# Battery Life



## Charc (Nov 9, 2008)

I was going to ask this via PM, but I thought I might confess my lack of knowledge, and ask this publicly, maybe it will benefit someone else.

I have been looking into the Dewalt DC936KA as being something I might want to invest in. That or the Makita Li-Ion Impact Wrench. I have had considerable hands on time with both guns, and although I can't quite put my finger on it, I much preferred the pistol grip DeWalt over a comparable t-handle. The Makita Impact-Wrench was a clever bugger in its own class, and the built in LED is ever so helpful when you're belly crawling under a show deck. So if anyone has any specific input in this match-up, I'd be interested to hear it.

My specific question relates to the battery lifespan. While I'd really like to purchase a screw gun, it would likely see occasional home use, and occasional theatre use. Would not cycling the battery over long periods of time have an effect on its overall life? I'm thinking also specifically in regards to any memory effect, though I believe that is primarily with NiCad, and the DeWalt would be NiMH, and the Makita Li-Ion. I'm not sure how, but I have managed to entirely kill some Li-Ion rechargeable AAs. It's possible that I overcharged the batteries to 2x-4x their charge time.

So how do you guys feel about screw guns for occasional use?


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## derekleffew (Nov 9, 2008)

Charc said:


> ...So how do you guys feel about screw guns for occasional use?


For occasional use, I find the Yankee Ratcheting Screwdriver is always charged and ready to use. 



Now you kids, *get off my lawn!*


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## ship (Nov 10, 2008)

Fore note, I'm not up on Lithium Ion batteries so any concept below of discharging, efficiency verses replacement cost, battery life etc. are preliminary in thoughts. As always follow the manufacturer guidelines of any battery.

Used to love the concept of the clip on light Milwaukee came up with like 15 years ago. Didn’t like their reversable batteries / exposed contacts however and for the most part Milwaukee cordless tools are in my opinion decent but not best. Makita, decent drills, so are the above, Panasonic, Porter Cable and Bosh for different reasons in each case. Others left off specifically or with the case of say Fein or a few other more remote brand ones - not tested over the years. Won’t go into those that were persay amongst Skil, Tool Shop, Royobi, Wagner, Craftsman and ... the Black & Decker / DeWalt economy home owner brand Firsestorm. 

Personal opinion of course, and in being the primary - this drill has a problem, the guy most go to see over the years when their tool is breaking down or in play testing them in general. I have used many tools over the years and over them gained some very specific opinions. While I loved my two speed with clutch wearing out constantly but easy to service and replace origional Makita "HD" without and before the cursid thermo switch 9.5v cordless cerca 1986, I wouldn't go back to it these days, but still have many of them I bought during the second generation of mass market cordless tool from in the days when 14.4v was the top and it still is given a balance of weight and power plus battery replacement. Granted dependant on how much you use a tool, yearly or at least bi-yearly professional maintenance is required. Drills these days you can’t just take apart and squirt some fresh grease into them after cleaning out the old.

When crawling under a show deck takes up ... X amount of your time. To buy a tool specific for that advantage when you have a Mag Light that could clip on to your arm/head or velcro to the drill, or a head lamp or could even gaff a light to the top of your drill seems kind of like buying a car because it’s yellow. The cordless drill with an internal bubble level is also a really useful concept yet one not available on either drill. Heck, for a hammer drill or drill in general the what’s normal to hammer drill’s drill depth bar is also useful yet not available to cordless hammer drills and other drills for some things.

The older versions of this DC 936KA in 14.4 volt - both versions of it is what I have and use. Have three of them. One that I have had for over 15 years now - when it first came to market I bought it to replace my old 9.6v HD Makita pistol grip following the T-Handle version, in that I hated the T-Handle version. I initially bought the pistol grip and I still like it and this version most even though only two speed. At least four motors later and not many origional parts left, it’s still very light weight and for as much as I use it which is daily and hard normally, it's very dependable. And at work two of the second later but now it would seem previous version before this model came out. Love the what is it in forgetting... $100 or $200.00? Tool repair maximum cost with DeWalt. After that if necessary a new tool. Think it’s the former and I have challenged that price often especially with my old tools I use most often. Still have an origional T-Handle 14.4v also, works well enough as a secondary tool but I prefer the primary. In general also, of 12x 14.4v cordless drills I’m responsible for, the pistol grips have no more problems than T-Handles. The T-Handles, be it my origional 14.4 T-Handle used often as a second drill on a project such as after the pistol grip drills the hole, the other taps it, or at work the T-Handles are the loaner tools to those not as trained. My department doesn't loan out the pistol grips where possible now that they are trained in how to hold them and why they are better.

