What maximum power inverter for 1G alternator

[BigBrother-84]

Hi Gentlemen!

Possibly planning a small road trip with Big Brother, end of this summer. Wife seems to become more positive to this crazy idea.

So, I am planning some little add-on.

Just in case.

We never know.

In order to respect a 1G alternator capacity, what maximum inverter to chose? 500W, more, less?

Thanks for your advices!

[Gary Lewis]

Most 1G alternators will throw 60 amps at full tilt, meaning with engine RPM of 3000, so the wattage output would be 60(a) x 14 (v) = 840. But, as shown below, you'll only get 50A at 1000 RPM, and more like 30A at 600 RPM idle so you'll have to have the engine spinning pretty good if you want to power the inverter completely off the alternator.

However, if you are willing to pull the battery down a bit you can pull more than 60 amps for a while, so you could get by with 1000 watts for a bit. Just make sure that you have all other accessories off and that you don't do it for very long.

But the inverter only pulls enough current to produce the power requested by the device you plug into it. So you could go with a larger inverter and keep the device to 1000W and be ok - for a bit.

What are you thinking of running on the inverter? http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/thinking-26_orig.jpg

[BigBrother-84]

What are you thinking of running on the inverter?

Nothing very energy hungry, probably only for recharging a laptop, a rechargeable spotlight, camping things like that.

[Gary Lewis]

What are you thinking of running on the inverter?

Nothing very energy hungry, probably only for recharging a laptop, a rechargeable spotlight, camping things like that.

I found a 12v recharging cable for my laptop so it doesn't need an inverter. Maybe you could do that for your laptop and buy lantern that recharges off 12v - both for less than an inverter?

[BigBrother-84]

I found a 12v recharging cable for my laptop so it doesn't need an inverter. Maybe you could do that for your laptop and buy lantern that recharges off 12v - both for less than an inverter?

Yes, I contemplated that solution, but strangely it could cost more than a small inverter.

The inverter solution offers more "flexibility". But, knowing that a 1G isn't very powerful, I want to stay in an acceptable load range for it.

[ArdWrknTrk]

Most 1G alternators will throw 60 amps at full tilt, meaning with engine RPM of 3000, so the wattage output would be 60(a) x 14 (v) = 840. But, as shown below, you'll only get 50A at 1000 RPM, and more like 30A at 600 RPM idle so you'll have to have the engine spinning pretty good if you want to power the inverter completely off the alternator.

However, if you are willing to pull the battery down a bit you can pull more than 60 amps for a while, so you could get by with 1000 watts for a bit. Just make sure that you have all other accessories off and that you don't do it for very long.

But the inverter only pulls enough current to produce the power requested by the device you plug into it. So you could go with a larger inverter and keep the device to 1000W and be ok - for a bit.

What are you thinking of running on the inverter?

Be mindful Gary that inverters get hot and that heat has to come from somewhere, even though it doesn't end up as wattage on the back end.

Fortunately IGBT are far more efficient than the transformer style inverters of old.

I'm just pointing out that there are efficiency losses beyond the load, and you would have to look at documentation specific to the inverter you purchase to know exactly what they are.

[Gary Lewis]

Be mindful Gary that inverters get hot and that heat has to come from somewhere, even though it doesn't end up as wattage on the back end.

Fortunately IGBT are far more efficient than the transformer style inverters of old.

I'm just pointing out that there are efficiency losses beyond the load, and you would have to look at documentation specific to the inverter you purchase to know exactly what they are.

Very true, Jim. But the 3KW one I got from you pulls so little w/o a load that it is hard to measure. So if all Jeff needs to do is to charge things like a computer he should be able to use a very small inverter that will have almost no load at idle.

[ArdWrknTrk]

Very true, Jim. But the 3KW one I got from you pulls so little w/o a load that it is hard to measure. So if all Jeff needs to do is to charge things like a computer he should be able to use a very small inverter that will have almost no load at idle.

Not "stand by" without load, the heat from the coils or IGBT's when it actually has to put out the rated watts.

That heat comes from somewhere, and that 'somewhere' is the lame alternator.

You're an engineer... I'm sure you can understand this.

Yes, if all Jeff needs is 120W to run a laptop that's one thing. But that doesn't address the title of this thread.

[ratdude747]

What are you thinking of running on the inverter?

Nothing very energy hungry, probably only for recharging a laptop, a rechargeable spotlight, camping things like that.

What kind of laptop?

I've gotten dell and lenovo cords 12V cords (for my fleet of personal and work laptops) for under $30 a pop on eBay (OEM- not knockoff Chinese fire starters).

I also know some dell chargers will not work on an inverter that isn't a pure sine output. At least the "Old" PA10 (90W) and PA12(65W) bricks. As lots of noise, errors, and blown inverters. Hence why I opted for dedicated car chargers.

Dell did make a 40W brick that was both AC and DC... I have one somewhere (120V brick with a 12V barrel plug input on the side). But I don't think it was common as I've only seen one once, and that's the one I found at a thrift store and have in the pile.

[BigBrother-84]

What kind of laptop?

I'm on Mac. All my office is too.

iPhones, iPads, iMacs, MacMinis, MacBooks, iGadgets, name it. I keep old G4, old PoweMac, old Quadra 700, just in case I have to access old softwares or files requiring old technology and chips (it happens, each 3-4 years).

Even a vintage Macintosh SE30 is running 24/7 the black&white Flying Toasters screen saver in my office meeting room, just for fun.

If instead buying Macs since 1989 I have bought Apple's stock shares, I would be rich right now...

Ok, back to the thread... I plan to charge various little things. For example, charging my drone batteries. My DSLR camera batteries. And so on.

So, buying a compatible 12V charger for each of these various techno tools would be expansive, and complicated. A little inverter would be much simpler and flexible for my hypothetical road trip.

I won't need a lot of power, and I wanna be sure to stay respectful to my 1G capacity.

Ideally, this inverter would be connected directly to the battery poles, in order to leave the 12V dash lighter plug free, for my 12V-5A-DC Koolatron travel cooler.