How come certain cables don't work to charge my iPad

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XacTactX

Supreme [H]ardness
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Dec 13, 2010
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Guys, this is really strange. There is an iPad 3 in my family and my mother wanted a longer cable so I bought two 6' cables off of eBay. They are from a third party, not original Apple cables. Now, this is my problem.

1.) Original Apple charger ---> original Apple cable ---> iPad = charges at full speed

2.) Original Apple charger ---> third party cable ---> iPad = 'not charging' message with slow charging.

Why is it that the iPad charges slowly with certain cables? How can I know if my cable will work with the iPad?
 
I have an original Apple charger for an iPad that is still in the box I can sell you. My iPad was stolen a year or two ago and it's just been sitting on my shelf since then.
 
It sounds like you're running into a classic case of Ohm's Law.

I = V/R

Where I = current, V = voltage and R is resistance.

As R increases (due to poor quality and/or very long cables), I (current) decreases and less current is delivered to your iPad. It's like trying to drink a thick milkshake with a very long and thin straw.

You could try getting a USB extension cable and using it with the original apple cable. ie:

Apple charger > USB extension cable > apple cable > iPad

USB extension cables are generally much thicker wire so that might work for you. That is introducing an extra break in the connection, so keep your receipt just in case it doesn't work, or just find a better spot to charge the iPad. ;)
 
There's no reason to try and mickey mouse it. The iPad charger's wall prong slides off so you can use the wall cable from a macbook to extend the range

the one I offered has the cable included
 
Roman79 said:
It sounds like you're running into a classic case of Ohm's Law.

I = V/R

Where I = current, V = voltage and R is resistance.

As R increases (due to poor quality and/or very long cables), I (current) decreases and less current is delivered to your iPad. It's like trying to drink a thick milkshake with a very long and thin straw.

You could try getting a USB extension cable and using it with the original apple cable. ie:

Apple charger > USB extension cable > apple cable > iPad

USB extension cables are generally much thicker wire so that might work for you. That is introducing an extra break in the connection, so keep your receipt just in case it doesn't work, or just find a better spot to charge the iPad. ;)
Click to expand...

Thanks Roman, this is a very logical explanation. I was looking at Monoprice's website for Apple cables and I noticed that the 3' cable only costs about $2 while the 6' cable costs about $6. I was wondering to myself why the 6' cable is so much more expensive, and it is probably because the 6' cable uses a thicker gauge.

Bummer, but at least I've learned my lesson. High quality cables or bust.
 
Roman79 said:
It sounds like you're running into a classic case of Ohm's Law.

I = V/R

Where I = current, V = voltage and R is resistance.

As R increases (due to poor quality and/or very long cables), I (current) decreases and less current is delivered to your iPad. It's like trying to drink a thick milkshake with a very long and thin straw.

You could try getting a USB extension cable and using it with the original apple cable. ie:

Apple charger > USB extension cable > apple cable > iPad

USB extension cables are generally much thicker wire so that might work for you. That is introducing an extra break in the connection, so keep your receipt just in case it doesn't work, or just find a better spot to charge the iPad. ;)
Click to expand...


I seriously doubt the resistance of the cable is enough of an issue to cause any problems, thus either the ipad is looking for a certain electrical signal on the cable that is not present on these third-party cables, of the cable is defective (which is not an resistance issue per se).

The real problem is buying the cables of eBay rather than amazon. On amazon, you simply buy cables that others have bought and left feedback on. I have several different 6 ft cables bought there and they all work fine...and I hate white cables so I always get black ones so I can know from whence they came. Again, I have a zero problems charging and syncing over 6ft cables that are third party and I don't need USB extension cables.
 
Roman79 said:
It sounds like you're running into a classic case of Ohm's Law.

I = V/R

Where I = current, V = voltage and R is resistance.

As R increases (due to poor quality and/or very long cables), I (current) decreases and less current is delivered to your iPad. It's like trying to drink a thick milkshake with a very long and thin straw.

You could try getting a USB extension cable and using it with the original apple cable. ie:

Apple charger > USB extension cable > apple cable > iPad

USB extension cables are generally much thicker wire so that might work for you. That is introducing an extra break in the connection, so keep your receipt just in case it doesn't work, or just find a better spot to charge the iPad. ;)
Click to expand...

XacTactX said:
Thanks Roman, this is a very logical explanation. I was looking at Monoprice's website for Apple cables and I noticed that the 3' cable only costs about $2 while the 6' cable costs about $6. I was wondering to myself why the 6' cable is so much more expensive, and it is probably because the 6' cable uses a thicker gauge.

Bummer, but at least I've learned my lesson. High quality cables or bust.
Click to expand...

I doubt it. Cables need to be of sufficient quality, it is not hard to make a cable that works. Price usually has little to do with cost to make. You can't draw many conclusions from how an item is priced.
 
Have you used the third party cables for data before? I wonder if they were wired as charge-only cables. The wiring would be messed up a bit from that and would cause your ipad to not receive the correct signals to start full current charging.
 
AQ_OC said:
I seriously doubt the resistance of the cable is enough of an issue to cause any problems, thus either the ipad is looking for a certain electrical signal on the cable that is not present on these third-party cables, of the cable is defective (which is not an resistance issue per se).

The real problem is buying the cables of eBay rather than amazon. On amazon, you simply buy cables that others have bought and left feedback on. I have several different 6 ft cables bought there and they all work fine...and I hate white cables so I always get black ones so I can know from whence they came. Again, I have a zero problems charging and syncing over 6ft cables that are third party and I don't need USB extension cables.
Click to expand...

You can't go by the reviews all the time for generic items. Sometimes a generic titled item will have multiple vendors selling nearly the same item and the good reviews may be from item x from vendor x but the current item listed is item y from vendor y.
Eventually you'll start getting bad reviews for the product when purchased from vendor y.
 
Zepher said:
You can't go by the reviews all the time for generic items. Sometimes a generic titled item will have multiple vendors selling nearly the same item and the good reviews may be from item x from vendor x but the current item listed is item y from vendor y.
Eventually you'll start getting bad reviews for the product when purchased from vendor y.
Click to expand...

Reviews are better than going blind when buying on eBay. And going by reviews on amazon has worked amazingly well for me. I have many third party 30-pin cables and now several third party lightning cables. And I'm not sure apple cables are generic items, either.
 
kijikadal said:
Not enough amerage so the iPad just ignores it
Click to expand...

The only difference stated is the cable and you could tell if the cable was not capable of carrying enough amperage...it would start to heat up.
 
You can never tell for sure with those cheap knockoff cables. Some are OK, some are not. The iPad charger drives the D+/D- lines to a specific value. If those cables only pass USB 5v and ground, or the resistance on the data lines is off by enough, then the iPad will not see the specific voltages it expects on the data lines before it draws 2.1 amps of power. By default, the iPad draws only half an amp until told it can draw more (by the D+/D- values on the charger), and that half an amp is not enough to charge the iPad when the screen is on, hence the label "Not Charging". It will charge the iPad very, very slowly while the screen is off, but it can take 24 hours or more, depending on how "asleep" the iPad stays during that time. This is the same behavior as when the iPad is connected to a PC's USB port.
 
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