What kind of Lion cells are these

[N4aeq]

I bought some store return tool battery packs to yield some high current 18650 cells, one pack was a EGO 56v 2a pack, looked new. I took it apart and found
14 cells, all measured 3 volts exactly, I thought they may be INR tool type cells that run 3.2 v but that won't equal 56v, 14x 4 volts = 56 volts so they must be
4 volt lion cells (the battery pack says: 56v 2a Lithium ion), weird how they all measure exactly 3v.
One more thing these cells are the same length as 18650 and same diameter on the ends but quickly taper out in the middle to 20.5mm for most of there length. They are lime green with no markings anywhere, cells are manufacture this way, can't find any info anywhere, if the battery pack is labeled Lithium ion so I guess it's ok the charge these to 4.2v like all lithium ion cells?

 

[ChrisGarrett]

Camera, picture, host and post.

I don't think I'd be doing anything with those cells until I first identified them.

But that's just me.

Chris

 

[andrewnewman]

So EGO makes high power electric yard tools. Their web site doesn't contain more than marketing information on their battery packs and I doubt (unless a former EGO engineer is on this board) a lot of information on these individual cells will be forthcoming. If they really are "traditional" (ICR / IMR / INR / NCA) cells then a storage SOC of 3.0V is awfully low. Since the funny shape of the cells makes them hard to re-use I vote that you just leave them alone.

 

[billcushman]

I have several Ego products and batteries. When the batteries aren't used for a couple of weeks, the battery pack goes into a storage mode with about 30% capacity. The 3.0DCV you measure sounds like the pack is in the storage mode. The fact that all cells are the same suggests that Ego's maintenance and balancing circuit works well. When fully charged, the Ego battery pack reads about 58.0DCV no load. 58/14=4.143VDC. Charge voltage to a little less than 4.2 only gives a slight capacity reduction and helps prolong cycle life. The special fast charger for the Ego batteries will fully charge the packs in less than 30 minutes. It has extensive forced air cooling for both the battery and charger. I have had the batteries for over two years and they continue to work as new.

I bought some store return tool battery packs to yield some high current 18650 cells, one pack was a EGO 56v 2a pack, looked new. I took it apart and found
14 cells, all measured 3 volts exactly, I thought they may be INR tool type cells that run 3.2 v but that won't equal 56v, 14x 4 volts = 56 volts so they must be
4 volt lion cells (the battery pack says: 56v 2a Lithium ion), weird how they all measure exactly 3v.
One more thing these cells are the same length as 18650 and same diameter on the ends but quickly taper out in the middle to 20.5mm for most of there length. They are lime green with no markings anywhere, cells are manufacture this way, can't find any info anywhere, if the battery pack is labeled Lithium ion so I guess it's ok the charge these to 4.2v like all lithium ion cells?

 

[Gauss163]

I have several Ego products and batteries. When the batteries aren't used for a couple of weeks, the battery pack goes into a storage mode with about 45% capacity...

Below is what the battery manual says about the battery's automatic storage discharge function:

Notice: This battery pack is equipped with an advanced self-maintenance function to extend the battery life. Depending on the battery charge, it will automatically perform a self-discharge operation after one month of storage. After this self-maintenance, the battery pack will enter sleep mode and maintain 30% of its charge capacity. If stored for a month or longer, fully recharge the battery before the next use.

It is not necessary to run down the battery pack charge before recharging. The Lithium-Ion battery can be charged at any time and will not develop a "memory" when charged after only a partial discharge. Use the power indicator to determine when the battery pack needs to be recharged.

 

[billcushman]

30% is correct. I have edited my original post. N4aeq, the Ego Manuals are on-line if you didn't get one with the battery.

Below is what the battery manual says about the battery's automatic storage discharge function:

 

[Gauss163]

The 3.0DCV you measure sounds like the pack is in the storage mode.

Based on the above excerpt from the manual, storage mode is initiated after discharging to 30%. Looking at HKJ's voltage at %charge charts we see that 30% charge is typically between 3.55-3.77V. So if the cells have self-discharged down to 3.0V then they have probably been stored for quite some time (or they were never discharged after being drained below 30%).

 

[billcushman]

The above excerpt from the manual says storage mode is initiated after one month of storage. N4aeq, I just checked a battery in storage mode. it measured 51.7VDC or about 3.69VDC per cell. Your battery is discharged to a lower voltage than typical for storage mode. Self discharge is typically very low, so your battery was probably run down to the 3.0DCV per cell you measure.

Based on the above excerpt from the manual, storage mode is initiated after discharging to 30%. Looking at HKJ's voltage at %charge charts we see that 30% charge is typically between 3.55-3.77V. So if the cells have self-discharged down to 3.0V then they have probably been stored for quite some time (or they were never discharged after being drained below 30%).

 

[Gauss163]

... One more thing these cells are the same length as 18650 and same diameter on the ends but quickly taper out in the middle to 20.5mm for most of there length.

The tapered shape is most likely the result of the cells being wrapped in phase-change material for cooling purposes (Ego calls this "Keep Cool Technology"), for example see here. Could you please post some photos.

 

[Gauss163]

There are some illustrations in this Ego youtube video, excerpts below. Note the cooling wraps around the center of each cell.

 

[ChrisGarrett]

There are some illustrations in this Ego youtube video, excerpts below. Note the cooling wraps around the center of each cell.

Thanks for the pictures.

That 20mm in the center, OP had mentioned, had me scratching my head and I thought maybe his cells had swelled in the center.

Chris

 

[N4aeq]

Thanks, I knew if there was a answer it could be found on CPF. Yep I may remove the shrink wrap and see if the cooling band is removable, it would be
interesting to have a high discharge INR cells for those high power led projects in the future. I did try charging some of cells up with Lion charger and they
went to 4.21v and holding for about a week now so I guess they are the typical INR18650 cells that are in all power tool battery pack.