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I've always wondered how long lithium-ion batteries could sit on the shelf before they self-discharged to such a low level that they became bricked. I've bought old stock batteries before, but never more than five years old based on their date codes at the time of purchase. Well, I now have one data point, and it is nine years. I just bought a new old stock discontinued WeedEater 20 volt battery that I've been using in some discontinued Greenworks 20 volt tools with a date code 032911 (March 29, 2011), so over nine years old and it's dead as a door nail. The open circuit voltage is under 4 volts and it will not charge. The charger reports that it is overheated rather than defective, but in any case refuses to attempt to charge it. Of course had someone charged it periodically and then placed it back on the shelf, it may have survived and I do have some batteries nearly that old that still work perfectly. So, sadly it seems that once my remaining stock of these batteries is gone, I will have to retire those old tools that otherwise work fine.

MowerMike said:

So, sadly it seems that once my remaining stock of these batteries is gone, I will have to retire those old tools that otherwise work fine.

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Maybe not. if the battery case is held shut with screws, pull out that soldering iron and screwdriver - you can always replace just the batteries.
Watch out as to not break the circuit board in the battery. Lithium batteries need this circuit to regulate usage and charge unlike NiCads.

upupandaway said:

Maybe not. if the battery case is held shut with screws, pull out that soldering iron and screwdriver - you can always replace just the batteries.
Watch out as to not break the circuit board in the battery. Lithium batteries need this circuit to regulate usage and charge unlike NiCads.

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I’ve opened these particular batteries, and it’s not easy to replace the battery cells. They are encased in a framework with elaborate metal connectors that are destroyed when you separate them. Also, soldering directly to lithium-ion batteries can be very dangerous, as they can ignite and even explode.

All li-ion cells degrade in time. Periodic use will lengthen their life but time will kill them regardless of how often they are used. I have used a company called Batteryrefill.com to keep a 15 yr old laptop running and some other laptops too. They cut open and re-cell the battery. Sooner or later OPE batteries will be re-celled by companies. After li-ion cells get discharged to a certain point they are dead and will not recover.

Hammermechanicman said:

All li-ion cells degrade in time. Periodic use will lengthen their life but time will kill them regardless of how often they are used. I have used a company called Batteryrefill.com to keep a 15 yr old laptop running and some other laptops too. They cut open and re-cell the battery. Sooner or later OPE batteries will be re-celled by companies. After li-ion cells get discharged to a certain point they are dead and will not recover.

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All batteries degrade. Why buy 5 plus year old batteries when you have an $1,200 cell phone?

slomo

Batteries are affected in different ways.
When they are in cold temps the life of them is less.
Charge cycle time (charging to frequently and how many times also) will lessen the life.
Poor brand of battery is another way they don't last.
The battery packs have #18650 batteries in them.
If you're good, you can replace them in the shell of the pack.
A lot cheaper than buying a new pack.
Here's something to watch about battery brands:

MowerMike said:

I’ve opened these particular batteries, and it’s not easy to replace the battery cells. They are encased in a framework with elaborate metal connectors that are destroyed when you separate them. Also, soldering directly to lithium-ion batteries can be very dangerous, as they can ignite and even explode.

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That's because they spot weld them from the factory. i cut around the weld. To each his own.

And those metal strip connectors can be cut easy and soldered. No magic in the connectors. But a lot of the Chinese replacement cells brag on their high ratings, but are pretty weak when actually loaded. A good source for powerful Li-ion batteries is a laptop battery pack. Most are connected in series/parallel and have 6 or 8 of those standard cells.

tom3 said:

And those metal strip connectors can be cut easy and soldered. No magic in the connectors. But a lot of the Chinese replacement cells brag on their high ratings, but are pretty weak when actually loaded. A good source for powerful Li-ion batteries is a laptop battery pack. Most are connected in series/parallel and have 6 or 8 of those standard cells.

