I posted a few weeks back asking about reliability and safety of using
12V car cigarette-lighter adapters for mobile phones, laptops etc (and
IIRC generated a major sh*tstorm as a result...!) Anyway here's a
followup to the query...

I decided to acquire a car adapter for my new notebook PC (an Asus EEE
PC900) to enable it to be used to double as a DVD player for the kids
on long journeys.  Had no option but to buy an unbranded 3rd-party
adapter since ASUS hasn't produced one yet, although rumour has it
that one may be in the pipeline).

Yesterday I tried out the car adapter for the first time, but
unfortunately it didn't work properly.  Although the adapter's LED
indicator lit up continuously, and there was definitely no loose
connections, the PC's notification window popped up to say 'AC charger
connected', only to be replaced 5 secs later by another window saying
'changing to battery power' (or words to that effect).  It then cycled
continuously between battery and charging mode every few seconds.

My impression is that the machine is trying to charge, but as soon as
it does so the current provided by the car falls below some threshold,
and the computer cuts it off and reverts to battery mode, whereupon
the current is able to increase again, allowing the computer to switch
into charging mode again, etc etc.  Sound about right?

What is "responsible" for the problem - is it the adapter, the
computer, or the car? Is it in anyway surmountable?  The laptop needs
"+12V, 3A, 36W" according to the label on its base.  Surely not too
much to expect from a cigarette lighter?  Wondering if a 240V inverter
would be better (I have one at home :-( )

I'm currently connecting on wifi from a tent in the middle of France,
with no electrical tools, instruments etc, but would *really* welcome
a solution before setting off on the journey home next weekend -
though somehow I don't think that's going to happen ;-(  )  Another 8
hours-worth of I-spy, number-plate bingo etc ahead....

David

On Sep 3, 12:22 pm, Lobster  wrote:
> I posted a few weeks back asking about reliability and safety of using
> 12V car cigarette-lighter adapters for mobile phones, laptops etc (and
> IIRC generated a major sh*tstorm as a result...!) Anyway here's a
> followup to the query...
>
> I decided to acquire a car adapter for my new notebook PC (an Asus EEE
> PC900) to enable it to be used to double as a DVD player for the kids
> on long journeys.  Had no option but to buy an unbranded 3rd-party
> adapter since ASUS hasn't produced one yet, although rumour has it
> that one may be in the pipeline).
>
> Yesterday I tried out the car adapter for the first time, but
> unfortunately it didn't work properly.  Although the adapter's LED
> indicator lit up continuously, and there was definitely no loose
> connections, the PC's notification window popped up to say 'AC charger
> connected', only to be replaced 5 secs later by another window saying
> 'changing to battery power' (or words to that effect).  It then cycled
> continuously between battery and charging mode every few seconds.
>
> My impression is that the machine is trying to charge, but as soon as
> it does so the current provided by the car falls below some threshold,
> and the computer cuts it off and reverts to battery mode, whereupon
> the current is able to increase again, allowing the computer to switch
> into charging mode again, etc etc.  Sound about right?
>
> What is "responsible" for the problem - is it the adapter, the
> computer, or the car? Is it in anyway surmountable?  The laptop needs
> "흥, 3A, 36W" according to the label on its base.  Surely not too
> much to expect from a cigarette lighter?  Wondering if a 240V inverter
> would be better (I have one at home :-( )
>
> I'm currently connecting on wifi from a tent in the middle of France,
> with no electrical tools, instruments etc, but would *really* welcome
> a solution before setting off on the journey home next weekend -
> though somehow I don't think that's going to happen ;-(  )  Another 8
> hours-worth of I-spy, number-plate bingo etc ahead....
>
> David

You dont say if the car was running or off when you tried it. Car
batts can go well below 12v when not being charged, plus there are V
drops in the wiring and connectors. You might find its fine with the
engine running.

If it was running when you tried it, you've probably got a poor
connection. If not, and the laptop doesnt like what its getting,
theres really nowt more you can do in the middle of a field.


NT

On Wed, 3 Sep 2008 05:01:35 -0700 (PDT), meow2222@care2.com wrote:

>> What is "responsible" for the problem - is it the adapter, the 
>> computer, or the car? Is it in anyway surmountable?  The laptop needs
>> "흥, 3A, 36W" according to the label on its base.  Surely not too>> much to expect from a cigarette lighter? 

Most lighter sockest are fused at 10 or 15A A so you are well within that 
limit.

>> Wondering if a 240V inverter would be better (I have one at home :-It might be but I have one charger that refuses to work off my invertor everything else is happy on it though.

