Emergency starting link

zoidberg

zoidberg

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While our good friend Noelex is away struggling, with Storm Freya in the frozen north....

A question of good practice - or best practice - relating to provision of a 'link' to provide emergency starting power in event of the Start battery being insufficient.

I have an Optima RedTop for a Start battery. This should provide adequate starting 'grunt' for a Beta 14, and then some ( offering 815CCA ). However, if/when it suddenly begins to feel its age, like me some mornings, I would wish to be able to provide some 'shouldering of the load' by the paired Optima BlueTops ( offering 2 x 845CCA ) close adjacent.

The RedTop has simple posts for connectors. The BlueTops have both posts and screw pillars.

I could carry a set of 'heavy duty' jump leads, but am concerned they haven't the 'meat' to cope with starting surge.

I could carry a 50mm/sq short 'jump cable' with suitable connectors on each end, to be attached if/when needed.

I could fit a similar 50mm/sq short cable between RedTop and BlueTop with a keyed isolator switch attached nearby.

What does the team think? Fusing? Get the wife to make the connection...? Or just sail her on and off the mooring as per the RYA booklet....? :rolleyes:
 
Could you not just link the Blue Tops to the starter circuit via a switch?

I have two switches, the normal battery one which I turn on normally to power up the engine circuits from the engine battery. An emergency one to power up the engine circuits from the domestic batteries instead. And if I ever wanted the whole lot in parallel I'd turn on both.
 
Almost all of those options would be good. One thing to consider however is that using a jumper lead you can make a spark which is OK unless the spark is at a battery terminal where hydrogen can be present. The resultant explosion can be harmful. Connect one end of jumper lead to domestic battery then the other end to the terminal on the stater motor. The other option is to remove the connection to the start battery and just connect to the wire to the starter. This would mean no spark and would also mean the dead start battery can not drag the starting down. However it might also mena you miss out on the assistance of the dead start battery. So best option is somewhat dependent on the nature of the start battery failure. (usually it can assist) ol'will
 
Just fit a 3rd isolator switch between the load terminal of the engine switch and the load terminal of the domestic switch.

It starts the engine if the engine battery is flat.
You can isolate a dead engine battery and run everything from the domestics.
You can isolate a dead domestic battery and run everything from the engine battery.
 
PaulRainbow said:
Just fit a 3rd isolator switch between the load terminal of the engine switch and the load terminal of the domestic switch.

It starts the engine if the engine battery is flat.
You can isolate a dead engine battery and run everything from the domestics.
You can isolate a dead domestic battery and run everything from the engine battery.
Click to expand...

That is precisely what I have.
 
NormanS said:
That is precisely what I have.
Click to expand...

+1

Used it recently when the 'dedicated' engine battery failed, after 20 years stalwart service, (your scenario) and started the engine using the house bank. then went off and bought a new engine start battery.

I might add - our engine start battery is so small the idea of running much from it - would be optimistic - but if the house bank went down (a major emptying of the wallet would occur) but in the interim we could run off the engine start battery - with the engines charging same.

jonathan
 
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zoidberg said:
I could carry a set of 'heavy duty' jump leads, but am concerned they haven't the 'meat' to cope with starting surge.
Click to expand...

Your Beta 14 is a tiny engine in automotive terms, it's less than half a litre displacement, smaller than almost all car engines. So a decent set of jump leads would certainly be up to the job.

You could wire a permanently switched emergency arrangement, as if often recommended, but you have high quality batteries and it's doubtful whether you'd ever need to use it.
 
On Anemone I had a VSR and two separate key switches. I had read about having an emergency link switch but thought that was unnecessary so when the inevitable happened, I had to swap battery leads. The batteries were all under a quarter berth so not all that easy to access so took 15 minutes or so. Fortunately I was on my mooring when I needed to do it and not in a more critical situation. Needless to say, I fitted the extra switch at negligible cost. I didn't leave the key in and had to swap keys around so their was no chance of leaving it in and flattening all the batteries. (I never had to use the switch).
 
Worst case, the engine battery has failed completely at short notice (highly unlikely, but..) and connecting it via jump leads may result in overheating or worse. To deal with that you need a 1/0 switch on the + off the start battery to isolate it

Incorporate an Anderson battery female connector pre-installed to the starter motor and earth, and have a pair of jump leads with clips at one end, and a corresponding Anderson male at the other. Then any battery can be used to start the engine.

https://uk.rs-online.com/web/b/anderson-power-products/connectors/
 
I’ve practiced hand starting my 2qm15 a few times. Old school I know. I have an emergency combine for the batteries too but would limit its use in a real emergency. Those last few amps are for communication.
 
I would think the heavy duty (thick wire) jump leads would be the simplest and most flexible solution - and without adding complexity to the wiring which can cause other issues.
Jump leads are designed for starting engines with flat batteries. And in the motor trade each set of leads often used on hundreds of engines very safely and effectively (provided used properly - generally only holding one lead at a time to avoid accidentally touching)
 
A lot of VSRs provide the emergency start assist function, so there may be no point in adding the switch.

