Potentially an incredible energy storage opportunity for me? Free Lion's

[PNjunction]

Aaron - just stop now because you do not have the knowledge with lithium to be effective or safe.

1) You do not know the actual chemistry of those cells. LiFeP04 for example differs in charge voltage than all the rest. You don't want to get the chemistry wrong.
2) Cells that won't hold more than 80% of their rated capacity have issues that you don't know how to deal with safely.
3) If these cells have not seen any consumer service in the first place, what caused them to drop their capacity? Bad QC from an *unknown* and unreputable cell vendor?

Put it this way - doing this would be starting your solar adventure on the wrong foot! Example:

My company is giving me an inpenetrable black box with a lead-acid battery inside that I want to play with solar. Problem:

You should ask yourself these questions:

Is it deep-cycle or a starter?
Is it a Gel, AGM, Flooded, or "maintenance free" flooded?
If agm, is it lead-calcium, or lead-tin/pure-lead?
Why am I dealing with batteries that have less than 80% of their rated capacity in the first place - what problems does that present right off the bat?
Who made the actual battery in the first place?

Basically, used/abused/unknown battery setups are starting out on the wrong foot. They are the WORST things to experiment with as a newcomer, until you know how a NEW battery operates.

Free used batteries are always tempting, but in most cases YOU just relieve the owners from recycling them properly, and now the dump is your house instead.

If your company doesn't know how to recycle those used li-ion batteries properly, and is just holding on to them and dumping them on to college kids, then that raises a big red flag.

[karrak]

Since you are trained in HV and part of your job has been to decommission these batteries from 600V systems I would think you probably have enough knowledge to look further at this.

I agree with Sunking that you really do need to find out what variety of lithium batteries are in these modules. I think another important factor is whether or not these modules have a working BMS (battery management system) installed in them. Another useful piece of information would be how the individual cells in the battery are wired up. How many cells are wired in series and parallel.

If the batteries have lost a considerable percentage of their capacity it is more that likely that their internal resistance will have increased which will limit the amount of power you can draw from them without them overheating.

48VDC to 120VAC inverters are readily available and will work down to a voltage of around 42V, but will work more efficiently with voltages around 48V. If you are going to be charging the battery from solar finding a solar controller that will work unless the nominal battery voltage is around 48V-55V will be tricky.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

[aaronllewellyn]

Since you are trained in HV and part of your job has been to decommission these batteries from 600V systems I would think you probably have enough knowledge to look further at this.

I agree with Sunking that you really do need to find out what variety of lithium batteries are in these modules. I think another important factor is whether or not these modules have a working BMS (battery management system) installed in them. Another useful piece of information would be how the individual cells in the battery are wired up. How many cells are wired in series and parallel.

If the batteries have lost a considerable percentage of their capacity it is more that likely that their internal resistance will have increased which will limit the amount of power you can draw from them without them overheating.

48VDC to 120VAC inverters are readily available and will work down to a voltage of around 42V, but will work more efficiently with voltages around 48V. If you are going to be charging the battery from solar finding a solar controller that will work unless the nominal battery voltage is around 48V-55V will be tricky.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

I'm going to do some more digging. mainly to find out the chemical makeup, and the "New" capacity in ah of these modules. both would be vital in determining the viability of using them as storage. if they're less than 80% original capacity, they wont be worth playing with, but if they're greater than 80% cap. and also LiFePO4 I may be able to use them for something, if only experimental. each module has an incredibly in depth BMS system attached to the top in the form of a weatherproofed circuit card, it logs voltages, time-in-use in seconds. and has it's own temperature sensor. the only problem there would be accessing the information, since I have little knowledge of the type of communication the card uses to relay that data to another BMS that handles all of the modules combined. I'm not sure if it functions independently at all, I would be more likely end up with raw lithium storage and no built in BMS functionality.

I've got a 140ah 12v AGM battery I've been meaning to play with, I'm sure that would be a far more forgiving and beneficial experience. I'll probably just keep these ones in the back of my mind...

[Sunking]

If you know the cell voltages, you can tell what they are basically.

2.4 = Titanate
3.2 = LiFeP04 aka LFP
3.6 = Cobalt Blend
3.7 up = Hybrid.

I will not bore you with details Do Not even think of using any cell above 3.2 volts Titanate is the safest followed by LFP. Second warning used cells are prone to have plating issues which means a short circuit cell and thermal runaway, and you cannot pu tout the fire as you should know.

Are the batteries labeled how many cells are in series and what the nominal voltage is? That will tell you a lot. example say 12S 43.2 Volts. Simple math is 43.2 volts / 12 cells = 3.6 volts per cell.

You can also tell if you know the charge voltage of the cells. It will be higher than nominal. You are looking for 3.6 volts or less. Runaway from anything 4 volts or more like 4.2

[jflorey2]

They suggest a standard DC distribution voltage of 380V which corresponds to the output voltage of a DC UPS which runs off standard (outside the US and Japan) three phase AC voltage of 400Y/230.

There are two competing standards out there for local DC distribution - an NEC standard of 380 volts and an ETSI standard of 400 volts. (IEC is also working on one.) They both have the same goal, which is lower losses and easier implementation of UPS systems. They're often called "DC microgrids" although that's somewhat misleading; they are really DC distribution systems.

[Sunking]

I believe there's around 80-90 cells in each 40 volt module, that would give us a voltage of around .5v per. I'll see what info I can get.

No sir that is impossible. No such thing as a .5 volt battery, lithium cells are 2.4 to 3.7 volts.

Now the packs may very well have 80-90-cells in them. To be an integer of 40 something volts means there has to be 11 to 13 cells in series. No other way to bet to 40 volts. Now there may be up to 8 stings in parallel.

Lithium battery packs are sometimes expressed in xSyP where x = number of cells in series, and y expresses how many parallel strings So lets say a batttery pack made out of 3.2 volt 2 AH cells could be 11S8P would be 88 cells. The pack would be 35.2 volts @ 16 AH.

No offense offered here but based on your comments and questions, you have no biz messing around with the batteries. Just because tou have HV experiences does not qualify you to work with batteries. In fact there is not much of anything in common.

[Sunking]

Lithium is not where you start your journey with batteries. When you turn 16, you do not hop in a Tractor Trailer Rig and start driving. You work your up to it. The issue with Lithium batteries is they are unstable and do not tolerate any kind of abuse. One mistake ends in one of two results: A Boat Anchor or Fire. I could care less if you turn them into boat anchors as it is not my money or time wasted. But I do care about your safety and those around you.

You start with Lead Acid and NiCd. They are rock stars of the battery world and can take all kinds of abuse and still come back strong. They will teach you what you need to know at 1/10th the cost and a lot less risk than a Tractor Trailer Rig.

Lithium holds a lot of promise, but they only have one advantage of higher energy density or put another way pack more power for a given space and weight. Other than that Lead Acid beats them in every other category. A Pb is a lot less expensive, last longer, more reliable, safer, and much easier and less expensive to maintain. The only places you can justify the cost and risk for Lithium batteries today is Transportation, aviation, power tools, cell phones, laptops, and military.

Can lithium be used in Solar? Absolutely. Are people doing so? Absolutely but most, not all know enough to get away with it, but they are paying to much and taking risk. But they already know that like me. Right now you do not even know the various types, how to care for them, the dangers and risk.

If you really want to play with them, then buy a couple of some 18650 LiFeP04 cells for $5 about the size of AA batteries of 3.2 volts @ 2 AH. If you destroy them, you are out $7. If they catch fire you can contain it. FWIW a Tesla Model S contain 7104 nickel-cobalt-aluminum 18650 cells.