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Old 05-28-16, 09:12 AM   #1
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Default Chevy Volt battery pack for off grid solar?

Yikes. I have the opportunity to buy a 2014 Chevy Volt battery pack for 1500 CAN.

Background:
As my FLA is dying (5 years of crappy performance was enough for me anyway) I thought. Gee. Why not go from 2kw of usable storage to 12!

So I looked at lifepo4. Easy to install into my current system. But $$$.

Now I have this chance to buy a Volt battery. The $/w is pretty good. You know. <$100/kw.

But I'm a writer. Not an engineer. My solar build (cough cough) has been a 5 year lesson in electronics. And I've learned a lot.

However. To retrofit a volt battery pack for off grid use ... I mean it sounds like fun. My FLA will easily last until Oct. Before the cloudy weather gets here. So I do have 4 months for the build. Still ...

Idea 1:
Take the pack apart and repurpose the cells at 48v.
Involves buying a 48v inverter. REC? bms.
Within my limited knowledge/skill set.

Idea 2:
Find a way to charge from AC. Keeping the charger and plug from the Volt. Involves finding an inverter for my solar panels (sunny boy?). Would work with my genny if bad stuff happens. Not sure at all about how the charger/wiring would work without all the brake regen etc. Could well be above my electronics ability (cough, seem to be catching a cold).

Ideas from 3:
Well. That's up to you'ze all.

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Old 05-29-16, 01:47 PM   #2
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At that price, I would go for it. The majority of your time will be spent disassembling buss connectors and testing cell banks. All this is DC - and safe.

There are a lot of people that are here on this site that can help you no matter what the direction you go.

Sounds like a FUN project and I think you are getting over your cold . . . .

No matter what, you are going to need a large multi kW inverter to convert that stored DC to 240 V, 60 Hz AC. But these are getting downright cheap.

I sure like the flexibility of using the already existing 240 V Chevy charging system already on board. In that case, little disassembly is required.

What do you know about this battery pack - was the Volt accident totaled and someone is parting it out?

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Old 05-29-16, 05:37 PM   #3
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That's a lot of juice.
48v option would work best I think, but how do you balance cells?
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Old 05-30-16, 04:51 PM   #4
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Well. I'm still in the fingers crossed stage. To be uncrossed the moment the pack is on the floor of my shop, top is off and I'm testing cells.

What I see right now looks good.

The plan:

Pull the 48v packs out and sell the two 24s. And maybe 2 of the 48s.

Say I keep 6 48s. That's 45ah at 48v x 6 modules for, um, should give me 13kw. With say a 50% dod and 50% for knees.

Allow me to start to rub my greedy little hands together. Bigger fridge. Internet on 24/7. TV binges well into the night. Midnight dishwasher, why not?

Now:

I will have to replace my inverter. Anyone for a TBS 12-1200? Beautiful inverter.

And ideas for a 48v inverter. I see some nice ones from Helios in China. Or that Victron 48-1600 looks like it would suit nicely.

Also debating the bms issue. A simple balancer with the big knees of dod and charge should work.

Looking at ideas to keep the costs down.
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Old 05-30-16, 08:48 PM   #5
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Here is a link that has been posted a couple times that might help with your build.

Use of Nissan Leaf battery in Solar installation. - My Nissan Leaf Forum

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Old 05-31-16, 09:22 AM   #6
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Thanks JJ. I have seen his post. Very interesting. I'm waiting until the battery pack is in my hands and then I will decide what kind of bms to use. The REC bms he uses is a top contender.

I am reading more and more about how GM handles the bms issue. They seem to count on the cells staying balanced after what I assume is a prebalance.

The voltages look to be a bit tricky too. Each pack uses 12 cells. So it appears so far that 49v is full charge. 38v at low. Makes it awkward to use with most inverters. So I will need a programmable inverter. Of course my morningstar solar controllers will have no problem with it.

Anyway. It's all moot until the battery is on the floor.
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Old 06-01-16, 08:57 AM   #7
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Here is some food for thought.
Schultz Engineering - Delta-11 Electric Motorcycle - Chapter 12 Adding Chevy Volt Batteries

Cool project post lots of pictures.
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Old 06-01-16, 10:05 AM   #8
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Thx Pinballlooking. I have seen his post and contacted him. He was nice enough to write a brief message back. Great build.

