Accessories Wall charger alternative

gearfarmer · 10-04-2010, 02:27 AM

Hi All

First post for me. New K3 owner, very happy. Didn't order the wall wart as I thought charging through the computer would be fine. However, I am going on a trip next week and thought I might take a backup. My Samsung camera uses a USB wall wart type charger which would also fit the kindle usb cable.
Specs are

samsung wall wart output: 4.4vdc 400mA

Kindle 3 specs: 5vdc 850mA

Will this work ok, or is the current mismatch significant?

Many thanks

zoran · 10-04-2010, 03:37 AM

Quote:

Originally Posted by gearfarmer

samsung wall wart output: 4.4vdc 400mA
Kindle 3 specs: 5vdc 850mA
Will this work ok, or is the current mismatch significant?
Many thanks

I would avoid this. Any 5v, 1A would be much better, for
quite low fee.

gollu · 10-04-2010, 06:12 AM

I use my Samsung Galaxy S charger for the Kindle as well and have had no problems...

el_brio · 10-04-2010, 09:12 AM

My blackberry car charger seems to work fine.

desertgrandma · 10-04-2010, 09:37 AM

Quote:

Originally Posted by gearfarmer

Hi All

First post for me. New K3 owner, very happy. Didn't order the wall wart as I thought charging through the computer would be fine. However, I am going on a trip next week and thought I might take a backup. My Samsung camera uses a USB wall wart type charger which would also fit the kindle usb cable.
Specs are

samsung wall wart output: 4.4vdc 400mA

Kindle 3 specs: 5vdc 850mA

Will this work ok, or is the current mismatch significant?

Many thanks

Welcome to MobileRead, gearfarmer!

booknut · 10-04-2010, 12:06 PM

My Kindle came with a plug for the wall to be used with the USB cable...

Tiersten · 10-04-2010, 01:16 PM

Quote:

Originally Posted by booknut

My Kindle came with a plug for the wall to be used with the USB cable...

Depends on your country. Amazon don't include the USB charger for all countries.

Tiersten · 10-04-2010, 01:18 PM

Quote:

Originally Posted by gearfarmer

samsung wall wart output: 4.4vdc 400mA

Its is a bit low but it is still within the USB 2.0 specifications for voltage. Just try it as you can't damage the Kindle assuming your USB charger isn't faulty. If it works then it'll charge. If not then you'll have to find another charger.

ConstantineXVI · 10-04-2010, 10:16 PM

The Kindle's microUSB, so any like-minded* charger is fair game. All that'd happen is it wouldn't charge as fast as the stock charger (given the battery life, this isn't a major issue)

*Recent BlackBerry, Samsung, HTC, Motorola, LG, etc. phones are all microUSB, and you can find them fairly cheap.

joelong · 10-04-2010, 11:31 PM

Quote:

Originally Posted by Tiersten

Its is a bit low but it is still within the USB 2.0 specifications for voltage. Just try it as you can't damage the Kindle assuming your USB charger isn't faulty. If it works then it'll charge. If not then you'll have to find another charger.

The voltage difference is probably OK, but it's not good that the power supply you intend to use provides only half the current of the factory supply. This can lead to damage. Best to find a supply that provides 850 mA, or more.

MrPLD · 10-04-2010, 11:36 PM

I'd sincerely go with finding a different wall-wart, as mentioned above, 5V 1A units are very common and you'll be wanting to get one that's listed as a legitimate USB type unit.

Plugging something other than 5V in there could potentially cause issues with the USB circuity in the Kindle, the 0.6V difference is enough that depending on the design of the K3's USB/power circuits things could even end up discharging (but that's me being hyper-paranoid - such is life as an EE).

Paul.

tarke9891 · 10-05-2010, 12:09 AM

I plugged my first K3 into a 12v to usb and it fried both the K3 and the 12v converter. I would not risk it. I don't think the Ks have anything to stop the charge, both under or over. I think i heard right that a too low charge can if the same problem was a high one.

badbob001 · 10-05-2010, 12:19 AM

The general rule is to keep the voltage the same as specifications and the amperage should be at or higher (higher is fine since it's the device that governs how much amperage it's going to pull).

