first, let me say that i am aware that the (more affordable) cordless power tools "suck" in comparison to their comparably-priced corded counterparts

that said, i have two drills, a circular saw, a jigsaw, and tiger saw that are of the 19.2V craftsman C3 variety that i received as wedding gifts a couple of years ago and they have done just fine for my purposes...in addition to the smaller, simpler projects like cutting bat boxes and making cornhole boards, i have used my cordless tools to remodel a bathroom, build a custom entertainment center, and fully rebuild/replace my front porch...so they've worked just fine for me and i have no reason to dislike them

out of curiosity, though, i was wondering how hard it would be to create a DC-to-AC adapter (inverter?) so that i could plug in my tools when going cordless isn't really necessary

my li-ion battery packs are still just fine, but i have a nicd pack that doesn't hold a charge anymore and thought i could use the case/power interface to house the adapter/inverter parts...i feel like this should be doable for $40 or less

thoughts? i don't NEED another battery pack and i don't NEED any corded tools...so while it might be easier (and depending on the tool, cheaper) to just get a new tool, i thought this might be fun

12/18/2012 1:10:50 PM

You need to look at the current rating on the battery. You already know that it is 19V.

Buy a laptop or similar AC/DC convertor (My HP 17'' laptop had a 18V 3amp I think), or a similar wall charger.

Unassemble the old battery that doesn't work.
Cut the cord off the power supply DC side and solder it to the leads inside the old battery.
Put the guts of the power supply in the battery case.
Run the AC cord out of the back.

Done.

Like this?
http://www.sears.com/hp-ac-power-adapter-charger-for-hp-pavilion-dc924ar-power-supply-cord-18.5v-6.5a-120w/p-SPM6258015509?pageInd=product&PRODUCT_TITLE_BRAND=hp-ac-power-adapter-charger-for-hp-pavilion-dc924ar-power-supply-cord-18.5v-6.5a-120w¤tProductTitle=hp-ac-power-adapter-charger-for-hp-pavilion-dc924ar-power-supply-cord-18.5v-6.5a-120w&prdNo=4&isSEOCanonURL=true&catgroupId=SPM6258015509&catalogId=12605&blockType=G4&storeId=10153&partNumber=SPM6258015509&blockNo=4&i_cntr=1355855972915

[Edited on December 18, 2012 at 1:40 PM. Reason : .]

12/18/2012 1:35:59 PM

the nicd battery doesn't mention amperage or amp-hours...the li-ion battery says:

19.2V and 2.4Ah/48Wh

okay, so i only know the very basics of electricity...and that is: watts = amps x volts

how do i figure out amps from the amp-hours/watt-hours information?

12/18/2012 2:22:07 PM

it pulls 2.4A

you need a 20V 3A AC/DC. put a fuse inline so you dont blow anything up. The parts most likely will not fit inside the housing.

this project is dumb

better idea is to just go to harbor freight or a yard sale and get a corded tools

[Edited on December 18, 2012 at 2:39 PM. Reason : ]

12/18/2012 2:36:59 PM

^ i thought that might be the case, but i thought i might be wrong because 19.2 * 2.4 doesn't equal 48 (it equals just over 46)...again, i admit to knowing very little about this

so these power adapters don't PUSH the power to the tool, right? the tool PULLS what it needs, and so any power adapter that meets the 19.2V/2.4A requirements would work?

what about this (19V/3.95A): http://www.walmart.com/ip/Denaq-Denaq-3.95A-19V-AC-Power-Adapter-for-TOSHIBA-Laptops/20836342

not that i would necessarily get that one, but a quick google search doesn't give me many laptop adapters that do more than 19V

and why is this project dumb? sounds like i could probably do it for less than $20 and if done correctly (i realize the operative word is "if" and that's why i'm checking with y'all, first), that makes ALL of my tools corded without needing to store more tools

*shrug*

[Edited on December 18, 2012 at 2:46 PM. Reason : .]

12/18/2012 2:42:58 PM

That would be fine. Think of it as the adapter is capable of contributing 3.95A.

12/18/2012 2:46:35 PM

^ so the 0.2V difference wouldn't really matter? i'm not gonna blow anything up, right?

i think adding a fuse is probably a good idea...would a 50A inline do the trick or is that allowing too much through (ie. would i do damage to the tool before blowing the fuse i screwed up somehow)?

[Edited on December 18, 2012 at 2:54 PM. Reason : found a 19V/4.74A adapter in my closet for a sony laptop that went bad a couple of years ago ]

12/18/2012 2:50:08 PM

.2V won't make a difference.

Probably look at a 5 or 10 amp fuse.

12/18/2012 4:06:21 PM

oh, duh, i was thinking watts

12/18/2012 4:38:59 PM

http://www.youtube.com/watch?v=flHGY29hS-0

12/18/2012 10:04:01 PM

an Amp-Hour is not an Amp. Saying a battery can store 2.4Ah says nothing about its max current discharge level. It could be 0.5A max or 10A max. You need more info before you know how to spec the AC/DC supply.

[Edited on December 20, 2012 at 2:43 PM. Reason : .]

12/20/2012 2:42:58 PM

^+1

With the NiCd battery or most Nimhs you can pull a ton of amps very quickly so long as the cell doesnt overheat. It varies wildly among specific types and manufacturers. Crack open the nicd battery pack and if you're lucky you can google the mfg and type to find the max discharge rates if they arent custom made. Same goes for the li-ion packs which seem much easier to find discharge and charging charts which simplify things based on the "C" rating which can also vary wildly; see the link below for what commonly are used in cheapo battery packs. Click on any of them and you'll see a crude spec sheet link for each type. Use that as a minimum baseline on your amp requirement. If you do have a custom nicd pack/block, then I'd try a bench power supply if you have access to it. It's a lot of work for not a lot of gain but I sort of get it's more of a hobby/ intereat in doing this.

http://www.batteryspace.com/NiCd-Sc-Size-Battery-Cells.aspx

12/21/2012 2:48:51 AM

Looked at doing this a while back, some of those tools can pull 15+ amps at full speed under load. Youll need about 3/4 laptop adapters.

12/21/2012 10:52:41 AM

need pics you cheap mexican

12/21/2012 11:20:36 PM

I was thinking of doing this a while back. I have a black and decker drill I've had for a while and I like it but the batteries won't hold a charge any more and I don't want to keep sinking money into new batteries. I bought a new cordless drill but I don't like it as much as the old one. I found a few links on how to do it but they are on my laptop. Next time I'm on my laptop ill post the links here. I decided not to do this project because it didn't seem worth the hassle. If you're successful with it post the results. Maybe I'll get motivated.



I think this may have been the link I was looking at.

http://www.instructables.com/id/Convert-a-battery-drill-to-wall-power/

12/26/2012 11:21:28 AM

i don't understand the point... i have a reversible drill i got from northern tool for $10 that will have 5 times the torque and probably cost less then the conversion...

btw its 5 years old and still works fine.

12/26/2012 12:13:06 PM

It makes more sense when you have a kit that uses the same batteries. I actually have the same problem with original batteries not holding their capacity, I need to cut several sheets of plywood and some 2x4s tomorrow and I'm not sure that my 2 year old, barely used NiCd batteries (which i maintained charged up since date of purchase) will be enough to power through it. Batteries is where the manufacturers get you after they sell you a subsidized tool kit, kind of like what printer manufacturers do with ink. Actually, it's hard to believe noone has made a universal power supply that would fit multiple makes and convert them to AC operation when needed. I'm sure manufacturers would cry out loud that it would void the warranty etc.

12/26/2012 12:58:27 PM