Now for a hammer drill, it ain’t much use for aged and or compressed concrete. For such things you need a Bosh Bulldog or Hilti tool. Works great for lighter masonry or sufficient for new concrete. A corded Milwaukee for general purpose hammer drilling is also better, but for light weight brick or block work the cordless hammer drill is decent. Use the SDS bits in the cordless drill, don’t waste time on the home owner type drill/driver bits not designed for a proper hammer drill.

Good drill this DeWalt and I agree in the pistol grip balance point - this as long as you have a big enough hand and are properly trained in it’s use. Otherwise it’s cumbersome and off balance. Looks like the newest version has some of the cooling problems in where the vents under hand are placed better situated and hopefully given the gearing stayed the same they lowered the weight some hopefully. Origional version had vents right under where if holding the tool properly as with a Skil Screw Shooter the pistol grip concept in holding, your hand was placed right over the vents. Though better ventilation was also another selling point of the pistol grip. The second version while heavier was a bit better in venting but still not optimum and even a bit more combersome to hold. Hopefully the newest version has that all corrected.

Even at 14.4v the previous version of the drill is a bit heavy. Like their three speeds and seeming more power but the extra weight throws them off a bit and makes them harder or heavier to use. Wish the safety cable ring down below were a bit more substantial and larger, and of course on this drill type if dropped just right, you will break the casting at center. Replaced more than one of just about everything on my drill over the years, this was once or twice but same with every other type or brand of drill in breaking them in the same way if dropped just so.

Still though, I prefer these types of drill. Make sure you get the front handle for it. Especially on a pistol grip, that front handle when drilling with big bits’ it’s needed. 



On battery life, still got one battery kicking about that’s about five years old. Only one out of like 20 in current service however. Expect normal NIMH batteries to last between three and five years. Used to be much cheaper in replacing but that’s part of the cost in owning a cordless tool these days.

Old school rules - back when they had memory chips to “fully discharge your batteries before charging” is years in the past and while this made a lasting impression on the industry, is no longer recommended or necessary. Modern batteries only have one need for the velcro strap around the trigger - or better and safer yet, battery placed in the flash light to run down. That’s for a battery that won’t be used for a period of about three months in storage of it for that period. In your case, if you don’t much use the tool, this might discharging option might be a good idea and the best one. Don’t leave for weeks on end a battery on the charger as per the instructions, and if not often used - I’m thinking if not more than at least every other week, perhaps discharging your batteries might be an option in extending battery life. 

Certainly normally at least you have an hour’s notice before you will be using your cordless tool so charging it back up will be an option. Though I would recommend the flash light as a better option for discharge of the battery than the drill that’s going to heat up a lot especially in the lowest charge range. Always store your tool if battery installed in it’s neutral position - the tool touching something and running in your box at a slow speed over a period of time is a known fire hazzard which would be a factor in tool maintenance or even burning up in time with a tool not well maintained. IN your case also you might consider a 12v cordless tool if you are not going to use it as much. About as much power, less expensive batteries and if on stage you are not going to be too far away from that battery in a charger. Many scene shops use 12v and the batteries will last at least an hour which is sufficient for the second battery to charge by than. This mostly the case with NIMH batteries because in the past it was fairly easy to burn thru NiCad batteries within an hour with a 12v drill. Than of course if efficient enough to do so you would also have to toss your tool into the shop freezer to cool it down also because it too would get very hot with use. Another bonus of the pistol grip over the T-Handle is they cool more efficiently.

On the NIMH verses LeIon type batteries and other technologies... don’t know much about LeIon batteries. I know that the 14.4v size is like a poor step child to DeWalt between the 12 and 18v that’s constantly not getting what the other children get for cordless tools, yet it is the best product for our industry.

Battery Pack efficiency: 12 v. =1700 mA-h High Endurance. (Bosch Cordless, 1995 Cat. #45920)
Nickel Metal Hydride (Ni-MH) batteries are about to hit the open market also, they boast 30% longer run time than normal Nickel Cadium types and less weight.

