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Discussion Starter · #1 ·
Hi everyone, I was hpoing you guys may be able to help me out. I have a 2013 Chevy VOlt that is going to die soon... I can feel it, it's acting strange and the 12V battery was already replaced. I measured the cells and the Delta is over 500mV between modules... 2 of them at 3.6 and 1 at 3.07. I want to get ahead of this and buy a Volt battery pack (Ideally a 2015 if they have it to gain better chemistry) and install it in my car.

Now the question, WHERE are you guys looking for these items? Google hasnt given me any solid info, just a bunch of auction salvage sites where I can register to bid and buy the whole totalled car (Which I dont need). I live in Miami, FL if that helps... ANy links, recommendations, places? Any where at all to start looking? Cause google is either giving me salvage cars or 12v batteries all day, but no "Chevy volt High voltage battery pack salvage" hits seeem to be of a place where I can buy a pack and have it shipped.

Also, how do you know trhe pack is good without testing it remotely? Anything the place I buy from can do to test it for me? Or is it just faith? Thanks in advance!!!!!!!!!!!!!!!!!
 

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Carpart is the web site I used to locate my volt pack out of a salvage yard. Unfortunately, they call it a battery. Limiting your search for Volt models cuts that down a lot. A lot of the salvage places don't know that the drive pack is a different thing, it's just a battery to them.

Back then you could get a pack for $500, but with the solar people sucking up anything storage, that avenue is dead. The packs are still cheaper than reman and you can sell your left over modules to recover some cost. If you find a prospect, act fast because it wont last long.

Most salvage places will warranty the battery as functional for some time frame, but it is yard specific.. however since the modules generally interchange you could assemble a Frankenstein pack very easily using the best of both packs. Since we're commenting about Frankenstein, there used to be places that would sell used verified good modules on the web.

Have you thought about bottom balancing the pack? 5-6 years ago that was the rage for getting more life out of a pack.

I can't help more, my pack is now 10 years old, no BMS, and most cells are within .02 volts charged using a fluke dvm.
 

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Discussion Starter · #3 ·
Have you thought about bottom balancing the pack? 5-6 years ago that was the rage for getting more life out of a pack.

I can't help more, my pack is now 10 years old, no BMS, and most cells are within .02 volts charged using a fluke dvm.
awesome, I'll start at car part and check from there.. it's a starting point at least,, which is great.. thank you!.

I'm not sure what "bottom balancing" is? Does it require dealer equipment to make it happen? Will it save my pack? I'll try it if it's something I can do...

And what do you mean your pack has no bms and using a fluke dvm? Can I do the same to mine and save it? Or maybe the new one to give it more life?
 

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best deals I ever find take some foot work, and are never retail or commercial, I would message all eBay sellers who sell any type of Volt parts / components and strike up a conversation with them

put up wanted ads on forums and on Craigslist, you are going to miss all the deals you don't take just sitting on your couch, ha ha

also I think you may be able to swing a deal on CoPart a used wrecked auto auction, yes you would have to buy a whole car, but you may have a better chance of finding out the health of the battery pack as it will be complete and inside what may be a immobile vehicle, you may test charging it, and you may be able to use the native console to see how much life is left, so wrecked is good, you can still part out the parts you do not need, and offset your initial expenditure, hope this helps, just giving you options
 

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I'm not sure what "bottom balancing" is? Does it require dealer equipment to make it happen?
"Top balancing" is the usual approach: charge the whole battery, measure which cells have more charge than the others, then discharge them slightly (with a resistor across the cell to be discharged) to match them to the others. The bypassing of higher-voltage cells (reducing their rate of charging) can start before charging completes.
"Bottom balancing" is the same thing at the other extreme of state of charge: discharge the whole battery, measure which cells still have more charge than the others, then discharge even more (with a resistor across the cell to be discharged) to match them to the others. Again, the bypassing of higher-voltage cells (increasing their rate of discharging) could start before discharging completes.
Either way, balancing is done at the extremes of the state of charge, because that's where voltage changes most with change in charge. There are more sophisticated technical solutions than just switched bypass resistors, but I don't know if any EV uses them.

A stock BMS is probably physically capable of bottom balancing, but won't be programmed to do it. I doubt that anything available to dealers would change that.

All of this is, of course, subject to correction by anyone with more practical experience with cell balancing.
 

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Balancing can be done at any point in the curve, including leaving the factory state at the midpoint.

And should only be done at that chosen point.

It does not change anything wrt the cells themselves, does not align their SoC vs Voltage points, does not increase pack capacity.

What it does, is let you

more safely use pack level voltage

at either HVC while bulk charging or LVC protection.

Bottom balancing lines the cells up as you approach the end of the discharge cycle. If your LVC is based on per-cellV do not bother. If your pack-level cutoff is well above say 3.2V do not bother.

