Some people say that if you run them completely dead, before charging, they will last longer. Both runtime, and lifetime.
Others say the opposite is true.
What is the truth about batteries ?
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used to be true. no more...tried it once and lost the battery
Myth 1. Batteries have a memory effect. For some time, tradespeople have passed along the myth that battery packs must be fully drained before recharging. Goger says that “memory†myth is based on cordless tools in a previous era. “Back in the '80s, it was possible to inadvertently limit battery capacity by methodically using a tool and draining the battery the same way over and over again,†he says. “Battery memory isn't an issue today because technology has improved and tools are used for a greater variety of tasks.â€
...The best advice for cordless tool users is simply to recharge a battery as soon as they observe a drop in performance, and to keep the battery in the charger until it's needed. Winston is more likely to run his batteries until they're completely discharged, but not necessarily because he's found that it yields better battery performance. “To be honest with you, I have a tendency to let them run all the way down, and that's just because I'm stubborn,†he says. “If it will still sort of drive the screw and I have to manually tighten it up a bit, that's OK.â€
http://www.taunton.com/finehomebuilding/PDF/Protected/021128108.pdf
http://ecmweb.com/mag/electric_taking_charge_cordless/
This has been covered a few times in the mag.
Here's some info I found
"One of the biggest myths is that you should run your battery all the way down before you recharge it". says Christine Potter, Senior product manager for Dewalt Industrial Tools. Doing so could cause individual cells within the battery pack to reverse polrity, rendering the battery incapable of accepting a charge. Instead recharge the battery as soon as you notice a dropin performance.
I also leave the batteries occasionally over nite to equalize the cells.
Have a good day
Cliffy
I understand conventional wisdom to say putting the batteries on the charger as soon as a drop in performance is noticed. From what I have been told it is heat from recharging which can shorten battery life.
I also remove the batteries from drivers and saws before leaving for the day and when I put them back into the cases.
Depends on the type of battery.
NiCads (almost extinct these days) needed to be run down.
NiMH (also getting rare) should be charged when you notice the first signs of slowing.
LIon -- dunno, haven't bought any yet, but have heard that you should recharge at the first signs of slowing.
>>LIon -- dunno, haven't bought any yet, but have heard that you should recharge at the first signs of slowing.<<
I don't know how other brands of Lithion batteries behave but, I have two 18v Ryobi batteries which seem to run along at 100% then just die instantly - no warning.
I bought one of the battery testers ("fuel gauge") to help me monitor them. As it seems the built in tester yields somewhat unreliable results.
Jim
Never underestimate the value of a sharp pencil or good light.
<< I have two 18v Ryobi batteries which seem to run along at 100% then just die instantly - no warning. >>What you're experiencing isn't a feature that's inherent to li-ion battery technology, it's an electronic protection feature that is added by the manufacturer to prevent the battery cells from discharging completely. If a li-ion cell discharges completely, it can be damaged. The limiter in the pack stops the power before it leads to problems.Justin Fink - FHB Editorial
Hmmm... Is that fact or personal experience? I've had a Milwaukee and now a Makita Lith-ion that
would run down (if I let them).
Thanks for the information! It definitely works.
>>The limiter in the pack stops the power before it leads to problems.<<
I wonder why the "high end" manufacturer's do not incorporate this feature into their batteries?
Maybe they figure the average Ryobi user will damage the batteries or, maybe....it is an underhanded plot to sell more batteries............;)
Jim
PS: I have had really good luck / long life with Ryobi cordless drills and impact drivers - wanted the LI batteries as soon as they were introduced -- managed to buy a 1/2" drill, flashlight, 2 full sized Lith Ion batteries, charger and bag for $ 99.00 after Christmas - considering the 2 LI batteries alone retail for $ 178. I could not turn it down......Never underestimate the value of a sharp pencil or good light.
Good answers.Another question...Imade a point of running the batteries completely down, before charging, when I first got my drill and impact driver.I thought you were supposed to do that.They now have less than half the amphours of when they were new. (new to me.)Is there any way to get those amphours back ? (Make the battery last longer, in use.)..Something is only impossible... Until it isn't...You are always welcome at Quittintime
If any spacecraft system tried to run a battery down ** below 50 to 60% of charge, Lloyd's would have the responsible engineer over to London for a serious BILLION dollar talk!
