# Building (& Testing) Battery Packs, made from Lithium Cells, out of a Chevy Volt



## Functional Artist (Aug 8, 2016)

I have dis-assembled a 12S 48V 50AH Chevy Volt (Gen 1) Lithium battery module.
* This is (1) of the modules that had been over dis-charged, a little bit & ended up "puffed slightly".








So, I figured this was a good opportunity to do some exploring, testing & experimenting.  








Here is a video on the module dis-assembly





** These modules have 36 cells 
...so, I used 28 of them, to build a couple of (14S) battery packs.

Here is a video on building a the (white) (14S) 48V 15AH battery pack 





...& then, I used a different construction & connection method for the second one.

Here is a video on building the (blue) (14S) 48V 15AH battery pack





These "DIY" packs have been sitting for a couple of days (for monitoring)
...& so, we'll be doing some charging & discharging tests (soon)


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## Functional Artist (Aug 8, 2016)

While monitoring these packs, I assembled (3) more, of these 3.7V (nom) cells 
...& connected them together "in series", to create a 12V 15AH battery pack.

* The low voltage limit, of a pack like this, would be ~9V
...& the top charge voltage limit would be ~12.45V
&
The average Lead Acid battery is low (dead) at ~11V
...& fully charged at ~13.3V

So, even if the 3S 12V 15AH lithium pack was drained (& or run down to) 11V it would still have a "safety margin" of ~2V
...& then, when fully charged to 12.45V it would be within (1) volt of the "top charge" of a Lead Acid Battery

Here is an assembly video


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## Functional Artist (Aug 8, 2016)

As for the charging & dis-charging of the DIY lithium battery packs, that I built, I figured that it would be best to start off with the little fella (3S) 12V 15AH 

The 3.7V (nom) cells have been sitting, for a couple of weeks now, at 3.2V 
...& after connecting (3) of them "in series" they registered at 9.6V 

So, to charge it up, I connected a 12V (1.2A) automotive type "trickle charger" 
...& monitored it starting with every 5 min (I wasn't sure just how fast this little battery pack would charge)

The battery pack started off at 9.6V 
...then, when I first connected the charger, it went to 9.7V (at 11:00 pm)
11:05 - 9.8V
11:10 - 10V
11:15 - 10.2V
11:20 - 10.03V
11:30 - 10.5V
11:45 - 10.7V (Well, this is going slow AF)

So, at 12:00 I connected a larger 12V (6A) automotive type battery charger 
...& it went up to 11V
12:15 - 11.2V (the gauge on charger showed a ~5.5A draw)
12:30 - 11.6V (~5A)
12:45 - 11.7V (~5A)
1:00 - 11.9V (~4.5A)
1:15 - 12.1V (~4.25A)
1:30 - 12.3V (~4A)

I figured 12.3V was good enough, for this first charge 
...so I shut the charger off (it dropped to 12V)
1:45 - 11.9V
2:00 - 11.9V

8:00 am the next, morning 11.8V
9:00 - 11.8V
10:00 - 11.8V

...& it stayed at 11.8V for the rest of the day

* I didn't do a video of charging the pack (boring AF)
...but, I did have the camera ready "just in case" anything interesting was to happen.


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## kennybobby (Aug 10, 2012)

Just a question or suggestion,

For a "12V" battery, why not use 4 cells in series, 4s? Then for use in a car the alternator or DCDC converter can charge it without worrying about overvoltage, e.g. 14.4V alternator output


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## floydr (Jun 21, 2021)

14.4V would be 3.6V/cell not much juice left in a 4s 3.7Vnominal/cell Battery @14.4V, less than half the capacity.
7.5Ah @14.4V=108Wh
15Ah @11.1V = 166.5Wh
Later floyd


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> Just a question or suggestion,
> 
> For a "12V" battery, why not use 4 cells in series, 4s? Then for use in a car the alternator or DCDC converter can charge it without worrying about overvoltage, e.g. 14.4V alternator output


Yes, a (4S) pack was my first thought too
...but, I wasn't sure what the max voltage capacity was, for most 12V components. 
...& ~16V just seemed too high

Plus, the low voltage limit of a (4S) pack would be ~12V (for a 12V system?)
...which doesn't leave much of a margin, for error
&
As Floyd mentioned, a lot of the capacity of the pack could not be used.

TBH I didn't even think about the compatibility of charging it with a car's charging system.
...hmmmm

See, that's why I enjoy forums like this
...great "feedback" from likeminded people


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## Functional Artist (Aug 8, 2016)

I did a dis-charge test on the (3S) battery pack





It started off at 11.8V 
...& I dis-charged it down to ~10.5V

Then, the next morning, when I checked, it was setting at 10.8V (a slight increase?)
...& for a day now, it has been constantly sitting at 10.8V


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## Functional Artist (Aug 8, 2016)

Next, I did a dis-charge test on the (14S) 48V 15AH (white) battery pack
It has been sitting at 54.4V for several days now (ever since I charged it up)

So, I mounted it on my ElMoto to test it out & gather some data  

It started off with 54.4V in the pack (or 3.89V per cell)
...& 605 mi. on the "trip meter"

I rode it around "leisurely" for a while
...& ran it down to 44.2V (or 3.16V per cell)

The wH meter showed that I used 350wH 
...& the trip meter showed 611.9 mi. 

* So, I went ~7 miles on this little 15AH pack


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## floydr (Jun 21, 2021)

Very good , now raise the voltage gradually to 57.4V (4.1V) or even 58.1V (4.15V). Let it complete a charge cycle. The voltage probably will drop slower. I would secure the circuit breaker box to the frame or battery box and fabricate some metal quick release hold downs for the battery.  a fully charged 14s 15Ah battery should give over 15 miles. @ 50Wh/mile
What was your average speed? 
_I_ would put a BMS on the Battery But that is me. You become the BMS when you don't use one. I would forget to check sooner or later.
Later floyd


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## kennybobby (Aug 10, 2012)

A "12V" battery made from 4s cells will never be at 16V unless you charge it to 16. Most alternators and DCDC converters don't charge above 14.4 since that is the hydrolysis voltage for lead acid--above that and the H2SO4 boils out.

For an ICE car the starter battery needs to supply the huge starter motor current to get the engine running, then it is immediately recharged from the alternator. A lead acid battery must be kept fully charged all the time or it will lose capacity due to sulfation of the plates.

There is little load on the 12V in an EV, it doesn't need to be big or carry excess capacity such as in lead acid.

i would much rather not have to worry about overcharging a 3s than to be the least bit concerned that i was only using a fraction of the total available capacity of a 4s.

You would need a BMS with a 3s pack, but only a low pack voltage indicator or maybe a "battery bridge" with a 4s.

p.s. How much does el moto weigh with you on it-- about 500 lbs?


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## floydr (Jun 21, 2021)

I personally would never use a 3s 15Ah battery on a permanent installation. but I might use one as a jump starter. Even here I would use a BMS for LVC controlled contactor. LiFePO4 are much better suited for 12V applications.
later floyd


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> A "12V" battery made from 4s cells will never be at 16V unless you charge it to 16. Most alternators and DCDC converters don't charge above 14.4 since that is the hydrolysis voltage for lead acid--above that and the H2SO4 boils out.
> For an ICE car the starter battery needs to supply the huge starter motor current to get the engine running, then it is immediately recharged from the alternator. A lead acid battery must be kept fully charged all the time or it will lose capacity due to sulfation of the plates.
> There is little load on the 12V in an EV, it doesn't need to be big or carry excess capacity such as in lead acid.
> i would much rather not have to worry about overcharging a 3s than to be the least bit concerned that i was only using a fraction of the total available capacity of a 4s.
> ...


As I said, when I was thinking about building this (3S) 12V 15AH battery pack, I was more thinking about the upper voltage limits of 12V components, not if it could be charged by an automotive 12V charging system.

Remember, these cells were (potentially) damaged
...so, this (or these) pack(s) "are" just for experimentation purposes 
...not any permanent type of an installation 

IMO Batt-Bridges SUCK & can't be trusted
* I killed several batteries testing them stupid things 
...& they NEVER worked (consistently or correctly)

** I even reached out to Lee Hart (the inventor/creator) for advice 
...& even went so far as to order & pay for a "premade Batt-Bridge"
...but, he NEVER responded or sent my order

Since, I've been using a couple of (matching) digital voltage meters, to monitor overall module balance, with each connected to half of the battery pack
...they are MUCH more accurate & reliable  





With me on my ElMoto I'd say ~450 - 500 lbs.


