Charge while you sleep?

Hi All,

I'm curious to hear from the more experienced harvesters what their approach is to personally monitoring charging. For instance how many people are comfortable tossing freshly harvested cells into a charger and then going to sleep for the night? Do people change how much they monitor a cell by class? For instance it sounds like most people are present 100% of the first hour that they try to revive <1V cells.

My setup is basic, a single Opus charger. I know some have advanced temperature monitoring setups, and it will be good to hear about these, but I'm curious about advice for those with basic setups/skills.

And before Wolf says anything I agree that by measuring IR you reduce the chance of having a heater and so can have higher confidence in charging while you sleep. Seriously amazing work he's been doing.

It's easy.

Starting voltage can indicate health, and recovery.

The lower the standby voltage between 3,0V, the lower current I charge them with.

Between 2,0-2,5V, I charge at 100mA.

Between 1,0-2,0V, I charge at 50mA.

Below that, I go at 25mA.

I recover cells using a buck converter so that I never have any risk of a cell heating itself up too much, so using a low current for low voltage recovery is very useful.

For any recovered cell above 3,0V before analysis, I charge at 500mA, and check if any of the cells are hot after a full charge, and if they are fully charged.

At 500mA, there's not much energy to dissapate for a faulty cell.

What about cells >2V. I have just been tossing a set into the charger in the morning and the next set in at night. Everything except the infamous Red Sanyos. After reading all the posts I'm a bit nervous about them and would like to be around when I charge them to check temperature more frequently.

So I suppose a related question is "how dangerous are heaters?" I've not yet encountered anything that I could, without a doubt, call a heater, but I'm only touch checking when I'm around, which is basically weekends. How hot do they get? Start a fire hot?

I have already set up the charger on an ATX to avoid the overheating issues with the undersized PSU, and have a fan blowing through the back grill so there shouldn't be heat buildup in either place.

Having a smoke alarm over the work/charge area's probably a good idea.
Temp sensors rigged to cut charger power might help too.
Having a fire resistant surface or a charging box, etc (many threads here on that one!)

There's video of a guy who's got some cells on charge & the security camera catches it going south at 3am (couldn't find a link to it!)

@Nemo, heaters aren't dangerous if you limit the current.

Even if all of the power was wasted into the cell, at 250-500mA charge current, you are at most releasing 2W of heat into the cell, which isn't much in the grand scheme of things.
Cells are really nice when you treat them nicely.

I've had tons and tons of heaters, and I've never had a problem even once.
It's the procedure that matters.

I first look at the cell type.
If it has a new capacity of 2000mAh and below, and is a laptop cell, I charge it according to the protocol above and check its voltage beforehand, and if it's above ambient after the average charge time and still charging, then I do a discharge down to 2,8V, and then charge back up again. If it charges up to full without heating at 500mA, I keep it for more testing. Otherwise I throw it out in the fun box, where it gets throw out for further testing down the line.

If it has a capacity between 2200-2600mAh new, I do the same thing, except I cycle it 2 times to check if capacity and internal resistance recovers.

If it has capacities above 2600mAh new, I do the same thing again, but I cycle it 3 times, and even higher if it's a very high capacity cell.

I'm actually writing my own paper about it with tests, findings, hypothesis, and others.
It's so amazing how few people actually did this kind of research, as the Sanyo cells between 2012-2016 proved to me with their extremely high internal resistance that once came down if the cell was charged back up at very low currents, and discharged back to remove blockage from the separator basically. I think I talked about it back in 2018.

TLDR: I will not release the paper itself, but will release the findings probably later this year or next year.
It's so interesting. Capacity tests, internal resistance tests, internal resistance progression according to charge current, recovery charge current, separator state from a new cell vs an old cell vs a Sanyo heater. It's so... fascinating really how much I discovered that can be applied to recover cells and "destroy" heaters.

Just got back from the recyclers and broke a bunch of medical packs down.
Netted 150 UR18650F Sanyos.



All above 3V and IR <55m?
Had 12 cells with IR over 60m? placed into the giveaway box. IR too high for me to use.

Charging/testing 44 now




and slow charging14 cells which were <2V with <55m? at CC/CV 4.2 50mA per cell to see if they recover.




