Fish Finder Battery Life

  I gotta bust out the Multimeter and take a look.  But for now, I gotta Vacuum...

That sucks......

  only problem will be when I go camping and no access to a way of charging the battery during a multiple day trip. 

      You should be able to re-charge your battery just by plugging into your cigarette lighter. 

      Lead cell batteries,   lead acid, or AGM,  will have a much longer life span by keeping it fully charged.  How far down you run the battery effects this life span.    for example, if you run it down repeatedly ( on an average ) to 11.5 volts, it may take over a thousand re-charges.  If you run it down to say... 10v  you may only get less than 100 re-charges.   So if your battery is no good after 6 months, that could be the reason it's losing it's capacity.    You might have to get a bigger Ah battery to prevent too  deep of a discharge.
    A good battery tender will have a three phase charge cycle.  Bulk, absorption and then float.      The output capacity of most AGM type batteries will  follow a fairly consistent downward curve, as the voltage drops.
     I was just at Batteries Plus a few days ago, they showed me a new Lithium 7 ah battery designed to replace the AGM
wow... what a weight difference.     What a price too...at 169 dollars.     But the Li output capacity will stay strong while in use, with a sudden drop in voltage at the end.   Another good feature is it's lifespan is not effected by running it down to empty.  They are internally protected from dropping below 10 volts.   No special charger is needed for this unit, it can be plugged into your  12 output source.   This means the battery should last for many years.
   
    Keep it charged! 

I was talking to the interstate battery guy about what would be a great battery for kayaking and he mentioned that the wheelchair batteries they have would be great. It seems they would charge easier on a normal car battery charger and have a long charge and come in compact sizes. Has anyone ever used one of these before? It does sound like a great option and the price is reasonable around 45.
Thanks
Jim