Boat Electrics

[Bob F]

Of course, the good old back emf.

 

Good point about the tilt power Kam. Imaging the scenario, you're fishing a mark by drifting over it. You come to start the motor but it fails to start due to the battery switch failing. The boat drifts towards a crab pot and the engine gets caught in the robe. You have no tilt power to lift the engine and cut the robe. Transom gets pulled down and water starts coming aboard.

 

Think I'll stick with my set up.

 

BF

[charlieannear]

Thanks for that definite answer Paul!

 

I do believe you all about blowing the rectifier, but what is the difference between turning off at the battery switch and the ignition switch?

 

Just want to know the complete answer as I will need to explain it to my Dad!

 

Bob- Do they secure crab pots with old dressing gowns then? Good point though- perhaps I'll sort out a hybrid along the lines of what Kam describes...

[Newboy]

  Bob F said:

Of course, the good old back emf.

 

Good point about the tilt power Kam. Imaging the scenario, you're fishing a mark by drifting over it. You come to start the motor but it fails to start due to the battery switch failing. The boat drifts towards a crab pot and the engine gets caught in the robe. You have no tilt power to lift the engine and cut the robe. Transom gets pulled down and water starts coming aboard.

 

Think I'll stick with my set up.

 

BF

It's funny how we see different scenario, you see it in a safty point of veiw while I see it as:

 

Boat on trailer on driveway, need to tilt up motot to get underneath it, tried tilt switch, it doesn't work cos I switch it off, get step from garage, hop on board, switch to on, jump down, hurt my ankle as a result, swearing loudly cursing every single thing in the immediate surrounding..........

[Newboy]

Charlie, think of it this way, when the motor is on, and if it has a charging circuit, it pumps electricity back from the motor to the battery, the flow is continous, as long as the engine is turning it generates electricity. If you break the circuit, by switching it to off, you are taking out the recipient i.e., battery, the current has nowhere to go but go back and blow your rectifier....... this is how the Merc man explained to me.

 

Turning off ignition, your engine also dies, so no electricity being generated.

[charlieannear]

  Quote

Charlie, think of it this way, when the motor is on, and if it has a charging circuit, it pumps electricity back from the motor to the battery, the flow is continous, as long as the engine is turning it generates electricity. If you break the circuit, by switching it to off, you are taking out the recipient i.e., battery, the current has nowhere to go but go back and blow your rectifier....... this is how the Merc man explained to me.

 

Turning off ignition, your engine also dies, so no electricity being generated.

 

So:

Igntion turns off ignition circuit, engine dies and therefore charging circuit dies.

Turning off battery switch breaks the charging circuit causing feedback that will damage rectifier.

 

Sorry to go on, and on, and on...

 

  Newboy said:

It's funny how we see different scenario, you see it in a safty point of veiw while I see it as:

 

Boat on trailer on driveway, need to tilt up motot to get underneath it, tried tilt switch, it doesn't work cos I switch it off, get step from garage, hop on board, switch to on, jump down, hurt my ankle as a result, swearing loudly cursing every single thing in the immediate surrounding..........

Ha ha!

 

Luckily I can reach the switch from outside of the boat, standing on terra firma.

 

Now someone's going to tell me why that's a bad idea...

[Bob F]

Reminder of a tip for getting back into the boat if you fall overboard.

 

Stand on the engine fins and use the tilt switch on the side of the engine to lift you up out of the water.

 

If this happens at night and you have moved your battery switch to BAT2 you would not be able to use the tilt switch to bring you back onboard if the switch is wired convensionally.

 

BF

 

 

[Newboy]

  Bob F said:

 

Stand on the engine fins and use the tilt switch on the side of the engine to lift you up out of the water.

Cool.... got to try this.

 

I'm off to try barebacking my outboard now.

[charlieannear]

  Newboy said:

  Bob F said:

 

Stand on the engine fins and use the tilt switch on the side of the engine to lift you up out of the water.

Cool.... got to try this.

 

I'm off to try barebacking my outboard now.

Think I'll stick to using the ladder

 

Or asking my mate in the boat to give me a hand

[duncan]

I'm with you.

 

Important test for any boat I have had is 'can I easily deploy the ladder from the water and is it long enough for a cold tierd overweight guy to get onto and start climbing up?'

 

Many many do not have the lower rung low enough.