Weights are on average, 4# for 9.6v., 4.3# for 12v., 4.5# for 14.4v., and 5.7# for 18 volt drills. This is part of an American Woodworker article from back in 99'. If you want the full article from a trade that’s more home owner based but had a decent article in this case I will post it in citing (American Woodworker 1999 Buyer’s Guide, “Cordless Drills” p 72-79)


In general that was a statement during the 90's and true with all NI-MH batteries though I could never tell the difference really.


Wood Magizine such as (Wood Magazine, “12 Volt Cordless Drills” Dec. 1999 p.72-77) has also had some good articles on batteries and cordless tools over the years. It over some “Consumer Reports” article that is very home owner based in it’s opinion would be more valuable and get into the details. Consumer Reports gets into the science some but not really as much as others in determining what would be more cost effective over a better drill to recommend. Valid resource and no doubt with others yearly they report on what’s best but take what they recommend in stride with the others and weigh what they and others recommend as per pro-tool for why they state.

You really want to search for the best battery technology or tool search the back issues of the woodworker trades. They go into stuff like Ah - Amp Hour ratings for the batteries which in addition to how many 3" drywall screws they will drive per battery is a factor that is specification of the battery that is important. 

From the above article (notes mine):
“The higher the Ah rating a battery has the more energy it can store and thus the more work it can do. 2.2 Ah NiMH is better than 2.0 Ni-Cad. 1.3 to 1.5 Ah Nicad batteries are common on low end and older model drills. 1.7 Ah is the standard to most cordless drills designed within the last five years, (1999) and 2.0 Ah is common to new drill designs or companies which specialize in or advertise their batteries as much as their drills (DeWalt, Panasonic and Makita).” 

.... “When the drill gets warm to the touch of your cheek, or bogs down to about half its rpms it is in danger smoking and possibly burning out the motor. If used well after it is warm it can also get hot enough to melt the wires feeding the motor shorting out the motor and possibly arcing its way thru the motor housing or melting the battery.” (Been there, done that in at one point and I think still having a drill with 200c heat wire replacing what was provided. Also a note about what could happen if a drill in your tool box is left running by accidental touching something.)

Also.... “If you plan to use your drill more than once or twice a month buy a better drill because the lesser ones will have parts in them which will wear out quicker, withstand less abuse, and be more expensive and harder to service when they do need it. This in addition to performance levels that are better. Knowing where a tool was manufactured is not necessarily as easy as looking at its name. In fact it is very rare a company originating from one country also makes their tools in that country for better or worse especially when parts are needed from overseas it can take a long time.” (Not as common these days you have to wait for parts to come in from overseas with a name brand but it was common with Makita in years before.) 
(Wood Magazine, “12 Volt Cordless Drills” Dec. 1999 p.72-77)


Also from the above article I think or me from back then in summing up what I read: 
“	Chargers are 1 hour , 15 and 12 minute in charging time. (Not normally available these days the quicker charger times but important note still.) Note: Most Batteries no-longer have memory chips in them, so it is not necessary to “run the charge out of a battery” before charging it, unless the battery is going into storage for a few months without being used. Also the faster the charger the better or more potent the charge the battery will receive. Leaving batteries in a charger is also okay for frequent use purposes, in most cases, it will not hurt the battery, and will receive frequent charges to keep it at its maximum potential. There is also a backpack mounted battery on the market for those who never want to change batteries. Chargers are available in car charger and multi-bay types also. Most modern chargers will also charge any voltage of battery under the same brand name and style. Some chargers are marketed to charge any type or brand of battery, this could simplify things greatly in shops with many different brands and styles of batteries in use in that round pegs will hopefully not be put into square holes by novice carpenters any longer, given they are put in - in the right direction.
Batteries: Ni-Cad, & A-H Hi-Capacity with Power Display (Supposed to have 25% more capacity)”

