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Hi folks, this is a simple technical query that one of you may have the answer to: How much current(amps)does a mobile phone charger draw whilist charging a phone when it is used in a car? Has anyone ever measured the current draw or have access to some technical data?
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Not sure as to current but my hands free unit in the car cetainly charges both my SIemens faster & fuller than the home mains charger. And the mains charger says 5V 0.4A.
Even leaving for work in the morning when my SL45 has been on charge all night & cut-off, putting it in its cradle always results in 10ish minutes of extra charging before the phone shows it's cut-off & that's irrespective of whether the phone is on or off. And once charged in the car the talk/standby time once removed is much longer than if it's on the charger at home.
Jim
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Its approx 400 milliamps.
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TourVanMan TM < Ex RF >
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400 milliamps (0.4 amps) from a 240 volt main is 8 amps from 12 volts in a car, if my very old school physics is correct. May be not, standing by for correction!
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The plug in mains chargers are dc transformers though, that 240V a.c is down to the order of 10v dc and a few hundred mA by the time it hits the phone.
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Thanks for the gentle correction! Of course the phone needs 400 m/amps and it gets it either from the mains thru a transformer OR from the car battery but whichever it is, it is still only 400 m/amps!
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400 milliamps on the DC OUTPUT side
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TourVanMan TM < Ex RF >
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Thanks for the replies, 0.4amps - that is just what I needed to know.
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Yup but the fundamental point is that 0.4A from the mains charger, but must be higher on car charger, I'd expect around 0.6-0.8 judging by the difference in charging times.
Jim
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Yup but the fundamental point is that 0.4A from the mains charger, but must be higher on car charger, I'd expect around 0.6-0.8 judging by the difference in charging times.
It *should* be the same - as already mentioned, 0.4A from the mains charger is on the DC (phone) side. The input current to the mains charger, at 230V from the wall socket, would be next to nothing.
Reason the car charger charges quicker is that they're generally poorly made, so they may well charge at a higher current. The cheaper ones often get extremely hot.
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Err, confused all the way along I've said that it's 5V @ 0.4Amps or 2VA, not fussed about the mains side because thats irrelavent. Oh and this is a Pukka Siemans in car plug in the fag lighter hands free so one would assume that they know what they're doing. I suspect they rely on the drain of the phone being on & also the fact that no-one would leave a phone aon a car charger for very extended periods but would on a mains home charger. I'll get the DVM out tomorrow & find out for sure!
Jim
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..all the way along I've said that it's 5V @ 0.4Amps or 2VA
So of it was 100% efficient (and it really is outputing 0.4A) then, with the engine running, the current draw from the socket would be around 0.15A.
of course, it won't be 100% efficient, and it probably isn't outputing exactly 0.4A, but whatever the actual numbers, it isn't drawing very much.
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I can confirm thst my genuine Siemens car charger also charges my A60 much faster than the Siemens mains charger.
Is there a problem with poor voltage regulation in the car chargers?
--
I wasna fu but just had plenty.
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I have two genuine Nokia mains chargers-one standard,the other,a rapid charger-the difference,the output on the rapid is one volt higher.
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All the messages here overlook one vital fact - the output quoted on the charger device is the MAXIMUM it is capable of delivering - not how much a cell phone will draw while charging the battery.
The actual demand will change as the battery charges, it is not a constant rate of charge and is dependent on the charge state of the battery. Typically, it will start at around 0.2 A, gradually increase to perhaps a little over 0.3 A and then decrease again (that's how Lithium Ion batteries are charged).
So the power demand will vary but never exceed the maximum that can be delivered by the charger device. So the maximum current from the car system would be less than that, theoretically it would be less than 0.1667 Amps at 12 Volts.
The cigarette lighter style sockets are rated at 150 Watts, so at 12 Volts supply they can deliver up to 12.5 Amps safely.
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The cigarette lighter style sockets are rated at 150 Watts, so at 12 Volts supply they can deliver up to 12.5 Amps safely.
My Vectra, the work's Focus, and Transit Connect are all rated at 10 amp.
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My 54 Vectra book says 10 A but the fuse is a 15A.
The specification for a 'cigarette lighter' socket states it must be rated for 150 Watts intermittent consumption. That means it can supply up to 12.5 Amps at 12 Volts for relatively short periods while the element of the lighter heats up to a gentle glow so it can set fire to the 'cancer stick'.
In reality, they are capable of delivering up to 150 Watts for a significant period without causing any ill effects to the wiring harness.
More vehicles are being fitted with Accessory Sockets that are the same basic design and power rating. There are devices available, called an inverter, to convert the 12 Volts from these sockets to the equivalent of European mains, 230 Volts. That lets you run mains type equipment, perhaps a portable TV? But the power demand must not exceed the 150 Watts. If you need more, a separate supply from the battery is needed that can deliver the power demanded. A 1 kW heater through a suitable inverter will need more than 84 Amps at 12 Volts!
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I think 42 years and counting is spot on.
Just tried my genuine Nokia phone charger in a 12v power supply via a multimeter. Current when not charging was around 6.52mA. Current when charging a partially drained Lithium ion battery in my 5130 was 0.20A. Voltage across the power supply is 12.13v.
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Mike Farrow
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One other related question whilst we are on this topic: The centre pole in a cigarette lighter socket/accessory socket is always the positive terminal right? Which obviously makes the outer circle the negative pole?
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Yes thats right...
Although I am sure some old person will come on here and say there is a chance that the person who owned the car before you deliberatley wired them the wrong way round.
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TourVanMan TM < Ex RF >
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there is a chance that the person who owned the car before you deliberatley wired them the wrong way round.
Yes that's right, and if you attempt to connect your equipment the wrong way round it may not work again (if you're lucky), but will probably self-destruct, causing massive personal injuries which require you to sue the previous owner for not warning you of such a death-trap!
You have been warned! ;-)
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