Tohatsu 5 HP Alternator

[CapnGrumpyBreeches]

The Tohatsu 5HP Alternator is rated at 60w/5amps. Does anyone know if the real life power output is anywhere close to this? I just got done installing solar on my 22 and had to put a power regulator in the circuit. Last year when I installed shore power, I also put a regulator in. Im just now realizing that the original owner of my catalina 22 hooked up the engine directly to the battery with no regulator. Sounds like I could fry my battery if I had to motor for an hour or more. (No access to my outboard today to check the output myself)...

Anyone have advice on this?

 

[Bill Roosa]

do you mean a Tohatsu 5HP outboard? 5 amps sound about right.
as for the PO hooking up the alternator with out a regulator that probably would result in stalling the engine from full fielding the alternator or no output at all (probably the latter)
or
there is an internal regulator and no problem

 

[CapnGrumpyBreeches]

do you mean a Tohatsu 5HP outboard? 5 amps sound about right.
as for the PO hooking up the alternator with out a regulator that probably would result in stalling the engine from full fielding the alternator or no output at all (probably the latter)
or
there is an internal regulator and no problem

Hey Bill, Yea I meant the Alternator on the outboard. I think other then the alternator the rectifier is the only other electrical component. Now that you mention it, I checked the output on the motor last year and i think it was .02 amps. Maybe i should get a regulator....

 

[kloudie1]

Captn' Sounds correct.. The alternator doesn't make anywhere near 5 amperes until you are almost at full rpm. These aren't normally hooked to a regulator because as the battery is charged, the volts come up and the battery won't accept the full output unless the battery is significantly discharged.. I wouldn't worry about it unless you are planning to motor continuously for days at high rpm.

 

[CapnGrumpyBreeches]

The only way to sail...

 

[svchickadee]

Adding a switch to the positive side between the outboard and the battery will solve the problem if you remember to turn it off when necessary. I have two 85W solar panels on my Oday 25 and I use the switch avoid overcharging the battery.

http://www.defender.com/product.jsp?path=-1|328|2290051|2290060&id=566688

 

[walt]

Also agree.. dont worry. Its a good idea to be able to watch the battery voltage if you motor for a long distance.

Very important caution!!!! If you add a switch between the outboard and the battery..

NEVER change the switch position while the outboard is running.

Its actually only opening the switch while the outboard is running that is bad as this creates a big voltage spike that can easilly blow out the rectifier in the outboard. The outboard still runs fine with a blown rectifier, but the charging no longer works.

 

[Jalepeno]

The 5 hp two-cycle Tohatsu outboard does not have an alternator. The charging circuit is a very simply a magnet in the flywheel (same one that is used for the ignition spark), a pickup coil and a rectifying diode. There is no regulator or smarts. The output is around 50 to 60 watts at maximum speed. The output is pulsed and needs the battery to dampen the pulses. It works out to about 2 to 3 amps at a voltage high enough to put a small charge into the battery. Think of it as equivalent to a 3 amp trickle charger at best. It will maintain the charge on a 12 volt deep cycle battery and let you use LED lights and a radio on low volume if you run the motor a lot at a high speed. There is no danger of over charging the battery and you may need to use an AC charger to top the battery if you use a lot of power.

 

[CapnGrumpyBreeches]

The 5 hp two-cycle Tohatsu outboard does not have an alternator. The charging circuit is a very simply a magnet in the flywheel (same one that is used for the ignition spark), a pickup coil and a rectifying diode. There is no regulator or smarts. The output is around 50 to 60 watts at maximum speed. The output is pulsed and needs the battery to dampen the pulses. It works out to about 2 to 3 amps at a voltage high enough to put a small charge into the battery. Think of it as equivalent to a 3 amp trickle charger at best. It will maintain the charge on a 12 volt deep cycle battery and let you use LED lights and a radio on low volume if you run the motor a lot at a high speed. There is no danger of over charging the battery and you may need to use an AC charger to top the battery if you use a lot of power.

I figure between solar, shore power, and the outboard. I'm probably ahead of the game in the trailer sailor world. Good info Jalepeno!