OT: 12v inverter for powering HF 4.5" grinder?

Looks like it would get a bit warm for a southpaw though :)

Looks like what is needed in the back road rallies that some go - and weld with batteries to fix the various 4 wheelers. Something like that could cut and grind. But then a simple generator and standard electrical tools might be better in the long run.

But the simple job that might be just it.

Martin

I'd think about putting a series dropping resistor or something to limit the in-rush current. Naturally a 400 watt unit is only a 3.3 amp unit.

Mart> My Craftsman 3/8 drill blows the 20a fuse in my 400 watt inverter

errr -- folks - I think we are talking apples and oranges here -- the 20A fuse is going to be on the 12v side not the 110 volt side of the inverter. 20A on the input side is about 2A on the 110 v side (assuming (hah hah) 100% efficient). Reality is probably more like 80%.

mikey

Keep in mind that the stated rating on inverters is usually peak, not continuous.

Interestng hmm???? 283 happens to be the RMS value of a 400 peak sine wave.

--- Rich

The thing I like about this one is the way they put the gas tank in line with the grinder wheel. Not too much of a stretch to see a user cranking the gaurd out of the way or removing it to get access to cut and buning a hole in the tank. Given the number of weedeaters I have had that had the tanks on the top, and that the engine will run happilly either way up, I am a bit surprised at the layout.

Does anyone make cutoff wheel units to fit small (like 2 c.i.) chainsaws ? I have seen units that bolt onto larger saws to convert them, but not smaller ones.

Cheers Trevor Jones

"Rich Lockyer" wrote: (clip) 283 happens to be the RMS value of a 400 peak sine wave. ^^^^^^^^^^^^^^^^^^^^^^ Here we go again. RMS calculations do not apply to power.

No...

I have to deal with products that use the term "peak rating" and have to deal with a boss that doesn't understand why it APPEARS that I over-engineer everything by 75% (100% if I can get away with it).

--- Rich

I understand that in a perfect world, but explain the factory 20a fuse supplied in my 400 watt inverter.

--- Rich

What do your meters read in then ?

Electricians use 120V or 130V or 125v depending on the locations... This isn't Peak. Current is measured and isn't peak. A product isn't peak...

You don't concern yourselves with Peak or Peak to Peak as an Engineer must from time to time. You deal with RMS and the voltage or current. With no calculations to generate them.

In other words, a volt is a volt. To some It is simply a volt, to others it is a ratio of a peak or peak value.

Martin

Be careful trying to calculate power in the AC world. Power is voltage * current, HOWEVER, you need to take that product at the same time reference. In the AC world, unless it is a purely resistive load, there is a phase shift in the current from the voltage so saying 3a rms * 100 volts rms = 300 watts only is true into a resistive load (tungsten light, heater etc.) coils (motors, transformers etc shift the phase). In the resistive world, peak current occurs at the same time as the peak voltage as most people think. However, with an inductive load, the peak current does not happen even close to the peak voltage due to the phase shift. Sort of the same effect you see with tides in the ocean - high tide and slack water are often quite a ways apart (which has proved very embarrassing to boaters expecting to go through the pass at "high tide" expecting slack water).

mikey

I happened to notice an add for a 1000 watt mini-generator for $169 at Pep Boys. Runs on a two-cycle motor IIRC. I don't have any idea how reliable or usable this might be, but it might be a better solution than an inverter.

Anybody have any experience with one of these?

Two cycle - I bet is is NOISY! The other issue - constant use of mixed gas/oil. Just like a leaf blower or the like.

Martin

lionslair at consolidated dot net"