If I want to run a laptop off of a 200 watt inverter plugged into vehicle
power receptacle or cigarette lighter how can I determine the power
requirements of the laptop? I have not purchased a laptop but am after
guidelines how I can determine if a selected laptop will run on the 200 watt
inverter. I recognize this is probably a broad question.
--
<Bill>

Brought to you from Anchorage, Alaska.

Bill Bradshaw wrote:
> If I want to run a laptop off of a 200 watt inverter plugged into vehicle
> power receptacle or cigarette lighter how can I determine the power
> requirements of the laptop? I have not purchased a laptop but am after

Laptop power supplies are typically rated for 65-75W at most. Often
less than this. And of course the laptop does not routinely require
this much power - it's a worst-case figure. You will have no trouble
with a 200W inverter.

A 200 watt inverter will run pretty much any laptop. I have not seen
any laptop that used more than about 120 watts. While that is it's
power supply output, it's power supply input would be under 200 watts as
long as the power supply was at least 60% efficient, and they are all
more than 60% efficient. Finally, although 120 watts might be the
laptop's rating, it's near certainty that it will run on far less. In
fact, there was a discussion in a Dell forum about the fact that Dell is
selling laptops that have a 90 watt power consumption label on the
laptop, but the Dell power supply is only rated at 65 watts max.


Bill Bradshaw wrote:
> If I want to run a laptop off of a 200 watt inverter plugged into vehicle
> power receptacle or cigarette lighter how can I determine the power
> requirements of the laptop? I have not purchased a laptop but am after
> guidelines how I can determine if a selected laptop will run on the 200 watt
> inverter. I recognize this is probably a broad question.

Barry Watzman wrote:
> A 200 watt inverter will run pretty much any laptop. I have not seen
> any laptop that used more than about 120 watts.

Just watch the ratings. My 400 watt inverter actually is rated at 150
watts continuous. My Tecra 9100 wower supply is rated at 120 watts
input and 75 watts output so the inverter is not a whole lot too big.

Ian Singer


--


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Ian Singer wrote:
> Barry Watzman wrote:
>> A 200 watt inverter will run pretty much any laptop. I have not seen
>> any laptop that used more than about 120 watts.
>
> Just watch the ratings. My 400 watt inverter actually is rated at 150
> watts continuous. My Tecra 9100 wower supply is rated at 120 watts
> input and 75 watts output so the inverter is not a whole lot too big.
>
> Ian Singer

Thanks for the information to look at the continuous power. I would like to
get a 400 watt but they want them wired directly to the battery and then I
would have to find a way through the firewall.

--
<Bill>

Brought to you from Anchorage, Alaska.

Bill Bradshaw wrote:
> Thanks for the information to look at the continuous power. I would like to
> get a 400 watt but they want them wired directly to the battery and then I
> would have to find a way through the firewall.
>

Right next to the steering shaft there probably is space. Also make sure
inverter has low battery cut off so if car battery gets too low it shuts
down and does not drain it.

Ian Singer

--


================================================== =======================
See my homepage at http://www.iansinger.com
hosted on http://www.1and1.com/?k_id=10623894
All genealogy is stored in TMG from http://www.whollygenes.com
Charts and searching using TNG from http://www.tngsitebuilding.com
I am near Toronto Canada, can I tell where you are from your reply?
================================================== =======================

RE: "My 400 watt inverter actually is rated at 150 watts continuous"

I'd call that a 150-watt inverter, and so would most people, I think, as
well as the Federal Trade Commission.


Ian Singer wrote:
> Barry Watzman wrote:
>> A 200 watt inverter will run pretty much any laptop. I have not seen
>> any laptop that used more than about 120 watts.
>
> Just watch the ratings. My 400 watt inverter actually is rated at 150
> watts continuous. My Tecra 9100 wower supply is rated at 120 watts
> input and 75 watts output so the inverter is not a whole lot too big.
>
> Ian Singer
>
>

Bill, I'd get the 400 watt inverter and plug it into the cigarette
ligher, with the understanding up front that you can't draw 400 watts,
but that you will have some "reserve".

Power (watts) = Voltage * Current

The voltage in a car is about 14 volts with the engine running, 12 to 13
with the engine off. Assume that the inverter is 75% efficient (that
is, to get 300 watts of 110 volt AC inverter output, you need 400 watts
of DC input to the inverter).

