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Inverter blew a fuse!!

I was using my new emachines M6811 laptop, which has an A/C adapter with a "90W" blue sticker on the end of it, with a 150W cigarette lighter DC/AC inverter, Tripp Lite brand, in a 2002 Toyota Echo. The car has a new battery and the cig lighter had never before been used. The first day, with about

7 or 8 hours on the road, there were no problems. Eventually, however, one day I plugged it in the inverter again and within about ten minutes the inverter alarm started sounding. I kept resetting it and in another five minutes the inverter's fuse blew, and the car's fuse blew, too, but it was somehow delayed by a few hours I think for some reason because we didn't notice the stereo wasn't working until hours later).

A few dumb questions:

- Is it possible that the laptop adapter is already going bad, drawing more power than should be? (Every time I plug it into the wall while the laptop is running I get a VERY visible and loud spark.)

- If I bought an inverter that supported more wattage--say, 250 watts--would that decrease the chances of the *car* fuse from blowing out, or does the car fuse not "care about" the power handling of the inverter? (I don't know much about electricity.)

- Would a direct DC-to-DC step-up converter be better? Any recommendations on a model of such an adapter for a laptop marked on the bottom with "18.5 watts"?

Thanks, Jon

Reply to
Jon Davis
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I am very sure that you have a short somewhere. This inverter can draw a bit more than 20 amps at its peak load. These inverters are very efficient, and draw very little power when there is no load. They normally do not have more than about a 5% to 10% internal loss.

I suspect that something in the power supply section for the laptop is defective, and it is drawing too much current. These low cost inverters are not pure sinewave, and this is what is keeping their cost down. It is expensive to make a true sinewave inverter. They are what is called a "modified sinewave". The waveform from these low cost inverters is a crude stepped sinewave, that is almost a square wave, and it is very high in its distortion because of this.

Many types of power supplies for appliances and devices can be damaged by one of these inverters. These inverters are good for lights, devices with brush type motors such as an electric drill, or similar devices. There are many types of switching supplies that can also work with these, but not all of them. I have seen some equipment damaged by these inverters. Before using one on any device, it would be a good thing to enquire to the manufacture of the product you plan to use with it.

You should take your laptop with its power supply (if it is an external supply), to the manufacture service rep to have it checked. This way you will know if there is a problem with it. I have seen a few computer power supplies damaged by some models of these inverters.

--

Jerry G.
==========================


"Jon Davis"  wrote in message
news:10i5qdbjnfimo1e@corp.supernews.com...
I was using my new emachines M6811 laptop, which has an A/C adapter with a
"90W" blue sticker on the end of it, with a 150W cigarette lighter DC/AC
inverter, Tripp Lite brand, in a 2002 Toyota Echo. The car has a new battery
and
the cig lighter had never before been used. The first day, with about
7 or 8 hours on the road, there were no problems. Eventually, however, one
day I plugged it in the inverter again and within about ten minutes the
inverter alarm started sounding. I kept resetting it and in another five
minutes the inverter's fuse blew, and the car's fuse blew, too, but it was
somehow delayed by a few hours I think for some reason because we didn't
notice the stereo wasn't working until hours later).

A few dumb questions:

- Is it possible that the laptop adapter is already going bad, drawing more
power than should be? (Every time I plug it into the wall while the laptop
is running I get a VERY visible and loud spark.)

- If I bought an inverter that supported more wattage--say, 250 watts--would
that decrease the chances of the *car* fuse from blowing out, or does the
car fuse not "care about" the power handling of the inverter? (I don't know
much about electricity.)

- Would a direct DC-to-DC step-up converter be better? Any recommendations
on a model of such an adapter for a laptop marked on the bottom with "18.5
watts"?

Thanks,
Jon
Reply to
Jerry G.

Emachines has little to no cust. support, certainly no "service rep" as I bought it through mail order. I'll get a third party adapter replacement for the laptop. Is there a good inexpensive inverter that you might recommend?

Jon

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Reply to
Jon Davis

This tells that there is something wrong... You should check things and not contonue to use the system unless you are sure that everything is right.

You continued usign the thing even though you got warning that things were not right... You could have for example beign overheatign the inverter and then the overhatign caused a short-circuits..

Delayed fuse blowing sounds strange.... You either did not ntice it earlier, or the incident with the inverter almost blew the use, and later the starting power spike on the stereo burned it completely...

Sparking when pluggin in power supplies is quite normal. Many PC power supplies take quite high surge currents when they are started or plugged in.

Higher wattage converter would not (at least theoretically) decrease the chances of the *car* fuse from blowing out. The car fuse will blow when too much power is taken from the outlet protected by it. This to much power intake could happen because of high power inverter powering very high load or because of inverter malfunction (short circuit etc.).

I would quess that DC-to-DC step-up converter would be better suited in your applications. With this kind of device you get the power your laptop needs with less conversion steps in the way. Better efficiency and at least theoretically more reliable.

Some inverters are not happy when feding power to devices like computer switched mode power supplies... They can take current in spikes while some inverters are designed for just pure resistive loads in their mind (this the load for what their power rating is specified).

Check carefully on the power rating and type of adapter you need. You are talking on the beginning of the mssage "90W" and now say "18.5 watts". Which one is correct figure.

--
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/
Reply to
Tomi Holger Engdahl

It's a little late to say so now. At any rate, I only did this because the bottom of the unit said so... "If the alarm goes off or the inverter stops functioning, simply turn the unit off and on a few times and continue use."

Thanks for your reply.

Jon

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Reply to
Jon Davis

This may not be anything. It it were really drawing over 150 W, something would be getting very hot very quickly.

The original inverter might just have been defective.

No, you're probably better off with the DC to AC inverter.

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Reply to
Sam Goldwasser

Could be but if it were drawing more than 150 W, something in the laptop or its power supply would be getting very hot very quickly. I gather that aside from the "spark", the laptop operates normally.

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Reply to
Sam Goldwasser

I don't agree at all!

Buy an adapter specifically for you laptop, that plugs into a cigarette lighter.

I have Compaq Armada series laptop(s). One I have mounted in the car. And YES it uses a Compaq brand DC to DC converter. It outputs 18.5 volts for my laptop.

To invert up to 120V AC, then back down is NOT efficient!

My two cents...

Jack :)

Reply to
Jack Edin

replace the LapTop's AC power supply.

J> I was using my new emachines M6811 laptop, which has an A/C adapter with a

Reply to
Jamie

That I agree with. What I don't agree with is just buying any old DC-DC converter to power your laptop. That would probably void the warranty.

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Reply to
Sam Goldwasser

recommendations

"18.5

Well I don't see how plugging the AC adapter into a step-up AC/DC inverter is any better. You're making TWO voltage transformations (stepping up to

120V, then stepping down again), plus your going from direct current to alternating current and then back to direct current which is undoubtedly going to be more likely to cause problems than just stepping up the voltage of a direct current.

I am sure a DC-DC step-up adapter will be the best solution for me. It's electrically IDENTICAL to the universal external laptop batteries you can buy to place under a laptop and hook directly to the power input.

Jon

Reply to
Jon Davis

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