WIth proper IR check I know these cells will be fine.
I will be sleeping like a baby

Wolf

BlueSwordM said:

I'm actually writing my own paper about it with tests, findings, hypothesis, and others.
It's so amazing how few people actually did this kind of research, as the Sanyo cells between 2012-2016 proved to me with their extremely high internal resistance that once came down if the cell was charged back up at very low currents, and discharged back to remove blockage from the separator basically. I think I talked about it back in 2018.

TLDR: I will not release the paper itself, but will release the findings probably later this year or next year.
It's so interesting. Capacity tests, internal resistance tests, internal resistance progression according to charge current, recovery charge current, separator state from a new cell vs an old cell vs a Sanyo heater. It's so... fascinating really how much I discovered that can be applied to recover cells and "destroy" heaters.

Click to expand...

Should bean interesting read when you're ready to share!

@BlueSwordM

It is interesting to hear your procedure, very different than what I read to be the standard around here. It almost sounds like you treat all cells like ones that need reviving, a "gentle wake up". I"m following more of the "cold bucket of water wake up" of tossing any battery >1V into the charger and doing a charge/discharge at 1000mAH. Under these conditions it sound like I may eventually be asking for trouble.

This, along with some other reasons I will post about soon, is why my next equipment purchase will be a YR1030 Internal Resistance Tester. Going by IR I can increase the chance of weeding out heaters and feel comfortable charging at night.

Have you done any comparisons of your gentle method versus a hard one to see if it improves viable cell yield, or elongates life?

I always treat lithium-ion cells very carefully, especially since I mostly find powertool cells these days, and these are extremely valuable, so I take every precaution possible.
It's been quite successful for now

An internal resistance tester, like an YR1030, a universal battery charger, some TP5100s, and buck converters are what everybody in the forum should start with.
That's enough to do a lot of testing already.

The best of the best would be an all included tester with charge current from 0,025A-1,000A, CC discharge up to 1A, internal resistance testing using very low resistance copper alloy springs, etc.

That would be great.

And I haven't done any comparison yet.

While my method has been proven, the results haven't been recorded.

The only thing that I know is that the % of recovery of 18650 cells has gone up significantly since I've started using this method.

@ BlueSwordM.
Would love to read your paper.
Thanks in advance, best

BlueSwordM said:

An internal resistance tester, like an YR1030, a universal battery charger, some TP5100s, and buck converters are what everybody in the forum should start with.
That's enough to do a lot of testing already.

Click to expand...

@BlueSwordM,

I applaud your choices esp. the YR1030.

Here is my List if I was stuck on an Island with nothing but a bunch of solar panels and a hugecontainer full of 18650s just floated to the shore.
YR1030, TP5100, (some cell holders) aBoost/Buck converter (and more cell holders) a PS to power the lot. Alsosome form of capacity tester whetherit would be a commercial unit such as an OPUS or similar. I prefer the SKYRC (Expensive) or the Foxnovo (Reasonable). You couldalso use aZHIYU ZB206 or a ZB2L3 for capacity testing.

The best of the best would be an all included tester with charge current from 0,025A-1,000A, CC discharge up to 1A, internal resistance testing using very low resistance copper alloy springs, etc.
That would be great.
Note: 1,000A not sure what you meant here but that's a lot of A

Click to expand...

The all in one concept would be the cats a** but for several reasons I don't think it would work.Certainly the charging and discharging can be incorporated into a single operational unitas the switching from charging and dischargingcan be done using relays whethermechanical or solid state.
The IR measurements are going to be a little more difficult to incorporateas we are dealing with m? and any resistance no matter how small will obviously affect the outcome. Could the delta of theresistance of the relays be calculated... absolutely. We actually may not have to do that as the IR sensing wires would be separate from the DC circuitry.We do have to remember that we still need to adhere to a 4 wire 1kHz AC m? reading. Sothe only delta we need to worry about is the actual resistance of the sensing wires.The normal cell holder used for charging and discharging would not work. We would need a 4 wire cell holder for each cell being tested. For now I think I will stick with the YR1030.

I think in the future I will build a single test unit to incorporate all three measurements. As the IR reading using the 1kHz AC method is separated from the DC charge/discharge voltage and current,it will be interesting to record the IR as a cells voltage changes.
Maybe it can be incorporated into a reasonably pricedDIY project.

We will see.

Wolf