Don't know if this is helpful or not... but I have a 12v 10amp battery from OEX that I use for my Lowrance Elite 5 and have been using this charger (see below) without any problems whatsoever.
You can pick one up on Amazon for $47
http://www.amazon.com/CTEK-800-Smart.../dp/B002QUT8IC
I also use the CTEK Multi US 7002 for my batteries that run my BassYaks motor, also without incident. These are very good quality chargers that keep your batteries in great condition and extend the life of the battery.
You can go to CTEK to find our more information here
http://smartercharger.com/
Good luck!