> If it was running when you tried it, you've probably got a poor
> connection. If not, and the laptop doesnt like what its getting,
> theres really nowt more you can do in the middle of a field.

Agreed. What is the adapter? Does it regulate and filter the cars voltage 
down to 12v. The raw car supply can be incredibly noisy and up to 14 or 15v with the engine running. What is the rating of the adapter? It has to 
be more than 12v 3A.

-- 
Cheers
Dave.

On Sep 3, 2:35 pm, "Dave Liquorice" 
wrote:
> On Wed, 3 Sep 2008 05:01:35 -0700 (PDT), meow2...@care2.com wrote:
> >> What is "responsible" for the problem - is it the adapter, the
> >> computer, or the car? Is it in anyway surmountable?  The laptop needs
> >> "흥, 3A, 36W" according to the label on its base.  Surely not too
> >> much to expect from a cigarette lighter?
>
> Most lighter sockest are fused at 10 or 15A A so you are well within that
> limit.
>
> >> Wondering if a 240V inverter would be better (I have one at home :-(> It might be but I have one charger that refuses to work off my invertor
> everything else is happy on it though.
>
> > If it was running when you tried it, you've probably got a poor
> > connection. If not, and the laptop doesnt like what its getting,
> > theres really nowt more you can do in the middle of a field.
>
> Agreed. What is the adapter? Does it regulate and filter the cars voltage
> down to 12v. The raw car supply can be incredibly noisy and up to 14 or
> 15v with the engine running. What is the rating of the adapter? It has to
> be more than 12v 3A.


Its also possible that the laptop might be objecting to too high a
voltage when its designed for regulated 12v. I dont run laptops on car
supplies, so I cant say from experience that will happen, but it could
be that. So if the car was running before, try it ignition off.


NT

In article <4185a7a8-b1a1-4948-b617-
1fb812c6039f@y38g2000hsy.googlegroups.com>,  says...

> 
> You dont say if the car was running or off when you tried it. Car
> batts can go well below 12v when not being charged, 

Only if they're knackered.

-- 
Conor

I only please one person per day. Today is not your day. Tomorrow isn't 
looking good either. - Scott Adams

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Lobster
 saying something like:

>What is "responsible" for the problem - is it the adapter, the
>computer, or the car? Is it in anyway surmountable?  The laptop needs
>"+12V, 3A, 36W" according to the label on its base.  Surely not too
>much to expect from a cigarette lighter?  Wondering if a 240V inverter
>would be better (I have one at home :-( )

Are you trying it with the car engine off? If so, see what happens with
the engine running and bringing up the battery voltage a bit.
-- 
Dave
GS850x2 XS650 SE6a

"It's a moron working with power tools.
 How much more suspenseful can you get?"
 - House

"Lobster"  wrote in message 
news:9af6344e-b70e-4129-b076-fbcd98c6011c@k30g2000hse.googlegroups.com...

> I decided to acquire a car adapter for my new notebook PC (an Asus EEE
> PC900)

> Yesterday I tried out the car adapter for the first time, but
> unfortunately it didn't work properly.  Although the adapter's LED
> indicator lit up continuously, and there was definitely no loose
> connections, the PC's notification window popped up to say 'AC charger
> connected', only to be replaced 5 secs later by another window saying
> 'changing to battery power' (or words to that effect).  It then cycled
> continuously between battery and charging mode every few seconds.
>
> My impression is that the machine is trying to charge, but as soon as
> it does so the current provided by the car falls below some threshold,
> and the computer cuts it off and reverts to battery mode, whereupon
> the current is able to increase again, allowing the computer to switch
> into charging mode again, etc etc.  Sound about right?

Yes

Is this adaptor one of the variable voltage ones, with voltages higher than 
12v available? If so, there should be an output power stated on it 
somewhere, it might be under rated for your laptop, so it...

1 trips out
2 resets
3 goto 1

> What is "responsible" for the problem - is it the adapter, the
> computer, or the car? Is it in anyway surmountable?  The laptop needs
> "+12V, 3A, 36W" according to the label on its base.  Surely not too
> much to expect from a cigarette lighter?  Wondering if a 240V inverter
> would be better (I have one at home :-( )

It's worth a try - make sure the continuous output (A or W) rating is higher 
than the input rating of the laptop's power supply though, or you will be in 
the same situation!

Toby...