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## Functional Artist (Aug 8, 2016)

floydr said:


> Very good , now raise the voltage gradually to 57.4V (4.1V) or even 58.1V (4.15V). Let it complete a charge cycle. The voltage probably will drop slower. I would secure the circuit breaker box to the frame or battery box and fabricate some metal quick release hold downs for the battery.  a fully charged 14s 15Ah battery should give over 15 miles. @ 50Wh/mile
> What was your average speed?
> _I_ would put a BMS on the Battery But that is me. You become the BMS when you don't use one. I would forget to check sooner or later.
> Later floyd


I charged the other (14S) 48V 15AH (blue) battery pack up to 57.6V 
...then, overnight it settled to ~56.5V 
...& stayed consistent at 56.5V for a couple of days

It was still at 56.5V when I mounted it on the bike
...& ran it all of the way down to 42V 

My target "low voltage limit" was 44V
...but, I (being the BMS) decided to shut it down when (with the voltage sag) the meter showed ~42V
...& had to push it home (~5 blocks)
* Them last few Volts seemed to drop really quickly

So, I was mainly just "putting around"
...but, racked up 482Wh on the meter
...& went ~9 miles

* Also, had a bit of an unanticipated component "failure" (incompatibility issue)
...& some interesting "info" at the end


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## kennybobby (Aug 10, 2012)

Functional Artist said:


> ...
> I was more thinking about the upper voltage limits of 12V components
> ...
> With me on my ElMoto I'd say ~450 - 500 lbs.


i was guessing 500 since you measured ~50 Wh/mile in your test ride.

What 12V components are you worried about? Any components on a car would be rated to handle at least 14.4V, e.g. lights, and any control unit that needed precision voltages would have it's own internal power regulation circuits.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> i was guessing 500 since you measured ~50 Wh/mile in your test ride.
> 
> What 12V components are you worried about? Any components on a car would be rated to handle at least 14.4V, e.g. lights, and any control unit that needed precision voltages would have it's own internal power regulation circuits.


It seems like you have in mind a 12V lithium battery for automotive use 
...& to be charged/maintained by its charging system

I guess that I had in mind more of a "stand alone" 12V power supply type lithium battery
...to be monitored & charged by (me) the user

So, IMO a fully charged (3S) 12V 15AH battery
...is/would more useful, than a partially charged (4S) 12V 15AH battery


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## piotrsko (Dec 9, 2007)

Actually an alternator car system can output up to 15.1 volts in very cold weather. Tends to crowbar 3s packs hence the useage of 4S. FA's statement is true if one expects to only get max current or watts the cells are capable of.


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## Functional Artist (Aug 8, 2016)

Functional Artist said:


> I charged the other (14S) 48V 15AH (blue) battery pack up to 57.6V
> ...then, overnight it settled to ~56.5V
> ...& stayed consistent at 56.5V for a couple of days
> 
> ...


So, I drained the (white) 14S 48V 15AH battery pack down to ~42V (with voltage sag)
...& when I stopped the test (meter showed 44V)
After 15 min the meter showed 42.7V
...15 min later 44.9V
...15 min 45.2V
...15 min 45.5V
...15 min 45.8V
The next morning (9:00am) the meter showed 45.8V
...then, at noon it showed 45.9V
...& at 8:00 pm it showed 45.9V
&
I drained this (blue) 14S 48V 15AH batt pack all the way down to ~42V (with voltage sag) 
...& stopped the test (meter showed 44V)

Within 15 min the voltage, in this pack, had risen up to 44.5V
...15 min later 45.3V
...15 min 45.8V
...15 min 46.6V
...15 min 47.4V
...15 min 47.5V
The next morning (9:00am) the meter showed 48.0V
...then, at noon it showed 48.2V
...& ~8:00pm, it showed 48.4V

These (2) packs are basically the same 14S 48V 15AH & built from cells, from the same module
...so, why would the (white) one "recover" ~4V
...& the (blue) one "recover" ~8V

* Also, I don't recall seeing this "recovery" phenomenon with my bigger 12S 48V 50AH modules. 

Was my test "mule" drawing too "much" from these little packs? (only ~20A - 50A during these tests)


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## kennybobby (Aug 10, 2012)

Cell bounce or recovery of voltage after releasing the load is commonly known and reported across the websticle, such as shown here along with temperature rise and bounce-back for two 18650 cells:









His website has a vast amount of valuable information about testing 18650 cells that can apply to pouch cells also:
HJK's website 

All these cells tests started at the same voltage, but you can see how the voltage varies depending upon the load current. Just monitoring the voltage to stop at 3V per cell can occur at different times and capacities, and the amount of bounce back will vary also.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> His website has a vast amount of valuable information about testing 18650 cells that can apply to pouch cells also:


\
There seem to be so many differences (voltage ranges, charge & dis-charge characteristics etc.) in the different Lithium chemistries, that it doesn't seem like a good idea (to me anyways) to "generalize" too much

So, was the "test mule" drawing ~20A - 50A pulling too much or drawing at too high of a rate, from this little 14S 15AH pack?
Because I haven't noticed this "cell bounce or recovery" when I had the larger 50AH modules &/or 100Ah modules on my bike.

* Also, after reading thru some of the other Chevy Volt threads, they discuss using a Celllog8, to monitor the cells & collect data
...but, looking around, it seems like they have been discontinued &/or are out of stock, at most places.

I found some here (~$32.00 ea.) Does this place seem reputable? 
(FF) CELLLOG 8S


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## kennybobby (Aug 10, 2012)

Assuming one pouch cell has a 15Ah Capacity, either from a datasheet, markings on the pouch, results of testing, etc., then a load of "1C" would be 15 Amps. 2C would be 30 Amps and 3C would be 45 Amps.

Also found in cell datasheets will be a rating of the Maximum Allowed Current, sometimes expressed as a C rate, e.g. 3C or 5C, which causes the cell to overheat in a very short time.

Another rating will be the Continuous Current, such as 1C. The cell can operate at this load "all day long" without overheating.

So a 45 Amp load on a single pouch (1p) module is 3C and is more extreme to the cells, than the same load in a 3p module where it would only be a 1C load.

The cell voltage sags more for higher current loads, as seen in the colored lines of the last graph previously posted. The Yellow line is the 30 Amp test and represents 10C for the 2.8 Ah cells. The test was cut short due to excessive temperature rise of the cell under this high load, and you can see the bounce-back of the voltage when the load was released.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> Assuming one pouch cell has a 15Ah Capacity, either from a datasheet, markings on the pouch, results of testing, etc., then a load of "1C" would be 15 Amps. 2C would be 30 Amps and 3C would be 45 Amps.
> 
> Also found in cell datasheets will be a rating of the Maximum Allowed Current, sometimes expressed as a C rate, e.g. 3C or 5C, which causes the cell to overheat in a very short time.
> 
> ...


Thanks for the reply, very informative  

This isn't a data sheet but, Brian posted this info on Chevy Batt packs 
...& has some comparison info, between the Gen 1 & the Gen 2 packs
https://media.gm.com/content/dam/Media/microsites/product/Volt_2016/doc/VOLT_BATTERY.pdf

So, battery cells are rated kinda like speed controllers are
...Continuous Current Rating (all day long rating)
...& Maximum Allowed Current (peak current rating) 
&
So, can the AH rating of a module (or cell) be used as an "indicator" of the Continuous Current Rating?

* It looks like the 8kW motor on my ElMoto draws too much from these little (14S) 48V 15AH packs
...so, maybe I'll test them on one of my karts with a 48V 1,000W motor (~20A cont)
...& see how they do


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## kennybobby (Aug 10, 2012)

The biggest factor to consider for continuous operation (and peak) is the available cooling for the cells.
Thermal limits apply to both driving and charging.

The difference between liquid cooled and air cooled performance would so large that liquid cooled performance metrics could not be extrapolated to an air cooled pack. e.g. the Gen 2 pack information package implies 25 Ah cells with ~8C peak current with the liquid cooled system of the 2016 Volt.

The Gen 1 column does not give a peak current. The usable versus total energy implies 10Ah versus 15Ah cell capacity, and this is also for a liquid cooled pack.

With just air cooling your packs might be considered as built with 10 Ah continuous cells limited to 3C peak discharge for 10 seconds. You might be able to extend your limits with the addition of internal temperature sensors, and determine the safe continuous operating region for your packs.

From another thread, Remy said:


> You can't willy nilly pull 10C or even 3C from a lithium-ion battery without a good liquid cooling solution.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> The biggest factor to consider for continuous operation (and peak) is the available cooling for the cells.
> Thermal limits apply to both driving and charging.
> 
> The difference between liquid cooled and air cooled performance would so large that liquid cooled performance metrics could not be extrapolated to an air cooled pack. e.g. the Gen 2 pack information package implies 25 Ah cells with ~8C peak current with the liquid cooled system of the 2016 Volt.
> ...


Extrapolating "implied" info from what little info we have available  

Isn't cooling a factor only "if" heat is an issue?

I have never ever felt a Chevy Volt module get even slightly warm
or 
These DIY battery packs, that I built, either (& I've been checking them regularly)
...even during the tests when I was drawing too much current from them

Here is a video from a few years ago (gathering data with an Analog Amp meter)
...& climbing the biggest bridge in Toledo 

* I only had (1) 12S 48V 50AH module on the bike at the time
...& so, a ~100A continuous draw, on this 50AH module, would be considered a 2C continuous discharge rate?


