Distinguishing between Different Battery-Types

One of the things I recently did, was to pair my Linux-laptop, which I name ‘Klystron’, with an external Bluetooth-Mouse, because even though this advanced, HP laptop has as its hardware, an advanced Synaptics touchpad, that emulates a mouse quite well, we can grow tired of always using the built-in touchpad. I documented here, what I needed to do, to accomplish this pairing.

Well one of the features which the KDE Desktop Manager gives us under Linux, is to indicate the battery-charge-levels, not only of the laptop’s built-in battery, but also those of attached BT-mice, or of anything else which is connected, that has a battery, and the hardware of which is able to report as telemetry, the battery-level.

What was surprising me about this arrangement, was that the indicated battery-level of the mouse seemed to track accurately over the days, that the mouse was connected. This surprised me, because as I was remembering events, I had placed Nickel-Metal-Hydride batteries into the mouse some time ago, and most devices which are physically designed to accept batteries in the AA-format, or in the AAA-battery-format, would be calibrated for Alkaline, Zinc-Manganese-Oxide batteries. When such accessories try to gauge the battery-level, if they have the chip to do so, the voltage-curve of a Ni-MH battery tends to remain lower than that of an Alkaline. A fully-charged Ni-MH only generates about 1.2V per cell, while an Alkaline generates 1.5V. And so when a Ni-MH battery is inserted, this chip will usually indicate a partially-discharged battery, even immediately after it has been charged, and then, when this battery-type finally goes dead, its voltage will collapse almost instantly.

Before the indicated charge-level dropped below ‘70%’, I decided to take the AA-format batteries out, and to put them into a charger I have, that’s designed for Ni-MH batteries, and what I found was, that the LEDs in the charger refused to light up, for the inserted batteries. They did not indicate partially-charged or anything, they just stayed ‘off’.

And so next, my thinking was, ‘Darned! I now have either batteries which have failed on me, or worse – a charger which has failed on me 100%…’

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