The limiting factor for the cigarette lighter is the wiring to the
lighter and it's fuse. The current carrying capacity of the cigarette
lighter varies, but it's typically fused at 15 to 30 amps, or about 200
to 450 watts. Try to draw too much for your car, and you blow the fuse
and/or melt the wiring. That's why the 400 watt inverter suggests
wiring direct to the car's electrical system or battery. However, the
fact that it's a 400 watt inverter only means that it's capable of
putting out 400 watts. But if you only plug a 120 watt load into it (a
worst case laptop power supply), it's going to draw less than 200 watts
(allowing for the efficiency losses in both the inverter itself and the
laptop AC adapter), not 400 watts, and the cigarette lighter will be
fine. But should you ever need 400 watts, you will have the higher
power inverter, although you won't be able to plug it into the cigarette
lighter. Also, the 400 watt inverter will supply 200 watts or less with
a lot less stress than you would place on a 200 watt inverter.


Bill Bradshaw wrote:
> Ian Singer wrote:
>> Barry Watzman wrote:
>>> A 200 watt inverter will run pretty much any laptop. I have not seen
>>> any laptop that used more than about 120 watts.
>> Just watch the ratings. My 400 watt inverter actually is rated at 150
>> watts continuous. My Tecra 9100 wower supply is rated at 120 watts
>> input and 75 watts output so the inverter is not a whole lot too big.
>>
>> Ian Singer
>
> Thanks for the information to look at the continuous power. I would like to
> get a 400 watt but they want them wired directly to the battery and then I
> would have to find a way through the firewall.
>

Barry Watzman wrote:
> Bill, I'd get the 400 watt inverter and plug it into the cigarette
> ligher, with the understanding up front that you can't draw 400 watts,
> but that you will have some "reserve".
>
> Power (watts) = Voltage * Current
>
> The voltage in a car is about 14 volts with the engine running, 12 to
> 13 with the engine off. Assume that the inverter is 75% efficient
> (that is, to get 300 watts of 110 volt AC inverter output, you need
> 400 watts of DC input to the inverter).
>
> The limiting factor for the cigarette lighter is the wiring to the
> lighter and it's fuse. The current carrying capacity of the cigarette
> lighter varies, but it's typically fused at 15 to 30 amps, or about
> 200 to 450 watts. Try to draw too much for your car, and you blow
> the fuse and/or melt the wiring. That's why the 400 watt inverter
> suggests wiring direct to the car's electrical system or battery. However,
> the fact that it's a 400 watt inverter only means that it's
> capable of putting out 400 watts. But if you only plug a 120 watt
> load into it (a worst case laptop power supply), it's going to draw
> less than 200 watts (allowing for the efficiency losses in both the
> inverter itself and the laptop AC adapter), not 400 watts, and the
> cigarette lighter will be fine. But should you ever need 400 watts,
> you will have the higher power inverter, although you won't be able
> to plug it into the cigarette lighter. Also, the 400 watt inverter
> will supply 200 watts or less with a lot less stress than you would
> place on a 200 watt inverter.
>
> Bill Bradshaw wrote:
>> Ian Singer wrote:
>>> Barry Watzman wrote:
>>>> A 200 watt inverter will run pretty much any laptop. I have not
>>>> seen any laptop that used more than about 120 watts.
>>> Just watch the ratings. My 400 watt inverter actually is rated at
>>> 150 watts continuous. My Tecra 9100 wower supply is rated at 120
>>> watts input and 75 watts output so the inverter is not a whole lot
>>> too big. Ian Singer
>>
>> Thanks for the information to look at the continuous power. I would
>> like to get a 400 watt but they want them wired directly to the
>> battery and then I would have to find a way through the firewall.

I have been looking at the APC
(http://www.apc.com/products/family/index.cfm?id=9) brand. The 150 watt one
is rated at 150 watts continuous with 225 watt peak. The 350 watt one is
rated at 350 watts continuous with a 800 watt peak. One of the problems
with the 350 is the battery cord is only 1 meter long which would not even
reach from the battery to the firewall. The cord would have to be modified.
The 350 watt will run off of a power outlet or cigarette lighter if you are
using under 140 watts. The nice thing about the 350 is it has two outlets.
I would like to be able to run a laptop and NiMh AA battery charger at the
same time. I have not been able to figure out how much wattage a NiMh
charger would require. The NiMh charger brick has 120VAC 60 Hz 250MA input
and 12VDC 1.5A output so maybe the NiMh charger needs about 30 watts. I am
sure these inverters have a safely factor built into the specs but the
questions is how much.

I do not know if they are on the same circuit but I have both a power outlet
and cigarette lighter outlet next to each other so I was thinking maybe I
could run two 150s connected to each of the outlets. This is difficult when
you know just enough to get yourself in trouble. I thank you for taking the
time to discuss this with me.
--
<Bill>

Brought to you from Anchorage, Alaska.