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## kennybobby (Aug 10, 2012)

Functional Artist said:


> ...
> Isn't cooling a factor only "if" heat is an issue?
> ...
> 
> ...


Heat is always a factor; temperature sensing is a good thing.

a 100 Amp draw from a 50Ah pack would be a 2C draw; not sure that it would be considered "continuous" by the definition as used by cell manufacturers on their datasheets. Need the sheet to know.


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## Functional Artist (Aug 8, 2016)

Speaking of heat, I've been looking into why & how Lithium batteries can catch on fire 
...& found





In the video Dr. Veronika describes the (3) main ways Lithium batteries can catch on fire
Thermal Abuse (overheat, extreme cold)
Mechanical Abuse (crush, penetration)
Electrical Abuse (over current, over charge, over dis-charge & spontaneous internal short)

She also discusses the life cycle of batteries
First Life (electric cars)
Second Life (golf carts, go karts)
Third Life (stationary energy storage)

* I also, notice she mentioned, misalignment of the separator, due to cell swelling 
...maybe this is why swelled cells can be dangerous. Because "if" the separator in a swelled cell gets too "misaligned" it could cause in internal short (& KABOOM!)


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## remy_martian (Feb 4, 2019)

Second life is EV conversions and offgrid solar storage, imo. We see this repurposing today with crashed cars. Golf carts and go karts can't consume the numbers.

Third life is grid storage. They'll take the 30-50% SoC stuff. Cheap $/kWh is the game here as it has to compete with V2G.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> The biggest factor to consider for continuous operation (and peak) is the available cooling for the cells.
> Thermal limits apply to both driving and charging.
> 
> The difference between liquid cooled and air cooled performance would so large that liquid cooled performance metrics could not be extrapolated to an air cooled pack. e.g. the Gen 2 pack information package implies 25 Ah cells with ~8C peak current with the liquid cooled system of the 2016 Volt.
> ...


I'm not trying to argue (just understand more)  

Are there many "performance" differences between a Chevy Volt (liquid cooled) battery pack 
...& a Nissan Leaf (non-cooled) battery pack? (other than, reports of capacity degradation)

Also, talking about cell/battery pack heat, what about DIY "fast charging"?

This seems to be another trend/goal 
...but, also an open-ended question (IMO)

Do most folks even know the "thermal limits" of the cells, that they are using (& in the way they are using them) 
...&/or "if" their packs can handle fast charging?
&/also
Are these folks even monitoring the cell temperatures? 
...or (if needed) actively cooling their packs, while charging?


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## kennybobby (Aug 10, 2012)

They both use pouch cells and the laef's lack of cooling doesn't seem too smart for longevity. i would guess that a volt pack used without cooling would do about the same as a laef.

DIY is such that some folks understand about vehicles, safety and critical systems, and those are the builds to follow and learn. evtv.me has lots of videos with good nuggets of information on diy conversions too. Study on the OEM EVs and learn how they build em and why, and the pros and cons of certain approaches. The technology used 10 years ago has evolved in some cases.

Most good BMS systems use temperature sensors.

Fast charging depends upon the specs of the cell, see the datasheet for details, but i have only used it when absolutely necessary to get home, i'm not a fan. Teslas can do it because they have a super thermal control system to manage it all, hence they can do supercharging.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> They both use pouch cells and the laef's lack of cooling doesn't seem too smart for longevity. i would guess that a volt pack used without cooling would do about the same as a laef.
> 
> DIY is such that some folks understand about vehicles, safety and critical systems, and those are the builds to follow and learn. evtv.me has lots of videos with good nuggets of information on diy conversions too. Study on the OEM EVs and learn how they build em and why, and the pros and cons of certain approaches. The technology used 10 years ago has evolved in some cases.
> 
> ...


Yes, most folks (on this forum, anyways) know about the Leaf's battery pack "longevity" issues (& why it occurs)
...& "if" the Chevy Volt didn't have a temp control system they would probably have some of the same issues.
...but, I was asking about actual "performance"



kennybobby said:


> The difference between liquid cooled and air cooled performance would so large that liquid cooled performance metrics could not be extrapolated to an air cooled pack.


Hmmm... would a Honda CRX with a Leaf motor (for example) powered by a (thermally controlled) 360V Chevy Volt pack be "exponentially" more powerful than, if it was powered by a comparably sized (but, non-cooled) 360V Nissan Leaf pack?

Here is some info on Leaf's (if anyone's interested)  
Nissan Leaf Gen1/2 Powertrain Overview on MotorReviewer.com


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## remy_martian (Feb 4, 2019)

On a Pikes Peak hillclimb? Absolutely.

You's can try to takes yer chances by pulling 10C continuous out of a cell, cooled or uncooled, but once it reaches the tipping point in temperature, the only way to stop the battery pack thermal runaway is to drive the car into a swimming pool...assuming you didn't build the battery box out plywood or plastic to where you can't make it in time, driving to your backyard. Carry marshmallows and some long sticks so you can have some good memories.

Thermal management is primarily about longevity, though. You can spend $15k on Tesla modules, throw them in a box and pray one weak cell out of several thousand won't light off the pack from excess temperature (there is no place for the heat to go if the cooling loop is not used - there are no airgaps for convective cooling) and use another prayer it'll last more than 500 charge cycles due to temperature cycling range, or you can spend the money & time to do it right to protect your investment and get the >2000 cycles out of it that's possible.

Brag to your ICE friends about $8 for a fillup in your EV, but did you then add $30 per fillup for your battery pack cost because you settled for 500 charge cycles, or do you add $7 because the battery is coddled?

Yup....there's a hidden efficacy cost nobody calculates (arguably, you get 1000 fillups in an ICE, so engine/trans cost adds $18/fillup). Charge cycles. In a $2000 leaf pack..almost disposable. $25,000 Plaid pack?

As far as Volt modules, it's in the middle of the road, imo. But you're also making bets on a supply from a vehicle that hasn't been produced for several years.


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## Functional Artist (Aug 8, 2016)

remy_martian said:


> On a Pikes Peak hillclimb? Absolutely.
> 
> You's can try to takes yer chances by pulling 10C continuous out of a cell, cooled or uncooled, but once it reaches the tipping point in temperature, the only way to stop the battery pack thermal runaway is to drive the car into a swimming pool...assuming you didn't build the battery box out plywood or plastic to where you can't make it in time, driving to your backyard. Carry marshmallows and some long sticks so you can have some good memories.
> 
> ...


So, Nissan Leaf's can't climb Pikes Peak without a swimming pool (& marshmallows) close by? (noted)  

Hmmm...this doesn't make sense, as this would be potentially (extremely) dangerous 
...& lawsuits just waiting to happen

How many reports of Leaf fires, that have been extinguished at the top of hills (because they didn't have time to drive home) have you heard of? 
...or Leaf fires caused by the battery pack? (on flat ground even)

* I've been researching Chevy Volt battery packs for many years 
...& from what I understand GM incorporated the thermal control system for:
1.) (mainly) so that the cars could be sold & used (successfully) in several different climates. 

The cooling system keeps the pack "operating within specified temperature parameters" in warm climates &/or summertime driving
...& the heating system is used for the colder climates &/or winter driving

2.) & for pack longevity, because GM warrantied these batt packs for ~10 years.
...but, NOT because the battery pack could/would overheat & catch fire while climbing a "steep grade"
& (from what I understand)
If &/or when the thermal control system is not needed (at a given time) it doesn't do anything.

** I'm not "making bets" on an outdated supply, I'm just researching & trying to learn more
...& I don't think LG Chem or Lithium pouch cells, are going away anytime soon.

Don't take this the wrong way
...but, I'm here for & interested in "good/accurate info" 
...not generalities & scary stories


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## kennybobby (Aug 10, 2012)

This is not knocking you personally or the wrong way, but you posted a very scary story in your other thread about the golf cart that could have ended much differently. Probably i wasn't the only one scared shifless about it.

What if the owners had not freaked out and stopped charging when they heard popping sounds while charging. Imagine if they had just put it on charge and left to do something else, expecting to return later--it very likely would have blown up and caught fire. Yall got lucky on this one.



> Discussion Starter · #27 · Aug 8, 2022
> 
> I just got more info, the guys kid was running around on the kart
> ...& when he brought it back, the meter showed the pack was @ ~25V
> ...


So hopefully you have learned some lessons the hard way and are now on the right track to learn about all the aspects of using cells for traction motors and their care, feeding and protection.

But the 2 reasons that you listed for the TCS sound more like research from GM sales and marketing literature. You need to step up your game to functional scientist or functional technologist to get to the good accurate info.

For example in a car:
The job of the BMS is to protect the cells and it has voltage and temperature sensor inputs as part of the system, and to be effective this needs to be active. There is never a time when it is not needed.

