Need info on AC-to-DC 18v power tool converter

[Ripshod]

Hi folks. I have several Bosch 18v power tools. They're very good tools but I'd like to take one of the old dead batteries (part no. BAT181) and convert it to 110 AC input. The physical logistics can be worked out easily enough. I'm sure I can find an 18v converter that will fit in the old battery case (it's about 5" x 3" x 1.5" outside dimensions) so the fitment issue is no big mystery. I have the experience to work out the wiring and make it durable enough for the job.

My question concerns the current output of the chosen converter. The battery output is labeled 2.4Ah. I can't find the amp usage on the various tools' labels. Since the tools are presumably rated at different amperages, how important is it that I get a converter with the appropriate output current?

After a quick google, I've located several 18v converters. This site has a plethora of them to choose from and those I've looked into have detailed specs. So if I assume that the most powerful of the hand tools is rated at 8 watts, I should find a converter that is rated at least that high and go for it, right?

I feel so completely ignorant. I learned Ohm's Law in high school 35 years ago but haven't used it since so I have no idea how to make this decision. Any help would be appreciated.

Also, being completely new around here, I may have put this in the wrong forum section. Please let me know if that is the case.

Thanks,
Jerry in Knoxville

 

[Nigel Goodwin]

Hi folks. I have several Bosch 18v power tools. They're very good tools but I'd like to take one of the old dead batteries (part no. BAT181) and convert it to 110 AC input. The physical logistics can be worked out easily enough. I'm sure I can find an 18v converter that will fit in the old battery case (it's about 5" x 3" x 1.5" outside dimensions) so the fitment issue is no big mystery. I have the experience to work out the wiring and make it durable enough for the job.

My question concerns the current output of the chosen converter. The battery output is labeled 2.4Ah. I can't find the amp usage on the various tools' labels. Since the tools are presumably rated at different amperages, how important is it that I get a converter with the appropriate output current?

After a quick google, I've located several 18v converters. This site has a plethora of them to choose from and those I've looked into have detailed specs. So if I assume that the most powerful of the hand tools is rated at 8 watts, I should find a converter that is rated at least that high and go for it, right?

No, 8W will be no where near high enough - I would expect it to require in the hundreds of watts - it all depends on the power of the drill and the motor in it.

 

[tcmtech]

At stall you could expect to see peaks of 30 - 40 amps on a 18 volt drill. Your best bet would be to do what I do and just by a cheaper 18 volt generic drill battery and refit the new cells from it into the old Bosch battery case.

 

[MrAl]

Hello,

I have a 9.6v drill that i converted to use 12vdc so i can use standard lead acid batteries. I have to run a cord to the battery, but i can still carry it around with me.
It's hard to beat as the original cells were rated at around 2Ahr and the smallest lead acid battery i have is rated for 7.5Ahr, almost 4 times as high which means almost 4 times the run time.
I also use an automobile jump pack made for jump starting cars. These are a bit expensive but they usually have at least a 15Ahr battery inside which works really nice.

You definitely have to get enough current to run the drill or it wont be able to handle heavy jobs like putting screws into studs or similar. You can measure the stall current with a clamp on meter that works with DC (make sure you get one that can handle DC or it wont work at all). My drill requires about 35 amps and if i try to power it with a 10 amp supply it doesnt have enough torque so i have to use a 12v computer power supply that puts out enough current to handle the heavy jobs.

An 18v drill might run to some degree on a 12vdc power supply, but i havent tried it. If it doesnt, you might try a 12v lead acid battery in series with a 6v lead acid both of the same ampere hour rating. You will have to keep an eye on the voltage of both batteries however as to avoid discharging one too much.

It gets a little expensive trying to build an 18v 40A power supply that runs directly from the 120vac line. It's not a tremendously complex circuit, but the parts start to run into some money when you need 40 amp diodes with heat sinks and a nice inductor to handle that much current plus some overhead.
If you can find a nice heavy duty 18v transformer in surplus or something you might try a bridge rectifier circuit (heavy current diodes) and some capacitance and that would do it too. Might want to go with a 16vac output though so the voltage doesnt go too high. This would be a simple circuit made of the transformer, four 40 amp diodes with two nice size heat sinks, and a decent size capacitor probably made from a few in parallel.

I converted one of my drill battery packs by simply removing all the cells inside and running heavy wires to the internal connections for plus and minus and ran the wire through a small hole to a cigar lighter plug. Thus, i can pull the pack out of the drill at any time and use the other pack if i ever rebuild it again.

 

[carmusic]

i have a mastercraft 18v drill connected to a 25 amp 18volt power supply and at full speed and medium load it draws about 20-25amps, if i block it completely the power supply trips on overcurrent!!! those small motors are very powerfull

 

[MikeMl]

I'm getting tired of getting raped when I buy those replacement batteries, too.

I like the Sealed Lead Acid Battery solution, since locally I can buy new (industrial surplus) 6V 8Ah SLAs for about $3 ea. Stick 'em in a small canvas bag, and make a 8ft cable to the tool in question.