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I think these batteries have about 20 cells, so I would need at least three of those laptop batteries, right ? All this assumes they are the correct physical size, voltage and capacity. How much does a good quality OEM laptop battery, not a cheap Chinese knockoff, cost ? If the total cost is more than $100, then it really isn’t worth it to salvage an old tool that cost less than $100 in the first place. The reason I bought this old stock battery was because it was only $40, so I figured it was worth a try.

Edit, I just opened an old dead one and it only has 10 cells. So, only 2 laptop batteries would be required.

Anyway, the circuit board has to be removed in order remove the end caps of the battery case, which involves a lot of desoldering of connections on the circuit board. I’m sure an expert could do this, but I’m not confident in my skills to do it.

One more thing to try, probably hopeless, but put some current into each cell with a charger that outputs around 4 volts for a couple minutes each. Then try your regular charger, if it sees some voltage on the pack it may actually recharge the pack.

tom3 said:

One more thing to try, probably hopeless, but put some current into each cell with a charger that outputs around 4 volts for a couple minutes each. Then try your regular charger, if it sees some voltage on the pack it may actually recharge the pack.

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It’s 10 cells in a 20 volt battery, so wouldn’t it be 2 volts. Perhaps you didn’t see my edited post. Anyway, I’m trying to get the eBay seller to accept a return.

Series: five batteries at four volts for the 20v output - parallel, two sets tied together for double the current capacity. But those are packaged pretty tight, oh well.

tom3 said:

Series: five batteries at four volts for the 20v output - parallel, two sets tied together for double the current capacity. But those are packaged pretty tight, oh well.

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Gotcha !

tom3 said:

One more thing to try, probably hopeless, but put some current into each cell with a charger that outputs around 4 volts for a couple minutes each. Then try your regular charger, if it sees some voltage on the pack it may actually recharge the pack.

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If you are going to try some thing stupid like this,
Do it outside on a concrete brick or steel surface with nothing flamiable nearby .
Lots of videos of people's garages / houses burning down because they managed to ignite the battery pack by incorrect charging .
Unlike a lead acid battery where you are just shuffeling lead between 2 valance states a Lithium battery under goes a complete redox reaction .
As the battery contains both the fuel & the oxidant, once they start to burn they can not be extinguised as several airlines found out the hard way.
You can toss them in a bucket of water and they will continue to burn under water

You can solder the terminal strips. I have done it.
Many YouTube videos on doing that and making a simple spot welder also.
Buying a laptop battery to me is expensive.
Buying quality individual batteries to me is less expensive.
LG, Panasonic and Samsung are three that come to mind.
The ones from China don't cut it.

Richie F said:

The ones from China don't cut it.

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That's what I've found out over the years too, even with Nicd and Nimh. Factory seconds? Thirds?

tom3 said:

That's what I've found out over the years too, even with Nicd and Nimh. Factory seconds? Thirds?

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Yep,
Selling rejects as good parts did not start with CHinese Briggs carburetors, it has been happening for decades.

bertsmobile1 said:

Selling rejects as good parts did not start with Chinese Briggs carburetors, it has been happening for decades.

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And then there's all those pharma factories in India and China churning out our generic meds...

And the Chinese Flu pandemic and the half billion masks that we've imported from, you know, China.

So, today the seller of the defective battery agreed to issue a refund w/o having to return the battery. Since it was a free return, the seller would incur the return shipping cost and it makes sense not to waste money on something that they could not resell. Since I did not need to return it, I decided to open to see what I could find. What I found was that all pairings of battery cells showed the same 0.5 volts, or 0.25 volts/cell. I'm not quite sure why they should all decline at the same rate, but for sure they are bricked. I'm definitely not going to mess with this, and will drop it off at a battery store for recycling. Nor am I going to buy any more of these, since most of the remaining old stock are probably bad as well.

MowerMike
It was junk to begin with.
Glad you didn't lose out.