How to increase lithium-ion battery pack life?

Does a high-quality commercial tool do enough to prolong the life of its lithium-ion battery pack?

Should they be recharged whenever convenient instead of waiting until the tool requires recharging?

I just had a lithium-ion battery pack die before it's time. I'm wondering if better handling would have prolonged its life. Seems that one of the 3 cells switched off. One cell is 3.75 V, one is about 4 V, and one is 0 v.

There is no way to turn the cell back on? Assuming that's what happened.

Thanks.

Reply to
John Doe
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They turn off when they get discharged so much that they can't be brought back to life safely.

I don't know what your charger is doing, but it sounds like it wasn't balancing the cells, or perhaps like you were really pounding on the poor battery pack. Lithium-anything cells really don't like being either fully charged or fully discharged. Keeping the tool charged up when you're working on it, plus one light use at the end of the day, is probably going to lead to the longest battery pack life.

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www.wescottdesign.com
Reply to
Tim Wescott

As Tim pointed out keep the cell in the 25% - 75% range of charge. The original LI-ion formula has nasty ageing outside that range. Newer cells seem to be better. Out of the LI-ion battery packs I've had, the one I rebuilt with individual cells has lasted the longest. If you can freeze them, you'd slow the ageing process. I have a little Hayer TV, for emergencies, that the pack is in the freezer all year.

Cheers

Reply to
Martin Riddle

Lithium cells are not yet ready for prime time use in tools. They have two advantages.

1) lightweight 2) When you pick up an infrequently used tool, it's more likely that it will work. I have one lithium screwdriver. Guess what, one of the cells is open. And there is NO replacement battery available for it. Even if there were, it would fail again if I used it. NiCd batteries are best when used in power tools. Problem is that Cadmium fears killed 'em. I don't have any power tools new enough to use NiMH.

Each cell has a "snap disk" that opens the circuit when the internal pressure exceeds some design value. I've read reports that suggest you can flip it back on by poking an object through the hole in the positive terminal. I played with the concept and was never successful. Also risky if you puncture something. I've thought about applying external air pressure, but never had any way to exert enough pressure. I thought about hooking up a 2000PSI argon tank to a pressure cooker...briefly...I didn't want to die when it exploded.

The primary failure mode of lithium cells is increased series resistance. The electrons are in there, but you can't get them out because the external circuitry won't let you. A side effect of increased internal resistance is increased heat. Heat raises pressure and the disk snaps. Can happen on charge or in use.

Power tools ABUSE batteries. Lithiums ain't up to the task...yet.

Ridgid addressed the issue with a lifetime warranty that includes the battery. Sounds good on the surface, but I worry about who's lifetime. More likely, the battery won't be available 20 years from now when I try to claim the warranty. And I'd be inconvenienced by the 10 weeks it takes them to send me a replacement.

Chemical reactions happen more slowly at lower temperatures. Conventional wisdom suggests that you should NOT freeze a battery. Depends on your definition. If the temperature in your freezer is below the freezing point of water but above the freezing point of the electrolyte inside the cell, you're probably ok. I don't know that number.

The suggested storage state of charge number for laptop batteries seems to be 40% It's a balance between the chemical reaction and the pack discharging itself through chemical reaction and drain from the battery supervisor. If any of the cells gets below the threshold, the controller shuts it off and you can't use the pack, even though all the cells would work.

Vendors don't care how much money we spend replacing battery packs. They care a LOT about getting sued if they do anything "better" than the competition. This causes everybody to be conservative. They also like to make new stuff incompatible with the old stuff so buying a new tools is an attractive alternative to fixing the old one.

Reply to
mike

It may, but it depends on what motivated the charger designer - maximum battery life or maximum tool performance per charge.

Assuming a sensible charger design, "opportunity charging' does NOT harm Lithium-Ion packs.

The "normal" pack protection modules have multiple functions related to safety. These include:

. overtemperature shutdown . pack overvoltage/undervoltage shutdown . overcurrent shutdown (discharge) . cell voltage differential.

