kevthorne

I have an 82 with a 22r engine running a 40 amp alternator. If I hook up a 5.5 amp drill pulling roughly 660 watts, then I would need a 60 amp alternator for continuous draw. Does this mean that I can run the drill and it will be fine as long as I have the car running 30 minutes for every 20 minutes I use the drill? Will the battery maintain charge, and the alternator function correctly with this formula, or am I just going to ruin my alternator?

wyoming9

iTrader: (1)

So what you have is a DC electric motor with a drill chuck.

This is only limited in theory by how many VDC are feed into it .After a certain voltage mechanical parts start to fail.

Meaning it can only draw as much as your system puts out.

Then the amount of pressure you put on the drill bit also increases the power draw .

Then the battery gets into the equation. The better the battery the more reserve to draw on.

If your using this as a drill it comes down to how long it takes you to get through what your drilling .

Just what is it your trying to do here??

Since there is no mention of using an Inverter I can only figure for a DC drill!!

osv

what Wyoming said! ^^^

that would be a typical 120v alternating current drill? i'd guess that there would be power losses involved with converting the truck 12v dc power source to 120v ac for the drill... so the calculations might be a bit more complex than what you outlined there.

kevthorne

it's an a/c drill so it would be hooked up to an inverter. all im interested in doing is running my new milwaukee drill off the battery of my 82 toyota pickup, and trying to figure out whether or not its going to work without harming the battery/engine/drill.

wyoming9

iTrader: (1)

Most inverters have a overload that will trip if you draw more then the inverter will handle.

What is the rated output of the inverter??

Have you figured the start up draw after all it is a motor so figure 3 x the normal draw.

Not a big factor plugged into a wall outlet could be real interesting .

Being it is a AC motor running on reduced power will burn it out in no time at all.

Then you get into loss from connections and how long of a cord your using.

Why not use a cordless drill and charge batteries with the inverter??

kevthorne

yeah, the inverter is sufficient to handle the start up draw. i appreciated your advice about the motor burning out faster as a result of not being able to draw sufficient power, thats the kind of answer i was looking for, so i returned it, thanks!

wyoming9

iTrader: (1)

Just really what were you looking to do?/

I have not used anything but a cordless drill in quite a while

kornhuskerwizard

U need a gas powered welder generator combo on the back. I recommend a MILLER

RJR

If OP has a drilling application that requires 5.5 amps at 120 volts for 20 minutes at a time, a cordless drill isn't going to cut it. After all, he's talking about running down a car battery, which easily stores about 10x more energy than most cordless drill batteries.

That being said, a drill only takes its rated current when it's under full load. Unless this is a pretty unusual application, like drilling through about 6 feet of landscape timbers in one shot, the normal intermittent nature of drilling should ease the requirements on the alternator considerably. If the inverter is up to the job, I wouldn't think there'd be a problem with the rest of the system. This is only a 660 watt load, much less than an electric winch, for example.

ThatGuy1295

SO you returned the drill cause it wouldn't suit your needs?

As mentioned above but put into different words, the drill could be damaged if it were to have insufficient power to run off of. But thats not possible with an inverter. The inverter will trip if its unable to provide the power needed. As for the alt, it can only produce what its rated for and it isn't bad for it to produce max capacity. As for the battery goes, whenever my inverter finally decides the battery is to low to power what I'm running, I still have enough power to start the vehicle. Always have. So I wouldn't worry about any of this, and go for it.


I have ran all sorts of tools off of my truck. Sometimes just to see if it would work, and sometimes cause I actually needed to. Ive never had any problems except the inverter either being undersized or tripping because the battery is to low.

Not to mention winches can draw around 300amps. Theres a few people that use those.

ThatGuy1295

Although you may want to consider a method for raising the idle to at least 1300rpms if you are counting on your alt to produce its max rating while using the tools.

scope103

It's not an "AC" motor (which is really an induction motor), it's a "universal" motor. So it can run off either 125VAC or 125VDC. More importantly, it can be speed-controlled just by reducing the voltage. So reduced voltage (if that is what your inverter does on overload) won't hurt it; it will just run slower.

But others have pointed out that it will take a little more amps to spin up (most inverters will handle a momentary overload), that it won't be taking the full 660 watts unless you're really working it, and there is considerable efficiency loss through the inverter. (So your 5.5 amp max 120v tool will require considerably more than 55amps into the inverter from the battery.)

So I agree that the limiting factor will be the inverter, and if you can get a setup with a 60amp input inverter, you can run it from the truck intermittently and hope the alternator will re-charge the battery in between. I've found that inverter specs are not always rock solid, so you may end up just taking a leap of faith and trying it out to see if it works.

Don't forget that you're going to need some pretty hefty (and short) cables to get 60amps from the battery to the inverter.

v_man

Also , it might be time to think of upgrading your alternator if you're set on running a drill off your truck's electrical system .

Plenty of threads here on Yotaech about swapping in a GM alternator , you would at least double your amps ...