Unauthorized Lightning cables are causing serious damage to an integral iPhone 5 component, resulting in certain handsets not charging beyond one percent or even failing to boot up at all, according to a repair firm.

The news comes from mendmyi (via iMore), which offers some troubling information concerning the cheap, unauthorized Lightning cables many iPhone 5 owners use with their handset. According to the repair firm, such chargers are known to cause serious damage to the U2 IC chip which is situated on the iPhone 5′s logic board.

This means that afflicted handsets will work as normal until the battery drains to zero. Then, when users attempt to recharge their iPhone, the handset won’t turn on or even begin charging; instead, it will remain lifeless and unusable.

While mendmyi found that replacing the battery in these iPhone 5 units did bring the smartphone back to life, as soon as the battery died the same problem was encountered. “After a few hours of fitting and waiting for batteries to discharge and seeing the same results we decided this was something a bit more sinister and got one of the logic boards under a microscope to see what the issue could be,” the repair firm explains online, adding:

After taking a look at the iPhone 5 circuit diagram and data sheet we tracked the issue down to a component called the U2 IC.

This IC controls the charge to the battery, runs the power to the sleep/wake button, controls the USB function and and regulates the charging to the power IC that charges the iPhone 5. (…)

The cause of this component becoming faulty is really quite simple – third party chargers and USB leads!

The original Apple chargers and USB leads regulate the voltage and current to a level that protects your valuable iPhone and prevents it from damage.

Charging your iPhone using a third party charger or USB lead that does not regulate this as much allows for larger variables in voltage and current, this then damages the U2 IC and can leave you with a seemingly dead iPhone 5.

Fortunately, the fault can be repaired — mendmyi is offering a repair service for £66 ($112.55) plus VAT. Of course, prevention is better than cure and in this case, prevention involves ditching your knock-off Lightning cable for an authorized model.

Though Apple has tried its hardest to stop iPhone owners from connecting their smartphone to knock-off Lightning cables, countless users are nevertheless relying on cheaper options for syncing and charging their handset.

Part of the problem is the price of official Lightning chargers: while the cables reportedly cost Apple just $3.50 to make, they retail on the Apple Online Store for $19.00 (and more).

Despite this, the price of a potential U2 IC chip repair means iPhone owners would clearly be better purchasing authorized replacements for their Lightning cable. Given that unauthorized cables have also reportedly been the reason behind freak cases of iPhone combustion, paying a little extra for an authorized product would definitely be a smarter move.