If a cell(s) start to get too hot or too cold, then the BMS would send info to the Vehicle Controller to request that the TCS take action. If the thermal system can't make sufficient countermeasures, then the BMS will notify the VCU again, and this time it will put the car in "Turtle" mode to limit speed and power. If that still doesn't work to limit the temperature then the VCU will cause the car to shut down. These warnings and scenario can happen for low cell voltage also. And not just driving, but during charging too.

If the car doesn't have a TCS, e.g. Laef, then Turtle happens sooner than in a Volt or Tesla.

The Pikes Peaks Hillclimb is a timed race ~12 miles up a gravel mountain rode driven by race cars as fast as possible.


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## remy_martian (Feb 4, 2019)

Used to be gravel...it's paved now, old timer.

^As KB stated, unlike cowboys like you and your neighbor, the manufacturer programs a BMS to turtle the car when the pack gets hot - it's a pretty popular feature with Turtle Model S owners on racetracks after a lap or two. Things could get harey[sic] pretty fast if they didn't.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> This is not knocking you personally or the wrong way, but you posted a very scary story in your other thread about the golf cart that could have ended much differently. Probably i wasn't the only one scared shifless about it.
> 
> What if the owners had not freaked out and stopped charging when they heard popping sounds while charging. Imagine if they had just put it on charge and left to do something else, expecting to return later--it very likely would have blown up and caught fire. Yall got lucky on this one.
> 
> ...


The "scary story" I posted about was the "true" backstory, to explain why the module(s) were "slightly puffed"
...but, I had nothing to do with the situation except help with the Lead to Lithium conversion (a couple of years ago)
...& 
"If" that guy "would have" done his "due diligence" 
...& programmed the LVC on his new SC, we wouldn't even be discussing this.

Here's another "scary story" (that I had nothing to do with) a local golf cart repair shop had a cart with (2) 48V 50AH (100AH) Chevy Volt modules (with a BMS)
...but, someone left the key/system switched on, over a whole weekend
...& when they came in Monday morning, they found, that the pack had been severely drained 
...& the modules "ballooned" so much that they lifted the seat up. 

I saw them they really looked like balloons.
I was surprised that the vinyl pouches could stretch that much, without bursting

From what I understand, the BMS was only connected to & used for charging (& balancing)
...but, "good thing" that pack had BMS protection  

DIY golf cart conversions & Factory produced electric cars are very different (application, use, requirements)
...kinda like Apples & Oranges
but
* Why are you guys "dancing" around the question?
"would a Honda CRX with a Leaf motor (for example) powered by a (thermally controlled) 360V Chevy Volt pack be "exponentially" more powerful than, if it was powered by a comparably sized (but, non-cooled) 360V Nissan Leaf pack?"
Maybe because the answer is "no"?

At least not "off the line" anyways
...but, maybe "later" when enough heat builds up & then "becomes" a problem 
...& then, your "turtle mode" kicks in

I understand "overall" thermal management in a Lithium battery pack is very important
...but, with a Chevy Volt module (for example) having only (1) temp sensor (at the very end) of a 36 cell module, I don't see how the BMS could possibly tell "if" a cell was getting hotter than its neighbors (seems impossible to me)
&
Now, with many of the "newer" packs/modules opting to forgo "liquid cooling" for their packs (Ford Mach-E & others)
...& just using a "heat sink" Ummm...


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## remy_martian (Feb 4, 2019)

The "liquid cooling" is actually worse than the "heat sink". Look at the charging rates of a Volt and of a Mach-E...

A lot of engineering goes into making the solution cheap AND delivering performance inside the packaging volume.

What does "more powerful" mean?


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## kennybobby (Aug 10, 2012)

Observations, questions, suggestions:

1. The function of a LVC in a SC is not for cell protection--it is not a replacement for a BMS.

2.


> Here's another "scary story" (that I had nothing to do with) a local golf cart repair shop had a cart with (2) 48V 50AH (100AH) Chevy Volt modules (with a BMS)
> ...but, someone left the key/system switched on, over a whole weekend
> ...& when they came in Monday morning, they found, that the pack had been severely drained
> ...& the modules "ballooned" so much that they lifted the seat up.
> ...


So what is the Lesson(s) to be Learned from this story?


3. What is the point of your question about the CRX? i could say yes it will be "exponentially more powerful", but what does that mean if anything? Over a 1/4 drag race, 0-60 times, a 1 hour drive? Do they have the same current rating, what is the kWh of the pack, etc? Obviously it depends upon the details of which none were provided, hence no answers were offered.

4. There is a temperature sensor at each module so the VCU knows the coolant temperature on the inlet and the exit. If a cel or modulel were generating excessive heat then the exit temperature would be out of the expected range and the VCU would throw a DTC and a warning light on the Instrument Panel. All the CELLS are in series so they see the same current and the BMS is monitoring the voltage of each CELL, so the power can be calculated and compared to the temperature tables determined from testing by the OEM. Would more sensors be better? Probably, but it costs more and may be unnecessary based upon the level of development testing.

5. Some of those who would forego a liquid thermal control system are now recalling their cars to replace the battery packs--oops, not ready for prime time it seems. 10 years ago that was okay but not today. 

Old Timer story: i went to Pikes Peak in the late '80s and parked at the bottom and hiked my way up to the top. i could walk on the road between car runs an hop to the side when they came blasting thru. Some people drove their cars up and parked along the side of the road on straights and in corners and hairpin turns; and many of those folks drove home with cracked windows and windshields from the flying catheads. It was the roughest coarsest gravel to be used for a road. i heard that some of it was paved awhile back but not really my thing and haven't kept up with it.


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## Functional Artist (Aug 8, 2016)

remy_martian said:


> The "liquid cooling" is actually worse than the "heat sink". Look at the charging rates of a Volt and of a Mach-E...
> 
> A lot of engineering goes into making the solution cheap AND delivering performance inside the packaging volume.
> 
> What does "more powerful" mean?


Volts were designed & built in the last decade
...now, everyone wants "faster charging" 

More powerful?
KB said, "The difference between liquid cooled and air cooled performance would so large that liquid cooled performance metrics could not be extrapolated to an air cooled pack."

This didn't make sense to me, because from my personal experience & use, I couldn't understand how a 48V 50AH module on my ElMoto could be so much more "powerful" if it was being liquid cooled.

Why?
...because according to the several different Amp meters, that I've tried in it over the years, I've found that it easily draws 100A constant
...& can pull over 300A peak 
...but, it never, ever even gets a little warm

Cowboy?
That was back in the 90's, like when I designed & built my first EV
It was a complete success
...& a total failure 
...but, a great learning experience  








It was motivated by a V8 Chevy starter motor








...& powered by (1) 12V car starter battery


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> Observations, questions, suggestions:
> 
> 1. The function of a LVC in a SC is not for cell protection--it is not a replacement for a BMS.
> 
> ...


I (& probably many others) look up to you guys as Professors
...but, when info is too generalized &/or conflicting 
It's Ummm, kinda confusing

IMO
1.) The LVC is for pack protection (it doesn't have a clue as to what (1) cell is doing)

2.) You can't just rely on a BMS

3.) you said, "The difference between liquid cooled and air cooled performance would so large that liquid cooled performance metrics could not be extrapolated to an air cooled pack."
...but, this didn't make sense to me, because from my personal experience & use, I couldn't understand how a 48V 50AH module on my ElMoto could be so much more "powerful" if it was being liquid cooled.

Why?
...because according to the several different Amp meters, that I've tried in it over the years, I've found that it easily draws 100A constant
...& can pull over 300A peak
...but, it never, ever even gets a little warm 

4.) For example, on the Chevy Volt modules, the temp sensor is located almost at the top of the module
...seems kinda far from away from either the inlet or outlet 
...& so, wouldn't a cell, located at the far end of the module, be able to get pretty warm (maybe even dangerously hot) before the temp sensor even knew about it?

5.) Um...all I can say is R & D (hopefully constant improvements)


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## Functional Artist (Aug 8, 2016)

Functional Artist said:


> From what I understand, the BMS was only connected to & used for charging (& balancing)
> ...but, "good thing" that pack had BMS protection


Why was the BMS connected & used this way? (only providing protection during charging)

Because of the BMS's AMP rating.

The BMS has to be "rated" to be able to "handle & control" the current (amperage) that will be flowing thru it.

For a 48V 50AH module, (I believe, from discussions with KB) a ~10A charging current would be considered ~1/5C
...a ~100A discharging current would be ~2C
...& discharging at ~300A (peak) would be ~6C
but,
A BMS that can handle a 1/5C current 
...& a BMS that can handle a ~2C current (or 6C peak) are very different "components"
...& priced accordingly

For example, a BMS like this one is only ~$20.00 
...but, as you can see it only has a 15A rating (adequate for charging at ~10A but, NOT discharging at ~100A)

High Quality sealed 12S 44.4V BMS 15A 30A with balance water proof | eBay
*High Quality sealed 12S 44.4V BMS 15A with balance waterproof
charging voltage:50.4V
Standard voltage:3.7V
over charge voltage: 4.25V
over load voltage:2.7V
balance active voltage:4.18V *

Whereas (another example) this SimpBMS, rated at ~400A is ~$750.00

This one could easily handle 10A charging & 100A discharging (even 300A peak)
...but, that is ~1 1/2 times, the cost of a 48V 50AH module (~$500.00)

SimpBMS Tesla Battery Management System For Tesla Model S/X Battery Modules | eBay

So, IMO The cost of a fancy BMS, to protect a large investment, like thousands of dollars in battery modules, used to power a whole (high voltage & high amperage) car (driving in traffic & on public roads) can easily be justified 
...but, for small applications, (used mostly in private settings) like go karts & golf carts, it's just not that practical.

