DC to AC inverter

Several years ago I found a great deal on a 2000W inverter that I intended to mount in my truck for powering tools away from home. The one time I used it was helping my son build a float for his Homecoming parade. Not having mounted it yet I used a set of jumper cables to connect the battery to the inverter. I used a 100 ft 12 gauge extension cord from the inverter to the float. When using my 3/8 drill to drive 3"screws into 2x4's it would pop the breaker on the inverter. By my math a drill that draws less than 5 amps would only be pulling 600 watts, a far cry from the 2000W of the inverter. Yes it pulls more current as the load increases, but is it actually enough to overload the inverter? Can anyone identify the weak link in my chain? I'd like to know what the weakness is because I think it would be a valuable tool, if it works reliably.

TM
 
Did it trip the breaker the moment you squeezed the trigger or after the drill was running? Motor startup current is typically much more than the rated amps. Also the 100 foot cord doesn't help. Someone else can probably elaborate better than I can.
 
Breaker tripped when I was about two-thirds of the way in driving a 3" screw. You could feel the load increasing for sure.
 
Lower voltage requires thicker wire. 1,000W @ 12v may require 10 ga. (for example - not sure if this is correct) for a 50' run whereas 1,000W @ 120v will only require 16 ga.

I'm thinking the wire would need to be thicker than 10ga. for a 50' run, so your 100' cord would definitely trip breakers.
 
The answer is here somewhere. Personaly I would use the biggest power cord you can get hold of. I have several number 10 cords and wow do they make a differance. You really want to make a shorter power cord run if possible.
 
The extenxion cord became part of the total load. The drill was likely trying to pull near or more than 1000w. Run the inverter directly to the drill and see how well it should work. Jim
 
5 amps at 120 Volts is 50 amps at 12 Volts. And there would be inefficiency as well, so figure maybe 10% loss there; up to 55 Amps or on that neighborhood.

To use the full 2000 Watts, you need to hard wire to the battery with really big wire.
 
I think there was something wrong, even with the long cord, the load was less than 5 amps, it should of been OK. I have a 400 watt inverter and have run small power tools off it,3 amps, with an extension cord. I was with some folks that ran a large 110V winch off an inverter and they kept the truck running when doing it, higher voltage is better. Like someone said, wire it up direct, my guess is the jumper cables were not making good contact.
 
(quoted from post at 22:29:56 03/07/17) I think there was something wrong, even with the long cord, the load was less than 5 amps, it should of been OK. I have a 400 watt inverter and have run small power tools off it,3 amps, with an extension cord. I was with some folks that ran a large 110V winch off an inverter and they kept the truck running when doing it, higher voltage is better. Like someone said, wire it up direct, my guess is the jumper cables were not making good contact.

My thoughts too, low voltage on the 12V side due to idling slow, low capacity battery or high resistance connections.
 
Sounds like the consensus is to use short heavy cables from the battery to the inverter, and keep the rig running while you are using it. This was a 1000CCA battery in my old Chevy diesel truck and I used 4 gauge jumper cables about 20' long. The truck was off while I was using the drill. Thank you all for weighing in.
 
I have some experience with a 2000W inverter. We used one to start
construction on a house with a skilsaw in 2x8's.
HEAVY cables with good connections to the battery were required
and the engine running at a fast idle.
PS.... for screws, you might try one of the new battery impact drivers.
These new tools have come a long way since the 80's!!!
 
Over the years of installing several inverters in my RV's I have learned:

1) Install Inverter as close to the battery as possible
2) Use bigger then normally expected (bigger the better within reason) high ampacity copper hard wired low resistance (not alligator clamps)
cables and connections from battery to Inverter
3) Size the Inverter not only for the loads running amps, but to allow the higher current surge required for start up.

Many Inverters have hyped up ratings, surge ratings are also important and remember they are not 100% efficient devices IE to get X watts OUT you may need X + 10% or 20% etc watts IN.

I doubt your overload problem is on the 120 VAC output (cords and drill etc) end but more likely has to do with the INPUT weaknesses such as cables and distance and resistance from battery to inverter AND/OR your battery capacity and/or its charging via alternator at X RPM isn't keeping up and battery voltage is dropping.

John T
 
I only had one experience with one. Friend had a young son that had a 400w and wanted to put it on his PU. I don't remember the hookup to the PU, but per the directions I did it for him and noticed that to get the power to what you'd expect to have to operate anything, the engine in the truck had to be running around 3600 rpm......400 cu in. gas engine running 3600 rpm to get a "guesstimated" 400 watt output?????? I told him I'd take it off so he could put it back in the box and take it back where he got it. I didn't and have no idea as to what he did with it.

Ref: 746 watts (volt-amps) per HP. 400 cu inch engine running at 3600 rpm, conservatively figure 2 cu in per hp, so 200 hp x 746 = 150kW in for 0.4 kW out. That's a real deal!!!!!!!!
 
I'll also say it was the clamps on the jumper cables not making good connection.
Also often times drill motors become over loaded and not harmed on short loads.

