batteries - Maximum charging current

[Robin]

Re: Sterling...

Not a big fan of theirs from the reaction friends have had from them when daring to ask them a question, though we do have one of their mains chargers. Actually the original TWCs didn't have a soft start either and we ran one of these on two engines without any problems admittedly with 50A alternators and not our current Adverc controlled 90A ones.

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[pvb]

In fairness...

In fairness, it's best to point out that both the Adverc and the Sterling are "fail-safe", in that they operate in addition to (rather than instead of) the alternator's standard regulator. If either the Adverc or Sterling were to give up the ghost, all that would happen is that the alternator would just keep charging as if a smart regulator were not fitted. This happens automatically, and no operator intervention is needed.

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[Anonymous]

Re: coming out

>>Advercs DO revert to the standard regulator if they fail. Unlike Sterling though they do this automatically, they don't need the extra complication of a switch<<

As an experienced electronics engineer, I can assure you that to design something genuinely fail-safe is very difficult - verging on impossible when the system is smart. In aviation and other high-reliability fields two out of three voting from three similar but not identical systems is used to decide which of the 'intelligent' systems is at fault. There is nothing more reliable than a switch in a piece of wire that could even be cut with clippers in a few seconds. I imagine that's why Sterling do it (did it?) that way.

>>Neither Zefender nor you have small engines so the maximum HP question doesn't arise,<<

I wasn't limiting my comments to Zefender or my present boat. My previous boat had an elderly 26 hp engine and I did on occasions disable the Sterling. Once in the Alderney Race when I was fighting a foul tide and on another occasion when entering St Malo at springs.

>>merely switching off a smart reg wouldn't neccessarily make a difference, <<

It makes a heck of a difference when you have a small engine - which many yacht auxilliaries are. Believe me. It's well known and has been mentioned in yachting magazines over the past years as well as being clearly stated in Sterling's manual.

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[Anonymous]

Re: In fairness...

>>In fairness, it's best to point out that both the Adverc and the Sterling are "fail-safe", in that they operate in addition to (rather than instead of) the alternator's standard regulator.....This happens automatically, and no operator intervention is needed. <<

It's not as simple as that. The output is linear - from a transistor. Transistors can fail open circuit or short circuit (or anywhere in between, come to that, but it's less common). If the transistor fails short then the output is hard on and if it fails open the output is off which, I imagine (but can't say for sure without seeing the circuit) is 'safe' - i.e. reverts to normal control. Any other component could fail in the unit which could result in almost any sort of incorrect output. With something so basic and essential as charging, I think it's best to be able to switch out the 'smart' charger and revert to a simple encapsulated module designed and installed by the alternator manufacturer.

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[pvb]

Maybe you should...

If that's the case, maybe you should lobby Adverc & Sterling to change their marketing claims and their installation instructions. Sounds like you've discovered a major shortcoming in these units, which thousands of people previously considered to be pretty reliable. Over some years, I've installed Advercs in 3 boats, with excellent results and no problems.

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[Robin]

Re: In fairness...

In the highly unlikely event of needing to disconnect an Adverc, it is very easy to simply unplug it's wiring loom, no switch required. This could also be done if you thought the difference in amp output would give you some extra speed, highly unlikely unless the engine were undersized and the alternator oversized. Of course you could always get the tides right and avoid being caught in places like Alderney Race with a contrary tide of up to 9kts anyway.


<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[Anonymous]

Re: In fairness...

>>In the highly unlikely event of needing to disconnect an Adverc, it is very easy to simply unplug it's wiring loom, no switch required. This could also be done if you thought the difference in amp output would give you some extra speed, highly unlikely unless the engine were undersized and the alternator oversized.<<

Or fit a switch, as Sterling suggest.

>>Of course you could always get the tides right and avoid being caught in places like Alderney Race with a contrary tide of up to 9kts anyway. <<

Being in the Alderney Race with a foul tide does not imply that it was running at 9 kts. The boat I was sailing was only capable of 6kts under power flat out - but from time to time I deliberately choose to fight the tide, particularly when it makes the passage more agreeable by arriving in time for dinner, or whatever. Anyway, the point is that 760W = one horsepower. A decent sized alternator delivering full power loads the engine by around 1.25 hp. Not insignificant for a sailing yacht with a small auxilliary.

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[Robin]

Re: In fairness...

>>>Being in the Alderney Race with a foul tide does not imply that it was running at 9 kts. The boat I was sailing was only capable of 6kts under power flat out - but from time to time I deliberately choose to fight the tide, particularly when it makes the passage more agreeable by arriving in time for dinner, or whatever. Anyway, the point is that 760W = one horsepower. A decent sized alternator delivering full power loads the engine by around 1.25 hp. Not insignificant for a sailing yacht with a small auxilliary.<<<

Wow! a whole 1.25hp extra on a 26hp engine in a boat that can only do 6kts. You will see that I said 'up to' 9kts. Thing is slack water there is very short lived and with a maximum of 6kts flat out that comes well into the category of flogging dead horsepower in my book, funny little switches or not. Of course if you had been flogging your motor flat out for some time which would seem highly likely then your battery would be pretty well charged and not taking anything like 1.25hp out of the alternator.