If anyone knows of a more cost-effective solution, for protecting a 48V 50AH Lithium battery module, I'm all ears


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## remy_martian (Feb 4, 2019)

This looks like it belongs in a Vincent Price movie 😂


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## Functional Artist (Aug 8, 2016)

remy_martian said:


> This looks like it belongs in a Vincent Price movie 😂
> View attachment 132351


That's some good & accurate info  Thanks for taking the time 

Now, back to our regularly scheduled program

Here is a pic of some of the notes that I've been taking (battery module monitoring data 

The (white) (14S) 48V 15AH module info is on the left
...then, (below) is info on the (3S) 12V 15AH module
...kinda, in the middle is info on the (blue) (14S) 48V 15AH module
...& info for the gray "slightly puffed" (12S) 48V 50AH module, is on the far right

* They seem to be staying pretty steady (voltage wise)


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> Assuming one pouch cell has a 15Ah Capacity, either from a datasheet, markings on the pouch, results of testing, etc., then a load of "1C" would be 15 Amps. 2C would be 30 Amps and 3C would be 45 Amps.
> 
> Also found in cell datasheets will be a rating of the Maximum Allowed Current, sometimes expressed as a C rate, e.g. 3C or 5C, which causes the cell to overheat in a very short time.
> 
> ...


FYI:
Here is where I got most of the info that I've been referring to: 

It's an old thread (2017) where I (we) discus info about the Chevy Volt 2kWh module
...& if & why a BMS is important &/or necessary
2kW Volt battery BMS & charging questions

* Some of the links are kinda outdated
...but, still lots of "good" info


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## Functional Artist (Aug 8, 2016)

remy_martian said:


> This looks like it belongs in a Vincent Price movie 😂
> View attachment 132351


This was my second EV endeavor (~2016)

It ended up being another tragedy 
...but, I was learning 

Enjoy


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## Functional Artist (Aug 8, 2016)

FYI:
Neither of these "contraptions" were my idea (but, the concepts seemed to have potential)

1st
A very, very long time ago, an old guy told me that I could make an electric bicycle with a car starter & battery
...but, I couldn't "see" how I could connect the chain
...& also, balance a big 'ol car battery, on it
...so, that's how the V8 Chevy starter kart came about 

2nd
I bought a Motenergy PM motor off of E-bay & the ad said "Use to make a super fast go kart, No speed controller needed"
...just make/use a simple "Variable Voltage Slide Contactor" (even had a diagram)

So, I did
...& again it "technically" worked
...but, "in the real world" a total disaster

So, I got a Kelly KDZ controller
...& Oh so, much better


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## Functional Artist (Aug 8, 2016)

*Back to our regularly scheduled program*

It's been ~2 weeks since I've done anything with the (2) 14S 48V 15AH modules & 3S 12V 15AH module, that I built
...& even after (2) weeks, they still seem to be maintaining their voltage levels, pretty well. 

So, "if" there was any Dendrite growth, going on (inside of these cells) would it affect the voltage?
... or resistance?
... or both?


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## floydr (Jun 21, 2021)

Functional Artist said:


> So, "if" there was any Dendrite growth, going on (inside of these cells) would it affect the voltage?
> ... or resistance?
> ... or both?


Resistance for sure would be affected. Voltage may be affected in that increased resistance could/would? mean higher self discharge. Looks good from here But I am not an expert having no training in Electrical engineering. Are the cells reasonably balanced under 20-30mV difference?
Later floyd


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## kennybobby (Aug 10, 2012)

deleted


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## floydr (Jun 21, 2021)

The way I test for voltage drop is to charge the cell/pack up to the Voltage i would be using the cell/module at then wait 2 weeks min. to a month. any drop more than .025V a cell would be too much.
14s = .35V 3s = .075V 12s = .3V . A higher resolution DMM would help. I suspect that The reason for increased voltage in pack one has to do with the meter more than an actual voltage increase. I use the same meters and find than just holding the probes slightly different can change the reading.
The 3s pack 20mV
Measure the cell voltages for the higher resolution readings, then add the readings up. changes resolution from 100mV to 10 mV
Later floyd


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> Maybe you could summarize the data?
> 
> Looking at the last two rows shaded with yellow, the delta voltages look like:
> 
> ...


Here is a bit of a "summary of the data"
...& also, I think I may have solved the mystery as to "why the voltage went up in the first module"  





* I'm trying to be consistent with the data 
...but, there are so, so many variables (using different meters, probes, probe pressure, are both comparison cells/modules at the same voltage (SOC) when tested? etc.)

** I'm still learning 
...but, I think I'm doin (a little) better

*** Also, I must say all of this "deep diving" into these Chevy Volt battery modules
...& building "experimental" modules 
...& then, testing them
...& collecting data
...& discussing ALL of this stuff, with you guys, has been such a wonderful adventure!!!


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## kennybobby (Aug 10, 2012)

deleted


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## floydr (Jun 21, 2021)

kennybobby said:


> vent the gas (oxygen)


if it is 100% oxygen it won't burn. Rather it is gases from the electrolyte which are flammable. Diethyl ether based electroytes which give a sweet sickly smell (some say sweet fruity smell) that is characteristic of venting lithium ion cells .


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> Are the cells in your 12V pack still swollen or has the pressure been vented? Can you find or see a relief vent in one of the 5 single cells?
> 
> Your 2 week data seems to indicate that so far there is no direct short internally such as from a dendrite puncture of the internal separator. There is no big drainage happening as far as you can measure.
> 
> ...


Here is a quick video with more (visual) info 
...on "if" there are any cell vents 
...& cell swelling 
...& preparing to build a 16S 60V module





"The stored energy in a full pack is comparable to that in a liter or half gallon of gasoline"

Are you referring to a "full 360V 16kWh Chevy Volt pack"? 
...or just (1) 48V 2kWh module?
...or maybe (1) 3.7V cell?


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> You could test one of your swollen cells for ignition if you can figure how to do it safely--puncture the foil and vent the gas (oxygen). Once water get in from the humidity in the air there can be rapid decomposition of the electrolyte followed by ignition and fire. There is likely somebody already done this and posted a video. i would want to know how bad they might react if trying to reuse these cells. There is still a large unknown element of how a swollen cell will react to charging and discharging.


Um...did he say just "test for ignition"? 😧
...as in like, blowing stuff up? (Oooh, I thought he'd NEVER ask) he he

Actually, I had thought about dissecting a cell 
...so we could see how they are constructed
...but, that doesn't sound like a good idea if: "Once water get in from the humidity in the air there can be rapid decomposition of the electrolyte followed by ignition and fire"

So, "if" were going to do it
...we should probably discuss "how to do it safely"  

I have (3) cells left/available for test purposes.

So, I was thinking maybe 
1.) a dis-charged too low test 
...so, we can actually see what happens when a cell gets dis-charged too low (& maybe see what's too low)
&
2.) a re-charged too high test 
...so, we can actually see what happens when a cell gets re-charged too high (& maybe see what's too high)
& 
3.) maybe a direct short test
...like if someone was to drop something conductive (like a tool) on a module 

Let's do this 
...but, safely


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## kennybobby (Aug 10, 2012)

deleted


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## Functional Artist (Aug 8, 2016)

Found this video on cell puncture

Notice the LG pouch cell module, they puncture, at the very end of the video (looks like maybe a 60V Pacifica module)


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## Functional Artist (Aug 8, 2016)

Here is another video, where they "test" a few different types of Lithium battery chemistries (Li-Pol, LTO, LFP)
...in a few different ways like: overcharge, short circuit, puncture, external fire (ignition)

They show the "timing" of the test
...but, they don't show much more data (voltage, temp etc.)


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## floydr (Jun 21, 2021)

Functional Artist said:


> Here is another video, where they "test" a few different types of Lithium battery chemistries (Li-Pol, LTO, LFP)
> ...in a few different ways like: overcharge, short circuit, puncture, external fire (ignition)
> 
> They show the "timing" of the test
> ...but, they don't show much more data (voltage, temp etc.)


I would like to point out that GWL sells LFP, LTO cells and battery packs exclusively from what I could tell from gwl.eu website.
Later floyd


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## Functional Artist (Aug 8, 2016)

Functional Artist said:


> Here is a quick video with more (visual) info
> ...on "if" there are any cell vents
> ...& cell swelling
> ...& preparing to build a 16S 60V module
> ...