99.99% of BMS and balance chargers do top balancing - not adjustable - using resistance/burn technology because that is the cheapest way for the maker. It is also very very slow, a balance current max under 0.1A is common.

And sitting at top SoC% for long periods is harmful to longevity, so that poor design actually causes more of the problem balancing is supposed to solve!

Many owners doing bottom balancing do it manually and thus only very infrequently.

Active balancer gear with much higher balance rates say 2A, capacitor based "charge shuttling" technology

automates the process at any voltage, but is really only needed with crap quality, mismatched or very worn cells.

If your pack does need them, look for ones whose balance current does not decline as the V delta narrows, IMO only these deserve that "Active" designation.
 

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Discussion Starter · #7 ·
"Top balancing" is the usual approach: charge the whole battery, measure which cells have more charge than the others, then discharge them slightly (with a resistor across the cell to be discharged) to match them to the others. The bypassing of higher-voltage cells (reducing their rate of charging) can start before charging completes.
"Bottom balancing" is the same thing at the other extreme of state of charge: discharge the whole battery, measure which cells still have more charge than the others, then discharge even more (with a resistor across the cell to be discharged) to match them to the others. Again, the bypassing of higher-voltage cells (increasing their rate of discharging) could start before discharging completes.
Either way, balancing is done at the extremes of the state of charge, because that's where voltage changes most with change in charge. There are more sophisticated technical solutions than just switched bypass resistors, but I don't know if any EV uses them.

A stock BMS is probably physically capable of bottom balancing, but won't be programmed to do it. I doubt that anything available to dealers would change that.

All of this is, of course, subject to correction by anyone with more practical experience with cell balancing.
Holy cow. I feel like I just spoke to a rocket scientist. I am assuming none of this can be done from inside the vehicle and I'll have to take the pack out to do these.
 

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Discussion Starter · #8 ·
best deals I ever find take some foot work, and are never retail or commercial, I would message all eBay sellers who sell any type of Volt parts / components and strike up a conversation with them

put up wanted ads on forums and on Craigslist, you are going to miss all the deals you don't take just sitting on your couch, ha ha

also I think you may be able to swing a deal on CoPart a used wrecked auto auction, yes you would have to buy a whole car, but you may have a better chance of finding out the health of the battery pack as it will be complete and inside what may be a immobile vehicle, you may test charging it, and you may be able to use the native console to see how much life is left, so wrecked is good, you can still part out the parts you do not need, and offset your initial expenditure, hope this helps, just giving you options
I'll try those options. Thanks! I've never used a auction bid type site... how do they get the car to me in Miami? Is this something they can transport to me here? I'm reading their site now to learn what I can.

Reading ebay sellers now to see if a battery is in their inventory.

Thanks!
 

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Discussion Starter · #13 ·
If the BMS won't do what you want, you need access to the tap wires used by the BMS... and yes, in the Volt I assume that means removing and opening the pack.
Oh dear, I don't know if I can do that without an awesome YouTube video, and even then I'd need Jack's or something to lift this heavy heavy car
 

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Dont need the whole car just the pack, so shipping was integrated into the purchase price. Make sure you get the fuse included and ask if you can get the connectors for the electric and cooling. Mine were just hacksawed and still attached to the case.

Other than 88 stupid 10mm bolts and washers, it comes apart easy and is still double insulated at the cell level, power cables not as much but nothing a blanket wont fix.. I didn't have internet, or you tube since nobody had done this yet. Did it on my own, easey peasey.

Haven't looked lately but for $2000 each they were common as dirt.
 

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With the Volt out of production for almost three years now (since early 2019), with no direct replacement (so no new vehicle using the same battery), the supply of good Volt batteries in salvage from wrecks will start tapering off. Eventually the cars will get so old that they are scrapped even without major collisions, but the batteries will be old and of questionable value.
 

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With the Volt out of production for almost three years now (since early 2019), with no direct replacement (so no new vehicle using the same battery), the supply of good batteries in salvage from wrecks will start tapering off. Eventually the cars will get so old that they are scrapped even without major collisions, but the batteries will be old and of questionable value.
Its funny when i hear commentators saying blah blah what will we do with all these used batteries.. Ive never seen a single used EV battery not get sucked up at auction for a high price. I dont know about the USA but in New Zealand a used Nissan leaf wrecked still sells for thousands of dollars. People with money buy them up then resell the batteries to you for a nice markup to themselves. I would be loath to buy batteries off them and would rather strip a car myself if I had access to it. I dont like lining others pockets unless I must. In the USA you have a zillion Teslas with many wrecked but the batteries sell for extreme prices. I imagine we need more market saturation so that there are simply too many batteries for the solar people. Only then will the prices come down to something reasonable. Until then you have to know the right person at the right time or have a bidding war. Still even with a bidding war its still cheaper than new Lithium batteries which I dont know why anyone but someone rich would bother with.
 
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