Info on trying to rescue a couple of overly dis-charged 48V 50AH Chevy Volt Lithium Battery Modules

[Functional Artist]

I helped a buddy of mine convert his 48V electric golf cart from Lead Acid batteries to Lithium, last summer, using a couple of Chevy Volt Lithium Modules.

Then, last week he called me "freaking out" because his kid was riding it around
...& overly dis-charged the battery pack. (Reportedly down to ~25V)

Then, the guy, trying to "save" the pack quickly connected the charger (charged back up to ~37V)
...but, within minutes, started hearing "popping" sounds

When he went to inspect, he noticed that the battery modules were expanding (breaking out of their enclosure)
...& immediately unhooked the charger & called me (thinkin' they were going to "blow up")

Here is what it looked like


I've been working with it over the last couple of days (just to see what I may be able to learn from it)

First, I tried slowly recharging it (just 4 cell groups at a time) with a small 12V "trickle charger" (monitoring for any changes in the sight, smells or sounds)
They stared off at ~12.6V
...& it brought them up to ~13.3V (without any issues)
...so, I let it sit overnight to "settle"

Then, the next morning (after not noticing any changes) I connected a 48V 10A Lithium charger (again, monitoring for any changes in the sight, smells or sounds)
...& charged it up to 48V (without any issues)
...& again, let sit to "settle"

That, evening I "clamped" it back together
...using some steel plates & some big 'ol nuts & bolts

Now, ima lettin' it "setttle" for a bit (still, monitoring for any changes in the sight, smells or sounds)
...& then, we'll see what happens


Here is a video of the "clamping procedure"

 

[redflash]

electric go karts are indeed creative.......but not worth the trouble. (my opinion after doing both !)

 

[Snaker]

So, did those batteries have any sort of internal monitoring circuitry for safety: shutdown/circuit breakers?
Or does the vehicle they come with have any of that sort of safety circuitry?

I know even the cordless tool batteries I have will shut off if out of parameters.

 

[Functional Artist]

electric go karts are indeed creative.......but not worth the trouble. (my opinion after doing both !)

Well, I've done both too
...& I'd never go back

IMO it's like getting used to driving a Corvette around for a while
...then, goin' back to your "daily driver" (just not the same)

What size electrical motor were you running?
...& on how big/heavy of a kart?

What size of an engine are you running now?
...& is it on the same kart?

 

[Functional Artist]

So, did those batteries have any sort of internal monitoring circuitry for safety: shutdown/circuit breakers?
Or does the vehicle they come with have any of that sort of safety circuitry?

I know even the cordless tool batteries I have will shut off if out of parameters.

These battery modules are out of a Chevy Volt electric car.
The stock Chevy Volt, BMS (Battery Management System) controls large groups of modules
...&/or the entire 360V pack
...but, it's not usable on just (1) or even (2) 48V modules

So, to re-purpose these modules you got to get kinda creative
& take advantage of/use other components.

The larger (higher end/more expensive) speed controllers have a "programmable" Low Voltage Cut-off
...that (if set properly) will shut the system down, when the batt pack gets down to a certain "preset" voltage.
(If used, this safety measure would have prevented this situation)
&
A "programmable" or pre-set battery charger, set to the proper Top Charge Voltage
...is used to "safely" re-charge these modules

* The guy with this kart just installed a new controller last summer
...but, never bothered to set the parameters
...so, this incident was kinda "self-inflicted"

 

[Functional Artist]

There were (2) modules in my buddy's kart, that got over-discharged & "slightly puffed"

So, I did some exploring
...& took 'er apart

Yup, I mean "all" of the way apart
...right down to the "cellular" level

Here is a video of the dissection

 

[Functional Artist]

I've been thinking of ways I can maybe re-use some of the cells from the 2nd "slightly puffed" module to build a smaller batt pack
...& also, maybe do some "testing" on some of them, too

Like:
I have previously thought about making/testing a 14S batt pack, out of these type cells
...because the 12S modules actually have a (nominal) voltage of 44.4V
...with a top charge of ~50V