Here is Building a 16S 60V 15AH Lithium battery module (part 2) 
...cell balancing & assembly


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## Functional Artist (Aug 8, 2016)

Look Ma!, "I'm making gadgets" 

They say "necessity" is the mother of invention. 

Well, I needed a small (~5V) battery "charger" (to be able to charge an individual Lithium cell)

So, I cut the "end" off of a cell phone charger 
...& added a couple of Alligator clips
&
Boom! I now have a small (~5V) single cell battery charger 








Next, I needed a small (~5V) battery "dis-charger"

So, I removed the (3) 1.5V batteries from a "free" HF flashlight
...& added a couple of wires with Alligator clips, to the terminals
& 
Boom!, I now have a small (~5V) single cell battery dis-charger.


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## Functional Artist (Aug 8, 2016)

kennybobby said:


> 1,2 & 3 sound like good tests to learn about your cells. You are the fleet leader for these cells so carry on.
> 
> You might want to monitor (measure and record) voltage, current and Temperature while doing these tests.
> 
> Better do some reading on hazards from cell puncture or bursting, search the web.


I've been thinking about how to perform these tests. Over dis-charge, Over charge & Direct Short

I figured that we should start with the Over dis-charge test, first.
I would think that, it should be the least dangerous (of the 3 tests) mainly because there will be less energy in the cell.

So, the first question is:

*Question*:
What happens when a Li-Mag (3.7V nom) pouch cell (out of a Chevy Volt) gets dis-charged below 3V?

*Cell specs:*
Low - 3V per cell
Nom - 3.7V per cell
High - 4.15V per cell

*Hypothesis:*
I think that in-between the (~3V & ~2V) range, the cell will swell up
...& then, in-between the (~2V & ~1V) range, it may even burst, the vinyl pouch
...but, I'm not sure "if" the cell will actually explode or burst into flames.

*Test Subject:*
(1) LG Chem. NMC-LMO Pouch (3.7V nom) pouch cell (out of a Chevy Volt) 
* I don't think it needs to be fully charged (for this test) because it shouldn't change the outcome & save time.

*Position:*
The cell should be placed on a hard surface
...that is fireproof
...& at least 20' from anything flammable.

*Connection:*
Use a 50' extension cord for connecting the dis-charger & monitoring device
* With both components connected on the "safe" end (away from the test subject)

*Data:*
Monitor & record the
...cell voltage
...keep track of the time
...& also, the cell temp (but, don't have a way of doing that, just yet) during this test
...but, not sure if the current reading would be helpful, for this test.

How does this sound?
Am I missing anything?


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## piotrsko (Dec 9, 2007)

I know on low charge levels ( <3v) the cells swell up, but I don't think that's a ventable scenerio, I think it's lithium oxide buildup which could lead to cell shorting and eventual overheat episodes. However, all my hobby lipo s swell up and go inert so far


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## Functional Artist (Aug 8, 2016)

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...


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## kennybobby (Aug 10, 2012)

Where did you get the crazy idea to charge a totally depleted cell and then cut it open? The only time to open a cell is after it has been completely discharged of energy, to reduce the chance of shorting and fire. i don't know what the point of your testing was but it is too scary to watch.

Unsub


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## Functional Artist (Aug 8, 2016)

Well...
there was this guy, on the internet, that told me that these things would swell up
...& could possibly even BLOW UP "if" over-discharged

But, when I tested that "theory" on this specific type of Lithium battery cell (drained all the way down to ~10mV)
...that didn't happen

Then, (the next morning) I dis-charged it again (all the way down to ~10mV again)
...& still nothing happened (NO heat, No swelling & No KABOOM!) nothing.

Contemplating the situation, I was thinking that when "the golf cart guy" originally over-discharged this pack he tried to re-charge it 
...& that's when it started swelling 

So, I figured "lets try that"
...&/so, that's what I did (I adjusted the test, as per the data)
...& STILL nothing happened

So, after NOT getting hardly any kind of reaction what so ever, I went ahead & cut a slit in the pouch
(again, that was NOT the original plan but, I adjusted the test, as per the data)

Because, (again) this guy on the internet told me that just the humidity, in the air, could/would react violently if the cell was to be opened it up.

So, I was like NONE of those other things happened, let's see if this "is" true 
...& STILL NOTHING HAPPENED

I was like WTF?

So, then (whether "you" like it or not) I went ahead & carefully dissected the cell.

So, um...(before you Unsub) can you explain WHY pretty much EVERYTHING you told me that would happen, didn't happen?


----------



## piotrsko (Dec 9, 2007)

Lion versus lifepo4?


----------



## Functional Artist (Aug 8, 2016)

*Silence falls upon the crowd * 

* As I mentioned, I have several of these Chevy Volt Lithium modules powering several of my EV's (yes, go karts & motorcycle)
...so, I wanted to know (for sure) "if & when" these bad things happen to these cells/modules (so, I can "be sure to" avoid them)

But, 

There were, was & still is many, many "generalities" regarding working with & using Lithium batteries
...but, not a lot of "clear & accurate" info on these "specific type of cells/modules" (just a bunch of scary stories & innuendo's)

&

Several of you super smart (I guess, institutionally trained) guys have been warning me, that these Chevy Volt Lithium cells could &/or would swell up 
...& get internally damaged (if over &/or under dis-charged)
...& could even possibly explode (into flames)

So, I set out to "test" these "specific" cells/modules "myself"
...but, the results, that I have been getting/got, have NOT been consistent with what you guys have been telling & warning me, would happen.

As I said, during the test, I drained the cell "really low" (under 1 volt) 
...& then, let it sit, to see (& record) what would happen
...but, nothing happened

So, I drained it "really low" again (under 1 volt)
...& let it sit (again)
...but, (again) nothing happened 

Then, I tried re-charging the cell (just to see what would happen) like (maybe adding energy will make it swell)
...& because, from what I've been told, it shouldn't even take a charge (due to internal damage)
...but, it did take a charge (up to ~3.8V)
...& then, (to my amazement) it even held that charge (3.8V) steady, for several hours

Well, "nothing" has "held true" so far 
...so, I figured lets "cut 'er open" (just to see "what" or "if anything" would happen)
...but, (still) nothing happened 

* So, in conclusion, the Over dis-charge test results were (very) inconclusive 
...& NOTHING that I expected to (or was told would) happened, actually happened 








* Also, attention, to all the "cringers" remember this is a DIY forum 
...& I was NOT playing with anywhere near High Voltage
...or even multiple cells.

I was only testing (1) 3.7V (nom) cell
...that was only charged up, to (3.8V) just about it's (nominal) voltage level (AKA ~1/2 way charged)

But,

What I don't understand is, there are many, many folks on this forum that really "don't have a clue" about all of the "intricacies" of EV's (& the dangers involved)
...but, as long as they are spending $1,000.00 of dollars, you'all are happily advising them
...& helping them "play" with 100's of Volts
...& 100's of Amps
...& huge 20kW, 50kW & even nearly 100 kW battery packs 
...with very little discussion about "the actual dangers" of playing with HV (High Voltage) DC (Direct Current)
...which is way different than household AC (Alternating Current) & has nothing to do with batteries

&/plus 

KB: WOW! just WOW!
you say I'm the "fleet leader of these cells & to carry on" (yes, that is a "quote", whether you deleted it or not)
...but, when I make a "command decision" concerning "my test" you have a COW 
...& then, you go to ALL of the trouble of deleting some of your responses because I "called you out" on them?

That's just plain childish 

* I've been doing "my thing" for many, many years 
...& will continue to do "my thing" for many years to come
...& NEVER, NOT even once, have I thought "Hmmm. I wonder if KB will approve"


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## Functional Artist (Aug 8, 2016)

Over-charge test parameters








...video & results


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## Functional Artist (Aug 8, 2016)

*Direct Short Test*

Q: What happens when a Chevy Volt Lithium battery cell gets directly shorted?

H: The cell should react violently. (swell up?, burst the pouch?, catch fire?)

I figured to "safely" perform the test, I could use a small solenoid (contactor) 
...& a remote switch, to "short" the cell
...but,?

So then, I just used a "jumper wire" (not really safe but, "did it" for the data & remember, it's only a 4V cell)
...& got a "little" fire 
...but, no swelling at all 
...& the cell still held a voltage (almost 4v) even after being shorted, to the point of catching on fire 

* I noticed that the fire seemed to start on
...& be mostly concentrated on the negative (-) terminal
...& even melted (1) side off of the negative (-) alligator clip


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## Functional Artist (Aug 8, 2016)

The (blue) 14S 48V 15AH Lithium Battery pack, that I built, has been sitting (steady) at 56.6V for a couple of weeks (9-23-22 thru 10-11-22)
...so, I mounted it on my Land Speeder kart, to see how it would do powering a small kart, with (2) 48V 1,000W motors. 

The battery seemed to perform well
...but, the balance of the kart was "off" a little bit

This kart was designed to be powered by a (~50lbs.) 12S3P 48V 50AH battery module 
...but, the (blue) 14S 48V 15AH pack only weighs ~15lbs.

