Solar Sportsmen Lithium Battery

Has anybody used these batteries? They look like they would be pretty awesome!

http://www.solarsportsman.com/lithium-batteries/lithium-ice-fishing-replacement-batteries/

Here’s a link to the page, I’m new to IDO so I wasn’t sure how to include it in the last post.

I used one of their batteries last year. I really like how light they are. It makes hole hopping really easy. I used it in my Vexilar and saw that I had less interference from other sonars. Also I was able to charge the battery after a full day of fishing in like an hour. Well worth the cost especially if its gonna last as long as they say it will.

How long are they supposed to last?