Lobster wrote:

> I posted a few weeks back asking about reliability and safety
> of using 12V car cigarette-lighter adapters for mobile phones,
> laptops etc (and IIRC generated a major sh*tstorm as a
> result...!) Anyway here's a followup to the query...
> 
> I decided to acquire a car adapter for my new notebook PC (an
> Asus EEE PC900) to enable it to be used to double as a DVD
> player for the kids
> on long journeys.  Had no option but to buy an unbranded
> 3rd-party adapter since ASUS hasn't produced one yet, although
> rumour has it that one may be in the pipeline).
> 
> Yesterday I tried out the car adapter for the first time, but
> unfortunately it didn't work properly.  Although the adapter's
> LED indicator lit up continuously, and there was definitely no
> loose connections, the PC's notification window popped up to
> say 'AC charger connected', only to be replaced 5 secs later
> by another window saying
> 'changing to battery power' (or words to that effect).  It
> then cycled continuously between battery and charging mode
> every few seconds.

How are you sure there's no loose connections?  When I tried
running one of these EEEPCs from a 12V car adaptor, I found
that the +ve centre pin in the EEEPC was a non-standard size,
and made only intermittent contact with a standard plug.  From
memory, the standard pin sizes are 2.1mm and 2.5mm, and the
EEEPC was neither of those.

> My impression is that the machine is trying to charge, but as
> soon as it does so the current provided by the car falls below
> some threshold, and the computer cuts it off and reverts to
> battery mode, whereupon the current is able to increase again,
> allowing the computer to switch
> into charging mode again, etc etc.  Sound about right?
> 
> What is "responsible" for the problem - is it the adapter, the
> computer, or the car? Is it in anyway surmountable?  The
> laptop needs
> "+12V, 3A, 36W" according to the label on its base.  Surely
> not too
> much to expect from a cigarette lighter?  Wondering if a 240V
> inverter would be better (I have one at home :-( )

That would work.

John

> I'm currently connecting on wifi from a tent in the middle of
> France, with no electrical tools, instruments etc, but would
> *really* welcome a solution before setting off on the journey
> home next weekend -
> though somehow I don't think that's going to happen ;-(  ) 
> Another 8 hours-worth of I-spy, number-plate bingo etc
> ahead....
> 
> David

"Lobster"  wrote in message 
news:9af6344e-b70e-4129-b076-fbcd98c6011c@k30g2000hse.googlegroups.com...
>I posted a few weeks back asking about reliability and safety of using
> 12V car cigarette-lighter adapters for mobile phones, laptops etc (and
> IIRC generated a major sh*tstorm as a result...!) Anyway here's a
> followup to the query...
>
> I decided to acquire a car adapter for my new notebook PC (an Asus EEE
> PC900) to enable it to be used to double as a DVD player for the kids
> on long journeys.  Had no option but to buy an unbranded 3rd-party
> adapter since ASUS hasn't produced one yet, although rumour has it
> that one may be in the pipeline).
>
> Yesterday I tried out the car adapter for the first time, but
> unfortunately it didn't work properly.  Although the adapter's LED
> indicator lit up continuously, and there was definitely no loose
> connections, the PC's notification window popped up to say 'AC charger
> connected', only to be replaced 5 secs later by another window saying
> 'changing to battery power' (or words to that effect).  It then cycled
> continuously between battery and charging mode every few seconds.
>
> My impression is that the machine is trying to charge, but as soon as
> it does so the current provided by the car falls below some threshold,
> and the computer cuts it off and reverts to battery mode, whereupon
> the current is able to increase again, allowing the computer to switch
> into charging mode again, etc etc.  Sound about right?
>
> What is "responsible" for the problem - is it the adapter, the
> computer, or the car? Is it in anyway surmountable?  The laptop needs
> "+12V, 3A, 36W" according to the label on its base.  Surely not too
> much to expect from a cigarette lighter?  Wondering if a 240V inverter
> would be better (I have one at home :-( )
>
> I'm currently connecting on wifi from a tent in the middle of France,
> with no electrical tools, instruments etc, but would *really* welcome
> a solution before setting off on the journey home next weekend -
> though somehow I don't think that's going to happen ;-(  )  Another 8
> hours-worth of I-spy, number-plate bingo etc ahead....
>
> David


Turn the notebook off and try charging it.  A running laptop requires a lot 
of power, 2 to 3 amps is typical.  Your car/adapter/wiring probably cannot 
supply this current and the current required to charge the battery without 
dropping the voltage to a level that the notebook refuses to use.  Maybe a 
notebook is 1 to 2 amps, but anyway, turn it off.


Gareth.



Gareth.

