When To Charge A Battery/when Is It Considered "dead"?

[MrTexasRigs]

Ok so our trolling motor was being worked on, and we borrowed a buddy's 55 lb trolling motor (never again.) I'm new to boat fishing. I know a full charged battery right off the charger will read 13ish and in like a day it will be down to around the normal 12.6. So we ran it from 6-12 and I tested the battery and it read 12.20 when we were finished. Battery was at 12.5 in the beginning of the day. When should I charge this battery and when is a battery considered dead, and needs a charge? Our other trolling motor is a 75 lb and requires both, so I will charge both to full charge before we use that again.

 

Thanks

[Wayne P.]

When the battery is not being used, it should be fully charged as soon as possible, no matter what the use was.

[Hubtech]

I've got two small slow charger/tender's that I use from Harbor Freight.  When i'm not in the water, they're connected.