[Richard230]

For bikes (or cars) that have a computer with presets that you want to save when your remove or replace a vehicle's battery, this 9V-powered "battery memory saver" looks useful. Not only is it cheap, but it also would make a good Christmas "stocking stuffier": https://www.amazon.com/dp/B07BLQ9WSS?ref_=ppx_hzod_title_dt_b_fed_asin_title_0_1

Of course for a motorcycle you will need an SAE/car-cigarette lighter adapter, but those are easy enough to source. I think I have several in my collection of 12V electrical adapters.