On 2008-09-03, Gareth Magennis  wrote:
> "Lobster"  wrote in message 
> news:9af6344e-b70e-4129-b076-fbcd98c6011c@k30g2000hse.googlegroups.com...
>>
>> What is "responsible" for the problem - is it the adapter, the
>> computer, or the car? Is it in anyway surmountable?  The laptop needs
>> "+12V, 3A, 36W" according to the label on its base.  Surely not too
>> much to expect from a cigarette lighter?  Wondering if a 240V inverter
>> would be better (I have one at home :-( )
>>
>> I'm currently connecting on wifi from a tent in the middle of France,
>> with no electrical tools, instruments etc, but would *really* welcome
>> a solution before setting off on the journey home next weekend -
>> though somehow I don't think that's going to happen ;-(  )  Another 8
>> hours-worth of I-spy, number-plate bingo etc ahead....
>>
>> David
>
>
> Turn the notebook off and try charging it.  A running laptop requires a lot 
> of power, 2 to 3 amps is typical.  Your car/adapter/wiring probably cannot 
> supply this current and the current required to charge the battery without 
> dropping the voltage to a level that the notebook refuses to use.  Maybe a 
> notebook is 1 to 2 amps, but anyway, turn it off.

If the car or wiring is unable to provide 5amps, I'd be rather worried.
Especially as the wiring is nominally for a cigarette lighter.

If the notebook charger is unable to provide the current it is unfit for
purpose.  Which I suppose is quite possible, since it obviously isn't
working -- whatever the reason.  I think it's most likely to be the
adaptor, possibly just a badly fitting plug as another poster mentioned.

-- 
David Taylor

"David Taylor"  wrote in message 
news:slrngbtvuc.emt.davidt-news@outcold.yadt.co.uk...
> On 2008-09-03, Gareth Magennis  wrote:
>> "Lobster"  wrote in message
>> news:9af6344e-b70e-4129-b076-fbcd98c6011c@k30g2000hse.googlegroups.com...
>>>
>>> What is "responsible" for the problem - is it the adapter, the
>>> computer, or the car? Is it in anyway surmountable?  The laptop needs
>>> "+12V, 3A, 36W" according to the label on its base.  Surely not too
>>> much to expect from a cigarette lighter?  Wondering if a 240V inverter
>>> would be better (I have one at home :-( )
>>>
>>> I'm currently connecting on wifi from a tent in the middle of France,
>>> with no electrical tools, instruments etc, but would *really* welcome
>>> a solution before setting off on the journey home next weekend -
>>> though somehow I don't think that's going to happen ;-(  )  Another 8
>>> hours-worth of I-spy, number-plate bingo etc ahead....
>>>
>>> David
>>
>>
>> Turn the notebook off and try charging it.  A running laptop requires a 
>> lot
>> of power, 2 to 3 amps is typical.  Your car/adapter/wiring probably 
>> cannot
>> supply this current and the current required to charge the battery 
>> without
>> dropping the voltage to a level that the notebook refuses to use.  Maybe 
>> a
>> notebook is 1 to 2 amps, but anyway, turn it off.
>
> If the car or wiring is unable to provide 5amps, I'd be rather worried.
> Especially as the wiring is nominally for a cigarette lighter.
>

Yes but the point is that a cigarette lighter doesn't care what voltage drop 
occurs, it just wants lots of current, while a laptop might be concerned 
about this shortfall and decide not to use it, particularly if the laptop is 
in use.


> If the notebook charger is unable to provide the current it is unfit for
> purpose.  Which I suppose is quite possible, since it obviously isn't
> working -- whatever the reason.  I think it's most likely to be the
> adaptor, possibly just a badly fitting plug as another poster mentioned.
>
> -- 
> David Taylor

On 3 Sep,  
     Lobster  wrote:

> My impression is that the machine is trying to charge, but as soon as
> it does so the current provided by the car falls below some threshold,
> and the computer cuts it off and reverts to battery mode, whereupon
> the current is able to increase again, allowing the computer to switch
> into charging mode again, etc etc.  Sound about right?

Yes

> 
> What is "responsible" for the problem - is it the adapter, the
> computer, or the car? Is it in anyway surmountable?  The laptop needs
> "+12V, 3A, 36W" according to the label on its base.  Surely not too
> much to expect from a cigarette lighter?  Wondering if a 240V inverter
> would be better (I have one at home :-( )

The cable (certainly in my car) feeding the 12v socket is so thin that when
the cigar(ette) lighter is in use (I don't use it normally, just a test) that
the volts across the socket drops to 9 if the engine isn't running
(10.something if running). This means I can't use the inverter to feed
anything more than a neon lamp with the engine stopped without the inverter
squeeling out a low battery alarm,and shutting down.

With a universal mobile PC psu I can use the PC. 