The cell differential mechanism would kick in with the 3.75 vs 4 volts, so how the other got to 0 volts is a mystery IF such protection exists in the pack.

Some cells also contain an internal safety fuse, which could explain the 0 volts and the failure. Unfortunately some less-than-prefessional manufacturers may skimp on the pack protection and place heavier reliance on the cell fuse.

Most reputable cell manufacturers list parameters such as terminal voltage point-of-no-return, typically around 2.5 volts. But for the yumcha cells most often found inside sealed tool packs, it is a safe bet that anything below 2 volts (at the actual cell) is terminal (no pun intended). If an internal fuse has failed then the cell is beyond resuscitation as these are not user-serviceable.

Reply to
who where

They are in the best tools.

That makes a world of difference in most hand-held power tools.

The battery pack that failed here came with a Dremel rotary tool. The charger is obviously cheap. You plug the battery in, the light turns on, the battery takes hours to charge, and then the light goes out. I have other hand-held power tools. Bosch 12V MAX pocket driver and pivoting angle drill that use lithium-ion batteries and a real charger. Lithium ion battery performance is stellar in most modern handheld power tools. That's why lithium-ion batteries are used almost exclusively in the best new handheld power tools. Lithium-ion batteries are what make cordless cutoff tools a reality, an extremely useful tool for a do-it-yourselfer.

I have a Bosch 36 V lithium-ion drill that has not been used so I can't say much about it, except that it's charger is fan cooled and beeps when the charge is complete.

That's why they include a heat sensing thermistor that can shut the tool down. Even my cheap rotary tool includes one. Going by the other replies, the cheap charger is probably what killed my lithium-ion battery pack. I don't like cheap chargers for my NiMH batteries either, that's why I got a Maha/EnerMax 9000.

Another reason is because it is nontransferable, you are a virtual stockholder.

Professionals who use their tools HARD and long love modern lithium battery powered tools. Festool is high class. Their expensive cordless drills are lithium. The same for the best Bosch cordless drills. The same for DeWalt. Ect.

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> Chemical reactions happen more slowly at lower temperatures.
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Reply to
John Doe

Yep, and LCD displays were in the best laptops before they were ready. You gotta start somewhere.

It'll likely last longer 'cause it draws 1/3 the current of a 12V drill.

except that it's charger is fan cooled

Lithium chargers are the simplest chargers around. All you have to do is limit the charge current and let it run till it reaches 4.2V/cell (some variation for variants of the lithium concoction) and shut it down if something goes awry. Yes, there's all manner of protection around it, but the charge algorithm is much simpler than NiCd or NiMH.

powered tools. Festool is high class. Their expensive

For professionals where time is money, I can't argue against expensive tools. For the rest of us, lithiums ain't worth the cost...YET.

Oh, there's another advantage to lithium. Because of the risk of fire, lithium tools just stop working when the battery is low. One of the main reasons for NiCd battery failure is people who drill just two more holes after the battery gives out and reverse the weakest cells. Doesn't take much of that before your battery is toast.

And you say: "I just had a lithium-ion battery pack die before it's time."

Sample size is small (1), but I've experienced 100% failure rate with lithium batteries in power tools. And the failure mode is characteristic of over-stressing the cell. The reason I don't have more lithium powered tools is that they're not yet ready for prime time....is there an echo in here??

Reply to
mike

Really? Laptops were better with CRT displays?

I have 6 LiIon cordless drills, four 10.2V/12V Bosch and two 18V Bosch. The only problem I've had is one of the 12V batteries had an early-life failure. Somewhat disappointing but as a little compensation my local Home Despot was closing them out and I bought five for $15 each. Love the drills/drivers. By contrast, my NiCd drivers are heavy and clunky.

You *obviously* know nothing about the subject. Cheap chargers are nothing but a T/R and resistor.

