alternator?

[thmlrmg]

i have a '75 evinrude 70hp motor and i would like to know how to tell what size alternator is on my motor and how difficult it is to put a bigger one on there. all i want to run is a radio. the one that the manual says is on there is a 6amp and my radio has a 7.5 amp fuse. i have more amps in than out. and how much does a bigger alt. cost? like a 15 amp? thanks

 

[oldboat1]

Re: alternator?

no can do. But it doesn't matter. Your radio doesn't draw 7.5 amps, I'm sure, but even if it did you are OK. Use a deep cycle marine battery with a 105 amp reserve capacity (pretty much standard), and work out the math (input/output, running time/playing time, etc.). You can throw in the usual additional items (lights? depth finder?) and still be OK. But if still in doubt, go to a two battery system to double your reserve capacity.

 

[mooseo]

Re: alternator?

thmlrng, outboards of that size don't use bolt-on alternators like cars do... they add the internal components of the alternator (magnets and coils) to the flywheel of the motor and then use an external voltage regulator to turn it to DC. <br /><br />oldboat is right: your radio doesn't draw 7.5amps for any length of time (if at all)... your motor can handle it with the battery to provide reserve.

 

[PsYcHo]

Re: alternator?

oldboat1 & mooseo are correct. Your radio would never pull that kind of current. The fuse is there purly to prevent damage to the radio circuitry in the event that a short occurs (ie speaker cables). Im sure even with your existing battery you would get a few hours listening time out...AND still crank the motor to start...unless you shove amps & huge speakers on and play at high volumes...

 

[thmlrmg]

Re: alternator?

thanks for all of your input my alt wasn't charging at all thanks to a bad rectifier. we are once again charging. thanks alot.