Flat Battery

I know that batteries don't keep their charge forever but it's only been thirty five days since Pan III was last on the road. As a result of going away for Christmas and then the snow I haven't been out on my bike for a little over a month. But, surely the battery should have held it's charge?

Pans I and II never suffered from a flat battery, yet this is the third time Pan III has let me down.

Fortunately my neighbour has a battery charger, thanks Dean.

I really must remember to 'borrow' my battery charger back from Katrine's Dad! Or maybe I should invest in a trickle charger of some sort to prevent this happening again.