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Discussion Starter · #1 ·
A friend of mine wants to upgrade his 48V golf cart from lead to lithium & I suggested to get some Chevy Volt modules.

So, looking around I came across a pack from a 2014 Chevy Volt for ~$1,500.00
...but, the donor car had ~104,000 mi. on it

What kind of capacity, would the lithium pack, in a car with this many miles on it have left?

Thinkin' about it/doin' some research, a 2014 Volt is advertised as getting ~38 miles on electric before the gas engine kicks in
...so, 104,000 miles divided by 38 miles would be ~2,736 discharge/charge cycles

I know these lithium packs usually are good for 2,000 - 3,000 discharge/charge cycles
...but, what kinda life would these modules have left?

Then, I've seen other packs advertised as coming from cars with ~60K miles on them (~$2,500.00)
...but, once it's removed from the car, they could be selling you/us whatever they have sitting on the shelf

How could someone know for sure, what their getting?
...or even be able to check anything more than the sitting voltage, with a MM, while @ the "scrap yard" before buying a used pack?
 

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I would never rely on the reported history to guesstimate.

Cap test allowed or walk, unless the price is so low you don't mind risking a very short lifespan, like under 10% of equivalent new price.

Then again many are wealthy, and/or much less risk-averse than me
 

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A friend of mine wants to upgrade his 48V golf cart from lead to lithium & I suggested to get some Chevy Volt modules.

So, looking around I came across a pack from a 2014 Chevy Volt for ~$1,500.00
...but, the donor car had ~104,000 mi. on it

What kind of capacity, would the lithium pack, in a car with this many miles on it have left?

Thinkin' about it/doin' some research, a 2014 Volt is advertised as getting ~38 miles on electric before the gas engine kicks in
...so, 104,000 miles divided by 38 miles would be ~2,736 discharge/charge cycles

I know these lithium packs usually are good for 2,000 - 3,000 discharge/charge cycles
...but, what kinda life would these modules have left?

Then, I've seen other packs advertised as coming from cars with ~60K miles on them (~$2,500.00)
...but, once it's removed from the car, they could be selling you/us whatever they have sitting on the shelf

How could someone know for sure, what their getting?
...or even be able to check anything more than the sitting voltage, with a MM, while @ the "scrap yard" before buying a used pack?
I own a Volt and have spent a lot of time the researching the failure modes of these batteries. My opinion is the general degradation of these packs at 100k miles is very very low and if the car was scrapped due to the drive battery it will almost certainly be a single cell group (1 of 96) or the temperature sensors. Most likely split into 48V packs these would have !5 KWh capacity or better
 

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Discussion Starter · #4 ·
Another buddy, another question,
He has a 36V golf cart needing batteries & wants to upgrade to lithium.
What is the highest voltage that can be applied to a 36V golf cart?
I would say that a 36V set of lead acid batteries should/would top out ~40V (13.5V x 3 = 40.5V)

It looks like a 10S (3.7V) Lithium battery would be about the closest match (4.2V x 10 = 42V)
...but, there's not a lot of "high out put" (50A - 100A) 10S battery packs available

So, I was thinking, would there be any issues with using a 12S (45V 50AH) module out of a Chevy Volt
...but, using a 10S battery charger & only charging it up to ~42V
...so, the voltage range would be ~42V (4.2V per cell) top charge, down to ~33V (3.75V per cell)

Would there be any issues with continuously not fully charging a lithium battery?
 

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No, in fact lithiums are happiest if they are not ever charged to 100%. The battery I bought out of a mercedes B series is nominally something like 36kwh, but they were limited to 28kwh by the car's charger - presumably to increase the lifespan.
 

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It looks like a 10S (3.7V) Lithium battery would be about the closest match (4.2V x 10 = 42V)
...but, there's not a lot of "high out put" (50A - 100A) 10S battery packs available
The Chevrolet Bolt has two sizes of modules, all using the same cells of course so the difference is how many are in series. The larger modules are 10S (eight of them) and the smaller modules are 8S (two of them). That means of the 60 kWh pack each large module is 10/96*60 = 6.25 kWh. The Bolt modules must be capable of over 400 amps (to meet the 150 kW peak motor demand at 360 V).
 

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Ive run a 36v motor on 48v chevy Volt packs for quite some time.
Gasp,even using both a Lester 48v charger and a 36v charger.
The 36v charger wont over charge even if left on for 8 hrs,
however need to make sure the pack is balanced.
the 48v charger needs a shutoff nanny. Ive got mine set to 49.2v

Charging to 3.75v is ok but youre leaving a lot of capacity on the table.
Never run them below 3.4v and they will be happy.
 

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I just purchased another Volt pack and it was at 381.6V
thats 3.975V per cell. This is pretty much what the system is charged to at factory settings.
What this shows is that the factory charge is less than 95% of capacity.
3,75V is around 89%
 

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I just purchased another Volt pack and it was at 381.6V
thats 3.975V per cell. This is pretty much what the system is charged to at factory settings.
Do you mean the EV manufacturer?

Or the data sheet of the cells themselves?

What this shows is that the factory charge is less than 95% of capacity
only measured against a "Full" capacity based on a stop-charge spec that is way too high for good longevity

3,75V is around 89%
Wut? What kind of cap test is that based on?

Do you mean isolated and well rested?

With most li-ion chemistries at 3.6 - 3.7V nominal, that is usually not much above the Ah capacity midpoint

especially if using 3.4V at rest as your "empty".

I realize specific cells can vary a lot

but measurement methodologies IRL vary a lot more.
 

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Please post a link - data sheet or for purchase - to what you mean by that?

unless you just mean functionality built into every source that is properly called a charger?

