Convert 18v DC reciprocating saw to AC power?

[mxnerd]

I have a 18v DC reciprocating saw and wants to convert it to AC.

http://www.harborfreight.com/18-vol...ciprocating-saw-with-keyless-chuck-68852.html

Can I connect a laptop AC adapter with 19v / 4.7A DC output to this saw's plug? The battery charger is only rated with 7.2v-24v and 1.3A, will the laptop adapter damage the saw? since 4.7A is a lot greater than 1.3A?

 

[SparkyJJO]

Unlikely to harm the motor with 19V. It is only 1V theoretical difference, plus an 18V battery fully charged is likely going to be pushing at least 18.5V anyway. Besides, it isn't like that is an expensive tool or anything

 

[MrTeal]

I have a 18v DC reciprocating saw and wants to convert it to AC.

http://www.harborfreight.com/18-vol...ciprocating-saw-with-keyless-chuck-68852.html

Can I connect a laptop AC adapter with 19v / 4.7A DC output to this saw's plug? The battery charger is only rated with 7.2v-24v and 1.3A, will the laptop adapter damage the saw? since 4.7A is a lot greater than 1.3A?

That saw is going to pull way more than 4.7A when you're actually trying to cut something. You're going to need a few hundred watts at least.

 

[mxnerd]

That saw is going to pull way more than 4.7A when you're actually trying to cut something. You're going to need a few hundred watts at least.

So in reality I can't use the 19v x 4.7A laptop adapter that I have to power the saw? How do I find out how much power I really need?

 

[mxnerd]

Probably found the answer. Don't have AC-DC converter that's powerful enough.

Guess buying another battery is easier for me.

http://www.instructables.com/id/Cordless-Power-Tool-Conversion-18VDC-to-120240VAC/

by ElectroFrank.

Hi pc-fan, NiCd means Nickel-Cadmium cells which are 1.2V, so 15 in series makes 18V. 1200mAh is the individual cell capacity (1200 mAh = 1.2 Ampere-hour). The battery pack is therefore 18V, 1.2Ah, when new it should provide (about) 1.2A for one hour. But drills can take more like 10A, if so you might (theoretically) get full power continuously for about seven minutes.

To discover the maximum current that could be taken by the drill, remove the battery and measure the motor's resistance with a multimeter. The maximum current taken will be the voltage divided by the resistance. So if the motor shows 3 Ohms resistance, 18V / 3 Ohms = 6 Amps, so you would need a DC power supply providing 18V at (at least) 6 Amps.

(If the drill has a speed control, you would need to open it up and disconnect the motor to measure it's resistance.)

An ordinary cheap car battery charger giving 12V at 5A would do some work, but at much reduced power (the motor could then only take 12V / 3 Ohms = 4 Amps).

Power rating in Watts = Volts x Amps. A power supply unit must be rated at or above the maximum current drawn by the appliance.

 

[Brian Stirling]

Yeah I bet the saw eats upwards of 350W or more so you'd be looking at 20A and probably more on power up -- I would not be surprised if the inrush was 30A or more.


Brian