Charger Too Powerful For My Battery Type?

Question

I have a HumminBird Sonar which I am having difficulties with battery/charger wise. I am looking for a charger which indicates when it is in charging mode and when it is fully charged. The battery which it uses is 12v 7ah rechargeable batteries, but it can also use 12v 8ah, 12ah, 18ah... So I am having difficulties finding such a charger for such small portable batteries, usually the sophisticated chargers are more common for the larger batteries. I read that for 7ah Batteries for example it is important not to use it with a charger more powerful then 700mA, is this true or can I use a product such as this with small portable batteries, 2000mA charger...

http://answers.canadiantire.ca/answers/9045/product/0111512P/questions.htm

Answer 1

you can get chargers at various places like The Source which will charge pretty much anything. do a google search for universal chargers too.  

Answer 2

Does your boat have a motor and battery to start it?  If so, just hook the sonar up to the boat battery.  If not, then use any relatively slow rate charger.  The battery for this sonar sounds like a lead acid type.  They like a slow charge and to be kept charged.  Try a motorcycle shop.  They should have chargers for small 12V lead acid batteries.