My Li-ion, 2kW, Battery Project

[sgschwend]

Here is a look at my Lithium Ion Battery project. The battery I am going to use is a new Chevy Volt 2kW 48VDC battery. It will deliver about 170-200AH of power.
Battery chemistry: Li NMC, much higher energy density than Li FePO4 batteries.





I will be strapping the twelve series cells to four groups of three series cells making 12VDC. The BMS (battery management system) is setup for the three cells, small board on top. It will control the charge for each series level and also protect the battery from over discharge. ` More details on this later.

Image of the battery top showing the cells strapped in series, I will be cutting three bridges apart and then wiring the four 12V power nodes together.

Cost: battery $550, Cover, BMS and cable extra. More on this latter too.

[truckasaurus]

Looks neat, interested to see how it progresses.

[sgschwend]

With the BMS and a relay I can use the AS power supply/charger and not worry about the charger since the BMS will stop the charge when full charge is met. It will start charging again after a setpoint of lower voltage is reached.

[BoldAdventure]

I can't wait to see the comments on this thread.

Looks like an interesting project. Interesting choice of battery too. True DIY modder here. Good luck.

[alano]

Which BMS will you be using? Are you planning on installing the battery inside your AS? Are there any references for modding this battery that you can share?

Sounds like a great project and potentially very inexpensive. Looking forward to learning more.

[amaier7771]

i will be following your progress on this. Where did you get the design details on this battery? From Chevy?

[Perker]

I am very interested too. May I get permission to contact you?


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[Photobum]

Interesting.....

[BigAl]

I read these type of discussions with interest. The only hesitation I would have with these new type of batteries is the risk of fire that may exist. We have all probably seen the problems with the hover boards or scooter( can't remember exactly what they're called) catching fire. Just wouldn't want that under my bed or under front couch.
I do like the weight to capacity aspect though.
They can't be all bad though;there are lots of them in the new electric cars.
Al

[KJRitchie]

Did you purchase the battery brand new from GM. I wouldn't think they'd sell this part other than to Volt owners under a warranty situation.

Kelvin

[Ohiobrits]

Originally Posted by KJRitchie

Did you purchase the battery brand new from GM. I wouldn't think they'd sell this part other than to Volt owners under a warranty situation.

Kelvin

This is very, very interesting. I'm subscribed.

Looks like these batteries are readily available new and used on eBay.

http://www.ebay.com/itm/Golf-Cart-Li...dVHbeo&vxp=mtr

For the battery illiterate (that would be me) here is a good article on Li battery types including radar charts showing relative ratings for different chemistries including safety.

http://batteryuniversity.com/learn/a...of_lithium_ion

sgschwend, you can't leave us hanging....more info!

[sgschwend]

I will provide full details of this project. I will also test out the performance to see if it really does put out 2kW.

The Chevy Volt has a T shaped layout with 288 cells, I purchase a 12 cell assembly form the guy on E-bay. My recommendation is to hold back and see how this project goes. He provided me with the bare minimum of information, enough to get most of the job done. However, I will eventually figure out the parts that he wants me to purchase from him such as the BMS board and connector. I feel like I have spent more ($100) going with this guy to get all the parts to make a working 12DC system.

To see what a Chevy Volt battery looks like: there are Youtube videos on the battery 288 cells Chevy BMS, not the same as the one I am starting with. BMS are programmed for the number of series cells or the DC voltage the batteries produce.

I did visit with the seller in his garage/shop and he shared about his work and methods for modifying the batteries. His highest volume consumers are golf cart.

So lets get to the next steps:
Summary: Changes the 12 cells in series to 3 cells in series. Three cells will make 12V. There will be four sets that I will wire in parallel.

1) Cut three battery bridges to separate the battery wiring, verify the voltage before I make the cuts. I will do this tomorrow and post a picture. The cutting is done with a rotary cut off wheel, I will show that too.

Next steps will each be expanded on so that other can do this:
2) Wire the four positive together and the four negatives together.

3) Cut clearance as needed in the top cover.

4) Verify wiring with voltmeter.

5) Connect the BMS connector and add the charge interrupter relay.

6) Install in the AS using the standard 12VDC power supply.

Other development: Finding a direct source for the BMS, optional power meter.......?

Yes I am open to sharing or PM messages.

As to the concern with thermal runaway: the main job of the BMS is to protect the battery during charging and discharging. Even laptop computers have had issues with thermal runaway. From what I have read there are two issues that cause this and are avoided by EV (electric vehicle) manufactures: 1)poorly made and low cost batteries, 2) overcharging the battery while under high power input.

[Gsmblue]

Very interesting!

[BoldAdventure]

On exploding batteries, these Li-ion batteries used in the EV community and now being used in RV's are not the same chemistry. EV battery cells are generally tested for on road use, which requires the cell not to catch fire or explode when dropped, over discharged, overcharged, baked, frozen, crushed or pierced with a steel rod. http://www.intertek.com/automotive/e...certification/
http://www.sae.org/standardsdev/vehi...rification.htm