My son & his friend helped test it too  





Here it is running around with the Chevy Volt module


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## Functional Artist (Aug 8, 2016)

I've been looking for better equipment, for monitoring & gathering internal battery data
...& the Hobbyking Battery Medic, has been suggested, many times by a few different folks.
...so, I ordered one. (~$15.00)
3 in 1 LCD RC Battery Discharger Balancer for 2-6s Lipo Battery Voltage Meter US | eBay

Here is a video showing what it does  





Yes, it's designed for use with little dinky RC batteries
...but, a 3.7V battery cell "is" a 3.7V battery cell 
...& voltage "is" voltage

* So, we'll see how it does with these Chevy Volt cells/modules


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## floydr (Jun 21, 2021)

For experimenting the Battery monitor should be fine. A 6s1p 15Ah pack is .333kWh so with a 450mA discharge current it is painfully slow to discharge a whole pack. Balancing current is not stated but if 450mA it would be faster than most Cheap BMS's.
A 6s1p pack is about 3 times larger than LIpo battery packs the Battery monitor is designed for. Watch the monitor for heat.
Later floyd


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## Functional Artist (Aug 8, 2016)

While waiting for my "new" test equipment, I mounted the 16S 60V 15AH Lithium battery pack, on my Atom kart 
...& then, went riding around (I mean I did some testing) 

Here is a video, with some conversion info
...& some "shaky" data


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## Functional Artist (Aug 8, 2016)

After watching the video/examining the data a few times, I noticed that the (5) old SLA's (~3-4 years old) were experiencing a "wicked" Voltage Drop of 8V - 10V 
...so, on hard acceleration I was "basically" running with a ~50V battery pack
...but, I must admit, she still "zipped" along nicely  

Whereas,

The 16S 60V 15AH Lithium battery pack (cells from 2014 Chevy Volt) only seemed to experience a ~2V drop in low & med "'gear"
...& maybe a ~4V drop during hard acceleration in high "gear"
...so, still a ~60V battery pack 

I'm still "testing" & working on running the 16S pack down
...so, "more to come"


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## Functional Artist (Aug 8, 2016)

Still riding the kart around (I mean testing) 

The Low Voltage cut-off, built into the speed controller, gradually started reducing the power, once the batt pack reached ~52V
...& then, pretty much shut the system down" when it got to ~51V

I was able to get 657WH (according to the meter) out of this 16S1P 60V 15AH battery pack
...while draining it from ~65V down to ~51V (4.06V - 3.19V per cell)





* I didn't notice, until I started removing the battery pack, that the batt pack looked "odd"  
(it's NOT a good idea to recharge an experimental batt pack, while still in the kart. Just in case) 








So first, I checked all of the cells. 

6:00pm
In the time it took for me to remove the batt pack (5 min) the pack voltage had recovered to 52.15V (from 51.49V) 
...& the individual cell voltages ranged from 3.22V - 3.29V (~.07V difference)

10:00pm 
The pack voltage had risen up to 52.77V
...& the individual cells from 3.32V - 3.37 (~.05V difference)

The pack measured ~9" (like normal) on the positive (+) side of the pack
...but the negative (-) side measured 9 1/2" (NOT normal)

10:00am (the next morning)
The pack voltage has risen up to 53.85V
...& the individual cells were 3.34V - 3.38V (~.04V difference)

But, I don't see any difference visually (good or bad)
...it's still ~9" on the (+) side of the pack
...& ~9 1/2" on the (-) side

** Also, I can't tell if this "is" from swelling, or those cells have simply "shifted" upwards (maybe from bouncing?)
...but, they were pretty "snug" in there (so?)
...& the upper "strap" doesn't seem to be any "tighter" or under any more pressure, than before.


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## Functional Artist (Aug 8, 2016)

I've watched the (game film) videos a few more times (research)
...& noticed that the batt pack started "looking odd" kind of early, in the test
...right after the high gear/high speed (~30MPH) run (in part 1)
but,
The highest Amp draw that I saw was ~34A
...& for these 15AH cells, a ~34A draw should only be ~2C

That was the "peak" draw (for a second here & there) not continuous
...& FMU these Chevy Volt cells should be able to (easily) handle a 2C draw

* Also, I was drawing more amperage out of these same cells, when I "tested" the 14S (white) pack on my ElMoto
...& I didn't notice anything "odd looking" during or after them tests (or during dis-assembly, to build this 16S pack)

So, should I charge it up?
...to see if "it" has any effect? (like, the "raising" on the negative (-) end gets any worse)
&
"If" not then, maybe repeat the "high gear/high speed" portion of the test again 
...& see/record "if" that causes the same "raising" effect (or it gets worse)


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## piotrsko (Dec 9, 2007)

Too many variables and not enough observation points to actively determine the reason it has a raised corner. Does look like it swelled sometime and got stuck. In the last ten years or so people have found they swell when not bolted into the case, AFAIK it is a condition normally part of the battery process. Even @Functional Artist has compressed them (recently) . Measure it precisely, or shove it back into the case, re run test to see if it swells more, it should if unrestrained because oxides always expand more than base metals


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## Functional Artist (Aug 8, 2016)

When I went to take the 16S 60V batt pack apart (to "fix" the raised end) I noticed that the negative (-) end of the pack had already "shrunk" most of the way down, into the housing
...& with a little bit of "persuasion" I was able to get it the rest of the way down. (back to ~9" like original)

* I also, implemented some "corrective measures" by adding a vertical strap, around the pack. 

** I remember, when I dissected the Chevy Volt module 
...& noticed that the last cell, on the negative (-) end was "glued to the end plate 
(maybe this "issue" has "risen" before) 








Then, I took another set of individual cell voltage readings (I've done this several times)
...& they were all (still) pretty consistent (NO RED FLAGS) 

So, I went ahead & re-charged it (constantly monitored visually & with a MM)
...& now, letting it sit or "settle" for a bit (before re-testing)


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## Functional Artist (Aug 8, 2016)

floydr said:


> For experimenting the Battery monitor should be fine. A 6s1p 15Ah pack is .333kWh so with a 450mA discharge current it is painfully slow to discharge a whole pack. Balancing current is not stated but if 450mA it would be faster than most Cheap BMS's.
> A 6s1p pack is about 3 times larger than LIpo battery packs the Battery monitor is designed for. Watch the monitor for heat.
> Later floyd


I got the HobbyKing Battery Medic (battery monitor)
...& some 6S "leads" (JST XH) to connect the individual cells, to the 6S port on the monitor

For my first test, I wired the 6S "lead" to the BMS plug of a Chevy Volt 6S 24V 45AH1kWh battery module








...but, the last cell showed .05 "off" (which doesn't seem right, these cells usually stay pretty well balanced)

* This is a "fresh" module, that hasn't been "abused" 

Here's some additional info, in video form


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## Functional Artist (Aug 8, 2016)

I used the (red) multi meter to double check the voltage readings of the 1kWh 24V 45AH module
...& it said the voltage of the cells, were all much closer. 

Then, I triple checked with the (orange) meter
...& it also showed the voltage of the cells, to be much closer too.


Next, I tried the Battery Medic on another 1kWh 24V 45AH module
...& it also, showed cell # 6 to be "off" or unusually higher than the other cells.

Then, I tried it on the (2) 1kWh 24V 45AH modules that power my Hell-raiser kart
...& it consistently shows cell # 6 to be higher than the others in both modules.

Defective?


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## Functional Artist (Aug 8, 2016)

I've been monitoring the 16S 60V 15AH pack. 

The voltage was 65.7V just after charging 
...& an hour later the voltage had settled (~.5V) to 65.2V. 

The next morning the voltage had settled just a bit more (~.1V) to 65.1V 
...& has been sitting there, nice-n-steady for a couple of days.

I also, have been doing individual cell checks
...& they have been staying pretty dang close








I monitored & recorded the data for a couple more days








So, NOT noticing any RED FLAGS 
(the voltage levels have been staying very consistent & no noticeable swelling or raising) 
I went ahead & mounted it back on the Atom kart, for another test. 









Here is a video "documenting" this test


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## CREWCAB (3 mo ago)

Appreciate all your effort with this. Enjoying this thread!


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## Functional Artist (Aug 8, 2016)

Hey, where did you get that Atom kart? 

Well, I'm glad you asked


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## Functional Artist (Aug 8, 2016)

CREWCAB said:


> Appreciate all your effort with this. Enjoying this thread!


