I assembled (14) of the Chevy Volt Lithium cells into a 14S 48V ~15AH battery pack
I didn't like a few things about it (especially, the connecting method) ...so, I dismantled it & re-assembled it (using a different mounting/connecting method)
To help keep an eye on, what is going on inside of a Chevy Volt Lithium Battery Module I first made up a simple Balance Monitor that could easily be plugged into the BMS connector on the module
It just had (2) voltage meters that simply showed the voltage of each side of the module
"If" the (2) readings were consonantly close, it indicated that the cells in the module, were pretty well "in balance" ...& "if" they varied much from the norm, it was a "sign" to look into the module further.
To get more accurate & be able to monitor all of the cells, in a Chevy Volt module at once, I wired in a couple of (6) cell, Cell Checkers
They quickly indicate the voltage of every cell
...& also, the total voltage, in each 1/2 of the module
The last video reminded me that the first-generation Chevy Volt Lithium battery packs were actually made up of (7) of the 48V 50AH modules
...& (2) of the 24V 50AH modules
* The 24V modules have (18) of the 3.7V (nom) ~17AH cells, arranged as 6S3P (that's (6) of the (3) cell groups connected together "in series")
...& are rated at 1kWh
They have a safe usable Voltage range of ~18V (~3V per cell) thru ~24.9V (~4.15V per cell)
...& only weigh ~25lbs.
Also, the graphs show some interesting facts:
Lithium-polimer batteries have a mostly "flat" discharge curve
...so, capacity testing is necessary to know how much energy, can be drawn from a pack
...but, the actual amount of energy used (up) can vary a lot, depending on the "draw" (driving style, wind resistance, tracks with elevation changes etc.)
Lithium Ion batteries have a more linear discharge curve
...so, the "rested" voltage (not, while under load) can be/is a good indicator of available pack capacity (at any given time)
What is the difference?
Li-Po batteries, with their flat discharge curve will output steady voltage & current until the battery just about "empty"
...so, they maintain a mostly steady Voltage level, as they are discharged
...& then, the "power" plummets (like it just drops off of a cliff)
Whereas, the Voltage level of these Lithium batteries, with their more linear discharge curve, will steadily decline as the module is depleted or "drained"
...so, their discharge characteristics are a bit more like Lead Acid batteries (where there isn't such a drop off)
The 24V 50AH modules may be of special interest, to the guys running 24V systems
...so, here is a bit more info
Again, a 24V 50AH 6S3P module is
...made up of (18) of the 3.7V (nom) ~17AH cells
...that are arranged with (6) of the (3) cell groups, connected together "in series"
This gives them a safe usable Voltage range of:
...Low ~18V (~3V per cell)
...thru High ~24.9V (~4.15V per cell)
...so, ~7 volts of usable range
These modules are rated ~50AH (so, a discharge rate of ~50A would be considered a 1C discharge)
* For example, if running a 1,000W motor at 24V, the draw should/would be in the ~42V range (higher when accelerating & less while cruising)
...& a ~42V draw would be considered as a less than 1C (draw) on/from this module (within specs)
...& so, (at this rate) the Voltage Drop should be pretty low or manageable
Also, if the module was recharged with a (let's say) 10A charger
...the recharge rate would be considered ~1/5C (well, within specs)
The module, in its original case is ~5" x ~7" x ~10"
...& can be mounted in just about any orientation They have good-n-strong terminals for connecting battery cables
...built in cooling capabilities (probably unnecessary in our application)
...& a cell tap connector (on top) for easily connecting an (automatic) BMS (Battery Management System)
...or (manual) BMS (Battery Monitoring System) or Cell Checkers These modules have been professionally/factory assembled ...are factory rated at 1 kWh (meeting rule book requirements) ...& (actually) only weigh ~20lbs. ...but, the cells themselves should only weigh ~14 1/2 lbs.) (technically-meeting rule book requirements?? IDK??)
This in interesting information. Keep in mind, for using them for Electrathon, there needs to be a sheet published by the manufacture giving the cell weights and Capacity (W-hrs). I am confused that if these are 24 Volt 50 Amp Hour modules, how they can be 1 KiloWatt Hour? 24*50= 1,200?
For some reason, the last three pictures do not load on my computer.
Hey ProEV, I agree ...but, I have been working with & searching for info on these batteries for years ...& we have even discussed the interest/need for a manufacturers data sheet on we DIYELECTRICCAR ...but, I haven't actually seen one
Where would such a thing be found? ...or please "feel free" to help locate & post one
* I know they were made by LG Chem ...& General Motors bought like zillions of these (gen 1) cells/modules, for the Chevy Volts from 2011 - 2015 ...so, now (in 2023) it's kinda old technology & I would think, should be available (somewhere)
** I believe the 50AH designation is what they are commonly referred to on the web
...but, the 1kWh spec, for the 24V modules, is from a factory label, right on the module
...& the 48V modules have a 2kWh spec label
*** When, I first click on this thread, some of the pics don't show for me either
...but, if/when I hit the refresh button, then they appear
