4/12/16

Today I got a battery pack out of a 2011 Chevy Volt with 50,000 miles on it. Let's hope their pack lives up to their 100,000 mile guarantee. It should as the car software is designed never to use the bottom end of the pack's capacity, which keeps it in a very stable voltage range.

I'm going to take the pack apart and rewire the cells into a 148 volt configuration, which I will charge with the PFC-2500 from Elcon. This is a 2.5kW charger so the charge times are going to be abysmal but it's all I can afford right now.

{{EDIT* 4/14/16

Last night I opened up each sub-pack to discover that the cells are spot welded together in sub-sub-packs of 3p12s and 3p6s. There are seven packs of 3p12s and two packs of 3p6s. I can't unweld them so I need to work with a voltage that can be accommodated by these packs. Also, I want to use all of the cells so they age at the same rate and I can reconfigure them later into a 360 volt pack once more. That means my only two options are 90volts or 180volts. I'm using (temporarily) an old Kelly controller that can't handle any more than 178 PEAK voltage so I have to run the 90 volt system until I can go back to the Smart car controller. This will be a slow car. }}

Here are some pictures of the inside of a Chevy Volt battery pack from 2011.

I took all the buss bars off to disconnect the four sub-packs before I went deeper.

The orange cables/plugs that go into the top of the batteries have cell level connectivity. So it should be pretty easy to put my own BMS on these batteries using those plugs!

I'll post more pictures soon of what is under these plastic covers. The battery cells are welded together. That's going to pose problems when I try to take them apart to rewire them.

{{EDIT 4/14/16

Sure enough. There's no way I'm getting those cells apart. Check out these pictures and descriptions of the Chevy Volt battery pack...

Here are the cells. Above are two sub-sub-packs of 36 cells (3p12s) and an 18 cell on the right (3p6s) You can see where they're connected with bus bars.

Check out these sweet spot welds... damn.

These huge bricks are held together with glue, steel bands and 3 foot screws. I wanted to see what the cooling system was like so I started taking this apart down to cell level. As soon as I loosed the 4 bolts that hold the black endplates together coolant started leaking out from every cell. Here's what the 4 bolts look like.

Here you can see the four bolts coming off to the left and you can see that all of the cells in the module are spreading apart and spilling coolant on the floor. More detail below.

Each cell has little o ring gaskets to seal the coolant inside.

After letting the cells separate I had to use a ratchet strap to pull the module back together before I could get the bolts back in.

Here are the three packs as they come off of the T-shaped metal plate. I don't have a picture of the hardware that holts them in place. It is a bar on each on at the base that bolts down and clams these plastic cell housings to the metal plate.

Now I'm stuck with the task of figuring out where these modules can fit in my car... woof. The biggest one is 33.5 inches long. My trunk could hold that one I guess. The next larges is nearly that long with the coolant pipes coming off each end. I think I can fit that under the hood above the motor. The small pack will just go in the passenger's lap.