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Met a fellow boater today who, advised that, when charging boat batteries (whilst stationary) it is better to run the engine in gear forward or reverse so as not to put excessive wear on the cylinder bores...

 

Is this just an old wives tale??

 

If its true at what engine revs do you need as I don't fancy ripping out my mooring pins :lol:

 

 

Androo

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Met a fellow boater today who, advised that, when charging boat batteries (whilst stationary) it is better to run the engine in gear forward or reverse so as not to put excessive wear on the cylinder bores...

 

Is this just an old wives tale??

 

If its true at what engine revs do you need as I don't fancy ripping out my mooring pins :lol:

 

 

Androo

When I come across a boat doing this I don't slow down but pass at normal cruising speed because I have found slowing to tick over the boat gets caught in the prop wash and I could end up anywhere. Its also against BW byelaw's I think to do it against the towing path.

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When I come across a boat doing this I don't slow down but pass at normal cruising speed because I have found slowing to tick over the boat gets caught in the prop wash and I could end up anywhere. Its also against BW byelaw's I think to do it against the towing path.

Despite repeated discussions on the forum there is still some debate on the subject.

Some say if you use the correct API CC spec oil on a modern engine you shouldn't need to run it under load, but perhaps for older engines its advisable.

I don't really know.

 

What I do know is that a stationary spinning prop on a moored boat is not only against BW bylaws because of bank erosion, but left unmanned its also dangerous - especially in reverse where anything or anyone falling into the water could get dragged into the prop.

Anyway, I don't bother charging while moored up with my engine - I'd rather use a quiet generator & battery charger.

Edited by blackrose
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What a great idea, wasting expensive diesel pumping canal water about! And incidentally damaging the canal banks. And breaking the by-laws. And annoying everyone else.

 

An engine fitted with a suitably large alternator(s), as most are, is already under load.

 

Modern engines and oils haven't suffered from bore glazing for years, this is definitely an OWT. Anyway, don't charge your batteries while tied up, go for a cruise, that's what we bought a boat for, isn't it?

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Anyway, don't charge your batteries while tied up, go for a cruise, that's what we bought a boat for, isn't it?

 

 

Hmmm... a 2 hour cruise, after work, every other day. Now I like cruising but I'd never get anything done...

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got back to the boat sunday evening to find el flatto batterio, i left the inverter charging the mobile all weekend,,,,ooopps.

so 5am monday morning went for a cruise ,watched the sun rise, moored at 7 am, and was at work in london for 9am.

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Just to add when the engine is running with no load (no electrical consumers switched on) you should be charging the batts even at idle speed, once your engine is running at cruising speed your alternator will generally not supply more than 14.6v, when you apply a load to the engine such as putting it into gear from neutral at tickover the charge rate will drop but so long as it is over 12.5volts its charging, when you switch on an electrical load such as lights, pumps etc the charge level may drop slightly, the alternator will deal with the load with a slight drop in engine speed, however as soon as you take the engine speed back up to over tickover speed the alternator will be charging at anything between 13 to 14.6v again the only problem you will have is, if you demand more from your batteries than the alternator can deal with in a short period or exceed its rated output, ie if your alternator has an out put of 85amps dont expect it to charge the batts and supply 85amps it will just wear out quicker.

 

I think some of your replies were relating to running the engine in gear at higher revs, (you dont need to do this for optimum charging) the manufacturers recommend doing this to clear the combustion chamber of soot due to the constant low running speeds, it has nothing to do with charging! In the old days people use to rev there car engines up before switching off so as to clear the cylinder of unburnt fuel and clean the plugs a bit, however modern engines have moved on but they do benefit from the occasional high speeds under load, better to do this in a marina, well tied up for at least 10 to 15 mins so long as the noise doesn't cause a nuisance to your neighbours. :lol:

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Just to add when the engine is running with no load (no electrical consumers switched on) you should be charging the batts even at idle speed, once your engine is running at cruising speed your alternator will generally not supply more than 14.6v, when you apply a load to the engine such as putting it into gear from neutral at tickover the charge rate will drop but so long as it is over 12.5volts its charging, when you switch on an electrical load such as lights, pumps etc the charge level may drop slightly, the alternator will deal with the load with a slight drop in engine speed, however as soon as you take the engine speed back up to over tickover speed the alternator will be charging at anything between 13 to 14.6v again the only problem you will have is, if you demand more from your batteries than the alternator can deal with in a short period or exceed its rated output, ie if your alternator has an out put of 85amps dont expect it to charge the batts and supply 85amps it will just wear out quicker.

