How would you verify the results? Unless you had a fully discharged key fob that started working after you charged it?

I have a Seiko watch which gets discharged if left to sit for a long time. And since I keep many watches, I do not wear it often. To continue to wear it just to keep it charged was not something that appealed to me. So I let it sit on a toothbrush charger. And it was charged up in the morning. The watch has an indicator which tells the level of charge.