Outboard power

[Tonygdodds]

How would I know if my outboard could provide charging power to a 12v battery?
It is a pull start if that makes a difference

[Paul_h]

Tony,
what make and model is the engine, some outboards don't have that facility, my Hondas have a kind of socket at the hood

[Tonygdodds]

It's a yamaha 40hp short shaft.
2 stroke.
Don't know much more than that to be honest about it

[Captain marky mark]

Good question pal. How do you know if any type of engine charges the battery. I'm not that clued up on it, not even sure if mine does to be honest. No doubt one of the lads on here will have the answer.

[Tonygdodds]

It's a cracking engine. Starts 1st time & goes like brown stuff on a stick.
But could do with something to keep my batteries powered up
I'm running Garmin fishfinder/plotter, Vhf radio, nav lights, bilge pump & don't think I'll get long out of 2 x 75ah batteries to last a full day at sea

[The seas away]

charging your battery

That engine can charge battery but you need to add a rectifier /regulator" you should have two green wires coming from under the flywheel these are your lighting wires ie: charge wires coming from a charge coil under the flywheel but the voltage is way to high so this is why the voltage regulator is needed because as the revs raise on your engine so does the voltage.
a regulator/rectifier keeps it arond 13.8 volts to charge a 12 volt batt and run accessories.
pm your number and i will put you in touch with a friend of mine who can supply the part and advise or fit for you.

[alcaucin]

unless you want to rely on remembering to manually switch over to whichever battery you want to use and always have your start battery full, then you should look at a "dual voltage sensing relay". these are easy to fit and takes out the guess work and does away with the manual isolation, have a look on ebay. I've fitted one on mine about a month ago and it's working fine. You would need one to suit your motor. I fitted a 140 amp for my optimax outboard with a 60 amp alternator output. it also prevents back charging from good battery to flat battery. Any battery falls to 12.8volts gets charged to 13.8v. Worth mentioning to an electrician if you talk to one.

[alcaucin]

to test your alternator output use a multimeter . connect to the terminals on the connected battery red to red black to black set to 20v dc and start the engine . you should see it reading about 14 - 15volts if it's less than 13.5volts then get it checked make sure all your cable connections are clean and tight.

[The seas away]

That old two stroke does not have an alternator it just has a charge coil and don't produce much in the way an alternator does and that engine is pull start so no starter motor.

[alcaucin]

ah, that's a different scenario.

[alcaucin]

just a daft thought but have you thought about a wind turbine charger like they use on the yatchs, not sure how much they are but I would maybe looking at utilising resources like the wind , sun or the water to help keep my batteries topped up as long as it was cost effective in the absence of a charging system.

[The seas away]

sólar panel

I have a brand new unopened sólar panel for trickle charging can leave connected all the time boat not in use to keep battery topped up.
will sell as no use to me now.

[Tonygdodds]

That old two stroke does not have an alternator it just has a charge coil and don't produce much in the way an alternator does and that engine is pull start so no starter motor.

is this the wire for charging power?

[The seas away]

That's just a cast part number" I need the model numbe it will be on the transom bracket tag be something like.
B40 LH
Meanings are as follows
B=Insore use
40= Horse power
L= Long shaft
H= year 1987

[Tonygdodds]

I'll check again on Sunday when I'm off work