Jump start your engine

[sailfreak]

Recently a sailing buddy asked me whether he should replace his still good starter battery after 4 years just as a precaution. His boat does not have a manual switch that allows him to connect the service batteries to the starter, and the battery cables are too short for an emergency connection. I told him I carry a simple set of car battery jumper cables on board just for this purpose. It's faster and simpler than any fiddling around with switches, connectors or cables in an emergency!Might this be something for you, too?

 

[LeytonC]

i do carry jump leads cos its to much of a pain to disconnect leads. If i was your mate i would get the battery tested, and if its ok leave it alone - but be aware cold weather will show up a duff battery quicker than anything - so make sure he has some good quality leads - or better still get some made that are the right length, but are mega thick so they will work! diesel engines pull more current so cheap leads are usally no good at all...

 

[Guest]

Done it at Folly one time .... car leads across to another battery on another boat .... he lifted his battery out to cockpit and worked fine .... why not ??

If his start battery is gettiung on in years .... add it to domestic side and install new start one .... more you have the better - no need to waste the last years of the old start battery ....

 

[ShipsWoofy]

I have a set of 14ft leads I built. This means I can jump one engine off the other if needs be. Also, if things got so bad should reach the next door boat for a jump, even a car on the wall at high water!

Used them twice now engine to engine, after too much use of Eberspächer!

 

[snowleopard]

My starters don't like it if the voltage is even a little bit low. If they won't turn over I connect a lead across the output terminals of the split charge diode. I have made a little lead about 6" long for the purpose.

 

[VicS]

Take great care using jump leads in what is probably a confined space as there is a risk of igniting hydrogen gas. A small risk maybe but nevertheless a risk, which could have very severe consequences, especially if one was in a bit of a hurry!

The normally recommended sequence of connecting jump leads (for vehicle starting) is <ul type="square">[*] 1 Connect one end of the red lead to the +ve terminal of the flat battery. [*]2 Connect the other end of the red lead to the +ve terminal of the booster battery. [*]3 Connect one end of the black lead to the -ve terminal of the booster battery. [*]4 Connect the other end of the black lead to a bolt or bracket on the engine block, well away from the battery (of the vehicle to be started). [*]5 Make sure that all leads are clear of belts and other moving parts. [*]6 Start the engine, then with the engine at idling speed disconnect the leads in the reverse order. [/list]
The final connection, and first disconnection, is made away from the battery so that the inevitable spark cannot ignite any hydrogen. The procedure for connecting the sevice and starting batteries in a boat will be complicated by them almost certainly having a common negative connection already, but probably not heavy enough for the starter current. So the point at which the risk exists will be the second of the +ve connections which may be difficult or impractical to make away from the battery.

IMHO the only totally safe method is to fit a permanent heavy negative connection between the batteries together with a switch and heavy wiring between the two positives. That way the system is available for almost instant use if required in a hurry and eliminates the risks associated with jump leads. The only down side is that you have to remember to turn the switch of again after use, but even that is not something which is urgent and is a lot easier than disconnecting jump leads.

I reckon if you have a dual battery installation it should be possible to use the domestic battery for engine starting in an emergency without mucking about with temporary lash ups!

Nigel Luther's method with a booster battery in the cockpit is safe provided the final connection is made to this rather than to the installed battery in a confined space. However, borrowing a battery in mid channel when the wind drops, you realise that there is a b***** great ship bearing down on you and the battery is flat is not an option.

 

[ShipsWoofy]

Order of connection is pretty irrelevant as my GRP boat does not have a negative earth.

Okais listen up, hydrogen gas is generally only around after heavy current charging, if that was the case, then there would be no need to jump start.

If we took everything at face value then we would be too frightened to flush a bog at home never mind go sailing. Not that I do not appreciate warnings, I just think in this particular case it is a bit over sensitive.

 

[Guest]

OOOOHHHHH Now you\'ve torn it !!!

I must admit I agree with you !!! But I'm sure another will be upset .....

 

[jamesjermain]

Beware adding old batteries to a bank of newer ones. The experts are adamant that all batteries in one bank should be of the same type, capacity and condition. An older battery will tend to drag the others down, age them prematurely and hasten failure.

I have committed this sin myself in the past, once with no noticeable ill-effects, and once with fatal consequences within a few months.

 

[Guest]

To correct my plain post ...

I would never parrellel old and new batterys ... in fact I don't do it to start and domestic ever ... only when switch is passing the "both" position !

