I was looking for batteries for my old phone on the cheap end of the net. The direct from china end. This thing popped up and I had one of those “hmm, I wonder” moments. Add to basket.

Essentially they are Li batteries stacked to form a pp3 size with all the gubbins for charging inside, even has a bi coloured led to say when they are charged. Twin pack with a neat twin usb charge lead for 12 quid. Easy to lift the lid off a loco and swap them out.

But are they any use? Well, 9V 1200 mAh . 9V is a bit low really, but two in series would give 18V at over an amp for an hour. In theory. So a bit of prototyping on the bench to test them. I was reasonably impressed, chop the 18 v down to 5V for the radio gear and constrain the mark- space ratio of the motor drive to about 66% to give 12 V equivalent to the motors gave a practical run time of about 2 hours under load. Realistically that would be a playing time of well over that.

Some old wheels and a bit of brasswork.

I’m not entirely sure where this is leading. A few vague ideas. Cardboard mockup time.