# Questions about chargers & charging a 2kWh section of a Chevrolet Volt battery

#### Functional Artist

Jul 21, 2018
18
Hello all,
I have converted a 1980 Kawasaki 440 LTD motorcycle over to a 8kW brushed DC motor.
Originally I set it up with (4) 12V 35AH SLA batteries. (very heavy & not much capacity)

Now, I am upgrading to a 2kWh section of a Chevy Volt Lithium ion battery. (less weight, more capacity, quicker recharge time)

I have done "tons" of research on this "battery" but, I could use some help on finding an "appropriate" charger.

Here is some info:
These batteries were made (for General Motors) by LG Chemical
The chemistry is Lithium Maganese Oxide (liMg204)
There are (3) pouches per cell & 12 cells in series (3P12S)
The cells are 3.7V (nominal) (x12= 44.4V (nominal))
The "safe" usable voltage range is 3.0V - 4.2V
...but, during my research I have found that, "to be safer" many are using them in the 3.3V - 4.1V per cell or 39,6V - 49.2V

From what I understand, this battery needs a "smart" charger or a charger with the top charge voltage "preset" at ~49V
but, most "48V chargers" have a top charge set at 54.6
Like this:
https://www.ebay.com/itm/48v10A-Cha...attery+charger&_from=R40&rt=nc&LH_TitleDesc=0

Can the top charge be "easily" preset or adjusted on a battery charger?

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,508
3P12S literally means 3 in Parallel, 12 in Series.

Normally, a charger for a pack like this will connect to each end of the battery, and in addition will connect between each set of series elements so it can ensure none get overcharged.

While discharging it can monitor these to indicate when the first series element his the low voltage limit.

Does your battery have 2 large, high current connections and 11 smaller, lower current connections?

#### dave9

Mar 5, 2017
1,181
With multiple parallel series Li-Ion cells in a larger vehicle like this, you'd want a BMS (battery management system) between the charger and cellls, which handles charge balancing and discharge cutoff.

Since I don't own an eBike I don't have much finer detail than that, and suggest you research ebike BMS to find a suitable product and wiring help. There are probably forum topics about this on eBike enthusiast websites.

I would definitely NOT just hook up a generic charger like you linked, directly to the battery pack. That would result in worse battery performance immediately and ultimately wear the battery out much faster.

#### Functional Artist

Jul 21, 2018
18
Yes, this battery pack has (2) large (1/4") terminals & a BMS plug that has (17) connections.
In the BMS plug, it looks like there are (12) "voltage signals" (1 connected to each cell), (3) labeled "low reference" & (2) are battery module temperature signals.

#### Functional Artist

Jul 21, 2018
18
Your exactly right but, don't worry, I am definitely NOT just "hooking up" a generic charger. I just used that charger as a "low cost" example for my question "Can the top charge be easily preset or adjusted?"

Here is a little "background info"
As I said, I have done "tons" of research on lithium batteries. I specifically chose this Chevy Volt battery because they are professionally designed & manufactured. (DIY lithium battery's "scare" me, too many variables (Ohm's, capacities, connections, construction etc.)

The Chevy Volt cells were specifically matched to very close tolerances & the quality control was set at such a very high level (probably due to a zillion dollar contract with General Motors) that they are very stable & maintain their "balance" very well.

During research I came across several DIY'ers (do-it-yourself) that are using this same battery pack to power go karts, golf carts, scooters, motorcycles, boats & some are even "drag racing" but, as for an "affordable/quality" BMS or a "proper" charger the results are scattered.

The "stock" Chevrolet BMS is for the whole pack (370V) & not really "hackable" to be used on individual (45V) sections. There are some "quality" aftermarket BMS's available but, many cost (~$500.00 & up) more than the battery ($400.00) they are protecting does.

Many folks have tried some of the "low cost" options with varying success but, I have read many stories where someone used/relied upon a BMS & it actually "killed" the battery instead of protecting it. The suspected "issues" vary from incompatibility to installation errors to component failure to even the "parasitic draw" of the BMS itself trying to maintain the "balance" of the battery.

So, I'm trying a different approach to using lithium battery's.

Start off with a "high quality" professionally manufactured battery pack

To monitor pack balance
...use (3) digital voltage monitors (1) that monitors the entire pack & (2) others (1) monitoring each 1/2 of the pack

To protect the battery from being "drained" too low
...set the speed controller on the motorcycle for a 39V low voltage cut-off

& to protect the battery from being overcharged
...is why I am interested in adjusting/presetting the "top charge" on a battery charger to ~49V.

#### Bluejets

Oct 5, 2014
6,203
With lithium battery management one must observe and control the individual cells, not the pack as an assembly.
As with all batteries there are good points and bad points and all versions of lithium are no exception. The particular one you have chosen is not the be-all end-all of lithium but simply a different type.
See the battery university site for more details.

Last edited:

#### Functional Artist

Jul 21, 2018
18
Yes, your exactly right, if your going "by the book" observing & controlling the individual cells in a lithium pack is the "proper" procedure.
If a company or factory is producing a product for the public, Yup!, "ya gotta go by the book"

I am adventuring & exploring different ways to potentially "safely" simplify the use of lithium battery's for myself & the Do-it-Yourself world.

