Chevy volt battery layout question

2423 Views 47 Replies 10 Participants Last post by Swogm, 2 d ago

Jnbrown3

Discussion Starter · 27 d ago

Hi there,

I have a full Chevy volt pack that has 7 12 cell 48 v 50 ah batteries plus 2 6 cell I assume 24 , 25 ah batteries.

for my lay out I would like to have a 144 volt setup.

please confirm if this is correct:

3 rows of 48v batteries in parallel making it 144 v total

theN each row makes a series. If I buy a few more I can have 3 12 cell batteries plus 1 6 cell battery in series, making one string. I think this would be 175 amps 50 + 50 + 50 + 25 = 175 amps around 21kw
Can someone confirm if this assumption is correct ? Many thanks

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Duncan

· #2 · 27 d ago

OK
You have the same pack I have - I'm being a little bit conservative and going from 3.5v to 4.1 volts per cell

7 off 2kWh modules - each with 12 cells in series - 42v - 49v - and about 42 Ah
2 off 1 kWh modules - each with 6 cells in series - 21v - 25v - and about 42 Ah

3 of your 2kWh modules will give 126v - 147v - still 42 Ah - 6kWh
Two of them in series
Will give 126v - 147v - 84 Ah - 12kWh

Will leave 1 off 2kWh module and 2 off 1kWh modules

Jnbrown3

Discussion Starter · #3 · 27 d ago

Thank you!

- How about your BMS, did you buy an external solution like an Orion? Do you need one for the volt battery?

- for your charger are you using a lithium rated charger, I have a lead battery kind, not sure if I need to replace it.

many thanks for your thoughts on this as well.

yours truly,
JB

Duncan said:
OK
You have the same pack I have - I'm being a little bit conservative and going from 3.5v to 4.1 volts per cell

7 off 2kWh modules - each with 12 cells in series - 42v - 49v - and about 42 Ah
2 off 1 kWh modules - each with 6 cells in series - 21v - 25v - and about 42 Ah

3 of your 2kWh modules will give 126v - 147v - still 42 Ah - 6kWh
Two of them in series
Will give 126v - 147v - 84 Ah - 12kWh

Will leave 1 off 2kWh module and 2 off 1kWh modules

w ab

kennybobby

· #4 · 27 d ago (Edited)

Rows, Series, Parallels--i think you guys have gotten your definitions crossed up.

Placing Modules in series will result in the same current rating but the voltage adds; placing modules in parallel will have the same voltage but the current adds; don't know what a "row" is

Reactions: 2

piotrsko

· #5 · 27 d ago

I think they mean module blocks which tend to be 48 volt nominal with one 24 and one 12 sub modules. In the gen 1 pack there's some modules that are multiples that can be seperated at the module interconnects under the black covers for the bms. 192/196 is a convienent nominal split pack voltage.

Neither Duncan or I run a bms, mainly because back when it was black magic voodoo and BMS was short hand for battery murder systems. Last I looked, after ten years, I was pretty much still in balance

Jnbrown3

Discussion Starter · #6 · 27 d ago

piotrsko said:
I think they mean module blocks which tend to be 48 volt nominal with one 24 and one 12 sub modules. In the gen 1 pack there's some modules that are multiples that can be seperated at the module interconnects under the black covers for the bms. 192/196 is a convienent nominal split pack voltage.

Neither Duncan or I run a bms, mainly because back when it was black magic voodoo and BMS was short hand for battery murder systems. Last I looked, after ten years, I was pretty much still in balance

Thank you,

piotrsko said:
I think they mean module blocks which tend to be 48 volt nominal with one 24 and one 12 sub modules. In the gen 1 pack there's some modules that are multiples that can be seperated at the module interconnects under the black covers for the bms. 192/196 is a convienent nominal split pack voltage.

Neither Duncan or I run a bms, mainly because back when it was black magic voodoo and BMS was short hand for battery murder systems. Last I looked, after ten years, I was pretty much still in balance

thank you! I think I will start with no BMS just to get the project going and then look into it further.

