Started unpacking my ice fishing stuff today in (very premature) anticipation of the upcoming season. I was using my 12v battery from my flasher over the summer with my hummingbird fish finder. I could have swore they both used the same battery (worked great with my hummingbird) but now I plug it into my charger and it says it's fully charged. The charger. Have is just one of those small ones that have a red, green, and yellow light. Regardless of what I do, the light stays green saying that battery is charged. Yet when I plug it in to the flasher or fish finder nothing works.
I get the feeling I probably fried it and need a new one, but I'm open to suggestions as I can't really do any more damage.
(Saving some time, yes I checked, the flasher and hummingbird cords are all attached and in good condition. No I don't have another battery to test everything with).