NiMH Batteries: Ever since the 1950s, nickel cadmium (Ni-Cad) cells have been the battery of choice for portable rechargeable applications. And over the years, Ni-Cad cells of the “sub C” size used in power tools have improved to the point where they can store about 2.0 amp hours (Ah) of energy. But only small, incremental improvements will come in the future. Because of this energy-storage limitation, as well as environmental concerns about cadmium, battery makers developed nickel-metal hydride (NiMH) cells about 
10 years ago. These batteries can theoretically hold about 40% more energy than NiCads, according to our sources at Energizer Power Systems, a U.S. based manufacturer of MiMH batteries. Our cordless-drill test included one drill with a MiMH battery pack with a 2.2 Ah capacity, but you will see mor NiMH batteries in the future. Several companies have hinted at having 3.0 Ah batteries soon. So why haven’t all manufacturers switched completely to MiMH? In a word, cost. NiMH batteries cost more than Ni-Cads, and manufacturers tell us their research shows that consumers may not be willing to pay significantly more for something as intangible as additional run time. (Almost 50% as much in price) to this end, which would sell better a $45 or $75.00 battery. Of course, with the proliferation of NiMH batteries, prices for them should come down. For example, cellular phones nad laptop computers used to be powered by NiCads, but now nearly all of them run on NiMH or lithiumion batteries. (Don’t expect lithium-ion batteries in cordless power tools any time soon; they store lots of energy, but dispense it in doses too small for power tools.) 
(Wood Magazine, “What’s With These New Nickel-Metal Hydride Batteries?” Dec. 1999 p.88)

(Note the note on the above Lithion Ion batteries from 99' that’s valid in not coming soon but potentially a below noted replacement battery cost in concept if they don’t last longer persay or there is other factors in battery life just as with lamp life for lighting tech people.)

Temperature and Ni-Cad or Ni-MH Batteries: the batteries are themselves not effected by temperature unless it is in the absolute extremes. They may run a bit sluggish on start-up when cold, but under use should warm up and be fine. In warm conditions, operating and discharging does not effect the battery the biggest challenge for either type of battery is in getting it to accept a full charge when it has been subjected to extreme temperature. Batteries charge best between 45 and 85 degrees to accept a full charge. If it has been in a temperature other than this let it cool down or warm up first. (Also be ware of “Rifle Sweat” problems when a battery or any really cold tool is brought into the warmth, and also the brittle ness of plastic under these conditions. In addition to extreme physical problems, the extreme temperatures of heat can be multiplied by the heat generated by a charging tool or running/working battery, and the tool and battery can suffer from melt-down easier in warm temperatures if dirty, (vents and cooling mechanism clogged, or over-used). Many of the current generation of chargers have thermostats which will prevent charging until the battery is cool enough. Otherwise if it charges outside the range, it will not accept a full charge. (American How To, May 1999 “Expert Answers”by Hal Handy. p.90)


Wish I had more time to stay up with my past magazines, they occasionally had really good stuff in them that was useful in tip or review, but alas these days, I have a stack of PLSN to get thru in only reading a few articles most often and no time for others beyond that. Back in 99' I had lots more time. Still the above I hope helps get a start onto concepts of batteries and drills - lots more yet since no doubt has been reviewed and studied.

So from it, here is my understanding. The more huge power a battery such as most modern lithium-ion or even the MiMH types for long term use don’t have the power for bulk usage and potentially say with a large hole saw wear down sooner and wear out the drill sooner, but for a not so fast pace, could be more efficient overall in storing a charge to expend over a period of time. The Lithium batteries I expect also would be more efficient in some way I would hope in balancing the two concepts of power verses battery life, but otherwise might just be what might be the better more efficient brother of the MIMH battery. Don’t know, not read much about them. Doubt the 14.4 in at least DeWalt will come out with such a battery - poor step child size.

On the other hand what I have noted over the years is also not science but tested to be true in my thoughts at least. Phase Harmonics destroys battery and lamp life as with battery chargers. Already replaced a few battery chargers over the years that didn’t blow fuses but instead a component went bad as analyzed by our electronics department. A few years ago my 3.6v Panasonic cordless screw drivers started to have fairly bad battery life over that of the one I had before I got to working where I work in them lasting just fine.

Frequently found phase harmonic problems at work - what starting up a few hundred moving light fixtures might cause pandomonium with other gear powered up? This or even as a concept battery chargers on the same phase/circuit/system as that of large power tools though they would need to be large in motor. Still the lag and whipping about Hz wave is apparent to cause trouble with say under 7.2v batteries and other electronics. Could be also a thing with dimmers doing this. 