I will send a note this evening with my charger specs, see if it’s safe to use . Great comments!

thank you
Jeff Brown

Duncan

· #7 · 26 d ago

I'm using a cheap and cheerful "BMS"

Electric Vehicle Discussion List - Lee Hart's Batt-Bridge Battery Balance Alarm

www.evdl.org

Dead simple - even I could understand it

You end up with 3 LED's - a green for "on" and two reds for "time to check your batteries"

My Volt cells have been superb - still balanced despite me slightly abusing them

Before I had them I had Headway cells that were nowhere near as good - at one stage I had four "strings" each with its own "Batt Bridge"

remy_martian

· #8 · 26 d ago

You need a lithium charger. Your lead-acid charger is now eBay junk to get rid of.

What vehicle is this for?

What's the motor/gearbox/diff/ DU setup?

AC, Permanent magnet, or brushed motor?

Terrain it operates in, or will be?

How will it be charged?

Mission profile? (competition, commuter, local grocery getter, drag car, etc)

Once we and you have considered all this, THEN you can decide if you need a BMS. The fact that two members got away without one is totally irrelevant.

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Jnbrown3

Discussion Starter · #9 · 26 d ago

remy_martian said:
You need a lithium charger. Your lead-acid charger is now eBay junk to get rid of.

What vehicle is this for?

What's the motor/gearbox/diff/ DU setup?

AC, Permanent magnet, or brushed motor?

Terrain it operates in, or will be?

How will it be charged?

Mission profile? (competition, commuter, local grocery getter, drag car, etc)

Once we and you have considered all this, THEN you can decide if you need a BMS. The fact that two members got away without one is totally irrelevant.

Thanks all for your comments.

solitron jr controller, warp 9 motor , put into a triumph tr6

I have a quick charge scpwx for wet cycle, starting, gel, agm battery. Sounds like you are indicating that I cannot use this on my volt batteries. Any suggestions are appreciated. Thank you

Duncan

· #10 · 26 d ago

Charger
A charger does not know or care about the chemistry
The important part is what the charger DOES

What you need - is a charger that shuts off when it has reached the required voltage

For your setup with 3 off 2kWh modules - 36 cells in series - is to shut off at 4.1 volts - 147 volts - tapering down will give you a wee bit more charge but is not nessesary

What you do NOT want is a Lead Acid "equalising charge"

With Lead acid a 12v battery is charged to 14 volts - a charger intended to charge 12 off 12v lead acid batteries will charge to 168 volts -
which would be 4.7 volts per cell with your Chevy modules - NOT GOOD

If you can set your charger to shut down at 147 volts then you should be OK

Before I got a decent charger I used to use a - JLD 404 meter -

store.evtv.me

JLD 404 Intelligent AH Meter

Intelligent Ampere Hour Meter displays volts, amperes, amp hours, and time. Used to monitor state of charge of LiFePo4 cells. BLUE or RED LED

store.evtv.me

I just set the meter to operate a relay to shut the charger off at the required voltage

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remy_martian

· #11 · 26 d ago

Lithium batteries are supposed to be charged at constant current, tapered down, then charged at constant voltage if you want to get your 2000 cycles out of it.

I like to do my battery costing as $/2000. So a Tesla pack will set you back $7.50 per charge cycle when charged properly.

Now, cowboy (does New Zealand have more than the one cowboy? 😂) charge it to get 200 max charge cycles (I pulled the number out of what I sit on, but it's probably within 2x either way, if I had to guess), enough to do track days and for a retiree-engineer to visit his mistress now and then. $75 per charge cycle. Same as a tank of gasoline, so why bother? But it is less than racing fuel...

Duncan

· #12 · 26 d ago

Hi Remy-Martian

If you look at what the battery actually sees when you are charging - it sees a steady away current that then drops slowly

If you want to get the maximum possible charge in your battery THEN you do as you suggest and keep on adding little by little

If you stop charging before that then you don't get quite as much charge into your battery - but it won't effect the battery life

In practice with a modern proper EV most people don't actually charge it right up anyway - 80% is the number most people use

My battery cost less than $2000 - so if I get 1000 cycles that is only $2 per cycle - electricity is $4 per fill
My Subaru cost me $150 per fill !! - it does go 10 times as far !

