Inverter power needed for Laptop (charger) in car

[news.rcn.com]

Either there is something obvious here I can't see or I have one of the
worst cases of dry joints in recorded history

I am trying to use a laptop in a car. I have an inverter rated at 50w. It
worked for a few months and then peremptorily stopped with a sudden rattle
from within and no light going on to show that it is ready. When I opened it
up I found a whole power transistor rattling around inside with all three
joints seemingly not connected and the glue from the rear of the transistor
seemingly having come off. Curiously the ends of the connectors don't
actually look as if they were ever connected?? (The holes on them from the
motherboard do look as if at least something was once connected to them as
they are filled with slightly disturbed-looking solder)

Is this just a lousy joint on some cheap chinese-looking inverter which
worked while the pin ends merely touched the mainboard slightly or does the
power charger need SUBSTANTIALLY more than a puny 50 watts to work: The
charger reports that it needs an input of from 100 to 250 volts at 1.5 amps
to give an output of 18.5 volts at 2.7 amps. Can someone do the maths for me
and let me know what power inverter this charger will need please?

I am suspicious of the puny nature of the inverter because although I can't
see a laptop using all that much power, I have also got a huge heavy duty
Coleman PMP400 inverter with fins all over the place and a heavy duty
sounding onboard fan rated at 400 watts (peak surge 800 watts at 3.5 amps)
and after about ten minutes of use, IT starts to overload on this laptop
charger (meaning the red warning light comes on and the inverter starts
giving symptoms of blowing): The red light won't now go off: I am wondering
if I have blown this inverter as well? (Curiously it didnt last as long as
the 50 watt one).

 

[mike]

Either there is something obvious here I can't see or I have one of the
worst cases of dry joints in recorded history

I am trying to use a laptop in a car. I have an inverter rated at 50w. It
worked for a few months and then peremptorily stopped with a sudden rattle
from within and no light going on to show that it is ready. When I opened it
up I found a whole power transistor rattling around inside with all three
joints seemingly not connected and the glue from the rear of the transistor
seemingly having come off. Curiously the ends of the connectors don't
actually look as if they were ever connected?? (The holes on them from the
motherboard do look as if at least something was once connected to them as
they are filled with slightly disturbed-looking solder)

Is this just a lousy joint on some cheap chinese-looking inverter which
worked while the pin ends merely touched the mainboard slightly or does the
power charger need SUBSTANTIALLY more than a puny 50 watts to work: The
charger reports that it needs an input of from 100 to 250 volts at 1.5 amps
to give an output of 18.5 volts at 2.7 amps. Can someone do the maths for me
and let me know what power inverter this charger will need please?

I am suspicious of the puny nature of the inverter because although I can't
see a laptop using all that much power, I have also got a huge heavy duty
Coleman PMP400 inverter with fins all over the place and a heavy duty
sounding onboard fan rated at 400 watts (peak surge 800 watts at 3.5 amps)
and after about ten minutes of use, IT starts to overload on this laptop
charger (meaning the red warning light comes on and the inverter starts
giving symptoms of blowing): The red light won't now go off: I am wondering
if I have blown this inverter as well? (Curiously it didnt last as long as
the 50 watt one).

What happens when you solder the transistor back in?

If you look at the numbers, you might conclude that your adapter takes
150W in to put out 50W. That's seriously overloading your 50W inverter.

The good news is that the numbers written on the brick are more likely
to satisfy some regulatory requirement rather than express what's
actually happening in your case.

The bad news is that while charging, your laptop probably does use all
all 2.7A = 50 watts. There is at least some loss in the adapter, so
you're still
seriously overloading the 50W inverter. Not surprised the transistor
melted out.

Switching power supplies do put a serious stress on square wave, or
modified sinewave inverters...but a 400W unit should work ok?
I had no problems with a 30W laptop on a 140W inverter.

Check the 12V input under full load. If you have losses reducing the
input voltage, the current will go up to compensate.

I once had a problem with a car installation. Turns out that I'd hooked
the inverter to the wire that was intended to dim the radio dial light.
Had serious problems if the dash lights were dimmed ;-)
mike

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[[email protected]]

You have other choices besides an inverter.
A DC to DC converter that takes in 12 volts and puts out 15 volts with
a plug soldered onto it that fits the back of your computer would work
a lot more efficiently than an inverter into a power supply.
Also, you can run a laptop directly off a car battery. Just make a
cable with a cigarette lighter plug on one end and a plug for you
computer on the other end. That's how I run my computer in the car.
Your laptop's battery won't recharge from a 12 volt supply, but you
won't be using the laptop's battery anyway. Why not keep it simple --
no inverter or anything, just a cable with a plug on each end.
What's more, your computer might even charge plugged directly into the
cigarette lighter if you are driving the car, because your car's
voltage will be between 14 and 15 volts when you are driving.
I don't use my computer when the car is running because I want to
protect it from the hash on the car's power circuits. But I would have
it plugged in to the cigarette lighter with the car running so it would
charge, as long as the computer is actually turned off. I'm to lazy to
put a filter on the cable I made, or I could use the computer with the
car running.

 

[mike]

You have other choices besides an inverter.
A DC to DC converter that takes in 12 volts and puts out 15 volts with
a plug soldered onto it that fits the back of your computer would work
a lot more efficiently than an inverter into a power supply.
Also, you can run a laptop directly off a car battery. Just make a
cable with a cigarette lighter plug on one end and a plug for you
computer on the other end. That's how I run my computer in the car.
Your laptop's battery won't recharge from a 12 volt supply, but you
won't be using the laptop's battery anyway. Why not keep it simple --
no inverter or anything, just a cable with a plug on each end.
What's more, your computer might even charge plugged directly into the
cigarette lighter if you are driving the car, because your car's
voltage will be between 14 and 15 volts when you are driving.
I don't use my computer when the car is running because I want to
protect it from the hash on the car's power circuits. But I would have
it plugged in to the cigarette lighter with the car running so it would
charge, as long as the computer is actually turned off. I'm to lazy to
put a filter on the cable I made, or I could use the computer with the
car running.

