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

 

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.
==========================


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

 

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

 

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.

 

This tells that there is something wrong... You should check things

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

 

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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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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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

 

replace the LapTop's AC power supply.

 

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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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