4 ms·You could also go the MagSafe/ Qi2 way, which is safer and officially supported.by m-p-3 3y agoYou could also go the MagSafe/ Qi2 way, which is safer and officially supported.astrange 3y agoIt's worse for the battery though, because it heats up more while charging. Or rather, to compensate for that it has to charge slower to keep the battery safe.throwanem 3y agoAnd $60 per charger.m-p-3 3y agoYou don't have to buy the "official" one.