Charging system help

[Dennischaves]

I have an 84 Evinrude 70hp
can all the pros on here give me a quick rundown of how the battery charging system works
Can I disconnect my battery after the motor is running or does it need the battery to run
And what size battery should I get
The only thing I got really drawing power is a radio
And how long can I safely use the radio before it won't start the motor

 

[oldboat1]

runs without the battery, but will burn out the rectifier (no charging thereafter). (Reversing polarity also blows the rectifier.) A 600cca battery would be good, with 100ah or more.

radio time depends on volume, and whether you listen to rock or classical. (dunno, obviously.) But can figure it out if you know the draw for your radio (5 amps per hour would give you 20 hours in a 100ah battery. But you would have to row home.)

If a concern, or if will be adding more electronics, consider a two-bank system and a battery switch.

 

[F_R]

Yep, never, ever disconnect the battery when running. Or buy stock in the rectifier factory because everybody else disconnects theirs (but normally learn after the first time).

 

[Dennischaves]

Ok I'm glad you guys told me to never disconnect the battery ...good to know
i was curious about the radio because I don't want my battery to die after an hour of radio use
I'm going to look into 2 batteries
With a selector switch
Thanks again

 

[oldboat1]

BUT -- Don't switch between batteries while the engine is running, just to be safe. If you hit the "off" setting for just a mini second, you will blow the rectifier! (hate to be a nag....)

Might read up on battery isolators too.

 

[Dennischaves]

Nope not a nag at all
thanks for letting me know that