# convert cordless tool to corded?



## jason41987 (Jun 2, 2012)

hmm.. is something wrong with this website? my text for the original post isnt there

anyway.. what my idea was, was to take an 18v DC power tool and install a socket somewhere onto it so that i would have the option of running a cord to a wall mounted 18v DC adapter to run the power tool without the use of batteries when i dont need them to be portable so that i can preserve the batteries... or just hollowing out an old battery pack and put the guts of an 18v power adapter into it so i can plug it into the wall and use it as a corded power tool

another idea of mine was to actually create my own battery pack that i could use 15 2.9AH AA NIMH batteries packed into a battery pack and create my own rechargable battery pack with removable batteries.. this way, the tool can last 20 years and when the batteries start to go bad i could simply buy a back of AA rechargables and replace them

these power tools run on 18v, rougly 1.5ah for a small pack, and 3.0ah for an extended pack... a AA NIMH battery is typically 1.2v and 2.9-3AH, which means fifteen of these would give me the required 18 volts and longer charge time with cheaper replacement... also, ive torn apart battery packs before on other devices and found they usually have AAA or AA size sells packed inside them anyway.. so this would be another option to ensure for the entire life of the power tool ill ALWAYS have some way to power it

reason is.. as much as i use these tools, id burn through batteries every 6 months or so at $150 a battery, also, what i see typically happens is every couple years the manufacturer starts using different types of batteries or a different voltage meaning the old stuff is incompatible... with these ideas of mine the tool, if a quality tool, would last forever

keep in mind, im looking at high quality brands of tools designed for long term heavy duty use.. like milwaukee, makita, etc


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## itguy08 (Jan 11, 2011)

You also need to look at the amps of discharge for these battteries. If running a saw or even drill at full bore with maximum load you could deplete a 4 Ah battery in quick order (say 10 minutes) which means your batteries need to supply a large amount of current. If I'm doing the calculations right that;'s a discharge rate of 10A (or in battery speak 2.5C). No AA battery would hold up to that kind of abuse long term. Most cordless packs have NiCad SubC batteries which will take the abuse. One other thing I learned from another "hobby" of mine - flashlights - is there are no 2900 mAH AA's - that #'s are grossly overrated and those that do get those large #'s are short lived batteries as the tradeoffs mean everything in the battery is thinner. 

LiIons will take the abuse but those need protection to keep the cells from overheating and going into thermal runaway. Google LiPo fires for an example of what that looks like.

If you want a good battery "education" - head over to www.candlepowerforums.com and hang out in the battery forums. The flashlight guys are way into batteries and technology as they are always trying to get maximum runtime and voltage to drive the LED's. 

I think the reason the corded plug hasn't been done is because it can't. You'd have to design an AC/DC converter that could deal with 10-40A at 18v continuous. Those types of things need to be quite large. At that point you are better off with a corded tool.

If you want cordless I think the best thing to do is resign yourself that batteries are a consumable and get used to rebuilding NiCad or LiIon batteries. But be careful with LiIon - one screwup and you could have a fireball in your hand. Hit up YouTube for an many examples of LiIon fires.

I think if an AC adapter could be done the manufacturers would be all over that in a heartbeat. I think the physical constraints at this time would make it impractical and that a corded tool would be your best bet.


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## jeffsw6 (Oct 28, 2012)

To do comparable work to a 120V corded circular saw, a cordless tool with wall-power DC would need 100 amps of 18VDC. That means it would need a really big, heavy cable that costs about $10/foot.

It's cheaper to just own two tools, corded and cordless.


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## ddawg16 (Aug 15, 2011)

If your 'burning' through batteries that quick, your doing something wrong.....even NiCad's will last several years.....I typically get about 5-6 years out of mine....

Remember...recharable batteries don't like to stay on a charger all the time....once the battery is fully charged...remove it.

Also....some chargers will discharge a battery if you unplug the AC cord and leave the battery in the charger.