I intend to re-wire the car socket directly (but via a fuse) with much
thicker cable. The cable used must be flexible suitable for automotive
applications, don't use mains cable, I nearly lost a car many years ago with
using 7/029 which failed due to vibration and shorted the battery making a
mess of the wiring harness in the process. I now use proper cable, suitably
fused.

-- 
  B Thumbs
  Change lycos to yahoo to reply

On 2008-09-03, Gareth Magennis  wrote:
> "David Taylor"  wrote in message 
> news:slrngbtvuc.emt.davidt-news@outcold.yadt.co.uk...
>>
>> If the car or wiring is unable to provide 5amps, I'd be rather worried.
>> Especially as the wiring is nominally for a cigarette lighter.
>>
>
> Yes but the point is that a cigarette lighter doesn't care what voltage drop 
> occurs, it just wants lots of current, while a laptop might be concerned 
> about this shortfall and decide not to use it, particularly if the laptop is 
> in use.

Sure, I'm not saying it's impossible -- just that I'd be rather worried.
Since the battery is presumably charging well enough to continue to
start the car, a significant voltage drop in the car wiring would imply
something is getting very hot and potentially about to burst into
flames.

-- 
David Taylor

On Thu, 04 Sep 2008 07:26:59 +0100, David Taylor   
wrote:

> On 2008-09-03, Gareth Magennis  wrote:
>> "David Taylor"  wrote in message
>> news:slrngbtvuc.emt.davidt-news@outcold.yadt.co.uk...
>>>
>>> If the car or wiring is unable to provide 5amps, I'd be rather worried.
>>> Especially as the wiring is nominally for a cigarette lighter.
>>>
>>
>> Yes but the point is that a cigarette lighter doesn't care what voltage  
>> drop
>> occurs, it just wants lots of current, while a laptop might be concerned
>> about this shortfall and decide not to use it, particularly if the  
>> laptop is
>> in use.
>
> Sure, I'm not saying it's impossible -- just that I'd be rather worried.
> Since the battery is presumably charging well enough to continue to
> start the car, a significant voltage drop in the car wiring would imply
> something is getting very hot and potentially about to burst into
> flames.
>


Cigarette lighter sockets often do that though.

me9@privacy.net wrote:

[...]
> 
> The cable (certainly in my car) feeding the 12v socket is so thin that
> when the cigar(ette) lighter is in use (I don't use it normally, just a
> test) that the volts across the socket drops to 9 if the engine isn't
> running (10.something if running). This means I can't use the inverter to
> feed anything more than a neon lamp with the engine stopped without the
> inverter squeeling out a low battery alarm,and shutting down.

I'm sorry, but there is no way that a marginally sized cable would drop that
amount of voltage if used within the 10A constraints of the socket rating!
You either have another fault, or an under-reading meter. (Or just possibly
an old Italian car :-)).

> With a universal mobile PC psu I can use the PC.
> 
> I intend to re-wire the car socket directly (but via a fuse) with much
> thicker cable. The cable used must be flexible suitable for automotive
> applications, don't use mains cable, I nearly lost a car many years ago
> with using 7/029 which failed due to vibration and shorted the battery
> making a mess of the wiring harness in the process. I now use proper
> cable, suitably fused.

If you were using 7/.029 when it was available, it was pre-1972! Most cars
at that time had lots of their electrics unprotected by any sort of fuse.

The correct cable to use for car wiring is (unsurprisingly) automotive rated
cable to BS6862. 


Most car makers would specify 1mm2 (14/0.3mm) for a cigarette lighter
socket. This has a rating of 8.75A. A better choice would be 1.5mm2
(21/0.3mm) with a rating of 12A. There would be no gain in going any higher
than this due to the inability if a plug/socket system designed for a very
low duty cycle at perhaps 5A, being unable to cope with a continuous load
greater than this.

If one was prepred to carry out rewiring in order to improve the limitations
of the installed connector, perhaps a better solution would be to also use
a more suitable plug/socket?

Chris

-- 
Remove prejudice to reply.

On 3 Sep, 12:22, Lobster  wrote:

> I decided to acquire a car adapter for my new notebook PC (an Asus EEE
> PC900) to enable it to be used to double as a DVD player for the kids
> on long journeys.  Had no option but to buy an unbranded 3rd-party
> adapter since ASUS hasn't produced one yet, although rumour has it
> that one may be in the pipeline).
>
> Yesterday I tried out the car adapter for the first time, but
> unfortunately it didn't work properly.

The Eee is quite a high current device, and needs something which can
pump out 2.5A continuously. I suspect that your charger is overheating
or otherwise cutting out every five seconds or so. Reports say that a
lot of el cheapo Eee chargers don't work well - which one do you have?