Thanks
its a lester 48v golf cart charger
the chargers with an OBC(3 wire plug) can be used with a charge controller.
Theres so many different models to choose from. Idea is to use what you already have for your cart.
 

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Do you mean the EV manufacturer?

Or the data sheet of the cells themselves?



only measured against a "Full" capacity based on a stop-charge spec that is way too high for good longevity



Wut? What kind of cap test is that based on?

Do you mean isolated and well rested?

With most li-ion chemistries at 3.6 - 3.7V nominal, that is usually not much above the Ah capacity midpoint

especially if using 3.4V at rest as your "empty".

I realize specific cells can vary a lot

but measurement methodologies IRL vary a lot more.
Yes Chevy Volt Gen 1
 

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I did not ask that?

Also, not talking about golf carts, have had zero exposure to that world.

Please link to at least one "charge controller" that is separate from the charger.

More than one would be great, and indicate which is better and why.

If you have time, thanks!
this one has worked for use with the golf cart chargers
Keep in mind I use it to control a master relay,so as not to put any real load on it.



search for model DVB01,shop for the voltage and price that fits best.

this is also set at 3.4v for low voltage shut off.
 

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yes just use the controller to do pilot duty
Im using a DPST relay and the DVB01 to turn off the main contactor on undervoltage
and turn off the charger when it reaches a set point at charging.
Sorry I wasn't more clear.

Could you please link to the relay/contactor model you control from the DVB01?

How much flowing current at 48V do you think it can abide and still have decent duty cycle lifespan?
 

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Sorry I wasn't more clear.

Could you please link to the relay/contactor model you control from the DVB01?

How much flowing current at 48V do you think it can abide and still have decent duty cycle lifespan?
Its rated at 400A

several sellers of same product
this one offers 3 yr warranty(cross fingers they are even around in 6 months)


Important thing is to stop before changing directions.
this will kill the contacts in no time.
 

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Discussion Starter · #19 ·
I came across a low cost BMS for a 12S 44.4V Chevy Volt module (~$20.00 shipped)
High Quality sealed 12S 44.4V BMS 15A 30A with balance water proof | eBay

Here is more info

Lithium-ion 12s 15a BMS Board/LiFePO4 PCB 15a 38.4v/18650 Li-ion PCM 15a 44.4v
Model: DL12S
common Version : common port for charge/discharge
separate Version : separate port for charge/discharge
We can customize any PCB from 1S to 30S lithium batteries with different current.

1. Overview
DL12S36V15A PCB is used for 12 series 36V LiFePO4 battery pack.
We can design it for various lithium batteries like LiFepo4, LiMn2O4, and Li-polymer etc.
The main functions are: over charge protection, over discharge protection, over current protection, short-circuit protection, temperature protection etc.
According to the customer request we can develop PCM in different sizes and structures.
BMS manufactured by high quality Mos and IC imported . Keep your battery long cycle serivce life time.

2. Advantage
Use top quality (A-level) protective integrated circuit IC, from the solution of Seiko of Japan.
Strong load ability, constant discharge current 15A, use high voltage resistance, low inner
resistance power Mosfet. The heat sink will greatly help cooling.
IC itself has power balancing function. The circuit is simple and reliable.
Typical voltage detection for each cell. So each battery will be prevented over charged or over discharged. Over current and short circuit protection
function is very reliable. Long time short circuit of the load won't affect the PCB and the battery. Temperature protection during charging and discharging.
Extreme low power consumption. The consumption of the whole device is less than 50uA.
PCB use high anti-corrosion, high water resistance, high impedance ESD conformal Coating.

[Hot Item] Lithium-Ion 12s 15A BMS Board/LiFePO4 PCB 15A 38.4V/18650 Li-ion PCM 15A 44.4V

My questions are:
If connected to a 12S Chevy Volt module via the BMS plug can/will the balance function simply "do it's thing"
...or does it only "balance" while/during charging?

Also, I noticed down in the FAQ section

"2.What is the balance function?
The working principle and function are as followings, when your one cell voltage is up to alarm voltage(Li-ion up to 4.18V, Life Po4 up to (3.6V), then the cell Balance starts to work, balance resistance starts discharge with 35ma(when balance discharge starts to work, BMS will starts a little heat up, which is the normal reflection), the cell is in both charging and discharging status, and others which are not reached to alarm voltage(Li-ion 4.18V, Life Po43.6V)are only in charging status, no discharging, when the fast cell voltage is reached to alarm voltage(Li-ion 4.25V, Life Po43.75V)BMS starts off power protection, all the other cells
are all in stop of charging, this process will enable your battery charging in balance current, and your battery voltage are in balance status, but when your cell voltage difference are in a big range, then balance can not be functioning.
well"

So, if I'm understanding this correctly, it doesn't even initiate the balance function until the "alarm voltage" of ~4.18V per cell
...but, my charger is set to only charge these 12S modules up to 49,8V (~4.15V per cell)
...so, it looks like the balance function would never activate (in this situation)
 

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Another buddy, another question,
He has a 36V golf cart needing batteries & wants to upgrade to lithium.
What is the highest voltage that can be applied to a 36V golf cart?
I would say that a 36V set of lead acid batteries should/would top out ~40V (13.5V
We would need to know the controller, some antiques can be WAY overvolted

Next a FLA 36v lead pack can achieve up to slight north of 45volts directly after charging on a dumb charger, this means that even the wimpiest 36v controller can handle at least 45volts plus a small overhead

If you look inside the car you might find a Curtis 1204 36/48 volt controller which can handle a full 60 volt FLA pack (75v max) but your charger will need replacement and you need to note the dcdc model as well.

The motor and other components shouldn’t care about the voltage you choose
 
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