Chevy Volt battery pack for off grid solar?

[creeky]

One month update.

Did a full cell check after letting the batteries rest last night.

Cell voltage - count
3.96 - 1
3.97 - 29
3.98 - 42

Total 72 cells. All cells within .02. This is fine. I suppose I could bump up the low one.

I am coming to full charge every day. Haven't missed a day. Yet.

The morningstar TS-MPPT-60s (2) continue to function as per program.

I have a BMS solution from China available that I am pursuing. Not sure I really need one though. Guess we'll see what it all costs.

Right. That's it. Enjoy the summer all. It's finally raining here. I harvested two hot peppers today. Made a great salsa with local yellow beans, corn and cucumber. Huzzah!

[stevehull]

Creeky - time for a recap (from you) as you enjoy your harvest and bask in your fine accomplishment..

I feel a little responsible as I was one of those who encouraged you to "do this" when you were initially feeling a bit overwhelmed with the entire situation (5/29/2016).

What I read is that the initial time to do this was not at all what you expected and progress was far faster.

So, in retrospect . . .

What price is good to buy a Chevy Volt battery pack.

Where were you "lucky". For example all cells appear to work No damage to physical parts. Some of us may not have such luck.

How much time did you spend on disassembly and did you really need to do all that.

If you were to start again, what would you have concentrated on?

How many specialized tools were needed (lets not count voltmeter).

A lot of discussion was on BMS - but it seems like this may be unnecessary?

Safety - I know that this is "low" voltage, but sweaty hands/fingers on 48 V with a lot of amperage behind it can create a nasty burn!

Other issues import to recap on . . . .

Lastly, I infer that you have about 1 kW in panels. Might be helpful to describe more clearly your PV infrastructure. It is VERY clear why you replaced your old lead acid storage.

Thanks in advance as you now have singular knowledge that is very valuable.


Steve

[creeky]

Thanks Steve. I appreciate the encouragement. Warning, I do enjoy a slight deprecation of intent. It makes the story more interesting (to me anyway.

I couldn't speculate on cost. It really is location dependent. Where I am, I saved a few thousand dollars over any other option (by size from 3 to 5k? By original budget I'm a bit under. And with 2.5x the capacity). There are benefits to being diy and an early adopter. smile. I have yet to sell off all the replaced assets. But having sold some of them; right now I sit somewhere below $155/kw. Installed.

From what I've read I was not "lucky". My experience seems to be standard. What was lucky was finding the battery pack at all.

I didn't spend much actual time on dis/reassembly. It occurred over two weeks/a month primarily as I had other obligations. I would do it exactly the same way if I had to do again. Of course, being my second time, the schedule would be greatly compressed. smile.

There were no specialized tools. I used a 10mm socket head on an electric drill and a voltmeter. I also used a socket wrench with a 10mm socket. Oh and some screwdrivers/pry bars. All pretty standard stuff.

To charge I was very fortunate that I have two Morningstar ts-mppt-60s. And two 1kw panel sets. This allowed me to use one controller/set for test charging the lithium batteries. And I was able to keep my electrical system online while I did so. It also allowed me to flash eeproms. Set new previously unheard of charge control limits etc with the security of knowing I had a fall back position.

For SESS (solar energy storage systems) I don't believe a BMS is necessary in the short term. And I have a month and 120 kws of power created and distributed to back that up.

In the long term I do believe that a BMS will be a good idea. Simply for peace of mind. If you can monitor your batteries online. Hopefully from a remote location as I travel a fair bit. This would be a good thing.

Also. If I was going to use more of the battery I would want better control. Charging to 80 and discharging to 30% offers a huge high/low safety net. I may want to go higher this winter when the days are short. A sunny day to 4.1 per cell vs 4 would give me another day of cloudy weather storage.

As mentioned. The inverter will shut down at 3.2v/cell. The solar controllers not only charge to a set point that has proven accurate. But there is a high voltage disconnect setting.

Safety - Its the same with any wiring you do. House. Battery. Car. Stereo. There are more dangerous jobs that I do. My tractor can easily do great damage. My tablesaw. Chop saw. Cook stove. Vegetable slicing.

Measure twice cut once. Look up and live. Etc. I imagine here we are talking to the converted. DIY demands clear thinking.

If I was to do it again I would make better protection for the cell bus bars. And probably wrap the handle of the socket wrench. Bicycle tube would work well methinks. Hmm. Think I just added something to my "still to complete list."

And yup. It turned out that the solutions I needed were accessible from online resources. Primarily from the electric bike and rc crowds. Also, early on GM released more info and there were some neat presentations given. Clues were found!

There was also some good info from other folks who have tried similar things. Nobody who did exactly what I did. But close enough. I was able to share with some of those folks too. Which feels good.

My explorations with Morningstar have always been rewarding. They are great folks to work with. And I appreciate their help. Plus. To be able to reprogram a 5 year old controller to an entirely new chemistry. In large part due to Morningstar continuing to update software and firmware for these products. Speaks very highly for them.