Ian

On 4 Sep, 09:26, Chris Whelan  wrote:
> m...@privacy.net wrote:

> > The cable (certainly in my car) feeding the 12v socket is so thin that
> > when the cigar(ette) lighter is in use (I don't use it normally, just a
> > test) that the volts across the socket drops to 9 if the engine isn't
> > running (10.something if running).

> I'm sorry, but there is no way that a marginally sized cable would drop that
> amount of voltage if used within the 10A constraints of the socket rating!

> Most car makers would specify 1mm2 (14/0.3mm) for a cigarette lighter
> socket. This has a rating of 8.75A. A better choice would be 1.5mm2
> (21/0.3mm) with a rating of 12A.

14/0.3mm has a resistance of around 18 ohms/kilometer (http://
www.relemaccables.com/Housewiring.html) so a drop of 3.6V (12.6 -> 9)
with 10A would require 0.36 ohms, which is 20m. Just about possible in
a stretch limo, I suppose!

Ian

"Ian"  wrote in message 
news:f41f8982-66ad-4a60-a4c3-cd7e64b0f66f@k36g2000pri.googlegroups.com...
> On 3 Sep, 12:22, Lobster  wrote:
>
>> I decided to acquire a car adapter for my new notebook PC (an Asus EEE
>> PC900) to enable it to be used to double as a DVD player for the kids
>> on long journeys.  Had no option but to buy an unbranded 3rd-party
>> adapter since ASUS hasn't produced one yet, although rumour has it
>> that one may be in the pipeline).
>>
>> Yesterday I tried out the car adapter for the first time, but
>> unfortunately it didn't work properly.
>
> The Eee is quite a high current device, and needs something which can
> pump out 2.5A continuously. I suspect that your charger is overheating
> or otherwise cutting out every five seconds or so. Reports say that a
> lot of el cheapo Eee chargers don't work well - which one do you have?
>
> Ian


Surely this is just a passive device, 12 volts in, 12volts out.   It is just 
wire.
My laptop supply is regulated, I suspect most of them are. Even an 
unregulated supply usually kicks out at least, usually a bit more, its rated 
voltage. I also suspect this is what is required here - a few amps at not 
less than 12 volts.  You are not going to get that with a car battery in a 
stationary car with its wiring harness etc etc.  The laptop will spit its 
dummy out and demand the whole 12 volts.



Gareth.

"Gareth Magennis"  wrote in message 
news:E-ednS-uzcmhLCLVRVnyhgA@bt.com...
>
> "Ian"  wrote in message 
> news:f41f8982-66ad-4a60-a4c3-cd7e64b0f66f@k36g2000pri.googlegroups.com...
>> On 3 Sep, 12:22, Lobster  wrote:
>>
>>> I decided to acquire a car adapter for my new notebook PC (an Asus EEE
>>> PC900) to enable it to be used to double as a DVD player for the kids
>>> on long journeys.  Had no option but to buy an unbranded 3rd-party
>>> adapter since ASUS hasn't produced one yet, although rumour has it
>>> that one may be in the pipeline).
>>>
>>> Yesterday I tried out the car adapter for the first time, but
>>> unfortunately it didn't work properly.
>>
>> The Eee is quite a high current device, and needs something which can
>> pump out 2.5A continuously. I suspect that your charger is overheating
>> or otherwise cutting out every five seconds or so. Reports say that a
>> lot of el cheapo Eee chargers don't work well - which one do you have?
>>
>> Ian
>
>
> Surely this is just a passive device, 12 volts in, 12volts out.   It is 
> just wire.

I hope not.
You can get spikes and allsorts on car supplies.
I would expect a DC-DC convertor.
I wouldn't buy one unless it was a DC-DC convertor.

Gareth Magennis wrote:


>>
> Surely this is just a passive device, 12 volts in, 12volts out.   It is
> just wire.
> My laptop supply is regulated, I suspect most of them are. Even an
> unregulated supply usually kicks out at least, usually a bit more, its
> rated voltage. I also suspect this is what is required here - a few amps
> at not
> less than 12 volts.  You are not going to get that with a car battery in a
> stationary car with its wiring harness etc etc.  The laptop will spit its
> dummy out and demand the whole 12 volts.
> 
> Gareth.

A fully charged car battery should produce around 12.7 volts even after
standing overnight. When 75% discharged, it should still be around 12.4
volts.

This should be enough to compensate for any wiring voltage drop at the
suggested current of 2.5A

Chris

-- 
Remove prejudice to reply.