 

Realise this is more for the larger boats of course but smaller ones need to have a solution available.

[Paul J]

While were on the subject- does anyone have a rectifier that will fit a merc 50?

 

PJ

[Seamouse]

  Newboy said:

I'm off to try barebacking my outboard now.

Although the 'scissors' during a lift are opening, not closing, bear in mind the hydraulic tilt has easily enough grunt to sever any extremity you might happen to leave dangling in the wrong place

 

Steve

[Coddy]

  Bob F said:

Document updated to conventional set up

 

Thanks for your feedback.

 

Coddy, you might want to update your website.

 

BF

Hi Bob

 

Thanks for the reminder, however one question

 

With the feed to the switch panel/+ve buz bar, if the switch is in the OFF mode, all the power from the outboard will be through anything that is switched on.

My concirn is that it "could" be excesive and cause more damage to your electronics, lights etc.

 

I would prefer to have supply feed direct from a battery and NOT from the COMMON conection.

 

I accept that one battery could fail but at least you can select BOTH batteries and start the engine and it would supply a feed to both batteries BUT smoothes the supply down to a suitable voltage.

 

Just my thoughts

 

Coddy

[Bob F]

Hi Dave,

 

When would you have the switch in the OFF position and the engine running?

 

BF

[Coddy]

  Bob F said:

Hi Dave,

 

When would you have the switch in the OFF position and the engine running?

 

BF

Hi Bob

 

I was thinking that some might turn the switch with the engine still running.

 

That's all

 

It would safeguard any possible expensive repairs.

 

Coddy

[Paul D]

I see where you are coming from Coddy. Presumably the same spike that would be caused by switching the swicth to "OFF" whilst running, you are assuming will be across the busbar and hence GPS / FF etc. ( lights wont be a problem ).

 

I guess there is a chance that this could damage electronic equipment in this case, although the rectifier in the outboard is more likely to be damaged, since it is connected by much thicker ( and hence lower resistance ) wiring.

 

Downside with your arrangement though is the battery will never by isolated from the busbar, therefore if you want to work on any wiring you have to physically disconnect the battery. ( also means in emergency you have no way of switching the power off ).

 

Bob, Puzzled why you have such distrust in the battery switch ( from your bad experience I guess ) and I am not so sure your setup ( where switched to Batt 2 the engine has no battery power ) is "conventional".

With a decent battery switch they can handle the starting current, so I opted for the engine connected to common and each battery positive to batt1 and Batt 2 respectively and I know not to switch to OFF whilst engine is running ( in fact I rarely change the switch whilst running anyway ).

 

Kam, Many outboards will not run without a battery connected. ( This is actually one of the plus points of the E-Tec engines ). Mercury Optimax's for example will not start without a minimum voltage being available - so no rope starting for them ( not that I would fancy rope starting Martin's engine ! ).

 

 

 

 

[Newboy]

  Paul D said:

Downside with your arrangement though is the battery will never by isolated from the busbar, therefore if you want to work on any wiring you have to physically disconnect the battery. ( also means in emergency you have no way of switching the power off ).

 

 

 

 

Kam, Many outboards will not run without a battery connected. ( This is actually one of the plus points of the E-Tec engines ). Mercury Optimax's for example will not start without a minimum voltage being available - so no rope starting for them ( not that I would fancy rope starting Martin's engine ! ).

The isolation issue can be solved if you fit an isolator switch between battery and outboard. Thus outboard can be worked on without having to disconnect battery. Other electronics is already covered by the switch (to off) so they can also be worked on.

 

Yes, it is true most outboard cannot be started without a decent battery but once the engine has started it run without the battery, in theory cos it draws the power from the charging circuit, but in practice it will blow the rectifier without the battery.

[Bob F]

Paul,

 

My set up is NOT the convensional one. Your set up IS convensional.

 

And yes, my distrust of battery swithes is because of the two failures of two different makes of switches.

 

 

BF

[Paul D]

Bob,

 

In which case I disagree with your statement :-

 

"If this happens at night and you have moved your battery switch to BAT2 you would not be able to use the tilt switch to bring you back onboard if the switch is wired convensionally."

 

I assume you mean "non conventionally" ( as in your setup ).

 

 

[Bob F]

Doh, yes you're right.

 

Another one of my senior moments.

 

Less haste, more speed.

 

BF

[charlieannear]

Glad I asked the question!