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## jason41987 (Jun 2, 2012)

i use power tools 6-8 hours a day for months at a time... they can only be recharged so many times and sometimes i do a lot of work with them... would be nice to rebuild the batteries, save a huge chunk of cost.. 

as for manufacturers doing the power adapter.. no, they wouldnt do it because it means people buying less batteries, which means less cost to them.. however, its quite possible, just not with a standard DC power jack youd buy for electronics.. 

actually looking at the spec sheets for these power tools, the average power drill will draw about 450-500 watts of power, power saws draw more, upwards of about 750 watts... so what you would need to power these is something closer related to what a PC power supply is, however, pumping out 18v as opposed to 12v... 500-750 watts isnt too bad, its about what a gaming PC would draw during a game... less than what the average space heater will consume

i think i can gut a PC power supply to use as a chassy, and build an 18v power supply that i could either plug into the wall outlet, then plug an extension cord into that.. or better yet, plug an extension cord into the wall and the power adapter into that, then i can use a different kind of plug to prevent someone accidently plugging the tool into an AC outlet and potentially frying something


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## joecaption (Nov 30, 2011)

Even my cheap Ryobi's get more life from the batterys then your getting.
Switch to Ridgid and the batterys are life time warrentyed.


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## itguy08 (Jan 11, 2011)

jason41987 said:


> actually looking at the spec sheets for these power tools, the average power drill will draw about 450-500 watts of power, power saws draw more, upwards of about 750 watts... so what you would need to power these is something closer related to what a PC power supply is, however, pumping out 18v as opposed to 12v... 500-750 watts isnt too bad, its about what a gaming PC would draw during a game... less than what the average space heater will consume


That sounds like a lot until you run the #'s as amps is directly related to the voltage.

To convert watts to amps you use A=W/V

So at 18v you have:
500/18 = 27.7A
750/18 = 41.6A

You're going to need cables roughly the size of car battery cables to carry that current as you need at least 20% more capacity in your cables. Building a 75A 18V power supply is going to be huge, probably easily the size of a comparable car battery charger. 

Sorry but it's just impractical as you'd have a box the size of, say a small dorm fridge and have to run jumper cable sized cables to your tools.....

Much easier to deal with a small extension cord.


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## mae-ling (Dec 9, 2011)

Usually the batteries in cordless tools are sub-C batteries (a little smaller then a C battery). You can buy them and rebuild them yourself.
https://www.google.ca/search?q=Rebuild+cordless+tool+batteries&aq=f&oq=Rebuild+cordless+tool+batteries&aqs=chrome.0.57j0l3j62l2.11672&sugexp=chrome,mod=7&sourceid=chrome&ie=UTF-8


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## jason41987 (Jun 2, 2012)

completely disreguard the idea about a power adapter or power supply... i was doing more research on the batteries i have.. 

the milwaukee M18 compact batteries... and well, these use five (i believe 18650) lithium cells.. the XC uses 10 of them.... so i started pricing out the 18650 size lithium sells and it would appear i can get these cells at 3.6 or even 4.0ah at less cost for five than a new pack would cost

so when these batteries die, and i replace them with new cells im going to be tripling the capacity of the pack, in fact theyll have 50% more capacity than the XC packs while still being lighter, slimmer, and offer a better balance and at under $30 for a set of cells... 

heck, i could probably get enough to rebuild both battery packs at the cost of buying a single new compact battery pack at standard capacity.. so.. im not worried about the cost of battery packs anymore... in fact, i cant wait for these ones to die so i have an excuse to upgrade the cells


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## woodworkbykirk (Sep 25, 2011)

if youve been using milwaukee cordless gear there lies part of your problem. its well documented that milwuakee batteries go stale really quickly.. they claim you can get 2000 charge cycles out of one of their batteries. but thats hardly the case. myself and countless others on another trades form have all had this issue. its part of the reason milwaukee keeps changing their battery technology they cant make batteries that last.. well not since TTI bought them out who also own rigid. ive owned every brand pro grade cordless tool, bosch and makita are the only two that have lasted for me

as for an adapter. hilti has the technology for it however its only for a very select few tools, which are large tools at that such as their sds hammers. 

if your running tools non stop all day just go corded. keep the cordless gear to drills and maybe a circ saw or jigsaw for light duty work.. hammer drills, circ saws, recip saws and tools of this sort only work well if they are corded, and be sure to be using a 12 gauge chord.. running tools that require 15 amps will burn up if your using a 14 or 16 gauge chord