I pick up the pack Friday. I'm trying to control my excitement and failing. It's starting to feel a lot like <holiday in winter> and I'm five years old.

Currently (nope, never gets old) I'm looking at the Victron inverter series. The 48v inverter has the advantage of being programmable. And is capable of inverting down to 37v (3.1v/cell). Which given that I will charge to a max. 49v (4.1/cell). Gives me comfortable knees for my charge discharge cycle.

Porsche 914 Electric
is an interesting chevy volt tear down and bms add

2015 Montana 3611RL The Adventure Begins: Chevy Volt Lithium Battery Packs For My Montana RV
this guy bought volt batteries configured as 12v and now is making/made his own arduino based bms. I haven't had a chance to read it yet.

Heart racing. Will Friday ever come? Will my girlfriend talk to me if I don't go help with the garden?
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Old 06-03-16, 08:03 PM   #9
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So. It's Friday. Drum roll.

The wrecking yard in far far far north Quebec was nice enough to deliver the pack 1/2 way to my house. They drove for 3.5 hours south. I drove 3.25 hours north. We met. Slid a pallet between two truck beds.

I drove home thinking. Please be 3. I gambled. No way to test it. Needless to say. First thing I get home. Tractor comes out. Fork lift bars go on. Pack gets carried to the tractor shed where it will reside while I work on it. I get the lid off. Out comes the voltage meter.

Front pack. 115.3v or 3.84 /cell. Middle pack. 92.1 or 3.84 / cell. Back pack. 161.4 or 3.84 / cell.

Huge sigh of relief. Minor dancing in the field.

So I now have a 2014 pack basically fully charged. All I need to do now is take it apart. Build/find a bms solution. Reconfigure my Morningstar solar controllers. Buy a Victron inverter. And a few other dozen things.

But that's a job for tomorrow.

Am now taking suggestions for BMS. I wouldn't mind trying an arduino atmini something. Anyone with ideas?

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Old 06-06-16, 04:43 PM   #10
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BMS musings:

After some initial research: Building my own BMS is probably a bit out of my time/capability ranges. Buying one does get pricey. So right now I'm leaning towards the basic cell monitoring with the option to turn on cell balancing. From what I've read, cell balancers gone bad kill more battery packs then packs left alone.

Some relatively inexpensive made in china offerings. Can anyone check my math/understanding. My brain is a bit fuddled lately. Lot going on besides the new battery fun.

Problem: What amp BMS do I need?

Given: 48v.

Max. of 2400 watts draw. Surge power for 10 secs or less. And usually a max of 1500-2000 sustained for more than a minute or two (vacuuming and the fridge starts and runs).

6 battery packs providing power.

So if I take: 48v with 2500w I have 50 amps draw.
Then I divide by 6 packs. And I end up with 8 amps draw.

If I consider expanding my system to two inverters. That might go 20 amps tops?

This is important as the BMS get more expensive per amperage.

Testing:

I haven't had the time to check the cell levels yet. Right now they look good as all the packs basically add up to 3.84/cell. Which might indicate that the cells are fairly well balanced.

Fun photos from the unload:

Here's the pack in the back. Of my truck.


The Eagle has landed

It was a bit tricky. The biggest battery was at the wrong end. I could slide the pallet in the bed but the tractor couldn't lift it. Finally, after three or four adjustments to the forks and then running the revs to the line. I got it up an inch. and very. very. very. slowly and carefully backed up. Heading for the shed.


Lithium pack is out

The tractor really can't support the weight and the pack begins to drop. It's a race to see if I can get to the tractor-run-in before it droops to the ground.



Huzzah. Al pays for himself again. Always good to have a buddy who can lift 500 lbs with his two iron arms.

After a good battle with the cover. The important part. Testing voltages.


Testing 1-2-3

As always. There's a bit more info at the blog.

***

Any body else with ideas re: BMS. Yes, No? Huh?

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