Jnbrown3

Discussion Starter · #13 · 26 d ago

Thank you for

Duncan said:
Hi Remy-Martian

If you look at what the battery actually sees when you are charging - it sees a steady away current that then drops slowly

If you want to get the maximum possible charge in your battery THEN you do as you suggest and keep on adding little by little

If you stop charging before that then you don't get quite as much charge into your battery - but it won't effect the battery life

In practice with a modern proper EV most people don't actually charge it right up anyway - 80% is the number most people use

My battery cost less than $2000 - so if I get 1000 cycles that is only $2 per cycle - electricity is $4 per fill
My Subaru cost me $150 per fill !! - it does go 10 times as far !

the d

Duncan said:
Hi Remy-Martian

If you look at what the battery actually sees when you are charging - it sees a steady away current that then drops slowly

If you want to get the maximum possible charge in your battery THEN you do as you suggest and keep on adding little by little

If you stop charging before that then you don't get quite as much charge into your battery - but it won't effect the battery life

In practice with a modern proper EV most people don't actually charge it right up anyway - 80% is the number most people use

My battery cost less than $2000 - so if I get 1000 cycles that is only $2 per cycle - electricity is $4 per fill
My Subaru cost me $150 per fill !! - it does go 10 times as far !

Thanks again for the detailed comments, I am certain that this charger is rated to go over 144v. Tonight I will read the specs, and share them here. These are really good comments, I appreciate the time.

Functional Artist

· #14 · 26 d ago

Here is an excerpt from my Mini-Jeep build thread

"All BMS'a are Battery Monitoring Systems
...& they all connected to (each cell)
...& monitor each cell, individually

There are (2) main types of BMS's
...Passive (Battery Monitoring System)
...Active (Battery Managment System)

A Passive BMS is just a monitoring system
...that "passes" the information to the user
...& the user must make the decisions
...& then, "act" upon them decisions (if & when, necessary)

An Active BMS monitors the pack
...but also, has the ability to "act"
...& "switch" things "On &/or Off (if & when, it deems it necessary)

Like:
Under-Voltage protection (Low Voltage cut-off)
Over-Voltage Protection (High Voltage cut-off)
Over Current Protection (High Amp draw cut-off)
Temperature Protection (High or low temp cut-off)
Balance Protection (Individual Cell Balancing)

So, whether to use a BMS is not the question
IMO if your using a Lithium battery you should monitor it (at the very least)

The question is, does the specific battery pack being used, need (or would it be best to use) an Active BMS or a Passive BMS?"

For simple monitoring of my Chevy Volt modules, I have used (2) volt meters

...& I have also used individual cell checkers

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brian_

· #15 · 26 d ago

Jnbrown3 said:
I have a full Chevy volt pack that has 7 12 cell 48 v 50 ah batteries plus 2 6 cell...

That's the first-generation Volt battery, just to clarify for anyone comparing to their Volt battery configuration.

Jnbrown3 said:
3 rows of 48v batteries in parallel making it 144 v total

theN each row makes a series. If I buy a few more I can have 3 12 cell batteries plus 1 6 cell battery in series, making one string. I think this would be 175 amps 50 + 50 + 50 + 25 = 175 amps around 21kw
Can someone confirm if this assumption is correct ? Many thanks

Maybe you should start again with your description, getting "parallel" and "series" correct. It's not at all clear what you mean in this, and I'm not going to bother sorting it out.