This is getting very boring to everyone else I fear, I will bid you therefore good night and good motoring.





<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[Anonymous]

Re: Maybe you should...

>>If that's the case, maybe you should lobby Adverc & Sterling to change their marketing claims and their installation instructions.<<

Sterling already recommend that you install a bypass switch. It really isn't a big deal to fit one - if you don't want to 'deface' your instrument panel there is usually somewhere less obvious to mount it.

>>Sounds like you've discovered a major shortcoming in these units, <<

Not at all. I haven't 'found' anything. I have simply repeated Sterling's published instructions and suggested to people that they use the bypass switch until they are well under way to reduce load on the belt. All pretty obvious stuff, I would have thought?

>>...which thousands of people previously considered to be pretty reliable.<<

We spend a lot of time and money on addressing failure of equipment - jury rigs, emergency steering, techniques to use in the case of total engine failure, navigation techniques when electronic aids have failed, emegency 'fan' belts, quick-change impellers, ..... Nothing is totally reliable and any prudent sailor will consider the consequences of failure in any piece of equipment and try to reduce those consequences where to do so makes sense. What could be simpler than a switch to bypass some sophisticated equipment, should it fail? And why not use it when to do so makes sense, even when the equipment hasn't failed?

There isn't a major shortcoming in these systems that I am aware of. I installed a Sterling in 2000 and was delighted with the performance. I was also delighted with the Sterling battery charger, which was left on float charge 365/365 for nearly five years and kept the batteries (cheap ones, at that) in good condition.

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[pvb]

To help us understand...

I'm sure I'm not the only one who's finding it difficult to understand your logic. You started off by warning people that "When you install your Adverc..." they should put a cut-out switch in the circuit. This was challenged by Robin, and you replied that it's in Sterling's installation instructions. Well I just looked on the Sterling website, and I can't for the life of me see anywhere in the installation diagrams where they recommend fitting a switch (although I have to say their website's pretty dire and not all of it works). Just to help us understand, could you give us a link to the Sterling publication which instructs people to fit a bypass switch?

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by kimhollamby on 05/11/2004 14:24 (server time).</FONT></P>

 

[Anonymous]

To help us understand...

>>>..you replied that it's in Sterling's installation instructions. Well I just looked on the Sterling website, and I can't for the life of me see anywhere in the installation diagrams where they recommend fitting a switch (although I have to say their website's pretty dire and not all of it works). Just to help us understand, could you give us a link to the Sterling publication which instructs people to fit a bypass switch?<<

I've no idea whether Sterling publish their installation instructions on their website but they do include them with the product. I still have a copy somewhere but are you seriously suggesting that I should scan it and post it somewhere? It is a fact that in 2000 Sterling smart chargers came with installation instructions including the instruction to provide a bypass switch. What does logic have to do with this? It is a matter of fact.

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by kimhollamby on 05/11/2004 14:25 (server time).</FONT></P>

 

[pvb]

They don\'t recommend it today...

It's nearly 2005. Old technology is dead. Time to embrace the new high-tech world!

 

[Ships_Cat]

To help us understand...

I am also having difficulty understanding any need for a switch and so have followed the thread. You said "always make a point of not engaging the smart charger until you are properly under way and the revs are at a decent level - say >1800/2000. This will greatly reduce the wear on your belt".

Does this mean that when you are in an anchorage you charge at 1800/2000 rpm to reduce wear on the belts? Or do you then just suffer the increased belt wear by charging at lower rpm's?

John

<hr width=100% size=1>I am the cat but I am only 6.<P ID="edit"><FONT SIZE=-1>Edited by kimhollamby on 05/11/2004 14:26 (server time).</FONT></P>

 

[Anonymous]

To help us understand...

>>Does this mean that when you are in an anchorage you charge at 1800/2000 rpm to reduce wear on the belts? Or do you then just suffer the increased belt wear by charging at lower rpm's?<<

Yes, I charged the last boat at about 1800 RPM until the charging amps reduced, then I reduced it to 1500. I never let the engine run for any length of time at less than 1500 RPM.

Using the main engine to charge batteries isn't ideal if the load is low compared with the engine rating as the cylinders tend to glaze when run under low load (i.e. low horespower, not to be confused with low revs) so when possible I have always tried to combine charging with moving the boat - e.g. use the boat to get ashore if you can stay alongside for an hour or so to shop and water, etc.


<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by kimhollamby on 05/11/2004 14:27 (server time).</FONT></P>

 

[Ships_Cat]

To help us understand...

Brrrmmmm, Brrrrm. Ok its your engine.

John

<hr width=100% size=1>I am the cat but I am only 6.<P ID="edit"><FONT SIZE=-1>Edited by kimhollamby on 05/11/2004 14:27 (server time).</FONT></P>