Salvage % expectations?

P

Ptjeff

New member
Joined
Oct 28, 2017
Messages
8
Hello all,
I'm new to the group and thought I'd throw out my first, of many I suspect, questions.
I've just harvested 168 batteries and have probably less than 25% that are above 2V.

Is that a normal amount?

should I bother withthe ones >1.5V andcharge them, or have they gone too low?

PTJeff
 
I'm also new and I'm charging everything I find up to 4.2V and then I wait for a few days and check for voltage drop. Too much drop, goes to recycling.

I've watched videos of people recovering cells that were at 0V and they turned out to be great cells.

I'm sure the experts here will chime in.
 
Ptjeff said:
Hello all,
I'm new to the group and thought I'd throw out my first, of many I suspect, questions.
I've just harvested 168 batteries and have probably less than 25% that are above 2V.

Is that a normal amount?

should I bother withthe ones >1.5V andcharge them, or have they gone too low?

PTJeff
Click to expand...

IMO, charge everything that will take a charge. Being discharged to a low point and stored that wayisn't ideal, but it may not have done much damage if it hasn't happened repeatedly.

I've had plenty of cells test over 2ah with a starting voltage below 1v.

Zero voltage cells that will take a charge are more effort for a lot less return though. Maybe only 10% over 1800mah

As for is it normal to have 75% of cells below 2v.... I probably have had about 50% below 2v, but it will vary. A lot of yours might have been sitting for a few years self discharging before you got to them.

I bring low voltage cells up to about 2.8v at a low charge rate (about 100ma or less) in NiMh mode on a hobby charger and then switch to LiPo at 500ma.

Forgot to say... there's a few youtube videos around on "resetting" a zero voltage cell with a screw driver. Don't do that! Getting a cell to go from 0v to 3v by poking around the +ve cap with a screw driver is bypassing a protective device (CID) which popped for a reason. (and we won't know what the reason was).
 
If it takes a charge, charge it. Sometimes it just needs to be pulled back up. True, its life has been shortened, but under the life of a powerwall cell, it should be fine in these applications.
The ones you want to watch out for are the cells that charge up, and then loose voltage in a few days or less. So, if you charge to 4.2V, and it has dropped to 4V in 2 days, I'd not use it in the powerwall, but for other applications (flashlights, etc)
You don't want a cell that discharges more than .1 V over a month.
So, self discharging would be of higher concern than low voltage out of a pack.
 
I dont care about initial voltage. I test ALL cells out of the packs. If they go through a cycle and have more than XXX mAh i call them ok cells. I test at 1A and my avg good rate for most people is around 30-40%.


I would say more than 80% of my cells have been below 2V and more than 40% below 1.5V... I have tested over 5000 cells and for instance I got one pack of over 2000 cells new old stock. All below 1.5v but 99% tested 98% of their capacity ;)
 
Anything below 2V i charge gently. 50ma, until it reaches 3v. Then I charge it to 4.2v at about 250ma. Leave it sit for a week, and check for self discharge. If no discharge is evident, cycle and test. So far this method has giiven 100% usable cells. Side some with humorously low capacity
 
Thanks for the input and encouragement everybody. After I posted I went back and divided the cells into 4 groups: 0, <1, 1 - 1.9 and >2. I'm getting about 30% in each that have a reading and only a few that have no voltage. Most of the 0 group come from whole packs that have some sort of damage. I've opened one with corrosion, water damage, and what I can guess as thermal runout. Whoever that belonged to is probably one lucky guy.
I've got another 40 or so packs to break.

PTJeff
 
What are you using to test your cells with?

I have the classic OPUS BT-C3100 and it will automagically charge at 50-6mA when the voltage is too low. Once it hits 3V or so, it will push whatever amperage you've got it set for.
 
This is how I test:

And yes the Opus is good in that sense that you just ut the cells in and it does the rest.
 
daromer said:
This is how I test:

And yes the Opus is good in that sense that you just ut the cells in and it does the rest.
Click to expand...

Impressive and not surprising.

What do you do about cooling? Your fan are very close to cables and if you charge/discharge at 1A, don't you get heat issues?
 
Heat issues in what sense? The cables have no issues with it. I also only have 10C in the area where I test so no problem with that. If the opus stops for a while due to overheat thats not an issue either. They have 12hour to complete 1 cycle untill Im back :)
 
daromer said:
Heat issues in what sense? The cables have no issues with it. I also only have 10C in the area where I test so no problem with that. If the opus stops for a while due to overheat thats not an issue either. They have 12hour to complete 1 cycle untill Im back :)
Click to expand...

As you said, the OPUS stops when overheating which I'm guessing has to affect the charge/test mAh test results.

If I only do the test at 500mA, it never stops and I get a rating.

If I do the test at 1000mA, it will stop often which leaves the results suspect.
 
I don't yet have any testing or charging equipment. I would love to have a 16 station charger all pimped out with the ts4056 and glass fuses, but I'm not in a time crunch. That would probably be overkill, although I'm still flirting with the idea. I'll probably get an Opus, or maybe the sort that, umm, and, um, and ... AvgRage Joe uses. ?
BTW, as I breakdown more laptop batteries the quantity of those >2.0 are dramatically increasing. Probably 60:40 (2+: >1). Much more encouraged that I'll have enough for my project.
PTJeff
 
There are plenty of options for charging and capacity testing. Depending on your budget. I like the Opus personally. I charge up the batteries using another charger so it is more efficient.

That said look around - there are all kinds of different setups people use. If you are on a budget TP4056 for charging and ZB2L3 for capacity testing.

There are plenty of Opus alternatives too. So long as you use the same method to capacity test for all your cells, that will be fine.
 
Oderus420 Thats correct. I run at 1A to weed out all heaters. i dont think the stopping is of a big issue as such since the total meassurement will be same on all cells tested.

The capacity should not differ that much just because you stop in the middle for a short wile. Its not like the cell regains capacity by resting :)
 
Just pulled almost 300 packs apart and I'm going back to the recycle bin again to try more cells after reading this thread.
My cut off point was anything above .1v but I'm finding many good cells just above that using an old Ultrafire charger to wake them up and then passing on to my Liitokala Li500's to finish the job. Still waiting (almost 2 months) for some TP4056's to arrive to do the real grunt work.
So I may as well amuse myself trying to recover the hopeless cases.

Jimmy
 
Speaking of waking up batteries,
If this link works, is this safe, and
Is this legit?
Looks like it would save a lot of time bringing low batteries up to a chargeable state
PTJeff
 
I will test any cell that I get. The custom charger I am currently building chargers them and monitors the initial temperature and the current temperature. I have set a 10C cutoff, so if it gets 10C above the initial temperature it stops the charging and it will be marked as faulty. The charger also measures internal resistance and mAh. I put all the tested (recharged) cells in parallel on my iMAX B6 and charge them all up to 4.2v (As the TP4056 are not consistent) store them for a couple of weeks and re-check the voltage if they have doped 0.1v or more are sent off to the recycles. I have a 72.11% total of original capacity from 1404 cell curently. Check out my stats dashboard from my database http://vortexit.co.nz/battery_statistics.php
Cheers,
Brett
 
You must log in or register to reply here.
Back
Top