 

:lol:

 

I wanted to edit that down but please excuse me... My engine, at tickover charges at 14.3 on the uncontrolled alt and 14.8 on the controlled one.

 

Measured charge rates quoted in the alt paralleling topic thread at the top of the equipment forum would go to contradict you, as do my personal readings, having spent 2 hours measuring the voltage increase across batteries.

 

maybe on older engines with slower revs this might hold true tho...

 

It has been said by authorties greater than I that even at 13.5 hardly anything is getting into the batts and it's only above 14.2 that any decent charge is getting into the batteries.

:lol:

Edited by Smelly
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I've brought this topic up before on the forum. There is always a difference in opinion so I now alternate with putting the boat in gear, or in neutral each time I'm charging the batteries. When you haven't got all day to cruise about, you need to leave it for at least 6 hours to a get a decent charge on them. An engine on for two hours will charge very little. I do get a little resentful when people assume one should always be able to cruise about, some of us have to work to pay the bills in a 9 to 5 way! Not resentful enough to get upset mind!

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What a great idea, wasting expensive diesel pumping canal water about! And incidentally damaging the canal banks. And breaking the by-laws. And annoying everyone else.

 

An engine fitted with a suitably large alternator(s), as most are, is already under load.

 

Modern engines and oils haven't suffered from bore glazing for years, this is definitely an OWT. Anyway, don't charge your batteries while tied up, go for a cruise, that's what we bought a boat for, isn't it?

I agree with your comment about oils and engines but it is clear that an abused engine when new can suffer from bore glazing. The most common time for an engine to glaze is when being run in incorrectly either using wrong oils and/or lightly loaded. The later can cause centralisation of the pistons when moving and so no/little pressure is placed against the walls of the bore. Once run in and the pistons/rings running happily in their bores the likelihood of glazing is very very small.

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I've brought this topic up before on the forum. There is always a difference in opinion so I now alternate with putting the boat in gear, or in neutral each time I'm charging the batteries. When you haven't got all day to cruise about, you need to leave it for at least 6 hours to a get a decent charge on them. An engine on for two hours will charge very little. I do get a little resentful when people assume one should always be able to cruise about, some of us have to work to pay the bills in a 9 to 5 way! Not resentful enough to get upset mind!

 

Does this mean you only charge the batteries at the weekend?

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I've brought this topic up before on the forum. There is always a difference in opinion so I now alternate with putting the boat in gear, or in neutral each time I'm charging the batteries. When you haven't got all day to cruise about, you need to leave it for at least 6 hours to a get a decent charge on them. An engine on for two hours will charge very little. I do get a little resentful when people assume one should always be able to cruise about, some of us have to work to pay the bills in a 9 to 5 way! Not resentful enough to get upset mind!

 

Running in gear whilst moored is a breach of licence conditions, so it isn't an option.

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Here we go...............

 

Just to add when the engine is running with no load (no electrical consumers switched on) you should be charging the batts even at idle speed, once your engine is running at cruising speed your alternator will generally not supply more than 14.6v, when you apply a load to the engine such as putting it into gear from neutral at tickover the charge rate will drop

 

Only if the engine revs drop and the alternator isn't correctly pulley'd up. Otherwise it won't make any difference.

 

but so long as it is over 12.5volts its charging

 

No it isn't. 12.5 volts is doing nowt.

 

if you demand more from your batteries than the alternator can deal with in a short period or exceed its rated output, ie if your alternator has an out put of 85amps dont expect it to charge the batts and supply 85amps it will just wear out quicker.