This 2kWh (45V 47AH) "Volt" battery costs (~$400.00) ...it would cost ~$1,000.00 to purchase an "aftermarket" 48V 50AH lithium battery
...the materials for making "unsafe/homemade" lithium battery packs + a cheap BMS (under $500.00) So, that's the way many are going "with catastrophic results" ...but, they all say "I had a BMS. (but, their garage is still burnt to the ground) A lot of thought & research has been invested in this theory, NOT "I'm gonna use a "big" lithium battery pack without a BMS...how do I do it?. I was just sharing some of my research + a little personal commentary. #### kellys_eye Jun 25, 2010 5,513 The basic principle behind a BMS is fairly simple - there is no good reason why they should be expensive other than an ability to 'gouge the market whilst the going is good'. People have built their own BMS boards for a for less than$500 but the abundance of cheap Chinese supplies (for now!) tends to put an end to the DIY route.

Of course, if you intend purchasing and using a 'cheap' Chinese system board, you'd do some tests and checks to ensure reliability and quality before putting it to proper use...... wouldn't you?

#### Bluejets

Oct 5, 2014
6,203
Yes, your exactly right, if your going "by the book" observing & controlling the individual cells in a lithium pack is the "proper" procedure.
If a company or factory is producing a product for the public, Yup!, "ya gotta go by the book"

I am adventuring & exploring different ways to potentially "safely" simplify the use of lithium battery's for myself & the Do-it-Yourself world.

Bms units are essential, not an expensive add on as you seem to suggest.
They are not a simple matter and things can and do go wrong even when attemps are made by experienced people.
You may remember the problems encountered by a particular airline using lithium ion cells or the problems that delay the release of dewalt a few years back for almost 2 years.

#### Functional Artist

Jul 21, 2018
18
Under this concept the operator "is" the BMS, aided by thoughtful design
...not some expensive added on component.

I am not an EE (electric expert)
IMO
The (3) most important factors when dealing with lithium batteries is:
1.) under voltage protection - drain them too low they will "die"
2.) balance - when kept "in balance" they perform better, last longer & are safer to charge
3.) over voltage protection - overcharge them = heat, gassing, fire etc.

Under this concept
1.) the under voltage protection is addressed by the "settings" in the speed controller
2.) the balance is addressed by using a "good battery" but, will be monitored (by the operator)
...& periodically balanced "if necessary"
3.) the over voltage protection is "to be" addressed by using a "special" preset battery charger

* Most drills don't have configurable speed controllers, on airplanes at "high altitudes & under pressure/pressurized" is a whole other situation & you didn't mention phones "in back pockets".

I am not looking to argue
I only asked you'all, if you knew, "if the top charge voltage on a battery charger could be easily preset or adjusted.

Here is my (electric) motorcycle (last summer using only 36V SLA's)

#### Bluejets

Oct 5, 2014
6,203
I only asked you'all, if you knew, "if the top charge voltage on a battery charger could be easily preset or adjusted.

Easy for some , not for others,depends on experience.
Bit like asking how long is a piece of string.
Too many variables on way to broad application.

#### Functional Artist

Jul 21, 2018
18

Ok, I bought a Yewi UY600 48V 10A battery charger with the top charge preset to 49V, right from the factory.

But, they messed up & set it up for 220V AC input instead of 110V AC, like it was supposed to be.

"Dear Kevin,
Sorry for the troubles, the chargers are 220v ac input, we made a mistake on input voltage, and caused the problem.
Do you have electronics engineers which can solder the PCB? It is very easy to change the 220vac to 110vac, just solder a jump wire.
I am very sorry for the mistake, we would like to replace but the freight is too high, can you do the changes?"

They sent some "repair" pics

& here is another

Here is the "instructions" they sent me

"The instruction is attached, use 17awb wires to connect the two places, for the NTC points, the green NTC can be removed out."

So, I need to add a jumper wire connecting A & B
…& simply remove the green NTC?
..., just clip it out?
...or is a second jumper needed?

What size wire = 17AWG (American wire gauge?)

#### kellys_eye

Jun 25, 2010
5,513
Bit cheeky of them - I'd be asking for a discount/refund for doing what THEY should be doing.....

Anyway, you can snip out the green NTC. You need to solder two links as they indicate and yes, the wire needs to be 17AWG or greater (which actually means a LOWER number i.e. 16, 14 or 12 etc).

Get someone to do it for you - and get a receipt for whatever \$ you think you should be recompensed for. Send them the bill.

#### Functional Artist

Jul 21, 2018
18
Thanks for the info
I opened both ends of the charger case expecting to just slide the circuit board out.

Not happening, there are things soldered to the board & also glued to the inside of the box.

But, luckily the area where the (2) jumper wires need to go is, easily accessible, right near the edge of the circuit board.

So, I clipped the Lima bean looking thing out
…soldered a ~1" piece of 16g. wire "jumping" (A) & (B) (as per the instruction pic)
…& soldered an identical piece "jumping" the (2) spots where the Lima bean was connected

It seems to work now
…& "No Magic Smoke" was released in the process

I'll let you know how it goes.
Thanks again

#### Sunnysky

Jul 15, 2016
530
The NTC is also called an Inrush Current Limiter ICL. To reduce stress on Caps, I suggest you order a few replacements.

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