You may not realize it, but USB chargers come in a variety of flavors. And by flavors we mean build quality, currents and suchlike. What this means to you is you’re probably not charging your tablet at the optimum speed if you’re using an old USB charger block you got for your phone a couple of years back.

It also means you may be putting your expensive phones or tablets in danger if you use a cheapo USB block or cable you bought on eBay for $0.50, if only because the components probably haven’t been stress tested at all, let alone manufactured to quality tolerances. Here’s where the Charge Doctor comes in.

This small gizmo slots in neatly between your charge cable and power socket block and gives a readout of the voltage/current coming down the pipe into your precious phone or computer. By doing a regular test you can make sure your charging environment is still delivering optimum results, and also pinpoint any possible issues before they can cause problems with your kit.

The device measures current up to 3A which should be enough for the hungriest tablet, and works with any USB port, including computers and laptops, car or wall mounted power blocks. Priced at $10.