Thanks! 
I'm learning as I go
...& enjoying the adventure  

This stuff is so fascinating 
...but, also extremely dangerous (that's why I've only been working with Low Voltage modules & systems)

IMO almost all info about battery characteristics & voltage & amperage & even the danger level, is "scalable"
...so, what "we" are learning from these Low Voltage tests (somewhat) applies to the Higher Voltage systems too

Thanks for following along
...& I'm glad you (& hopefully others) are enjoying my adventures


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## Functional Artist (Aug 8, 2016)

*Test recap:*
The 16S 60V 15AH battery pack seems to be holding up pretty well, since the last test.
No noticeable raising or swelling

During the test, I ran the pack down to ~51.5V 
An hour after the test the pack had recovered to ~53.5V
...then, the next morning recovered to ~54.5V
...& has been sitting nice-n-steady ~54.5V (since)

According to the meter I used ~664Wh

Doing the math: 
The 36 cell module, that these cells came from, was listed as 2,000Wh 
...& 2,000Wh/36 cells = 55.56 Wh per cell
...& 55.56Wh x 16 cells = 888.96 Wh pack

So, (it looks like) we had a couple of hundred Wh still left in the pack (quite a sizable Safety Margin)  

Next, it seems like most of the "energy" is available &/or released "in" the "top" or upper voltage range.

Because going from 0Wh -~400Wh, was going from (fully charged) ~65V down to ~60V 
...but, then, going from 59V down to 51V was only ~264WH
...& the "energy" seemed to "go" or "drain" much quicker (in the voltage range) too

The voltage drop seemed to be in the ~2V - 3V range 
(which seems like a lot, for lithium cells, only under a moderate load)

The Amp draw averaged ~18A 
...& the peak, I saw was ~35A

So, on this 15AH pack the ~18A const draw would be considered ~1C
...& the ~35A peak would be considered ~2C 

Top speed seemed to be pretty consistently ~26MPH while in the 65V down to ~60V range
...then, seemed to steadily reduce as the voltage level went down

The Low Voltage Cut-Off "kicked in" & started reducing the power output at ~52V
...& then, pretty much shut the system down at ~51V

* Also, notice how the voltage meter "can" be used as a "fuel gauge" to let the driver know, how much is left "in the tank" at any "given time", with these type of Lithium cells (anyways)

So, that's what I got out of, watching the video, of this last test (a few times) 
...let me know if you'all noticed anything I didn't


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## Functional Artist (Aug 8, 2016)

Functional Artist said:


> I used the (red) multi meter to double check the voltage readings of the 1kWh 24V 45AH module
> ...& it said the voltage of the cells, were all much closer.
> 
> Then, I triple checked with the (orange) meter
> ...


Yup, the HobbyKing Battery Medic (that I have) seems to be defective 

So, I picked up a couple of Battery Medic "clones" to confirm the results.
*Hehe, a Chinese clone of a Chinese product, I bet the Chinese are really pizz'ed, at themselves 🤣








I'm happy to report that they (both) seem to be more accurate, than the original 

* I really like the ease of just plugging a meter in 
...& knowing "exactly" what's "going on" inside of a module 

I also, made up a "double connector" to be able to connect (2) cell checkers to a 12S 48V batt module 








Here is a video with more info


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## Functional Artist (Aug 8, 2016)

I have been working with & promoting EV's in the go kart "world" for years.  

Here is a question posted by a fellow member, in my HobbyKing Battery Medic thread.

"Should it be assumed those are just for checking in the shop, not while driving? My Magoo eyes would never be able to read those in the glaring sun while they vibrate on the steering wheel or wherever."

My answer,
"Yes, they are mainly for "in shop" use 
...or can even be used for quick checks "in the field" (if an issue is suspected)

Most of the time, you really don't need to "constantly" monitor the pack, at the "cellular level" (unless there is an issue)

It's just that monitoring the individual cells of a battery pack is the best way to know what's "going on" in there
...& it's so much easier to do this, when you can just "plug in" a little meter
...& not have to "pop" the top off the battery pack
...& check each & every cell, one-at-a-time 

The voltage level of "all" the cells, in a pack, should (ideally) be really close
...so, they "all" re-charge & dis-charge evenly

The balance function is to help "even" the voltage levels out (if they "drift")
...& the dis-charge function is for dis-charging a pack down to a "safe" level (like for storage)
The modules I have been working with are a bit "too big" to use those additional functions (probably overheat its wittle wesistors) 
...so, the plan is to just use them for "easy" periodic monitoring."

* Most everything I learn (here & on my own) I try-n-share with others (in my own little way) just a FYI


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## Functional Artist (Aug 8, 2016)

Still playing with my "new" little cell checkers
...enjoying how easy they are to use
...& the additional info they provide 

For comparison, here is the Digital Battery Balance Monitor that I've been using for years. (~$10.00)








It's simply (2) digital voltage meters & a switch, mounted in a box & wired to a Chevy Volt BMS connector

It told me what the voltage level was, in each side of the module. (at the flick of a switch)
...& this info was very helpful because "if" both voltage readings were the same, it gave me a "rough" indication that the module was "in balance" & "should" be safe to use.





The "new" 3 in 1 meter's (~$15.00 ea.) also, show what the voltage level is in each side of a 48V pack 
(same quick indicator of a balanced pack)
...but additionally, they also show what the individual voltage level "is" of each & every cell. 

This pic shows what is going on inside of a used 2014 Chevy Volt battery module
...& even after ~8 years it still seems to be pretty well "balanced" 








Here is some more info (if anyone is interested)


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## remy_martian (Feb 4, 2019)

Measuring open circuit voltage is meaningless - kids do what you are doing here, with potato batteries. 

This is the problem with skipping the fundamentals learned from a massive brain trust of experts, like you consistently seem to skip with your "experiments". By not understanding the fundamentals, you go down rabbit holes.

You need to measure the change in impedance of the cell as you electroplate lithium in the cell(s) at low voltages during charging. 

There IS a change to the cell you are not detecting. Rather than conclude a flawed experimental method, you are incorrectly concluding nothing is happening.


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## Functional Artist (Aug 8, 2016)

You already sent me down both, the Dendrite & the Internal Resistance "holes" 

I've been working, for years, trying to simplify this EV stuff (safely)
...& trying to take the "Voodoo" out of it.

Mainly so, "my uninstutionally untrained self" can understand "it" better
...but also, so I can try & explain "it" to other uninstutionally untrained folks too. (your average DIY'er)

FWIU the simplest way to access the "health" of a battery pack or module is to check the "rested" voltage 
...& then, compare that voltage "reading" with the "rested" voltage reading taken after a couple of hours 
...or the next day 
...or next week etc.

Then, observe the data for things like irregular voltage variations (spikes or dips) 
& also, monitor the self-discharge rate (if there is one)


For a deeper evaluation of the "health" of a battery pack or module, check the "rested" voltage of each individual cell
...& then, compare those voltage "readings" with the "rested" voltage readings, taken after a couple of hours 
...or the next day 
...or next week etc.

Then again, observe the data for things like irregular voltage variations (spikes or dips) 
& also, monitor the self-discharge rate (if there is one)

These "tests" would tell the user "if" there was a potential issue
...& "if so" indicate that they needed to look deeper (like checking the IR or even looking for Dendrite growth)

But, IMO "if" this is the case, the cell or module probably shouldn't be used 


So, my "old" Digital Battery Balance Monitor simply told me "if" the voltage levels of each side of my battery module were the same 
...& "if" they were, it indicated to me that it was safe to charge or dis-charge the module
...& "served me well" for years 

The "new" Cell Checkers also, quickly tell me the voltage levels of each side of my battery module 
...but, takes it a step further & tells me the individual cell voltages too 

* Pretty much the same info that most ($500 - $1,000.00) BMS's monitor 
...& use to indicate "if" a module or pack "is" safe to charge or dis-charge


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## Functional Artist (Aug 8, 2016)

To look at it another way, Chevy Service Techs are instructed to use a MDI 2 Scan Tool to "troubleshoot" individual Chevy Volt modules.

The MDI 2 a "fancy box" (who knows what it costs) with (5) knobs that are used to "cycle" thru the individual cells
...plus, it has the "unique feature" of "requiring" a separate multi meter to be connected, which "actually" measures & displays the individual cell voltages 
As seen in this (very long) video (@ ~47 min mark) 





So, IMO the Cell Checkers seem to "tell" the same info
...they're just a way lower cost "tool" (to obtain or replace)
...& "technically" easier to use


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## remy_martian (Feb 4, 2019)

The cells being checked in that Chevrolet technician procedure were never cycled below voltages where lithium plating occurs. Vehicle logs would indicate such low voltage alarms and flag it as a diagnostic code long before getting to the procedures you cite.

Again, ignore the basics, label them as "institutional" knowledge, and look for validation of flawed assumptions...."confirmation bias."

Fail.


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## Functional Artist (Aug 8, 2016)

In the video, (~49:30) the professor mentions a scan tool that uses Global Diagnostic System software.

Technicians use it (with the battery pack still installed in the car) to read individual cell voltages 
...& help "troubleshoot" the diagnostic codes. 
...& "if" they find a more than (>0.3mV) difference, the technician is to remove the pack from the vehicle, for further review.

Like checking for loose or corroded connections
...& then, use the scan tool (mentioned above) on the individual modules, to check the individual cell voltages. 

Just like a Cell Checker
...just way more expensive 
...& harder to use


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