**(any type, most sats are NiMh, some not Li-ion, a few NiCds (esp russian))
Any type battery that discharges past the knee of the curve means $$ out of your pocket.
DW has a battery powered hair clipper, told her when you hear it slow down, STOP USING IT and recharge.
Every few hundred cycles some NiCds do benefit from full discharge.
Previous points on protection circuitry are to be noted. Spacecraft and even laptop Li-ion systems have very extensive charging circuits, have not yet torn down any power tool Li-ion charges to see how good of a job they do, probably only mediocre.
Is there any way to get those amphours back ? (Make the battery last longer, in use.)
No.
The "limiter" isn't incorporated in all li-ion batteries, I'm just explaining why some behave that way - why they stop all of the sudden and appear like the drill is just broken. It was a big discussion when Milwaukee's V28 hit the market in 2006.Justin Fink - FHB Editorial
The Bosch 10.8v tools I have seem to use a cut out when the voltage dips too low = time to recharge. Would be a good idea for all battery tools.
I had one today which was attached to a flashlight - seemed bright one second - totally gone the next.
Glad I wasn't way back in a crawlspace or something.
Note to self - use the old Nicad or whatever they were batteries on the flashlight........
JimNever underestimate the value of a sharp pencil or good light.
Just one thing to add to your summary of battery types.Recharge when performance starts to drop. DO NOT try to wring the last few turns of the screw or saw blade out of that battery. When the tool performance drops, one or more cells have run down and further power demand stresses the rest as they try to push current through them. At that point heat builds up rapidly, causing damage to the cells.It's best to let batteries cool down before recharging. I think most newer chargers sense battery temp and don't start charging until they cool off enough, but older chargers may not be that smart.BruceT
Hi Luka,
Been using and recharging batteries of various types for 30+ years.
Best thing I've found is to run them down to about 10% which is normally where they show a performance drop. Lithion batteries tend to run all out then they're out. In the mean time try not to allow the battery to overheat from overuse. And let one cool before you charge it.
Once you begin charging one, bring it to a full charge before using it....and once again let it cool before you use it.
Lastly, I've heard all sorts of horror stories about my next suggestion but I've never had a problem.....so try at your own risk......dead power pack......seal it up in a ziplock bag removing as much air as possible....wrap in second bag.....freeze for 48 hours.....thaw for 24 hours.....remove from bags....charge......if it won't charge.....recycle it.......I have about a 60% success rate recovering non rechargeable batteries to full recovery.
Pedro the Mule - The shocking truth of it all
I've heard of that trick, too, Pedro, but I've never tried it. I've got the perfect candidate right here, though, a Festo pack circa Xmas '02, which should have lasted a LOT longer than it did.I'll pop it in the freezer right now, and report back as soon as I'm all the way though the process.AitchKay
Hi AitchKay,
I'll pop it in the freezer right now, and report back as soon as I'm all the way though the process.
Remember to back it......keeps condensation from building up in the pack wrappings and don't forget the warning....I've heard of stories about melt downs, flaming, etc. but I have no proof and I've done this for years without incident.
Pedro the Mule - Save a $ safely
Yeah, double-bagging seemed like a good idea. Anyway, it's in there now!AitchKay
sounds like an opportunity for a food saver vacuum packjose c.
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"Though I don't think" added Deep Thought "that you're going to like it."
Hi jose c,
sounds like an opportunity for a food saver vacuum pack
Yeah, never had any.....are those reuseable?....I leave my used ziplocks in the shop and use over and over.
Pedro the Mule - Chirping like a chick I'm so cheap
You can reuse the bags until you can't get them into the vacuum device through judicious cutting off of just the sealed strip on the edge. Works really well on big bags. We also reseal other kinds of plastic bags with it like frozen vegtables, and it works very well. I wouldn't get one just for batteries ;^) , but if you buy in bulk and cut packaged stuff down to smaller portions they are great to have.jose c.
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"Though I don't think" added Deep Thought "that you're going to like it."