Harbor freight sells the security bits for less than $10 for a wide collection of sizes.

@@drescherjm you underestimate how lazy I can be! 😂

Small ones break easily but any bigger than T20 are basically impossible to snap, and difficult to drill

Lol

Hi Jeff! BigClive would open it with a vise, a d sometimes a hammer (although he's usually more careful with battery packs)

Me: Uses security torx as my only torx bits.

Needs to make a bandsaw out of old batteries, then use that bandsaw to cut open a battery. That would be peak Matthias Wandel

Man is amazing, I tell ya!

Also never run them down too low and if you can wait for 10-15 minutes to cool them off before charging them again. If you can, avoid fast charging that will help their lifespan as well.

it's not woodworking directly, and my battery related stuff is on this channel. It has a tenth the subs, but the views the videos get are the same, so which channel really doesn't matter in that regard.

I've encountered many different opinions regarding how charging affects battery life. I've always been "keep 'em charged" kind of guy. I usually run them until tool performance suffers rather than until they stop working. If they're not in use and below 50% I charge them, and if they're below 75% and I plan to use them hard I charge them first. Some people have told me that Li-ion batteries have a fixed number of charge cycles regardless of the depth of discharge, so if I charge one from 70% to full, I'm "wasting" a charge cycle and shortening the life of the battery. I would love to know if it's that's true or not. I suspect there's a kernel of truth to it, but like so much conventional wisdom on the internet, it's probably exaggerated or only partially true. For now I'm more concerned about excessive discharge than charging too often.

@@charlesenfield2192 You've got the right approach to making your batteries last. The charge life of a lithium battery isn't "wasted" for any given charge -70% to full is not equivalent to say 10% to full. There are charge profiles that reduce the lifespan of the battery - for example charging at 1C (charge current equal to battery Ah rating) is more stressful than charging at 0.5C and less stressful than charging at 2C. Many lithium ion batteries keep better when stored between 30%-70% charge while not in use, and avoiding a complete discharge may extend the life somewhat. Extreme temperatures when charging or in storage can also wreck batteries - keeping the batteries in a climate-controlled place will help more than micromanaging every charge event.

@@PaulSchaffert Except that lithium batteries don't like being kept fully charged. Modern phones have a "smart charge" feature which engages if you're charging overnight - it charges to 80% and then holds, only doing the last bit to 100% shortly before your alarm is scheduled - for exactly this reason. So regular charging is good, but charging to 100% is only good if you're going to use the tool fairly shortly afterwards. For longer periods without use the battery should be at mid charge ideally.

Only if used infrequently. Probably not a regular use case for an expensive pack like that.

​@@matthiasrandomstuff2221 For my own needs, I only have two of the giant flexvolt packs, and I use them exclusively for my mower. I use them every couple weeks during spring/summer/fall, but they sit all winter unused. I'll have to make sure to leave them a little discharged going into winter, and top them off before the first cut in the spring!

On the contrary, the engineers are more than likely aware and the bean-counters love it that way. More dead batteries = more battery sales.

@@Orcinus24x5 this is the most likely answer sadly. Every aspect of something like this is understood and engineered to the nth degree. Any flaws this fundamental are absolutely 100% deliberate.

@@JeffGeerling Leave them at 60% for over winter. Li-Ion cells don't like to be stored at 100% long term.

It still happens. Thanks for reminding me that I need to put my batteries through a charger cycle.

Yeah. First generation has a controller board the ran off one cell and if unused for several months would kill the whole thing buy locking out the charger. The trick to keeping them alive was to charge them every few weeks. I still have first generation ones that work from more than 10 years ago. The newer ones that have a star cast into the plastic case changed the design so the control board runs off the whole string of cells and has cell balancing. Still a good idea to keep them charged up at least once a month. And maybe even leaving them on the charger for a day or so so the cells can properly balance

Have you tried building a portable battery bank or a car booster?

Yes, if the voltage of an individual cell is close to but just under the threshold for charging, then that individual cell can be charged by itself, or the entire pack can be, but in either case it would have to be charged using something other than the factory charger.

@@stevebabiak6997 You just have to get that 1 cell up to about 3v with a hobby charger attached with clips or magnets and the factory charger will finish charging it.

@@Bob_Adkins - exactly, the factory battery charger for the entire battery pack won’t be able to do its job until that low cell is charged up using something else. And I didn’t bring into the picture that some tool battery manufacturers have a component in the battery pack that remembers a cell was low and keeps the pack disabled - I just can’t say that the brand being discussed here does that. But a brand that does that could leave the pack disabled even after the cells that were low were externally charged up to a proper minimum level.

@@stevebabiak6997 That's possible, but not very wise.

@@Bob_Adkins - there are brands out there that do that, and those who try to repair those battery packs have to bypass that “feature”.

A single bad cell in this 3p configuration would pull down its two siblings as well. I seem to recall that the red shipping clip is called for during storage. It mechanically disconnects the battery from a 5s3p to three 5s1p. That would protect a single bad cell from becoming three bad cells. Until we try to use it.

Hmmm, I thought that the BMS circuit board is supposed to prevent draining of the cells to a point below the low voltage limit. Good for you that the batteries were replaced under warranty.

@@stevebabiak6997 this is what Matthias got into near the end with the dewalt batteries. They do but only halfway down the chain and only when charging. If they sit on the shelf for too long, some batteries may discharge faster than others and can cause them to break if you run the entire battery flat

actually, stated by dewalt in its website

It is for Li Ion batteries. But previous battery chemistries needed to be run down once in a while.

@@Nono-hk3is Actually, not only for Li-ion batteries, it applies to nickel chemistry too. Where a battery has a number of cells in series, then running it all the way down is likely to reverse and damage at least one cell. For lead acid chemistry like car batteries it is even worse. Running a normal car battery even 50% down can damage it.

@@Nono-hk3is Bs myth.

How to charge the cell individually? What kind of charger can be used?

you have to inject low voltage with a probe on each cell until it gets to a detectable safe charging voltage for the dewalt charger@@harenthiran

The one in his diagram is in the pack.

the problem is that the tool is the one with the low volt shutoff, and it just sees the total voltage

Concrete nails are more available.

Problem is the PCM, it's pretty much potted so impossible to reverse-engineer the circuit.

@@zaprodk We ended up turning off the control system when we weren't using the battery or an extended time.

@@ahbushnell1 i was talking about the DeWalt FlexVolt pack :)

the pack would die very quickly under any load, analogous to a high rpm engine with no torque.

the math is like this. 5p = 4.2 * 5 = 21 volts at full charge AND 16v at design lowest (assuming a 3.2v cell cutoff, which is typical, though they may use as low a 2.6v cutoff to shorten pack life). Below 3.2v, a typical li-on battery has almost no power. This is called the "knee" because ampacity falls off logarithmically below this voltage. In a motor analogy, there's "no torque". So let's imagine the loaded cell depleted down to 2v, and the rest of the cells floated down to 4.15v. You'll measure 18.6v, which might be around 50% on your "fuel gauge", however you have mere seconds worth of "torque" because the voltage on bad-cell is going to collapse on you (down to 16v). Make sense?

keeping batteries always fully charged doe cause them to deteriorate faster than if you keep them half charged

@@matthiasrandomstuff2221 that's not true where did you pull that horse sht from?