Phone maintenance guide

This page intends to be an all-encompassing resource about how to keep older mobile phones (and any other portable device, for that matter) in good shape.

The issues described in this page seems to happen to some phone brands worse than others, and storing conditions certainly plays a major role in speeding up or slowing down when they happen.

= "Rubber rot" = "Rubber rot" or "rubber reversion" refers to deteriorating rubber products and coatings found in many different portable devices. This can be seen most often on the rubber stops of flip phones and rubber-coated back covers of other kinds of mobile phones.

Several factors are thought to cause rubber reversion, such as temperature, UV exposure, and simple age.

No matter how little or how much reverting rubber is present, interacting with a mobile phone that has the problem can be downright infuriating, as it will smear on plastic parts of the phone, attracts dust and fibers from cleaning wipes, and seems impossible to remove.

Fortunately, with the right materials, removal of rotting / reverting rubber does not take too terribly long.

Removal
Prerequisites: 90% or higher isopropyl alcohol, cotton swabs or other dry wipe, gloves

Dip the cotton swab in the isopropyl alcohol, and then rub the wet cotton swab onto the affected rubber. It will appear to 'melt' and stick to the cotton swab.

You'll most likely need to go through multiple cotton swabs to fully remove the affected rubber spots.

For larger areas, such as rubber-coated back covers, you'll want to use a paper towel or other wipe with isopropyl alcohol applied.

Once the melting rubber starts to adhere to the wipe, either apply more isopropyl alcohol or use another wipe.

When all of the melted rubber is removed, you should be left with the smooth metal or plastic that was behind it.

= Batteries = As batteries of any kind age, how long they last and how reliable they are is bound to change.

This is especially true for devices from the early 2000s and below, and in the 2020s it is close to a miracle if a device from that age has a working battery.

Lithium-ion batteries
The vast majority of li-ion and li-po batteries found in mobile phones run at 3.7 volts, and have a charging voltage of 4.2 volts.

This page won't go into the specific chemistries and the science behind them, but in short, applying 4.2 volts to a 3.7 volt li-ion battery will charge it.

Other charging voltages
Although li-ion batteries will charge at other voltages, it is strongly recommended that you do not exceed it.

It is possible to charge 3.7 volt batteries using the +5 volts from a USB interface, but this generally is not a good idea.

At best, charging 3.7 volt li-ion cells with USB power can be done to "jump start" batteries that appear to be entirely empty (e.g. reads 0.00V on a multimeter), but there are safer ways to go about doing this.