I bought a griffin 5V 2A usb chargers for the wall and the car, which allows me charge even the newest devices. And there is enough amps for me to add an usb y-cable so I can charge two devices at once.

Tiersten · 10-05-2010, 12:45 AM

Quote:

Originally Posted by joelong

The voltage difference is probably OK, but it's not good that the power supply you intend to use provides only half the current of the factory supply. This can lead to damage. Best to find a supply that provides 850 mA, or more.

No. A standard USB port on a PC is rated for 500mA and the Kindle will charge from a PC as per Amazon's specifications. Amazon don't even bundle the charger for everybody. If you plugged the Kindle into a USB hub then you'd get less than 500mA. Assuming your USB port/charger isn't faulty and isn't badly made then nothing will be damaged as devices have to be able to accept these variations in voltage and current to be certified as a USB compatible device.

Tiersten · 10-05-2010, 12:45 AM

Quote:

Originally Posted by tarke9891

I plugged my first K3 into a 12v to usb and it fried both the K3 and the 12v converter. I would not risk it. I don't think the Ks have anything to stop the charge, both under or over. I think i heard right that a too low charge can if the same problem was a high one.

Your USB charger was faulty or badly designed.

10-04-2010, 02:27 AM	#1
gearfarmer Junior Member Posts: 1 Karma: 10 Join Date: Oct 2010 Device: kindle 3	Wall charger alternative Hi All First post for me. New K3 owner, very happy. Didn't order the wall wart as I thought charging through the computer would be fine. However, I am going on a trip next week and thought I might take a backup. My Samsung camera uses a USB wall wart type charger which would also fit the kindle usb cable. Specs are samsung wall wart output: 4.4vdc 400mA Kindle 3 specs: 5vdc 850mA Will this work ok, or is the current mismatch significant? Many thanks

10-05-2010, 12:19 AM	#13
badbob001 Fanatic Posts: 556 Karma: 1102020 Join Date: Sep 2009 Device: Kindle Keyboard (rip), Kindle Voyage, Fire Tablet 10 '17, iPad '19	The general rule is to keep the voltage the same as specifications and the amperage should be at or higher (higher is fine since it's the device that governs how much amperage it's going to pull). I bought a griffin 5V 2A usb chargers for the wall and the car, which allows me charge even the newest devices. And there is enough amps for me to add an usb y-cable so I can charge two devices at once. Last edited by badbob001; 10-05-2010 at 12:22 AM.

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10-04-2010, 06:12 AM	#3
gollu Unsullied Posts: 249 Karma: 759693 Join Date: Jul 2008 Location: Israel Device: Kindle 2i	I use my Samsung Galaxy S charger for the Kindle as well and have had no problems...

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10-04-2010, 12:06 PM	#6
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10-04-2010, 10:16 PM	#9
ConstantineXVI Member Posts: 16 Karma: 10 Join Date: Jul 2010 Device: Kindle2I	The Kindle's microUSB, so any like-minded* charger is fair game. All that'd happen is it wouldn't charge as fast as the stock charger (given the battery life, this isn't a major issue) *Recent BlackBerry, Samsung, HTC, Motorola, LG, etc. phones are all microUSB, and you can find them fairly cheap.

10-04-2010, 11:36 PM	#11
MrPLD Author's pet-geek Posts: 933 Karma: 1040670 Join Date: Sep 2010 Location: North Queensland, Australia Device: Kindle 3 Wifi, Onyx Boox M96	I'd sincerely go with finding a different wall-wart, as mentioned above, 5V 1A units are very common and you'll be wanting to get one that's listed as a legitimate USB type unit. Plugging something other than 5V in there could potentially cause issues with the USB circuity in the Kindle, the 0.6V difference is enough that depending on the design of the K3's USB/power circuits things could even end up discharging (but that's me being hyper-paranoid - such is life as an EE). Paul.

10-05-2010, 12:09 AM	#12
tarke9891 Enthusiast Posts: 30 Karma: 126 Join Date: Sep 2010 Device: Kindle 3 3G	I plugged my first K3 into a 12v to usb and it fried both the K3 and the 12v converter. I would not risk it. I don't think the Ks have anything to stop the charge, both under or over. I think i heard right that a too low charge can if the same problem was a high one.