Car power inverter- enough to run a PC?

[Fritzo]

Originally posted by: chiwawa626
This idea sounds pretty out there...

Generator still sounds like a better idea....

it's heavy and needs to go down three floors to get outside

So is your car...

No it doesn't. Only an extension cord does .

 

[Fritzo]

Originally posted by: cavemanmoron

Originally posted by: nwfsnake
I think a UPS is a much better choice. Same idea, only with automated switch over when the power goes out.

Our UPS system will give 3-4 hours of power. I want a temporary backup plan against a longer outage.

 

[BBC454]

I would never idle a car for that long. On most engines, the cam and pistons get their oil from the crank counterweights splashing into the oil in the oil pan. If you idle for too long the oil only hits parts of the cam, therefore giving no oil to other parts. So for straight idling for 18 hrs, you could definitely do some damge, unless you want to go out every 10 minutes or so and vary the rpm. Also, most alternators put out 100-140 watts max, which means even less at idle. A generator is definitely the way to go.

 

[sharkeeper]

Hah!

You want to be blackout proof?

How much money you want to spend? I like clients that give me a blank check. I'm happy and they are happy and they have a solution that works.

That said, your "solution" is not acceptable. It's dangerous at best.

At the very least consider a UPS that can keep things running long enough for you to prepare a generator for long term use. Consult with an engineer to get a wiring plant going.

The ideal solution is UPS/UBS/DGS based. Typically these start out at 18 kVA and higher but I've spec'd them as low at 3.5kVA for people in residential settings, etc.

 

[JoeKing]

offsite/out of state data server with auto load switching :thumbsup:

and in this day and age it's not that expensive at all.

 

[amdskip]

Originally posted by: BBC454
I would never idle a car for that long. On most engines, the cam and pistons get their oil from the crank counterweights splashing into the oil in the oil pan. If you idle for too long the oil only hits parts of the cam, therefore giving no oil to other parts. So for straight idling for 18 hrs, you could definitely do some damge, unless you want to go out every 10 minutes or so and vary the rpm. Also, most alternators put out 100-140 watts max, which means even less at idle. A generator is definitely the way to go.

I agree! It's also hard on the crankshaft, you just don't want to do it.

 

[Eli]

Originally posted by: BBC454
I would never idle a car for that long. On most engines, the cam and pistons get their oil from the crank counterweights splashing into the oil in the oil pan. If you idle for too long the oil only hits parts of the cam, therefore giving no oil to other parts. So for straight idling for 18 hrs, you could definitely do some damge, unless you want to go out every 10 minutes or so and vary the rpm. Also, most alternators put out 100-140 watts max, which means even less at idle. A generator is definitely the way to go.

Sorry to bump an old thread, but good lord, this is just plain BS.

Maybe on some old engines, but no new automotive engine worth it's weight in metal is splash lubricated, lol. An engine can idle 24/7/365 and it will absolutely not suffer any mechanical damage from that fact alone.

And.. 100-140 watts max? What are you smoking man?

140W at 14V is only 1.1 amps.

I'd say the typical alternator makes about 25A at idle. I'm sure it varies widely, but that sounds like a good number.

25A @ 14V = 350W.

What's the typical alternator's max output? 65A or so? Probably varies widely....

Well, 65A @ 14V = 910watts. There are alternators that put that out at idle.

sharkeeper, why exactly would it be dangerous? And dangerous in what way? For the equipment, or?

 

[Calin]

Taking the current from the battery will reduce quite a bit the voltage variations - as the internal resistance of an automotive battery is extremely small, as long as the current in it (incoming or outgoing) doesn't reach very high levels, the voltage on battery is almost constant. For 300A max discharge current on a 12V 55Ah battery, the internal resitance would be a 20th of an ohm.
The typical car alternators have fuses for something like 120+A, so it will generate enough current to keep things going. However, I don't know if it will generate enough when idling - you might want to accelerate the engine a bit.
However, another thing - you will need real cabling for 100A

 

[sharkeeper]

sharkeeper, why exactly would it be dangerous? And dangerous in what way? For the equipment, or?

Misapplication of equipment in this case is dangerous.

Automobiles were not designed for this purpose. The catalytic converter will run hot enough to ignite combustible material that may find its way under there. Is someone going to be assigned a fire watch for this?

The exhaust must be dealt with as well. Fumes entering the livable space creates a hazardous condition. Fusible links in the charging system are not designed to deal with high loads for extended periods of time - the charging system may be damaged! This has to be considered as well.

The inverter itself! It will have a duty cycle. Exceed SOAR continuously and it will fail, often catastrophically causing interfering anomalies to upstream/downstream components not designed for such conditions. Fire may result and the outcome could be disastrous.

Remember, when you're dealing with mains power standby/backup systems, leave the designing up to a pro with years of experience! I would not want to be your insurance broker!