For at least my 3.6v batteries, I installed a 30min timer on them. Shuts down the power to the charger after that timer is out. Since than I have found normal battery life out of the mini cordless tool batteries again. Larger batteries don’t seem to be as effected by this - battery in the charger and for the most part living in it for a day or few at times between use. Still the concept of corporate power supply rectifiers and or 1:1 transformers to plug into are mostly beyond budget for a simple battery charger power supply. Larger batteries at least NiCadd ones are not as effected by local power seemingly to the extent I can detect - I still date each of my batteries in seeing if they live up to three years or not or even a year’s warranty, but for the most part not much to worry about in a production sense. For a home owner sense however, I would say if you have the choice of leaving your battery at work in a charger and or taking it home, take home your batteries to charge in less problems with even a huge air conditioning harmonic type loading on the battery shortening it by even a few days as my assumption seems to lead.

Again, not familiar with the newer batteries persay. My wife charges her phone only when it’s out of charge, I charge my phone every night. I seem to have a constant charge without any less battery life but that’s also at home and with a slightly newer phone more frequently. Replace a cell phone every other or every year thus also expect at least a few years in getting over the expense already on a cordless tool battery.

Still though not knowing what the Lithium Ion battery benefits are over that of NiCadd I cannot say at this point other than with heavy use, you should get about two hours out of a NICadd which should be enough. Balance that with replacement battery costs also. While you might not hope to get 15 to 20 years out of a cordless drill you really like, that should be a goal to consider still.


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## gafftaper (Nov 11, 2008)

Benefits of Lithium Ion: 
no memory effect
Recharges very quickly
More power packed into a smaller lighter battery than NiMH 

I have 5 of these Makita 18 volt Lithium Ion's at school. They are awesome. Incredibly powerful. The battery lasts a long time. They recharge in less than 20 minutes. I put a socket driver on it and use it to drive lag screws... It'll torque your arm off if you aren't careful. It's the same size and weight as my old NiMH 12 volt at home with twice the power. If you are buying a new drill these days get Lithium Ion no point in spending your money on old technology.


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## gafftaper (Nov 12, 2008)

The vast majority of work I do is with wood. The driver drill can handle all typical tasks... including driving some pretty good sized lag screws. It's got a lot more torque than you might expect. If I'm doing a lot of long or larger diameter lag screws I switch to an air powered ratchet as it has a lot more power and stamina. I thought about buying one of the impact wrenches but I don't see a need for it. If I was doing metal work, LOT's of big fat lag screws into wood in locations that it's hard to run an air ratchet, or didn't have the air ratchet in the first place then I would get one. I guess I would say think about the majority of what you are driving. If it's mostly drilling small holes and driving screws the driver drill is a better fit. If you are drilling more large holes and driving large diameter lag screws or bolts then the impact wrench makes more sense to me. If you only occasionally drive large diameter stuff then that's what your socket wrench set is for. 

During the current show's construction one of my students was driving a 3" x 1/4" lag screw through a 2x6 into a 2x4. He forgot to put on a washer and before he knew it he buried the sucker in the wood so deep I'm going to have to chisel the head out so I can remove it.  The drill/driver packs that much power. 

What do you plan to do with it? Take a look at the list below and estimate a percentage of time you will do each. 
Drill holes less than 1/2":
Drill holes larger than 1/2":
Driving screws: 
lag screws smaller than 1/4" x 3":
lag screws larger than 1/4" x 3":
tightening nuts to bolts: 

If most of the time you are doing the larger things you should probably get the impact wrench. If most of the time you are just doing the smaller stuff the drill/driver will do just fine and costs less. By the way I just made up the dimensions above as cut off points for various sizes. Don't let the fact that you drill a lot of 5/8" holes be the determining factor here. Just think in general about your usage.


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## gafftaper (Nov 13, 2008)

Tonight I installed about 60 1/4"x3" lag screws in my home made hammock. I used my Makita Drill Driver. I switched batteries once after about 40 screws (it could have probably done more but it was starting to sound a little sluggish and with less than 20 minutes to recharge I swapped them). I was driving them through 2x4 into 4x4. I was going at some weird angles and didn't always have a good feel for how much power I was exerting. Consequently I snapped the heads off of 3 of the 1/4" thick lag screws. 

How much power do you need Charc?


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