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## jason41987 (Jun 2, 2012)

i cant have an opinion on cordless tools, i never really had them.. as for the batteries in milwaukee tools, as stated before i can, and do intend to rebuild the battery packs myself later, with better, longer lasting cells

i use most these tools for woodworking, but i also work on automotive projects as well, so i was thinking of using these cordless tools for everything else, and pneumatic tools for the bulk of the work as corded electric tools dont seem to have the raw power needed for things like impact wrenches...and the pneumatic ones are mechanically simpler and more reliable

so... once these drill batteries die, maybe even before then im going to rebuild the battery packs with better cells and over time, probably add an impact driver, circular saw, and reciprocating saw to the setup for home improvement tasks as i will be doing a lot of remodeling of an old house soon, and they could come in handy when i start building my own house from the ground up


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## bcgfdc3 (Jan 28, 2012)

I donlt know as much as some on these forums about the batteries but i beleive there are different charger capabilities for NiCd vs LiIon batteries.


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## itguy08 (Jan 11, 2011)

jason41987 said:


> completely disreguard the idea about a power adapter or power supply... i was doing more research on the batteries i have..
> 
> the milwaukee M18 compact batteries... and well, these use five (i believe 18650) lithium cells.. the XC uses 10 of them.... so i started pricing out the 18650 size lithium sells and it would appear i can get these cells at 3.6 or even 4.0ah at less cost for five than a new pack would cost
> 
> ...


Please, please, please do research before you even think of rebuilding your LiIon packs. They are immenseley more dangerous than doing a NiCad or NiMH pack. With the NiCad if you overdischarge the battery or discharge it too fast it will get hot and maybe weld itself together or outgas. With a LiIon battery you * will have an uncontrolable fire*. 

Read this from a guy wo does this for a living:
http://toolboyworld.com/eBay/Ryobi_Batt_Rebuild.htm

Please Google LiIon fires and read up. Read and ask questions here:
http://www.candlepowerforums.com/vb...d-Close-Calls-The-dangerous-side-of-batteries

http://www.candlepowerforums.com/vb/forumdisplay.php?9-Flashlight-Electronics-Batteries-Included

Read up on what the RC (Radio Controlled) folks do with and to their LiIon batteries as their use is very close to a power tool - powerful motor run at full tilt for a long while.

Also be aware that the cheap LiIons that you see:
1. Probably are over rated as to their actual capacity.
2. Are not rated for the high discharge current of a power tool as they are designed for laptop batteries and other relatively low drain devices.

Again the flashlight and RC communities have been playing with LiIons for years and there are some * very real dangers if you don't know what you are doing.*

I'm not trying to sound like a prick but it's not as simple as the old days where you swapped cells and you were back in business. There's a reason most battery places do not rebuild LiIon packs now.

If you do decide to rebuild the packs, be careful and choose your LiIon cells wisely - you need the right LiIon chemistry (There are many and not compatible with each other), and cells with the right discharge rate.


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## woodworkbykirk (Sep 25, 2011)

not only that but you can fry the tool if you dont do it right


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## itguy08 (Jan 11, 2011)

woodworkbykirk said:


> if youve been using milwaukee cordless gear there lies part of your problem. its well documented that milwuakee batteries go stale really quickly.. they claim you can get 2000 charge cycles out of one of their batteries. but thats hardly the case. myself and countless others on another trades form have all had this issue. its part of the reason milwaukee keeps changing their battery technology they cant make batteries that last.. well not since TTI bought them out who also own rigid. ive owned every brand pro grade cordless tool, bosch and makita are the only two that have lasted for me


I know in the early days of LiIon in power tools it seemed as if everyone (except Panasonic) had issues with the batteries. Heck, DeWalt had issues with NiCads for years. 

My guess is that Milwaukee changed from the V series LiIon to the new M series about the time TTI bought them. I think it was more of a break from Atlas Copco's designs that were primarily NiCad designs with LiIon batteries to a new "clean slate" design geared towards LiIon only.

If they didn't stand behind their products, they wouldn't warrant the new M (12/18/24) batteries for 2 or 3 years. About the only changes to the M18's were going from M18 to M18 Red Lithium (which was probably a marketing trick than anything else) and now to M18 Red Lithium 2.0 and 4.0. I hope and think the M12/M18 is here to stay.

I have no interest in any of these companies other than I really like my M12 tools as well as my new M18 Fuel hammerdrill. The Milwaukee stuff fits my hands better and seems to be built really, really well.


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