USB charging via iMac/ other power adapters

[bobsaget123]

I plugged a USB-C to USB-A cable from my new MacBook to iMac and while I'm using the MacBook, the battery indicator has the little lightning bolt indicating it's charging. If you click the icon, it says "Battery not charging" but under it says "Power source: Power adapter." I figured since it is using the power adapter for power, it may not be charging battery but at least not draining it.

All the while I was using it (a few hours) the battery level dropped from 70% to about 40%. I heard some people saying that the MacBook can charge/not drain battery hooked up to iMac or iPad/iPhone power adapter? Don't really even need it to charge, but would be nice if it could just use that as the power source and not dip into battery while work during the day. Anybody able to figure out a solution to this, of course other than just using the power adapter intended for the MacBook?

Thanks

 

[zhenya]

There is a whole thread on this page, updated today or yesterday about this topic. In short, your iMac isn't going to provide enough USB power to charge while the MacBook is in use. It would probably charge it very slowly if it were shut down. You can however use an iPad or other similar 2.1 amp+ charger just fine.