So, I have a small collection of consoles and handhelds.
I am now wondering how worried I should be about whether or not the internal battery of the New 3DS (or any other console with an internal battery for that matter) will still hold up, say, 20 or 30 years from now? I know that old gaming consoles can still be functional to this day, provided that the owner has taken good care of them. But when batteries come into play, I am not so sure one would even be able to power on a console if the batteries cannot hold up charge anymore, even if the internal hardware is in good condition.
I don't want to rely on 3rd party batteries (bad experience with 3rd party laptop battery), but it seems to be pretty difficult to find original batteries for the New 3DS (and also Wii U gamepad, PSP, Vita, etc) nowadays.
So the question is: how likely are my current batteries to still be functional when, for example, I want to have my hypothetical grandchild try out these consoles (assuming we won't be living in a Mad Max scenario by then)? I don't play that often, btw, maybe 2 hours a day until I finish a game, then I don't really touch my 3DS for the next 2 or 3 months.
When it comes to lipo/li-ion batteries age is not really much of a factor, but they have a limited number of charge cycles, so with enough use, they are always going to wear out. But when not in use, you just have to keep the battery charge around 50%, say you charge it up to 80% once a year or up to 60% every 6 months, so the charge never drops down too close to 0.
The battery produces more heat when charged/discharged closer to 100% or 0% which increases wear, so it lasts the longest when kept around 50%. Keeping the battery charge above 20% and below 80% can actually double or even triple the battery lifetime. That's why keeping any device on a charging dock (or keeping a laptop plugged in all the time) is bad for the battery as it's always kept near 100%.
What you want to avoid at all costs with lipo/li-ion batteries is letting them discharge fully. And I don't mean using the device until it turns off from low battery. There is actually a small amount of charge left at that point because discharging a battery fully will at best reduce the battery life, at worst completely ruin it. A battery that has been discharged below 2.5V is considered faulty per the manufacturer's spec sheet - that's the rated minimum safe voltage of every lipo/li-ion battery (with some odd exceptions having different voltages than normal, Samsung for example uses 3.8V nominal voltage cells instead of the usual 3.7V, and LiFePo4 batteries have a 3.2V nominal voltage, different rules apply for those), similarly they are not designed to be charged above 4.25V and that is the absolute max safe limit, but 4.2V is still considered a full charge as past that all the power escapes as waste heat)
A battery that has been discharged below 2.5V can often still be rescued by trickle charging, with little permanent damage, but the battery protection circuitry may not allow you to do so.
Also, in the scenario a device or battery has multiple cells in series, such as laptops or RC batteries, due to the batteries discharging at slightly different rates (they're not 100% identical from the factory) it can actually lead to reverse charging, where one cell is fully depleted but another still has some charge in it, the electricity can start flowing in the wrong direction charging the depleted battery with a reverse voltage, which damages the internal structure of the battery (metal gets deposited where it shouldn't) and that is a guaranteed killer of any li-ion/lipo battery over time if someone has a habit of letting batteries deplete, because every time a cell is reverse charged, the damage gets exponentially worse.
Charging circuitry and battery protection will keep a battery within the safe limits, but when left for a long time in a depleted state the voltage will drop even further, eventually below the safe minimum voltage.
Bottom line is, if you don't plan on using a device again for a long time but you want the battery to stay good, you
must make sure it's charged up to 60%-80% before you put it away, and you
must check on the battery charge every 6 months to make sure the battery level hasn't dropped too much, and charge it up to 60%-80% again if necessary. As long as you do this, the battery should still be good decades later if it hasn't gone through a lot of charge cycles.
The fridge method though sounds interesting is not ideal, as i fear batteries could be affected by condensation specially if stored for long periods..
Store it in an airtight container or ziploc bag.
@KleinesSinchen , still on the topic of the Wii U Gamepad battery, which one do you think is worse, letting the battery die and leaving it uncharged for a long time (almost a year since I last touched my Wii U, I think), or charging it every 2 months or so?
Take it out. The gamepad discharges the battery really quickly so it's just unnecessary wear and tear if you're not using it. The gamepad battery is user removable.