by Charles Miller

Several times over the years as I have written these columns I have reiterated the importance of using the correct cable for recharging batteries in portable devices. The reason for this is that several times over the years I have seen expensive laptop computers utterly destroyed just because the wrong charger was plugged into it.

Recently a good friend arrived in San Miguel for a visit. He arrived, his $1,000 laptop arrived, but his $20 charger did not. I dug into my closet and found a couple of chargers that might have worked but both were incompatible. Understandably irritated, my friend said he would look around the house to "find one that would fit." When I warned him that the wrong cable could blow-up his laptop, he replied "If it blows up it blows up!"

I am still not sure if he believed me, but what I told him is true. Several of the times I have seen this happen is because the owner had lost their original charger and tried to replace it with one of these "universal" charges that can be set to different voltages and which come with plug adapters to fit different models of laptops. These "universal" adapters can be okay when used very carefully, but if the voltage setting is wrong you might not know it until you see sparks or smell smoke… by which time it is already too late to save your computer.

Time to queue the recording of the lugubrious wail of "But the plug fit!" Unfortunately, this is something I expect to hear more people lamenting in the future because of something called USB Power Delivery (USB PD).

The electronics industries, phones, computers, appliances, medical equipment, etc. are all migrating toward using the USB-C connector as a standard size plug. If you look at USB chargers you can find ones that say 5 volts, but others can say "Output 5V=5.0A, 9V=2.78A, 15V=2.1A, 20V=1.5A." So which is it? Answer: all of the above! The voltage could be 5 volts or 20 volts. The circuitry in the charger chooses the correct voltage to deliver… or it is supposed to.

USB-C chargers and devices use the USB-PD negotiation protocol communicate with each other to agree on the appropriate voltage and current to use. The charger then delivers 5 volts or perhaps 20 volts as agreed.

The big problem with USB-PD and standardizing on the USB size "C" plug is that it makes it far too easy to believe that just because a plug fits into a device that alone means it is safe to use. Instead of getting a good charge for their battery, some people who fail to use the correct charger could get the smoke and fireworks show.

It is therefore of great importance to label your chargers and to only charge your devices using the original charge cords that came with your devices. Substituting some less-expensive after-market charger requires caution. The electronics required by USB-PD are expensive, meaning this is something the third world sweat shops employing slave labor are likely to scrimp on during the manufacturing process. Caveat emptor. If you do choose to buy an inexpensive USB charger you should also invest in a USB voltage/amperage meter you can use to test it to verify it actually delivers the correct voltage and amperage required by your device.

It is likely that everyone reading this has some portable electronic devices with batteries that need to be recharged. Understanding how to do this safely will make using your devices the pleasant experience it should be. Many years ago I received a call for help from someone who had just arrived in San Miguel, reporting she had purchased a brand-new laptop days before in the States, and now it was dead. Seeing that the battery needed to be charged, I asked her where the charger was.

"I threw it away!" she said. Taken aback, I explained she needed the charger to recharge her battery, and then her new computer would probably be okay.

"You're wrong!" she said. "The salesman told me the battery would be good for years." At least that was only a $20 mistake and not a $1,000 one.

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Charles Miller is a freelance computer consultant with decades of IT experience and a Texan with a lifetime love for Mexico. The opinions expressed are his own. He may be contacted at 415-101-8528 or email FAQ8 (at) SMAguru.com.

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