"dennis@home"  wrote in message 
news:g9obso$5q2$1@news.datemas.de...
>
>
> "Gareth Magennis"  wrote in message 
> news:E-ednS-uzcmhLCLVRVnyhgA@bt.com...
>>
>> "Ian"  wrote in message 
>> news:f41f8982-66ad-4a60-a4c3-cd7e64b0f66f@k36g2000pri.googlegroups.com...
>>> On 3 Sep, 12:22, Lobster  wrote:
>>>
>>>> I decided to acquire a car adapter for my new notebook PC (an Asus EEE
>>>> PC900) to enable it to be used to double as a DVD player for the kids
>>>> on long journeys.  Had no option but to buy an unbranded 3rd-party
>>>> adapter since ASUS hasn't produced one yet, although rumour has it
>>>> that one may be in the pipeline).
>>>>
>>>> Yesterday I tried out the car adapter for the first time, but
>>>> unfortunately it didn't work properly.
>>>
>>> The Eee is quite a high current device, and needs something which can
>>> pump out 2.5A continuously. I suspect that your charger is overheating
>>> or otherwise cutting out every five seconds or so. Reports say that a
>>> lot of el cheapo Eee chargers don't work well - which one do you have?
>>>
>>> Ian
>>
>>
>> Surely this is just a passive device, 12 volts in, 12volts out.   It is 
>> just wire.
>
> I hope not.
> You can get spikes and allsorts on car supplies.
> I would expect a DC-DC convertor.
> I wouldn't buy one unless it was a DC-DC convertor.
>


Actually, I'll take that back, it most probably isn't wire, but may itself 
need a minimum voltage to operate at its full output or spit its dummy out.


Gareth.

Gareth Magennis wrote:

> Surely this is just a passive device, 12 volts in, 12volts out.   It is
> just wire.
> My laptop supply is regulated, I suspect most of them are. Even an
> unregulated supply usually kicks out at least, usually a bit more, its
> rated voltage. I also suspect this is what is required here - a few amps
> at not less than 12 volts.  You are not going to get that with a car 
> battery in a stationary car with its wiring harness etc etc.  The laptop
> will spit its dummy out and demand the whole 12 volts.
> 
> Gareth.

A 12v car battery is seldom 12V, unless it only has some 30% charge left 
in it. Fully charged, it will be around 12.8V and up to around 14V 
whilst being charged. It drops to 11.6V when fully discharged assuming 
deep discharge wet cells. Typically, this is too great a range for a 
laptop normally designed to run on its own batteries having a closer 
specification. Unless they are designed for car battery use, you will 
need some form of regulated power supply.

My laptops have had DC to DC switching-mode converters for external 
power, usually to boost the voltage up to something like 18V to charge 
their batteries.  They would run with an external regulated 12V but 
wouldn't charge the internal batteries. These converters will function 
for input voltages down to some 7V, so will work fine over the discharge 
range of typical car batteries. The awkward designs were those expecting 
12V input. For these the converter had to be of buck/boost design.

-- 
John W
To mail me replace the obvious with co.uk twice

On 4 Sep,  
     Chris Whelan  wrote:

> I'm sorry, but there is no way that a marginally sized cable would drop tha
> amount of voltage if used within the 10A constraints of the socket rating!
> You either have another fault, or an under-reading meter. (Or just possibly
> an old Italian car :-)).

It is exactly what it is on my Nissan Primera. Minimally specced cable going
the long way round (not mentioning the route of the return).
> >  I nearly lost a car many years ago with using 7/029 which failed due to
> > vibration and shorted the battery making a mess of the wiring harness in
> > the process. I now use proper cable, suitably fused.
> 
> If you were using 7/.029 when it was available, it was pre-1972! Most cars
> at that time had lots of their electrics unprotected by any sort of fuse.

1971 to be precise.


> Most car makers would specify 1mm2 (14/0.3mm) for a cigarette lighter
> socket. This has a rating of 8.75A. A better choice would be 1.5mm2
> (21/0.3mm) with a rating of 12A.

If I ever get round to doing anything about it I would use at least 2.5mm^2
to reduce the voltage drop. Fuses also drop enough on a 12 volt system to be
significant.

> There would be no gain in going any higher than this due to the inability
> if a plug/socket system designed for a very low duty cycle at perhaps 5A,
> being unable to cope with a continuous load greater than this.
> 
> If one was prepred to carry out rewiring in order to improve the limitation
> of the installed connector, perhaps a better solution would be to also use
> a more suitable plug/socket?

I'm happy with an average of 5A, but the ability to supply nearer 12volts at
occasionally higher loads would be desirable. 

