Jump starting

[Rsmitshoek]

I have an R25. It has four deep cycle batteries. All the batteries are interconnected. If the batteries run down for some reason is it possible to jump start the boat to start the engine? If so do i have to disconnect some of the batteries and where do i connect the jumper cables? Lastly are there considerations as to the battery used to jump start from?

 

[Levitation]

The only answers I have are more questions.
Has someone changed the factory wiring? Your post suggests that.
Let us know that and then we can discuss your questions.

On the off chance there is simply a misunderstanding of the standard setup in our tugs.
1. Think of the four batteries as made up of two pairs.
The right hand pair (towards the bow) are the house batteries.
The left hand pair (towards the stern) are the engine battery and the thruster battery respectively.
The thruster battery is the outboard one and the engine battery is the inboard one.

2. The set is not electrically one big battery UNLESS the combiner switch is turned on.
The combiner switch is one of three switches just inside of the opening to the quarter berth (cave)

2A The top two switches are for controlling DC power throughout the boat.
Straight up and down is OFF.
Rotated clockwise one click (horizontal) is ON

2B The single switch below the top two is the Combiner switch.
Straight up and down is OFF (batteries not combined into one)
Snapped one click clockwise (horizontal) is COMBINED (all batteries connected in parallel)
Most of us do not leave the combiner switch set to ON so that if the house set is drained we still have a hot battery for starting the engine.

3. So, if your engine start battery is down but the house/thruster set has some juice left, turning the combiner switch to ON will give you cranking power. I have used it that way twice when starting the engine in very cold weather and the engine battery by itself would not crank the engine fast enough.

4. And finally to answer your question. If the engine start battery is run down and you want to jump start the engine, turn all three switches to OFF. Then put the jumper cables on the engine battery only.

5. And lastly there is a switch for the thrusters. It is half buried under the floor of the cockpit. Open the port side storage locker, get down on your knees and look for it under your left knee. (on my 2009 R25)
Your boat bieng an SC all bets are off but I expect the basics to be similar.

 

[knotflying]

I have an R25. It has four deep cycle batteries. All the batteries are interconnected. If the batteries run down for some reason is it possible to jump start the boat to start the engine? If so do i have to disconnect some of the batteries and where do i connect the jumper cables? Lastly are there considerations as to the battery used to jump start from?

There should be a parallel switch that connects all the batteries. So if you have a dead engine battery you should be able to start the engine by switching the parallel switch to parallel. This is providing the other batteries are good.

If for some reason you need to get a jump from another boat to start the engine, a) make sure that the parallel switch is off. Hook the cables correctly to the engine battery and you should be good to start.

Now if all your batteries went dead, I would figure out what caused the issue.

 

[Rsmitshoek]

Thanks - that answers my questions on a number of fronts.

Much appreciated.

Roy