Some boats, the batteries are accessible enough that simply moving a cable to the house bank is quick enough, and has the advantage of taking the duff engine battery out of the circuit.

If you have a linking switch, it's useful to know whether it's upstream or down of the bank isolation switches.
 
We are tucked away in nice little anchorage so all is well. I didn’t expect any internet coverage, but if we swing the right way there is a weak signal. Isn’t modern life great.

Our previous yacht suffered an engine failure (mechanical not electrical) and we sailed for a few months without an engine. It sounds romantic, but is mostly a giant nuisance, so anything that improves engine reliability is worth doing in my book.

A facility to be able to start the engine using the house bank is an obvious simple step.

Jumper cables are fine, but rather than the normal alligator clips (which can jump off and create a short) the correct size ring terminals are better. However, by the time you obtain the correct wire ring terminals etc it is not much extra trouble to have a permanently wired system that can start the engine via the house bank. An extra “emergency” battery switch is needed, but the cost is not great and this option removes the difficulty and time taken to connect the jumper cables.

In a similar vein, knowing how to bypass the starter switch and the starter solenoid will fix many electrical starting problems. This can be done with a screwdriver but you need to know how. It is easy to short the wrong connections, especially if access is difficult, and even when done correctly sparks will fly when bypassing the solenoid. An alternative is to pre-make a jumper cable (once again with the correct fittings) with a heavy duty switch that can be used instead of the screwdriver trick especially for the solenoid failure. I did this for my old boat.

With a combination of the option to start the engine with the house battery and the option to start the engine with a defective start solenoid or start switch you can fix a high percentage of boat electrical starting problems.
 
PaulRainbow said:
Just fit a 3rd isolator switch between the load terminal of the engine switch and the load terminal of the domestic switch.
Click to expand...

Perhaps obvious, but important to ensure in that case that the domestic battery wiring and its fuse can take starting current.
Because I wanted to keep the 80A fuse in my normal domestic battery wire (sized for charging current), I opted for a separate 'emergency' wire and fuse (250A) from the domestic battery to an 'emergency' switch, placed on the load side of the starter wire run.
 
So, we've opted for jump leads.

We've just arrived at the marina and want to go sailing. The batteries should be nicely charged, been on charge since the last time we used the boat. Damn, the engine won't start ! No problemo, out with the jump leads and up with the sofa cushion, beneath which the batteries live. Connect the jump leads and discover just why the engine battery won't start the engine, BOOM ! The battery has a shorted cell and has been boiling away for some time, lots of luverly explosive gas in the battery compartment (or at least there was a couple of seconds ago). I'm sure most of the burns will heal in time and with luck one of my eyes will be at least a little bit useable.

Wish we'd have gone with a 3rd switch. Could have just isolated the dead battery by turning the switch off and turned the emergency one on.
 
BabaYaga said:
Perhaps obvious, but important to ensure in that case that the domestic battery wiring and its fuse can take starting current.
Because I wanted to keep the 80A fuse in my normal domestic battery wire (sized for charging current), I opted for a separate 'emergency' wire and fuse (250A) from the domestic battery to an 'emergency' switch, placed on the load side of the starter wire run.
Click to expand...

Good point. I always connect the domestic batteries to the isolator with the same size cables as the starter battery, along with all negatives and obviously the cables to the emergency switch. The load cable from the domestic isolator would then be lighter cable and a lower rated fuse.

Your method obviously works too.
 
noelex said:
In a similar vein, knowing how to bypass the starter switch and the starter solenoid will fix many electrical starting problems. This can be done with a screwdriver but you need to know how. It is easy to short the wrong connections, especially if access is difficult, and even when done correctly sparks will fly when bypassing the solenoid. An alternative is to pre-make a jumper cable (once again with the correct fittings) with a heavy duty switch that can be used instead of the screwdriver trick especially for the solenoid failure. I did this for my old boat.

With a combination of the option to start the engine with the house battery and the option to start the engine with a defective start solenoid or start switch you can fix a high percentage of boat electrical starting problems.
Click to expand...

It's rare to find an engine now with a non pre-engaged starter. A pre-engaged solenoid cannot be bypassed if it fails to energise and engage the drive pinion. If you short the terminals as you used to do with the older style starter motors the motor will spin but will not be engaged with the ring gear. So if the solenoid fails you are screwed.

If the solenoid engages the pinion (load clank), but does not make contact at the end of its travel and turn the starter over, you can then sort the two big terminals and get the starter to spin. It's vital that someone keeps the key turned or the starter button pressed whilst doing it, or if alone you can short the solenoid terminal with one screwdriver and short the starter terminals with another.
 
Paul are the switches you fit explosion proof switches. If not you may still have the same event.

The other point is the the hydrogen produced is lighter than air so would tend to disperse anyway.
 
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