I've also found the headlights on this car rather dim and yellow, also due to
voltage drop in the wiring. 

-- 
  B Thumbs
  Change lycos to yahoo to reply

On 4 Sep, 10:58, "Gareth Magennis" 
wrote:
> "Ian"  wrote in message

> > The Eee is quite a high current device, and needs something which can
> > pump out 2.5A continuously. I suspect that your charger is overheating
> > or otherwise cutting out every five seconds or so. Reports say that a
> > lot of el cheapo Eee chargers don't work well - which one do you have?

> Surely this is just a passive device, 12 volts in, 12volts out.   It is just
> wire.

The Eee needs 9.5V, and car have horrible nasty 12-ish to 14-ish volts
with added spikey goodness. It'll be a DC-DC convertor, or at least
some sort of regulated supply. www.eeeuser.com has some pictures of
the bits that let the magic smoke out when you supply an Eee with
12V ...

Ian

Lobster wrote:

> Yesterday I tried out the car adapter for the first time, but
> unfortunately it didn't work properly.  Although the adapter's LED
> indicator lit up continuously, and there was definitely no loose
> connections, the PC's notification window popped up to say 'AC charger
> connected', only to be replaced 5 secs later by another window saying
> 'changing to battery power' (or words to that effect).  It then cycled
> continuously between battery and charging mode every few seconds.

[...]

> I'm currently connecting on wifi from a tent in the middle of France,
> with no electrical tools, instruments etc, but would *really* welcome
> a solution before setting off on the journey home next weekend -
> though somehow I don't think that's going to happen ;-(  )  Another 8
> hours-worth of I-spy, number-plate bingo etc ahead....

Thanks for all the responses to the above query.  As anticipated, there 
was no 'in-the-field' solution, so my kids gave me another taster of the 
hell that me and my siblings put my parents through on long drives a 
generation ago...

So, back home now, and some responses to the queries raised:
1. The cycling occurred with the engine running; same problem with it 
switched off.
2. AFAICS the 12V adapter the PC OK when the PC is powered down and the 
engine's running (ie the charging LED stays lit), but haven't put this 
to the test yet (it wouldn't be a solution since the PC needs to be on 
for use as DVD player).
3. The adapter I bought was just a cheapo ebay item from China, though 
FWIW(!) was sold as bespoke for the ASUS EEE PC900, and has a label with 
the correct 12VDC/3.0A rating, and definitely has the correct plug.
4. Have just tested out my 240v inverter with the PC; that does seem to 
charge the PC OK while the PC's running, so that would seem to be a 
solution for next time.

So, I presume that the problem's just a crappy adapter, would that be right?

Is there any reason *not* to just use my inverter for this task in 
future, in terms of personal safety, damage/wear and tear on the 
car/PC/battery or whatever?  It would be used exclusively while on the 
move (which makes me slightly uneasy having 240V mains around - is that 
just irrational?)

Thanks
David

> 4. Have just tested out my 240v inverter with the PC; that does seem to  
> charge the PC OK while the PC's running, so that would seem to be a  
> solution for next time.
>
> So, I presume that the problem's just a crappy adapter, would that be  
> right?
>
> Is there any reason *not* to just use my inverter for this task in  
> future, in terms of personal safety, damage/wear and tear on the  
> car/PC/battery or whatever?  It would be used exclusively while on the  
> move (which makes me slightly uneasy having 240V mains around - is that  
> just irrational?)
>
> Thanks
> David


Connect inverter chassis to car chassi, plug rcd in inverter output.

Lobster wrote:

> 4. Have just tested out my 240v inverter with the PC; that does seem to 
> charge the PC OK while the PC's running, so that would seem to be a 
> solution for next time.

Oh yeah, forgot to mention: when using the 240V->12V PSU with the 
inverter, the PSU buzzes moderately loudly whereas it's silent when used 
in the house.  Is that an issue?

David

Lobster wrote:

> Lobster wrote:
> 
>> 4. Have just tested out my 240v inverter with the PC; that
>> does seem to charge the PC OK while the PC's running, so that
>> would seem to be a solution for next time.
> 
> Oh yeah, forgot to mention: when using the 240V->12V PSU with
> the inverter, the PSU buzzes moderately loudly whereas it's
> silent when used
> in the house.  Is that an issue?

I shoudn't think so.  But a cheap inverter will output "modified
square wave" (with lots of harmonics) rather than sine wave,
and this often causes an audible buzz in electromagnetic
components downstream.  The PSU may run a little warmer, but
shouldn't let the harmonics through.

John