 

[MrAl]

I'm getting tired of getting raped when I buy those replacement batteries, too.

I like the Sealed Lead Acid Battery solution, since locally I can buy new (industrial surplus) 6V 8Ah SLAs for about $3 ea. Stick 'em in a small canvas bag, and make a 8ft cable to the tool in question.

Hi Mike,


Wow, sorry to hear about that

Yes the SLA batteries work out pretty nice right? They have plenty of power.
I stick my smaller SLA into a camera case with a shoulder strap to carry with me when needed.

 

[kinarfi]

I'm getting tired of getting raped when I buy those replacement batteries, too.

I like the Sealed Lead Acid Battery solution, since locally I can buy new (industrial surplus) 6V 8Ah SLAs for about $3 ea. Stick 'em in a small canvas bag, and make a 8ft cable to the tool in question.

Where are you getting those batteries?
Thanks,
Kinarfi

 

[plankwood]

I had a 12 volt craftsman that had bad batteries so I wired in a cord and cigarette lighter plug to it so I could use it with my jump starter power pack. It works great but the jumpers fuse and wire needed to be bigger. the ten amp push button fuse would pop every time I loaded it down so I put in a 25 amp and heavier wire and have not had problems since.

 

[MikeMl]

Nps nps nps nps nps nps nps nps

 

[ericgibbs]

Nps nps nps nps nps nps nps nps

hi Mike

Babel Fish translator just quit with that 'nps'...please translate..

 

[MrAl]

hi Mike

Babel Fish translator just quit with that 'nps'...please translate..

I'll take a guess at the translation..."nps store"?

 

[kinarfi]

I have a compaq server power supply and I have plugged it in, but get no power out of it, I assume that it needs to be "instructed" to turn on by the server it is supplying power to. Does any one know how to turn it on? Which pins to power up or short or what ever? To further complicate this question, any one have any idea of how to boost it's output to 18V?

Kinarfi

An old saying, look before you leap, guess I should have looked before I posted. found the answer else where, but just in case some one else can use the info, you only need to short two sets of pins out.
x x x x x
x-x x x x
x x x x x
x x-x x x

 

[MikeMl]

**broken link removed**. They seem to sell UPS shipments where the customer refused delivery, or got lost, or the truck crashed, etc.

 

[Ripshod]

Well, thanks everyone. I guess my simple idea was a little too simple. I guess if it was that easy, everyone would be doing it. I'll have to rethink my idea of converting a battery to AC adapter. Though I would say that at the retail price of around $80, if someone came up with a practical solution, I'd pay a good amount to be able to replace the battery with a plug-in for when it's appropriate.

You are a helpful bunch and I appreciate the answers and the ideas.

 

[Arthur Hugo]

Hi folks. I have several Bosch 18v power tools. They're very good tools but I'd like to take one of the old dead batteries (part no. BAT181) and convert it to 110 AC input. The physical logistics can be worked out easily enough. I'm sure I can find an 18v converter that will fit in the old battery case (it's about 5" x 3" x 1.5" outside dimensions) so the fitment issue is no big mystery. I have the experience to work out the wiring and make it durable enough for the job.

My question concerns the current output of the chosen converter. The battery output is labeled 2.4Ah. I can't find the amp usage on the various tools' labels. Since the tools are presumably rated at different amperages, how important is it that I get a converter with the appropriate output current?

After a quick google, I've located several 18v converters. This site has a plethora of them to choose from and those I've looked into have detailed specs. So if I assume that the most powerful of the hand tools is rated at 8 watts, I should find a converter that is rated at least that high and go for it, right?

I feel so completely ignorant. I learned Ohm's Law in high school 35 years ago but haven't used it since so I have no idea how to make this decision. Any help would be appreciated.

Also, being completely new around here, I may have put this in the wrong forum section. Please let me know if that is the case.

Thanks,
Jerry in Knoxville

Try this one, go to computer parts supply and buy a POWER SUPPLY FOR LAPTOP rated output must be 18-19 volts DC with a minimum Amperes of 4. Then connect the wired output inside your battery pack. This may need some modification like removing one battery cell to free your wire connector, a hole to let the wire in, cutting off positive and negative terminals and connect it to the output of the Power Supply. Positive to Positive and Negative to Negative respectively. I had made one, proven working well.

 

[DerStrom8]

Try this one, go to computer parts supply and buy a POWER SUPPLY FOR LAPTOP rated output must be 18-19 volts DC with a minimum Amperes of 4. Then connect the wired output inside your battery pack. This may need some modification like removing one battery cell to free your wire connector, a hole to let the wire in, cutting off positive and negative terminals and connect it to the output of the Power Supply. Positive to Positive and Negative to Negative respectively. I had made one, proven working well.

Hi Arthur, welcome to ETO!

I just wanted to point out that this thread is over 5 years old. The OP was active for two days and hasn't been online since January 14, 2011.

Regards,
Matt