car 12v phone chargers

[Ivan Vegvary]

Why do they take longer to charge than mt wall charger. The output of my wall charger is 5v. Seems like my car should be able to imitate that level. ??
Thanks
Ivan Vegvary

 

[George Herold]

On Wednesday, May 7, 2014 11:37:57 AM UTC-4, Ivan Vegvary wrote:

Why do they take longer to charge than mt wall charger. The output of my wall charger is 5v. Seems like my car should be able to imitate that level. ??

Thanks

Ivan Vegvary

Charging time will depend on the current and not the voltage.
I'll guess that the 12V auto charger just has a linear regulator..
(not a switcher) and so to do (say) 1 amp at 5 Volts it would need to
dissipate 7 or 8 watts... that's too much so they cut dwon the current.

Just a guess,
George H.

 

[Ian Field]

"George Herold" <gherold@teachspin.com> wrote in message
news:9f005aaf-1576-4c0f-a057-a4a709ad4a1f@googlegroups.com...

On Wednesday, May 7, 2014 11:37:57 AM UTC-4, Ivan Vegvary wrote:
Why do they take longer to charge than mt wall charger. The output of my
wall charger is 5v. Seems like my car should be able to imitate that
level. ??

Thanks

Ivan Vegvary

Charging time will depend on the current and not the voltage.
I'll guess that the 12V auto charger just has a linear regulator..
(not a switcher) and so to do (say) 1 amp at 5 Volts it would need to
dissipate 7 or 8 watts... that's too much so they cut dwon the current.

They probably have a switcher these days - the really cheap crappy plastic
case would deform with the heat from a dropper resistor inside.

There's a discussion on another group whether the ones from the Ł shop are
even safe to use - I was going to pick one up to crack open to see what's in
it, but they were out of stock and I don't go into town that often.

 

[Jasen Betts]

On 2014-05-07, Ian Field <gangprobing.alien@ntlworld.com> wrote:

They probably have a switcher these days - the really cheap crappy plastic
case would deform with the heat from a dropper resistor inside.

There's a discussion on another group whether the ones from the ÂŁ shop are
even safe to use - I was going to pick one up to crack open to see what's in
it, but they were out of stock and I don't go into town that often.

The ones I've looked inside have some sort of DIP8 based switcher...
I've not tested the max output current,



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[Ian Field]

"Michael Black" <et472@ncf.ca> wrote in message
news:alpine.LNX.2.02.1405071844550.9304@darkstar.example.org...

On Wed, 7 May 2014, Ian Field wrote:



"George Herold" <gherold@teachspin.com> wrote in message
news:9f005aaf-1576-4c0f-a057-a4a709ad4a1f@googlegroups.com...
On Wednesday, May 7, 2014 11:37:57 AM UTC-4, Ivan Vegvary wrote:
Why do they take longer to charge than mt wall charger. The output of
my
wall charger is 5v. Seems like my car should be able to imitate that
level. ??

Thanks

Ivan Vegvary

Charging time will depend on the current and not the voltage.
I'll guess that the 12V auto charger just has a linear regulator..
(not a switcher) and so to do (say) 1 amp at 5 Volts it would need to
dissipate 7 or 8 watts... that's too much so they cut dwon the current.

They probably have a switcher these days - the really cheap crappy
plastic
case would deform with the heat from a dropper resistor inside.

There's a discussion on another group whether the ones from the Ł shop
are
even safe to use - I was going to pick one up to crack open to see what's
in
it, but they were out of stock and I don't go into town that often.

I needed a USB charger recently, and thought of buying one of those cheap
small cubes. And I decided I wouldn't trust it (not the cheap kind)

If you're that wary, build a breakout box to contain a SCR crowbar
protection.

 

[Ian Field]

"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:lkf9ed$mvc$1@gonzo.reversiblemaps.ath.cx...

On 2014-05-07, Ian Field <gangprobing.alien@ntlworld.com> wrote:
They probably have a switcher these days - the really cheap crappy
plastic
case would deform with the heat from a dropper resistor inside.

There's a discussion on another group whether the ones from the ÂŁ shop
are
even safe to use - I was going to pick one up to crack open to see what's
in
it, but they were out of stock and I don't go into town that often.

The ones I've looked inside have some sort of DIP8 based switcher...
I've not tested the max output current,

A common type is the MC34063 - its actually hard to find versatile switcher
chips that don't have UVLO at a lower voltage than you want to run it from.

Although I missed out at the ÂŁ store - I've just been in Lidl, among their
weekly offers was a ÂŁ3.99 car to 5V adaptor with loads of pluggable phone
charging connectors.

I'll crack it open for a look inside later.