Which is kind of "anemic" or "lackadaisical" for a 48V system

FYI: the top charge voltage of (for example) a 48V SLA batt pack is ~54V
...& so, by only using a 50V (top charge) batt pack I'm/your "missing out" on the power (& capacity) of them extra 4V

So, I was thinking that maybe, I could use/try (14) of these cells to create a (14S) 48V ~15AH batt pack
...that would have a top charge voltage of ~58.1V (4.15V x 14 = 58.1V) which would be a HUGE boost, over a ~50V pack or even a 54V pack
...& then, try/test it on one of my karts with a little MY1020 48V 1,000W motor (ie. light load test)

* As far as I understand, these 48V ~50AH modules, are made up of (36) - 3.7V (nom) ~15.5AH cells
...so, when (3) of these cells are connected "in parallel" it creates a 3.7V (nom) ~50AH cell group
...& then, when (12) of these 3.7V (nom) ~50AH cell groups are connected "in series" it creates a (3P12S) 48V ~50AH Chevy Volt Module, like the ones we are working with.

So, by using 14 of these cells, we could create a "hotter" or higher voltage 48V 15AH pack

** The peak Amperage draw of a 48V 1,000W motor is ~30A
...but, I've seen them draw well over 100A (in other "tests")

The average draw is usually ~20A (1,000W/48V=20.83A)
...but, once you're up to speed, they seem to draw a little less (like maybe ~15A)

*** I usually get ~30 min of good "run time" using (4) 12V 12AH SLA's
...so, I'm thinking that I should be able to get a bit more "run time" out of a 48V 15AH Lithium pack

 

[Functional Artist]

I assembled (14) of the Chevy Volt cells into a (14S) 48V 15AH batt pack

I also, installed a 48V 50A circuit breaker (as a re-settable fuse & a main cut-off switch)
...& a volt meter (ta help me keep an eye on what's goin' on "inside")

Here is a video of doin' it

 

[Functional Artist]

While monitoring (very boring) the 14S 48V 15AH (white) battery pack, that I built, I used (14) more of the (36) cells, out of the Chevy Volt module & built another one (blue)

I didn't install a circuit breaker or voltage meter on this one
...just a 40A fuse
...& I'll monitor it (manually) with a MM

 

[Snaker]

So, what's the mystery with these things?
Stories of cars burning up are still pretty common.
But then, the other "incidents" seemed to have come and gone.

The powered skateboards were going up like crazy, then nothing.
Laptops and phones were such a problem that airlines came up with specific prohibitions, then nothing.
Even claims of phones catching on fire in pants pockets.

Are these products simply being improved and dangers being removed, or what?

 

[Functional Artist]

So, what's the mystery with these things?
Stories of cars burning up are still pretty common.
But then, the other "incidents" seemed to have come and gone.

The powered skateboards were going up like crazy, then nothing.
Laptops and phones were such a problem that airlines came up with specific prohibitions, then nothing.
Even claims of phones catching on fire in pants pockets.

Are these products simply being improved and dangers being removed, or what?

I'd say, just like with any newer technology, they had to "work the bugs out"

 

[Functional Artist]

I've been doin' lots of testing on these Chevy Volt cells/modules (& learning)

Here is a comparison video, of some data from the 48V 50AH "slightly puffed" module
...& some data from a "fresh" 48V 50AH module.

* Also, I have made several "test & data" videos (about these Chevy Volt Lithium cells)

They're all on my YouTube channel, if any is interested

 

[Functional Artist]

Over the weekend, I did an Over dis-charge test on (1) of these Chevy Volt Lithium cells. (cell #36)

I dis-charged it down to ~.5V
...then, let it set

Then, I dis-charged it some more, all the way down to ~.09mV
...then, let it sit (overnight)

The next morning, (after recovering to ~2.5V)
...I dis-charged it some more, down to ~.10mV
...then, let it sit, some more

That eve, (after recovering up to ~2.5V again)
...I connected the 5V charger
...& re-charged it up to ~3.8V
..& then, let it sit some more

...
Then, (a couple of hours later) I decided to cut it open...