
Not quite: while the original A123 Systems of the cylindrical cell era may have produced only LFP cells (in 18650, 26650 and pouch formats), the company died in 2012 and was revived, with the current product line including both LFP and NMC pouch cells (and apparently no cylindricals).
A123 Systems - Cells

On the other hand, the cells provided to GM for the Spark (until 2104) were LFP, and any pre-2013 A123 cells are presumably LFP as well.

The 2014 Spark EV modules shown are 28S 3P, with ~20 Ah 3.3 V (nom) LFP cells. If the mystery modules are composed of the same cells, they would be a 26S 3P configuration. I have only seen one spec for the Spark EV with A123 modules, so presumably these are from (or for) something else.

Since there is no current A123 LFP cell at about 20 Ah (or 58.8 Ah) intended for EV use, it seems unlikely that a 2017 module like this would be built with them... but perhaps they were the last of a product which was recently discontinued. If they are NMC, they would need to be a 23S configuration, but I don't see how any of the currently produced NMC cells could be combined for 58.8 Ah capacity.

No one seems to like to show the bottom of a module. If these are EV modules, they likely have a metallic bottom face for contact with a thermal management plate, which is the system used in the Spark EV and other similar modules without internal plumbing for heat transfer liquid.
 

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And one more question: do you have dimensions (length, width, height) for these modules? Just curious to see if they match anything known, or are compatible with the dimensions of known cells.
 

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I found an eBay seller but much higher price and listed as out of stock.

Being pouches, I guess not easy to reconfigure as nominal 48V (16S).

That's what I'm really trying to get to, strictly LFP only.

20-25Ah would be a decent pack increment to work with,

but if needed to be higher, up to 200Ah would be OK.

1S, 4S or 8S increments good as well.
 

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Discussion Starter #10
And one more question: do you have dimensions (length, width, height) for these modules? Just curious to see if they match anything known, or are compatible with the dimensions of known cells.
I should have attached the datasheet to the original post. This is what the seller provided.
 

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want!

Before ordering, get set up to do a constant-current load test:

Charge to 91V at say 5-10A, maybe hold until trailing amps drop to say 2A, if you're feeling generous.

Start a timer, draw down at say 5.9A constant

How long (X.xx hours) precisely to get to LV cutoff at 77.9V ?

Start recharging immediately, up to say 80-85V for storage.

X's proportion to 10 hours is your % State of Health / residual capacity.

If you want to be hard-nosed, anything under 95%, send 'em back, not NOS as claimed, or otherwise compromised.

And if buying multiples, all should be the same result within 1-2% anyway.
 

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Discussion Starter #13
want!

Before ordering, get set up to do a constant-current load test:

Charge to 91V at say 5-10A, maybe hold until trailing amps drop to say 2A, if you're feeling generous.

Start a timer, draw down at say 5.9A constant

How long (X.xx hours) precisely to get to LV cutoff at 77.9V ?

Start recharging immediately, up to say 80-85V for storage.

X's proportion to 10 hours is your % State of Health / residual capacity.

If you want to be hard-nosed, anything under 95%, send 'em back, not NOS as claimed, or otherwise compromised.

And if buying multiples, all should be the same result within 1-2% anyway.

Thanks for the advice!

The seller has agreed to extend a return policy that if I am dissatisfied in any way, I can return them.

However, I don't have a testing setup built yet. The donor vehicle I am using has a pair of functional 18kw EDN chargers, but these are 360v output and I don't have configuration software for them yet.. do you have a recommendation for a charger that is configurable for the test you propose? should I be searching for an inexpensive EV charger, or a big variable power supply?

For the discharge, I am in the same situation, I don't have a lot of equipment yet. My first thought is a small electric motor & controller throttled based on a ammeter output, but I don't have a 90vdc motor... is there a better solution?
 

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For the discharge, I am in the same situation, I don't have a lot of equipment yet. My first thought is a small electric motor & controller throttled based on a ammeter output, but I don't have a 90vdc motor... is there a better solution?
A motor isn't a useful place to dump energy unless it is driving a load. If you're just throwing the energy away, you want a big resistor (plus of course a controller).
 

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I should have attached the datasheet to the original post. This is what the seller provided.
I suppose that could be composed of the still-current 20 Ah NanoPhosphate cells, although the package dimensions are pretty tight for the 161 mm x 227 mm cell size. The module isn't current, and they don't promote that cell for EVs any more (the current version of the 20 Ah LFP cell is "optimized to balance the power and energy requirements of 12V starter batteries"), but as I suggested earlier it might be a very late example of a recently discontinued module offering. The date on the datasheet is 2013, but it could have been in production for four years.
 

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Discussion Starter #16
For the discharge, I am in the same situation, I don't have a lot of equipment yet. My first thought is a small electric motor & controller throttled based on a ammeter output, but I don't have a 90vdc motor... is there a better solution?
A motor isn't a useful place to dump energy unless it is driving a load. If you're just throwing the energy away, you want a big resistor (plus of course a controller).
I didn't stop to consider that a motor controller could just as easily drive a power resistor. Sounds like a good DC ebike controller and some power resistors is the way to go for discharging.
 

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Being pouches, I guess not easy to reconfigure as nominal 48V (16S).

That's what I'm really trying to get to, strictly LFP only.

20-25Ah would be a decent pack increment to work with,

but if needed to be higher, up to 200Ah would be OK.

1S, 4S or 8S increments good as well.
The datasheet lists "laser welded internal connections", suggesting that you might be guessing correctly about reconfiguration within a module.

What you want is actually a good match to what A123 Systems has made. Currently, though, their LFP 48 V modules are only 6 Ah and 8 Ah (for mild hybrids), and their modules of the style we're discussing are only NMC (although they come in 12S 1P and 4S 3P with 37 Ah cells).
 

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Currently, though, their LFP 48 V modules are only 6 Ah and 8 Ah (for mild hybrids)
Which means 24-32Ah equivalent to 12V, which would be OK.

Never see these come up retail direct to, users though.

> their modules of the style we're discussing are only NMC

Huh? all the modules discussed in this thread so far are LFP afaict.

I have no interest in any other non-lead chemistry personally.
 

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their modules of the style we're discussing are only NMC
Huh? all the modules discussed in this thread so far are LFP afaict.
All of the modules which are built in the style shown in this thread and which are currently offered by A123 Systems are only NMC, as shown on their website. The LFP modules which are the subject of this thread appear to be discontinued products, as are of course the 2014 Spark EV modules (replaced by LG modules like those of the Volt for 2015).
 

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Discussion Starter #20
want!

Before ordering, get set up to do a constant-current load test:

Charge to 91V at say 5-10A, maybe hold until trailing amps drop to say 2A, if you're feeling generous.
How important to the results of this test is the starting charging current? Would I be better off buying an programmable EV charger like the thunderstruck(https://www.thunderstruck-ev.com/tsm2500-and-charge-controller.html) or would a variable supply like this work? https://www.ebay.com/itm/Sorensen-DCR-300-3B-Power-Supply-300vdc-5A-Output-19-Rackmount/303094292589?hash=item4691d3e06d:g:7cQAAOSwgBVciDFE
 
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