What I should have said is to add it to the domestic bank as an extra option ...

Maybe I posted a little quick there and agree that old tired batterys can drag a good one down ....

 

[VicS]

I suggested the risk was small, but accidents can and do happen, even in vehicles where the hydrogen can dissipate much more readily than in the confines of a battery compartment of a boat. I also said that the quoted procedure for connecting jump leads was that for vehicles. (It came from a w'shop manual but a similar sequence is described in my car owners manual and should come with the jump leads.) The most relevant part of the sequence is making the final connection, and first disconnection, away from the battery, which for the reasons indicated may not be possible. It is also my understanding that hydrogen is produced when a battery is subjected to high discharge loads. It is likely that the need to used an auxillary battery will follow an attempt, perhaps prolonged, to start the engine with the failing one, thereby producing hydrogen.

I can't see that the material used for the construction of the boat has any relevance except that in metal boat, be that steel or aluminium, greater care would be needed to avoid shorts to the hull of the +ve leads in most cases or of the -ve lead if the boat had a +ve "ground". If you have a positive "ground" then the reccommended order in which you connect the leads would obviously be different for any boat, or vehicle.
By the term "ground" I mean the engine block, starter motor and alternator outer cases etc which will most likely be battery -ve.

I have avoided the use of the term "earth" because of its special meaning in connection with "mains" electrical installations.

I have never seen any warnings about the hazards of flushing the toilet at home but we take sensible precautions to avoid risks when sailing by using safety harnesses and life jackets, carrying flares, liferafts, epirbs etc etc. In the case of connecting jump leads we can take sensible precautions to avoid the risks involved, however small you may think them to be. The hazards will be accentuated in an "urgent" situation, perhaps in the middle of the night when you have been called from your bunk by an anxious crew member who has already left things a bit late. Then you are groping around half asleep in poor light in the battery compartment with jump leads. It would not, in those circumstances, be difficult to get a complete short circuit! Far better IMO to have a switch that can change over the battery functions or interconnect them in an instant.

Remember "If it can happen, sooner or later it will"

 

[fireball]

[ QUOTE ]
I have never seen any warnings about the hazards of flushing the toilet at home but we take sensible precautions to avoid risks when sailing by using safety harnesses and life jackets, carrying flares, liferafts, epirbs etc etc

[/ QUOTE ]

I think your waste outlet may be a little too large if you feel that you need to carry this lot when going to the heads!! /forums/images/graemlins/tongue.gif

One safety aspect that needs to be checked is that the catch cannot fall down and lock you in (as happened to my father ... we let him out 5 minutes later once we'd picked ourselves off the deck!)

 

[DeeGee]

Since hydrogen is so much lighter than air, surely the likelihood of accumulation of hydrogen in a non-airtight container is pretty unlikely, and opening the area up to do the jump-starting would allow any hydrogen to just 'bubble' up to the roof? I am NOT an expert, just asking the obvious question.

 

[castaway]

I would get one of those budget price starter packs, I got mine from Macro 4 years ago.

Its about the same price as a half decent set of J/leads but more use.

I have used mine on a few occasions to swing my Perkins 4107 and it works a treat, and I still only bother charge it once or twice a year, but it can be charged either from the fag lighter on board or mains.

Great bit of kit for £20 and don't listen to the people who say that 'a little battery like cant possibly swing a diesel' 'cause it does.

Trouble with long jump leads is that by the time the volts have made their way down the 3 meters of cable and a couple of crocodile clips there is'nt much left to start the engine.

Regds Nick

 

[VicS]

Yes one would have thought so but the fact remains that people have managed to blow up batteries while using jump leads, even in vehicles where they are even less enclosed.
Perhaps the trouble is that the space above the electrolye is much more of an enclosed space and will contain high concentrations of H2 and O2 in just the right proportions for maximum effect if ignited. The lower explosive limit for H2 is very low, 4% in air and probably lower if there is some extra O2 about. It does not, therefore, take much H2 escaping from one of the battery vents to form an explosive mixture ready to be ignited by a little spark. While that itself may not cause a big explosion it probably ignites the gasses in the battery then that does. That's my theory anyway.

My point is that there is an acknowledged risk which can be avoided. In vehicles by connecting the leads in the correct order and in a boat by having permanent wiring and a switch to connect the domestic battery to the engine starter circuit, quickly, easily and safely, if needed.