1973 Evinrude 65HP 65ES73R... Want to power onboard electronics

Berkeley

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Nov 16, 2012
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Hi- I have a 1973 Evinrude 65HP 65ES73R and I'm wondering if it is returning power to the battery while it is running. (Unfortunately, it is not running right now so I can't put a meter on it). I want to

1) be sure that the battery is being recharged while underway. Does this engine return power?

2) would like to hook up an inverter to power onboard electronics. I would like to power these off of a second battery that is not the starter battery. What is the simplest way to accomplish this? Thanks... I've taken physics plenty of times and am a scientist but somehow electricity always turns me inside out!

Thanks folks!
 

Silvertip

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Sep 22, 2003
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Yes -- it does charge the battery but the output is 6 amps or less. So the question for you is what accessories do you plan to run? If you add a second battery how do you intend to charge it? The alternator can barely keep up with the starting battery so trying to charge two batteries is simply not practical. You mention an inverter! As a scientist, you know that perpetual motion hasn't been invented yet so using an inverter to convert 12 volts to 115 volts to power accessories is also not practical in your case. That conversion is a 10:1 ratio so to get 1 amp of 115 VAC requires roughly 10 amps of 12 VDC. Inverters are simply not practical unless you have a large alternator to keep the battery topped off. You don't!
 

alldodge

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Mar 8, 2009
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Hi- I have a 1973 Evinrude 65HP 65ES73R and I'm wondering if it is returning power to the battery while it is running. (Unfortunately, it is not running right now so I can't put a meter on it). I want to

1) be sure that the battery is being recharged while underway. Does this engine return power?

2) would like to hook up an inverter to power onboard electronics. I would like to power these off of a second battery that is not the starter battery. What is the simplest way to accomplish this? Thanks... I've taken physics plenty of times and am a scientist but somehow electricity always turns me inside out!

Thanks folks!

Not an outboard expert but appears the stator output is only about 6 amps. The 6 amps would be enough to charge the starting battery back up given enough running time but is not sufficient to recharge a battery which was used heavy. If this is the case you can still use a two battery setup but keep them separated with a 1, 2 and both battery switch. Also add a 2 bank battery charger to be used when trailered.


A 2 bank battery charger would be connected to each battery separately. The switch could be rotated to combine the batteries if need to get the motor started.
 
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