Not at all. The "all manner of protection" *is* a necessary part of the algorithm. Neither are terribly difficult, anymore, since there are chips designed to handle both, well. It costs an extra buck, though.

powered tools. Festool is high class. Their expensive

They are for me. Though for things like saws, I'll likely stick with NiCd.

Yes. By the time you know it's dead, it really is.

Of twelve packs, I had one die after maybe three uses. Yes, it happens.

I have a half-dozen dead NiCd packs. Two of them were just rebuilt and hadn't been used in a year or so. Dead. No battery technology is perfect. If you dead batteries worry you so, used corded tools.

Yes, you're talking to yourself, again.

Reply to
krw

I just noticed that's not the case here. The tool has only two inputs, for the battery.

But my 10.8 V Dremel rotary tool has been converted to use Bosch

10.8 V batteries. The lousy charger problem should be solved.
Reply to
John Doe

You're *obviously* smarter than me. Here's another chance to demonstrate your superiority. Please edumacate me on lithium ion chargers. I wanna git smarter. What's your definition of T/R? Then go on from there.

Again, please explain how the protection does anything until it detects a fault???? And how that affects the charge algorithm...other than preventing you from charging or discharging a "faulty" battery pack.

Neither are terribly difficult, anymore, since there are chips

powered tools. Festool is high class. Their expensive

Methinks you're looking at the wrong end of my assertion. The point is that you are UNABLE to drill that one more hole that would harm the pack. Cell reversal often happens with NiCd tools without this shutdown feature.

What few samples I have suggests that the fully discharged shutdown function is in the tool. A removable pack will probably have additional safety shutdown features that may not be recoverable by simple external means. Overvoltage, undervoltage, cell imbalance.

Overheat, undertemperature, etc. should recover without intervention.

Each cell has additional protection often based on internal pressure being too high.

Normal use does not activate ANY of the shutdown features of a battery pack. They're there as the last line of defense for a system fault or a battery fault.

yes, There were a zillion tools, flashlights, radios that charged the crap out of batteries and terminated the charge when the battery got HOT. Works surprisingly well for NiCd packs IFF you fully discharge the tool, but don't over-discharge it, before recharging. For devices that aren't in continuous use with properly scheduled recharges, the batteries get cooked in short order.

But we're talking about LITHIUM batteries here. All the NiCd stuff is a preemptive strike that will hopefully suppress ranting off topic with issues irrelevant to lithium chargers...yeah, right!

The important thing is that I listen to myself. ;-)

Reply to
mike

Well, you said it.

Transformer/Rectifier. You're not an engineer, right?

Now, go back and read what you wrote.

It keeps you firm setting fire to your pants.

powered tools. Festool is high class. Their expensive

Me thinks you're right. I *am* smarter than you.

Please read what's written, not what you think has been written.

What *are* you yammering on about?

Clueless.

You were talking about batteries, in general. It's understandable that you can't read what others write but most illiterates can read what they wrote, anyway.

Good thing no one else does.

Reply to
krw

Which makes them very definitely ready for prime time use in tools. Maybe it's a case of "some people like vanilla while others like chocolate". Is there a definitive comparison of battery types in tool usage?

Ed

Reply to
ehsjr

Since every manufacturer is moving swiftly to Li-Ion, there will be little choice. The benefits of Li-Ion over NiCd are significant for most tools. I'm not sure I'd want a Li-Ion circular saw, though.

Is there a "definitive comparison" between vanilla and chocolate? OTOH, the direction that manufacturers are taking is pretty definitive.

Reply to
krw

If it is a "closed" pack rather than loose cells (sic), then the only requirement externally is the two end terminals - all the protection functions can be executed internally without dialogue with any external device.

Reply to
who where

If you read what I said, there is no, zero, none, not any wire connected to the junction between the two cells. The cells are not removable without disassembling the screwdriver.

Reply to
mike

Read what WW wrote. "It's in there."

Reply to
krw

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