Dusty
 
Is it the fuse or the trip that is shutting off the inverter? It will automatically shut down if battery voltage drops below 10.5 or 11 volts - even if for just a millisecond. One battery is not capable of running a 2000 watt inverter at full load. Your drill probably draws 100 amps for a fraction of a second when you first turn it on. That takes a good battery and good connections. Keep in mind that a so-called "500 CCA" truck battery is designed to make 250 amps @ 9.5 volts. NOT at 11 volts as the inverter needs. So there are two factors to consider. #1 is the drop in the cables and connectors (need at least #4 cable if 6 feet long0. #2 is the actual voltage drop of the battery itself under load.

I have a 3000/6000 watt inverter hardwired into my truck with dual type 27 DC batteries and it works great with power tools.
 
All of my trucks have had 2500 wat power inverters and they will run power tools no problem. However they draw a LOT of power from the battery and in all mine they have 2 positive and 2 negative cables about 3' long from the battery to the inverter and they will sometimes get hot. Battery cables will be shorting the inverter a lot even if they are good. Get it wired in close to the battery with large cables and it should run power tools no problem. My 2500 wat will run both a microwave and electric grill at the same time. A 1500 wat will run just one at a time. Be carefull if you do much work with it because they will leave you with a dead battery. Most have an automatic shut down for low voltage, but on my truck by the time that happens it won't atart anymore.
 
watts out = watts in minus losses. They have to come from somewhere for the battery to have the energy to supply power.
 
The 12 volt amperage will be 10 times the 120 volt so the 12v wires will have to be 10 times what the 120v tool needs. Inverters shut off if the voltage drops to far. (2000watts/120)12=200amps or 00ga cu wire. That's big honking wire! Imagine the cables on an industrial welder.
 
2000 watt inverter when run at 2000 watts, draws 170 amps @ 12 volts. NOT "200 amps." Four feet of #4 copper cable can do the job with a 3.4% voltage-drop.

Note that a good 2000 watt inverter is made to run up to 4000 watts and that is why big cable is needed for high surge loads. 4000 watts with four feet of cable needs at least 1/0 copper (2.6 % drop).
 
MEDJ, looks like you are "assuming" 100% inverter efficiency with those numbers.

What would "real world" efficiency and current draw be @ 2000 watts output?
 
Just an addition to your post, in order to draw 2000 watts at 120 VAC on the OUTPUT since the Inverter is NOT 100% efficient, you would have to provide approximately 2000 + lets use 10% or 2200 Watts INPUT and at 12 volts nominal that would mean you would have to draw 183 amps out of the batteries !!!!!!!!!!!! If the inverter were 85% efficient you would draw even MORE from the batteries. Big current loads causes battery voltage to drop making things even worse

There are HEAT LOSSES involved when using an inefficient electrical device, what you get OUT = whats in less heat losses.

If the Inverter is rated at 2000 watts INPUT and is 90% efficient, you only get .90 x 2000 or 1800 watts OUTPUT. If its rated 2000 OUTPUT and lets use 90% efficient, then again it requires 2200 watts INPUT

So often electrically challenged gents don't use big enough cable on the INPUT from batteries to Inverter which causes a voltage drop so the inverter sees less then battery voltages. I advise gents to use BIG cables and locate inverter close to batteries

John T too long retired electrical engineer and rusty so no warranty
 
I not "assuming" anything. I own over a dozen inverters. My house runs on a pair them. My truck has one. My car has one. My Toyota RV has two of them. I have two in an off-grid solar-powered cabin. I own many and have tested many. I know exactly what they do and exactly what the power usage is, along with wiring needs.

RE: efficiency? Depends on the inverter and the actual load. 93% efficiency is common for a modified wave and 90% for a so-called "sine wave" inverter.
 
Inverters trip if battery voltage drops below 10.5 to 11 volts, even for just a millisecond. That can be a problem.

Batteries have their own internal drop under load and that is a huge factor, not including the wiring. keep in mind that when cranking the starter motor in a car or truck, the battery is designed to deliver 9 to 9.5 volts under load, NOT 11-12 volts like an inverter needs under load. Inverters run 88% to 94% efficient, depending on type and load. Cheap mod-waves tend to be more efficient then the more expensive "sine wave" inverters.

E.G. Let's say there is only one, 115 AH deep-cycle battery being used. Under a 1500 watt load, it will, at first surge - drop to 11 volts and then recover and rise up to around 11.5 volts. If the inverter has a built in trip set at 11 volts - you can see where almost no voltage drop in the wiring can be allowed. If a pair of batteries is used, or the engine is running so the alternator can add power - it gets better.

One example: One type 27, deep-cycle batter rated 115 AH. Inverter delivering 2000 watts to an appliance. Load @ 12 volts is 180 amps. Load @ 11 volts is 195 amps. Four feet of #2 copper will have a 2.3% voltage drop, so if 12 volts at the battery - it will be 11.7 volts at the inverter. If 1/0 copper is used, voltage drop will be 1.4%.

Now if only using one battery an it drops to 11 volts at the battery (very common). If there is a 2.3% drop in the wiring, voltage to the inverter will be 11.1 volts and might shut itself off.
 
JDEM "2000 watt inverter when run at 2000 watts, draws 170 amps @ 12 volts. NOT "200 amps."

Yea, correct, noticed my mistake a few seconds after posting. A thousand years from now people will be seeing my mistake. Wish I could edit. Duh.
 

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