NO,NO,NO,NO,NO,NO,NO,NO,NO,NO!!!!!!!!
DO NOT DO EITHER OF THESE THINGS.

Using a car adapter NOT DESIGNED for your EXACT model computer is very
risky. You can probably get away with it if you take out the battery.
If you leave the battery in, you risk serious damage to your battery
and maybe yourself when it explodes. Does this happen EVERY time?
Of course not. HOW LUCKY DO YOU FEEL?

PLUGGING ANYTHING NOT SPECIFICALLY DESIGNED TO PLUG INTO A CAR
DIRECTLY INTO A CAR ELECTRICAL SYSTEM IS A SUICIDE MISSION FOR YOUR
LAPTOP. THE BATTERY ISSUES DESCRIBED IN THE PREVOUS PARAGRAPH ALSO APPLY.
Go read this before you contemplate a direct computer connection:

http://www.littelfuse.com/data/en/Application_Notes/an9312.pdf

THEN QUIT CONTEMPLATING IT.

Yes, you'll find idiots who claim they never had a problem.
Again, how lucky do you feel stuffing 300V high energy pulses into your
laptop???

Get an inverter that works.
mike



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Return address is VALID but some sites block emails
with links. Delete this sig when replying.
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Wanted, PCMCIA SCSI Card for HP m820 CDRW.
FS 500MHz Tek DSOscilloscope TDS540 Make Offer
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Bunch of stuff For Sale and Wanted at the link below.
MAKE THE OBVIOUS CHANGES TO THE LINK
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[news.rcn.com]

I figured that if the computer's power supply says it needs 100 to 250
volts, it must mean something which doesnt equate to "use any old 12 volt
supply, if possible bumped up to 15 volts"

So the position is that the 50 w one was simply too weak and the 400 watt
one probably had something wrong with it? I also have a 1200 watt Coleman
one which I am now reluctant to use (principally because it is so darn huge)
but if this is the rationale, I should just go ahead and try.

I just thought that those big Coleman units dont go wrong all that often but
there again I have come across warehouses full of dead inverters. Maybe
Coleman just arent too much more reliable than all the others?

 

[James Sweet]

If you look at the numbers, you might conclude that your adapter takes
150W in to put out 50W. That's seriously overloading your 50W inverter.

There's no way it's *that* inneficient, even a linear power supply would
have far lower losses. More likely it draws about 65W, but the power factor
is probably quite low, so it pulls a lot more amps than the wattage would
suggest which may well have killed the little inverter.

 

[Bennett Price]

Do you know for a fact that the charger is working correctly when
connected to house current? If the charger is defective it could be
killing your inverters.

 

[news.rcn.com]

No, the charger is fine, it is more likely that the power consumptoin killed
the little inverter and there is something wrong with the bigger 400 watt
one: I should call Coleman and ask them if those inverters were unreliable?

 

[James Sweet]

No, the charger is fine, it is more likely that the power consumptoin killed
the little inverter and there is something wrong with the bigger 400 watt
one: I should call Coleman and ask them if those inverters were unreliable?

LOL what do you expect them to say? "Yeah our products suck, sorry!"

Even if they know they're unreliable they won't say anything, Coleman
doesn't actually make the inverters anyway, they buy them from some company
in China and slap their logo on them. They're cheaply made just like all the
other cheap inverters on the market.

 

[news.rcn.com]

Good point, I didnt know that: I thought that the weight, complex
APPARENTLY high quality circuitry, not low price (for high power items) and
all those fins meant something. Is that why no one seems to bid on them on
ebay?

I wonder if this means that like Sony, they will instantaneously replace any
non-repairable unit or will they just deny responsibility for what they know
to be poorly made products?

 

[Keith Jewell]

I have a friend who is using one of those Coleman 400-watt inverters
with a couple of AGM batteries for lighting and small electrics at a
remote home site. She has been using it over two years, and during that
time the fan has failed and it has been filled full of gypsum dust, but
it still works fine. It's mounted in the back of a car and runs 24/7 as
we found that the idle current was less than 150mA, so it is more of a
headache to deal with turning it off and on than to just leave it
running. It has been absolutely troublefree.

-Keith

 

[James Sweet]

I have a friend who is using one of those Coleman 400-watt inverters
with a couple of AGM batteries for lighting and small electrics at a
remote home site. She has been using it over two years, and during that
time the fan has failed and it has been filled full of gypsum dust, but
it still works fine. It's mounted in the back of a car and runs 24/7 as
we found that the idle current was less than 150mA, so it is more of a
headache to deal with turning it off and on than to just leave it
running. It has been absolutely troublefree.

It really depends, the cheap stuff can be just fine, but it's hit or miss,
the quality control is not always there. You don't have a lot of choice
though, virtually all inverters are pretty much the same inside.

 

[news.rcn.com]

The QC goes straight down the toilet once they start outsourcing to CHina:
The chinese will apparently just cut any corner they can and use any
inferior component they want to if they think it will reduce costs. That is
why as high quality a company as Sony realises that now they have outsourced
they need to replace everything as soon as any complaint comes in because
the product is so lousily made that they need to do this to preserve their
reputation.

Other companies take the opposite view: 'We have provided you with a
ludicrously cheap unit. Don't be surprised or blame us if it fails
(hopefully) not-too-quickly'