Ocean

· #16 · 25 d ago

I have worked a lot with the Gen1 Volt Packs. The 16kWh pack breaks down into 7 x 12S Modules (2kWh each, 50v at full charge) plus 2 x 6S Modules (1kWh each, 25v at full charge). So you can build an 8th 12S module with the two 6S modules. Thus you finally have 8 x 12S modules, 50V each. You can put 3 of them in series for a 150v String, at the 43Ah rating. You have enough in 1 pack to make two such strings, putting them in parallel you then have a 150v, 86Ah pack - that being 12kWh. You still have 4kWh in two modules which you then cannot use. Each string should be wired with a battery balancer at the least. I ran for a couple years without a balancer, and eventually lost 1 cell in 1 module. that was a mistake because I lost use of that entire string. If you want to utilize the entire pack, you can make 4 x 100V strings, each string having 2x 12S modules in series. You are then running 100V at full charge, with 172Ah pack which will ultimately be much nicer to the batteries. If you buy another pack you could make another set of 150V strings and run them in parallel. I would not recommend combining modules from different packs in the same string unless you know for sure they both have very similar miles on them and definitely wire in the balancer to make sure that string does not get out of balance. Good luck!

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Reactions: 2

Swogm

· #17 · 14 d ago

Ocean said:
I have worked a lot with the Gen1 Volt Packs. The 16kWh pack breaks down into 7 x 12S Modules (2kWh each, 50v at full charge) plus 2 x 6S Modules (1kWh each, 25v at full charge). So you can build an 8th 12S module with the two 6S modules. Thus you finally have 8 x 12S modules, 50V each. You can put 3 of them in series for a 150v String, at the 43Ah rating. You have enough in 1 pack to make two such strings, putting them in parallel you then have a 150v, 86Ah pack - that being 12kWh. You still have 4kWh in two modules which you then cannot use. Each string should be wired with a battery balancer at the least. I ran for a couple years without a balancer, and eventually lost 1 cell in 1 module. that was a mistake because I lost use of that entire string. If you want to utilize the entire pack, you can make 4 x 100V strings, each string having 2x 12S modules in series. You are then running 100V at full charge, with 172Ah pack which will ultimately be much nicer to the batteries. If you buy another pack you could make another set of 150V strings and run them in parallel. I would not recommend combining modules from different packs in the same string unless you know for sure they both have very similar miles on them and definitely wire in the balancer to make sure that string does not get out of balance. Good luck!

I have 4 pack that run With a solotron jr controller for 96v
no bms
tested each cell all at 4v
but when push it hard I hear a beeping sound I’m guessing low pack voltage warning??
my other eve had lg batteries but one expanded
so trying to get this one going
any ideas?
Thx

Duncan

· #18 · 13 d ago

Swogm said:
I have 4 pack that run With a solotron jr controller for 96v
no bms
tested each cell all at 4v
but when push it hard I hear a beeping sound I’m guessing low pack voltage warning??
my other eve had lg batteries but one expanded
so trying to get this one going
any ideas?
Thx

Make a Batt Bridge

Electric Vehicle Discussion List - Lee Hart's Batt-Bridge Battery Balance Alarm

www.evdl.org

That will tell you if you have problems
Fit a cheap and cheerful volt meter
Then re-set the low pack voltage warning on the Soliton to a lower number

I run my Volt cells at between 3.5v (empty) and 4.1v (full)

The voltage under load is NOT really useful - you have to take your foot off the loud pedal and THEN look at the voltage

Swogm

· #19 · 13 d ago

Duncan said:
Make a Batt Bridge

Electric Vehicle Discussion List - Lee Hart's Batt-Bridge Battery Balance Alarm

www.evdl.org

That will tell you if you have problems Fit a cheap and cheerful volt meter Then re-set the low pack voltage warning on the Soliton to a lower number I run my Volt cells at between 3.5v (empty) and 4.1v (full) The voltage under load is NOT really useful - you have to take your foot off the loud pedal and THEN look at the voltage

ok thx have to look into that so 3.5 would be 84v total never had the beep before seemed to just happen the key use to turn on the solatron jr but now have to run wire strait from battery to get steady green light on it for it to work saw a cable that seems to fit into a computer dose solatron jr need special software to see how set up? thank you

remy_martian

· #20 · 13 d ago

Don't know where the 3.5V came from. Seems like you're throwing away a lot of usable SoC.

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