Interesting conundrum

PaulRainbow said:
You should be fusing each output, at the battery. The fuse should be rated to protect the cable and be a little bit more that the total output of the charger. It's usual for each output to be capable of supplying the max rated current.
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He is using CB's Paul. Don't know how close to the battery(s) they are?
 
Graham_Wright said:
Typo. - mounted.
30A.
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What I can't understand from the OP is the rational of trying to "Protect" a 30 amp fuse in the -ve with 3 X 15 amp breakers in the +ve? You could conceivably, under fault conditions, have 45 amps flowing in the -ve. without the breakers tripping :unsure: I assume that the charger outputs are 10amp max. under normal conditions.
However, none of that explains why one particular breaker trips when any of the other two are switched on.
Edit:- I am assuming the 30A is the fuse? Could be the charger on reflection :oops:
 
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See post #20

Each output can charge at up to the chargers maximum rating, subject to a cumulative charge of the max rating. So i the batteries connected to outputs 1 and 2 are fully charged there will be minimal current flowing through those two outputs, leaving most of the 30A current to go to the depleted battery on outlet 3, in which case a 15A breaker will trip on outlet 3. Mix that up in any way you want and as long as no single outlet exceeds 15A all will be OK. As soon as batteries start to become charged it's anyone's guess which breaker will trip first.

The fuse in the negative cable is to protect the charger, although this is questionable. The three positive cables should be fused, but this should be done close to the batteries and each fuse should be rated at the chargers maximum current output, or a little above to be safe from surges. This assumes that the cables are correctly rated, as the fuses purpose is solely to protect them.

Circuit breakers could be used in place of fuses, but it would be an extravagant waste to use circuit breakers in this case, when a 25p automotive blade fuse is perfectly adequate.
 
PaulRainbow said:
See post #20

Each output can charge at up to the chargers maximum rating, subject to a cumulative charge of the max rating. So i the batteries connected to outputs 1 and 2 are fully charged there will be minimal current flowing through those two outputs, leaving most of the 30A current to go to the depleted battery on outlet 3, in which case a 15A breaker will trip on outlet 3. Mix that up in any way you want and as long as no single outlet exceeds 15A all will be OK. As soon as batteries start to become charged it's anyone's guess which breaker will trip first.

The fuse in the negative cable is to protect the charger, although this is questionable. The three positive cables should be fused, but this should be done close to the batteries and each fuse should be rated at the chargers maximum current output, or a little above to be safe from surges. This assumes that the cables are correctly rated, as the fuses purpose is solely to protect them.

Circuit breakers could be used in place of fuses, but it would be an extravagant waste to use circuit breakers in this case, when a 25p automotive blade fuse is perfectly adequate.
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Thanks Paul. Makes, absolute, obvious, perfect sense. I was assuming, through lack of knowledge of such things,:rolleyes: That each outlet was limited to one third of the charger rating, but not cumulative to individual outlets. Simple when you know how;):ROFLMAO:
 
Alex_Blackwood said:
Thanks Paul. Makes, absolute, obvious, perfect sense. I was assuming, through lack of knowledge of such things,:rolleyes: That each outlet was limited to one third of the charger rating, but not cumulative to individual outlets. Simple when you know how;):ROFLMAO:
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Paul, Further to my last, re. your theory, which I still think is obvious, and why didn't I think of it!
Rereading the OP Graham says:-
"Frequently, I cannot make all three together.
Engaging 1, the second trips the first.
Engaging 2 and 3 is ok. Then I add the third and it trips.
The total current is below the rated output."

This would indicate that he can:-
(1) Make breaker 1 OK,
(2)Make breaker 2 +1 and 1 trips?
(3) 2 & 3 make OK
(4) add breaker 1 +2 & 3 and 1 trips.

If your theory is correct then he should not be able to make breaker 1 on its own? Am I correct or missing something again. :unsure:
Perhaps Graham could clarify !
 
Alex_Blackwood said:
Paul, Further to my last, re. your theory, which I still think is obvious, and why didn't I think of it!
Rereading the OP Graham says:-
"Frequently, I cannot make all three together.
Engaging 1, the second trips the first.
Engaging 2 and 3 is ok. Then I add the third and it trips.
The total current is below the rated output."

This would indicate that he can:-
(1) Make breaker 1 OK,
(2)Make breaker 2 +1 and 1 trips?
(3) 2 & 3 make OK
(4) add breaker 1 +2 & 3 and 1 trips.

If your theory is correct then he should not be able to make breaker 1 on its own? Am I correct or missing something again. :unsure:
Perhaps Graham could clarify !
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Sorry, but it isn't a theory. The charger only has one set of electronics inside with a single charging profile. The 3 banks are simply separated by 3 diodes. Unless it's a 15A charger the breakers are underrated and they are in the wrong place, they serve no useful purpose whatsoever (even if they were the correct rating). They are there to protect the cable in the event of a short and they should have been fitted when the charger was installed.