A tip of the hat goes to my buddy John. I'm not an electrical wizard. And I usually have to do things a few times before it "clicks." So having him help out was good.

<B>All the pointers here</b> were really helpful. You'ze all made things easier for me. Much appreciation.

While I'm handing out kudos I'd better mention my girlfriend. She who rode in the truck. She who listened to untold hours of ideation. Maybe we should have a moment where pause in celebration of our significant others

You know. I guess us DIYers are like bulls in china shops. We charge in where others fear to tread. Sure, there's an element of original thinking / solution creation in what I did here. But its not the first time. I mean I over paneled my solar panels to controller initially because it made sense. later the idea was supported "officially." I put my panels on dock hinges for seasonal adjustment. Still one of the best ideas I've seen for mounting small panel sets. Cheap. Strong. Durable. Efficient. Proven particularly useful in the winter. Who knew?

And of course there are tonnes of great ideas on this site. From you folks who have done the same. Charge on! (yes that is a deliberate pun)

Huzzah!

Creeky. The somewhat knowledgeable about one fragment of the lithium solar world.

[stevehull]

Great idea to use an old bicycle inner tube on the socket wrench . . . .

Great review. There must be at least a few brewski bottle tops popped!


Steve

[creeky]

Well. No brewski's. But some general dancing about with my hands in the air.

Had a record 7200w/day a few days back (blowing past the previous record of just over 6kw). largely because I ran the a/c. used the induction hob to make supper. watched a movie. listened to music. ran the dishwasher. all after dark.

Hit a record low on the battery voltage. 45.43 according to the tristars.

Which is crazy to me. Seeing as "full" is 48.36. And "empty" is 42. So half of the power available? Of course some power was used during daylight hours.

And. Sunny day. Summer. Fully recharged by 1 p.m. Huzzah.

Heat wave today. No doubt some a/c use coming up. Better get to my chores.
Anybody else watching the Perseid meteor showers? Thu/Fri night looks awesome.

[pinballlooking]

Very nice…
We use 5-6.5 KW overnight. We have used over 100 kw hours in a day but about 76 kw has been the highest this year so far.
Keep in mind we charge our Volt from empty to full two two three times a day that is 12 kw hours each charge.
People’s usage sure varies.

[creeky]

lol.

Being a single guy living off grid in a moderate manner certainly helps. The 7.2kw day was my girlfriend visiting. Making her supper. Keeping her cool. Entertaining her. She loves movies. Doing the dishes.

Even with leaving the internet on 24/7 now. With idle draw of 40w/hr. (Okay. I upgraded the firmware on my IoT plugs. They read voltage/watts now. 36.512w is the current usage). I typically use around 3.5kw/day.

An all electric vehicle would be a joy. (Your Volt use is an inspiration.) I'd like a little 3 wheeler with room for 2 and good sized trunk.

I can expand to 6 kw panels with my current controllers. So I think I could fit in another 12kw battery pack.

Chores. Oh ya. Back at 'em.

[creeky]

2 month Lithium report

The cells continue to check out exactly at the voltage spread noted in my first test.
I have 1 cell at .02 lower than the highest. Many cells .01. And most cells within .003v. There has been no change I can see.

My power use has been:

My 2kw off grid system produced
July: 140,210 watts
Aug: 129,710

for a total of 269,920 watts produced.

A/B (I have two 1kw panel sets and two controllers)
July: 73470/56240
August: 84740/55470

Note that the panel sets produce unevenly due to two factors.

One: the panels are set at different angles. The first set is adjustable and is currently (sorry) at 30 degrees (now that it is fall I'll be adjusting to 45 degrees). The second set is fixed at the "winter" angle of 60 degrees.

The fact that I am usually fully charged before noon also means that one controller will typically pick up most of the day time loads. For reasons I don't know of, the adjustable panel set carries most of these loads.

Of note:

I also saw 1023w being produced by my "summer angle" 1kw panel set. That this number was produced from 8 year old panels is interesting. This is a record high for my panels. I was "overpanelled" at 12v. But at 48v I can add up to 4kw more panels should I wish to. While overpanelled I frequently saw "current limiting." The high number comes after a good rain storm washed the panels.

I also set a personal record. One day power creation of 8.12kw. I ran the dishwasher on "high temp wash." smile.

My power use is dropping dramatically as I am not using the a/c unit in the studio anymore. Sigh. Today is the first day in months I don't have the doors to my studio wide open for the fresh morning breeze. It's too cold!

[jjackstone]

Creeky,
Just wondering if you live somewhere with a lot of cloud cover. I would expect about 10kwh production per day from a 2kw array. Just a quick average of 5 good hours of sun per day times your 2kw array. That would produce around 300kwh per month. I realize that your panels are not all at optimal angle but 50% of rated seems a bit low. I did a quick check on Pinballlooking 12.5 Kw array and using the same 5 hours of sun per day and his production numbers are pretty much what I would guestimate for the month. Anything I overlooked in your system or is my math wrong? Thanks, JJ

[jjackstone]

Ah, maybe you're only measuring what goes back into the batteries each day since you are off grid. JJ