SMC reset fright

I have mentioned previously that I sometimes need to do an SMC reset with my Retina Macbook to get it to “see” USB drives. I did a reset just then and got a fright because it would not start afterwards - it seemed totally dead. Luckily I eventually realised that the power supply was off. Once I turned it on the Macbook booted normally. The lesson is that it seems the Macbook will not start from the battery only after an SMC reset - the power supply must be connected. I suppose that is because an SMC reset affects the battery status.
BTW - the USB SSD drive is now mounted and receiving the backup.
Incidentally, there was a solar storm alert over the weekend that made me more diligent with backups. Fortunately it was not as bad as first expected. I hope some of you in the high northern latitudes got to see an aurora.