First from 10W, then from 20, from 30, from 65 and even from 120: in the last 2-3 years we have seen a constant growth in the power of smartphone power supplies. The greater the amount of watts delivered, the faster the recharge will be of the mobile phone battery: in some cases it reaches from 0 to 100% even in less than 20-30 minutes, an incredible result and which until recently seemed unthinkable.
Each time we are amazed by this prodigy, and each time we ask ourselves the usual question: but isn’t it that charging so fast damages the battery? There is no clear and unambiguous answer to this question: in theory yes, but in practice no. Or vice versa: probably not, but there is a risk of yes.
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The two problems of super fast charging
“The charging process works by moving the lithium ions from the positive to the negative pole of the battery,” he reminded us Vittorio Pellegrini, former director of IIT’s Graphene Labs and one of the founders of the Be-Dimensional startup – Simplifying, this movement is made possible by the current we feed through the power supply, causing the voltage to rise up to the peak level (just under 4V, ed), where it remains stable and then drops in the final part of the procedure “. Obviously, the more powerful the charger, the faster it gets to 4V and the faster the charge is completed.
The point is that the battery is closed, physically small and fits inside a physically small object (because we want smartphones more and more rich in functions and yet more and more subtle), and this creates a problem. Indeed, it creates two: “The first problem is that the passage of current generates heat, and the faster it is, the more it generates – explained Pellegrini, who in Italy is one of the leading experts on the subject – The second concerns electrolyte, the liquid that separates the positive and negative poles, which in the presence of heat begins to evaporate “. Except that this vapor cannot go anywhere, precisely because the battery is hermetically sealed: “In extreme cases, this leads to a swelling of the back of the phone (this is a bit like what happened to the Samsung Galaxy Note 7 in 2016, ed) and moreover, over time and by dint of evaporating, the electrolyte dries up and runs out “. And then the battery gets damaged and loses its effectiveness.
The two solutions to continue using it
That being the case, the answer to the original question seems easy: heat is not good for the battery, super fast charging generates a lot of heat, then super fast charging hurts and should be avoided. Is that so? Actually no, because companies have found some solutions to the problems: there are mainly two, and they both seem to work well.
First of all, “many companies use two batteries in parallel, rather than a single and larger one, so each receives half the watts of charging”, and therefore half heat; it’s a good solution, even if not easy to make: “We need space (and we know that in smartphones there is little space, ed) and we need thinner and less bulky, but still capable batteries”. The other possibility is to manage the heat externally to the battery, take it away or make less of it: “The ideal is to build them or coat them with materials with better conductivity, through which the current passes more easily (therefore generating less heat, ed) – Pellegrini told us again – One way is to cover them with a layer of graphene paint, which is a good conductor of heat and electricity and makes the whole process more efficient “.
Okay, but how do you know if whoever produced the smartphone we would like to buy used one of these tricks, or both? It is necessary read the technical data sheet carefully, looking in particular for the data on charging cycles: “The industry standard says that at least 500 must be done before the battery degrades from 100% to 80% of its capacity.” And since many companies guarantee many more (such as Xiaomi, who insists a lot on monster power supplies), “we can be relatively calm, also because there are also many software-level controls that manage the amount of current supplied by the charger and received by the phone and internal circuits that minimize any unwanted effects “.
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The real enemy: induction charging
It is obviously up to us consumers to assess whether the promised 500 recharge cycles are sufficient for our needs: recharging once a day means almost a year and a half of use without problems. Trying again a answer the original question: Super-fast charging isn’t a problem in itself, but it could become a problem in some cases. For example: if there were two recharges per day, then perhaps the discussion on the duration over time of the smartphone would change.
An issue on which there seems to be little doubt concerns the fact that the real enemy of batteries is induction charging, towards which more and more producers (us) are pushing. Because? “From the point of view of charging, the ideal is that the battery is as close to 0 as possible, so that the voltage rises constantly”. Simplifying, if the charge level is low, the battery is in the ideal conditions to receive current: “Continue to activate and interrupt the charging process, repeatedly placing and removing the phone from the base, causes the incoming current flow to be fluctuating“. Which is not good.
So what do you do? “Before recharging, it is better to wait until the residual autonomy falls below 15-20% – is Pellegrini’s advice – There will be fewer changes and less risk will be taken“. In short: it is better to reload everything at once, and it’s okay to do it too fast or super fast.