Battery Advice / Depth Finder Troubleshooting

For my depthfinder - - - I have a small 7 amp, 12 Volt Battery, nicely mounted in a dry storage container within my kayak.  Have used it as the power source for a year or so  now.  

I may have overcharged the battery by accident last week ( I forgot I plugged it in, letting it charge for a week on a standard wall charger).  It does not have an auto shutoff when capacity is reached, so although the battery still carries a charge, it may have damage.  

The depth finder unit is now not picking up a read on the bottom (It just flashes 0 feet).  The manufacturer indicated that is common problem if the battery is not outputting enough power for the transducer (possibly because of the overcharge).

Looking to replace the battery, so I wanted to ask if this is the most common type the board uses?  &    What type of battery chargers you use to power the battery back up?.  (I know some have a trickle charge / Auto Shutoff to prevent overcharging).

Thank You

Jim

I power my FF with a battery from an old UPS.  Same 7AMP 12V battery.  Drop the battery back in the UPS to charge.  

Cabelas also sells charges that have auto shut off.

Kevin

I use a 5 Amp-Hour 12 V battery and use a simple motercycle battery charger (basically a transformer and two wires).  I charge it every third trip or so and charge it overnight.  Never had a problem.

Erik

Get a slow recharger that has automatic shut-off.
DelTran SuperSmart Battery Tender automatic battery charger.  
RedLight: charging
GreenLight: Storage

I am a big fan of rechargeable AAs.  Small, light, long lasting, and if you can't recharge you can get regular ones.  Fix your battery, and then see if theres anything wrong with the ff.  Good luck!

If you can't remember to unplug it, get a timer the plugs into the wall first. I have the same setup and I have a cheap volt testing meter to check the charge on the  battery.

Since the fish sonar uses so little power, you are constantly overcharging that battery if you charge it every time you go out. I charge mine more like once a month and use the voltage meter to see how much charge it has and then check it as it charges to see how it is doing.

Thank you for everyones helpful advice.