Thread: What did I Blow???

I have seen batteries showing a full charge on my engine test cell yet not have enough ummph to turn th engine over

I took the boat out yesterday morning and it started right up, ran great all morning and was charging fine. I looked at the fuse I thought was blown and the filament was still intact but it was black at the base of the fuse on both sides of the filament where it comes out of the base of the fuse. I guess it was not blown. It looks like the reverse polarity did no damage and I just had a bad battery.