Fit appropriate fuses, close to the battery and the issues go away.
 
PaulRainbow said:
Sorry, but it isn't a theory. The charger only has one set of electronics inside with a single charging profile. The 3 banks are simply separated by 3 diodes. Unless it's a 15A charger the breakers are underrated and they are in the wrong place, they serve no useful purpose whatsoever (even if they were the correct rating). They are there to protect the cable in the event of a short and they should have been fitted when the charger was installed.

Fit appropriate fuses, close to the battery and the issues go away.
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Sorry Paul, I think you completely misunderstand what I was saying. Don't disagree with anything you say.
Think best to drop the subject. :cry:
 
Alex_Blackwood said:
Paul, Further to my last, re. your theory, which I still think is obvious, and why didn't I think of it!
Rereading the OP Graham says:-
"Frequently, I cannot make all three together.
Engaging 1, the second trips the first.
Engaging 2 and 3 is ok. Then I add the third and it trips.
The total current is below the rated output."

This would indicate that he can:-
(1) Make breaker 1 OK,
(2)Make breaker 2 +1 and 1 trips?
(3) 2 & 3 make OK
(4) add breaker 1 +2 & 3 and 1 trips.

If your theory is correct then he should not be able to make breaker 1 on its own? Am I correct or missing something again. :unsure:
Perhaps Graham could clarify !
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I can make breaker 3 on its own which, maybe, rules out a breaker fault.
Due to convenience, it happens that all connections to the batteries are by separate breakers each limited to 30A which exist to protect cabling to the usual loads.
I forgot to remember that so perhaps Paul will forgive?!
 
Graham_Wright said:
I can make breaker 3 on its own which, maybe, rules out a breaker fault.
Due to convenience, it happens that all connections to the batteries are by separate breakers each limited to 30A which exist to protect cabling to the usual loads.
I forgot to remember that so perhaps Paul will forgive?!
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In that case, the 15A breakers serve no purpose, you should take them out.
 
PaulRainbow said:
In post #7 you say you fitted 15A breakers,

In post #31 you say 30A at the batteries

In post #33 you say 40A

Confused.com
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Sorry for 40 read 30. (Actually they are two 15A ganged together. You'll probably find fault with that!).
To be clear. The ship's systems are supplied from 2 domestic batteries selectable downstream each protected with the twin 15A breakers. They are rated to protect the cables (50sq.mm core) to the central distribution system.
The triple 15A breakers at and on the output of the charger protect against individual excessive charging loads. I understand that maximum charger rate should be around 10-15% of capacity. If all the charger output goes to one battery, that 30A is deemed excessive.
Here begineth another discussion!
 
Graham_Wright said:
Sorry for 40 read 30. (Actually they are two 15A ganged together. You'll probably find fault with that!).
To be clear. The ship's systems are supplied from 2 domestic batteries selectable downstream each protected with the twin 15A breakers. They are rated to protect the cables (50sq.mm core) to the central distribution system.
The triple 15A breakers at and on the output of the charger protect against individual excessive charging loads. I understand that maximum charger rate should be around 10-15% of capacity. If all the charger output goes to one battery, that 30A is deemed excessive.
Here begineth another discussion!
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Can I suggest that perhaps you need professional , onsite, advice. I think you have what could be described, professionally, as a mess. The scenario of what is where and does what keeps changing. With all due respect I don't think that you have understood what Paul has been saying, or deliberately ignored it! To a somewhat lesser extent this applies to myself as well.
You don't seem to understand how a battery will accept charge, never mind the use of circuit breakers and fuses in electrical circuitry.
Apologies if the above seems harsh. However it my professional opinion, that in this instance, your problems would be better rectified on site rather than back and forth on this forum.
Sorry Graham:cry:
I am off for a beer:)
 
Graham_Wright said:
Sorry for 40 read 30. (Actually they are two 15A ganged together. You'll probably find fault with that!).
To be clear. The ship's systems are supplied from 2 domestic batteries selectable downstream each protected with the twin 15A breakers. They are rated to protect the cables (50sq.mm core) to the central distribution system.
The triple 15A breakers at and on the output of the charger protect against individual excessive charging loads. I understand that maximum charger rate should be around 10-15% of capacity. If all the charger output goes to one battery, that 30A is deemed excessive.
Here begineth another discussion!
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Not much more for me to say really. The 15A breakers are serving no useful purpose, they should be removed. You should have fuses, rated for the max charger output, close to the batteries. That's to protect the cables. There is no point trying to limit charge current to individual batteries/banks by fitting underrated circuit breakers. The batteries will only accept the charge that they "want" you cannot ram additional current into them. You are trying to fix a problem that doesn't exist, at the expense of creating additional issues.
 
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