 

No it won't. It just won't be ale to do it and the batteries won't get charged.

 

Gibbo

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Here we go...............

 

 

 

Only if the engine revs drop and the alternator isn't correctly pulley'd up. Otherwise it won't make any difference.

 

 

 

No it isn't. 12.5 volts is doing nowt.

 

Your right, 12.5volts won't do much but I said over 12.5volts, a fully charged batt will generally deplete from anywhere between 13.6 down to 12.6volts if left standing.

 

 

 

No it won't. It just won't be ale to do it and the batteries won't get charged.

 

What I'm trying to say is that an alternator is rated for the amperage it can supply as well as the voltage produced, if an alternator is rated at 85amps and you are asking it to supply 90amps due to the extra lights you fitted last week burning away with everything else switched on then the alternator can't match the demand and will likely fail earlier, however if the demand does not exceed its rating and the voltage drops to just above 12.5volts due to low engine speed then the voltage is still above 12.5 volts then technically it is still receiving a charge, not a good charge but still a charge. a fully charged lead acid battery generally holds just above 12.5volts with the engine off but of course will reduce over time if not charged.

 

 

Gibbo

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What I'm trying to say is that an alternator is rated for the amperage it can supply as well as the voltage produced, if an alternator is rated at 85amps and you are asking it to supply 90amps due to the extra lights you fitted last week burning away with everything else switched on then the alternator can't match the demand and will likely fail earlier, however if the demand does not exceed its rating and the voltage drops to just above 12.5volts due to low engine speed then the voltage is still above 12.5 volts then technically it is still receiving a charge, not a good charge but still a charge. a fully charged lead acid battery generally holds just above 12.5volts with the engine off but of course will reduce over time if not charged.

 

Even I can discuss that bit. :lol:

 

An alternator cannot supply more than it is rated (85Amp) at, if the load is greater (90Amp) then the batteries will take up the extra load and effectively there will be no charging but a discharging of batteries.

 

Why will it fail earlier ? It is running at its full rating so is within its parameters, so should not fail earlier.

 

This is a very tenical bit and leave it to the experts to discuss, but I do know that there are many factors involved in using voltage measurement to to give state of charge. I believe that the 12.5V is incorrect but willing to be proved wrong.

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fully charged baty`s give out 13.2 volts i believe,2.2 volts per cell X 6.

or has it changed in the last decade

 

12.6 to 12.8 depending upon the type (wet cell, AGM, gel etc) but you have to wait several hours for the voltage reading to be worth anything. If you measure 13.2 that means they've recently been on charge and the voltage hasn't yet settled.

 

Either way, 12.5 volts won't do sod all.

 

Gibbo

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Even I can discuss that bit. :lol:

 

An alternator cannot supply more than it is rated (85Amp) at, if the load is greater (90Amp) then the batteries will take up the extra load and effectively there will be no charging but a discharging of batteries.

I'll agree with that

 

Why will it fail earlier ? It is running at its full rating so is within its parameters, so should not fail earlier.

 

An alternator that is being stretched to the limits because it is trying to keep up with demand I would say is likely to fail quicker than one working half as hard, Alternators are generally rated to supply for demand and charge the batts and are usually a tad over what is required.

 

This is a very tenical bit and leave it to the experts to discuss, but I do know that there are many factors involved in using voltage measurement to to give state of charge. I believe that the 12.5V is incorrect but willing to be proved wrong.

 

I'd guess at this point we all know what we are talking about, but I'll take on board the replies and will leave this subject to the experts. Thanks anyway.

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Well, I was a tad reluctant to believe that bore glazing would have much effect in all but the most extreme cases, but after about 20-30 hours of ticking over under no loads other than electrical my engine was starting to smoke a fair bit from the exhaust. Took the boat out for a cruise and within 15 minutes the exhaust had cleared completely. I suspect the bores must have been starting to glaze and allow oil past. A bit of time under heavier loads and higher revs must have removed the glazing. It looks like we'll be taking her out a bit more often to clear her throat :lol: .

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