Many people are already using an iPad as their desktop 'computer', and with the launch of the new magic keyboard, this may rise further. The new magic keyboard for iPad Pro has a USB-C passthrough for power and as such will mean your iPad could be left on charge all the time while on your desk - is this safe to do? That's a hard question to ask, but hopefully, I found an answer.
This question isn't a new one, and it's one that everyone has an opinion on. Much as everyone complaining in a shop has a friend that works for trading standards; everyone becomes a physicist when talking about charging your battery. Leading to much hearsay and loads of conflicting information.
The straight to the point answer is that battery technology has drastically improved since people started charging their mobiles every night. Back then, there were all sorts of scare stories about exploding Blackberry's and only charging your phone from below 10%. The myths are vast and frankly downright weird at times, but it's safe to say that there is loads of technology built into the battery of your iPad to porotect it.
Since 2012, Apple has made charging much more complex and made loads of improvements aimed at maximising your battery life. This is universal across the range of devices, so what's suitable for one is ideal for another. Battery university (yes that's a real thing) has a vast array of information on Lithium-based Batteries, and are often quoted as a good source for information.
In theory, such a mechanism should work forever, but cycling, elevated temperature and ageing decrease the performance over time. - Battery University
They conclude after much research and loads of graphs that the user can do a few things to prolong the longevity of their battery. Highlighting that "The worst situation is keeping a fully charged battery at elevated temperatures" - so avoiding high temperatures should be a significant indicator towards maximising life.
The number of cycles that you iPad will go though does add to the wear on your battery, but there is no clear answer to what a cycle is. A more important factor is elevated temperatures. So in theory, keep your battery charged and away from heat and you should be ok. Apple says between 0 and 35 degrees C.
Evaluating battery life on counting cycles is not conclusive because a discharge may vary in-depth and there are no clearly defined standards of what constitutes a cycle - Battery University
The second piece of information you hear is the level of battery charge you should be completing. A considerable wealth of forum posts and opinions display numbers that seem plucked from thin air. However, research does suggest that a battery should not be charged to 100%. Ever. The good news is that your battery never reaches that far, 100% in the software is not 100% battery capacity - so there is no need to worry.
Since iOS13 Apple has been working on machine learning your habits and maximising battery life. Once the OS displays your iPad is at 100%, it will intelligently discharge and recharge the battery very gradually. Apple has also intelligently accounted for issues that seem to arise after 80% capacity. Once your iPad is charged to above 80%, the charging rate is dramatically reduced. So think of the last 20% as what's generally referred to as a trickle charge.
You do not need to cycle your battery down to 0% every so often, despite what many on the internet will have you believe, your battery does not have a memory! Apple recommends charging to 50% if you plan on storing your device long term and charging every six months or so. There is no need to discharge you iPad if you leave it plugged in, but it can't hurt discharging it down to 50% every month so.