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Post by canaldweller on Oct 26, 2016 10:27:18 GMT
It is my understanding that, during absorbtion(sp?), it is the batteries that dictate the alternator output. Is this correct? If so, then why doesn't the alternator react when, say, the fridge kicks in (or vicky vercky)? I would have thought that the alternator would see that the batteries can take more (or less) than it was supplying and so react accordingly. This doesn't happen though. Why?
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Post by tonyqj on Oct 26, 2016 10:38:40 GMT
It is my understanding that, during absorbtion(sp?), it is the batteries that dictate the alternator output. Is this correct? If so, then why doesn't the alternator react when, say, the fridge kicks in (or vicky vercky)? I would have thought that the alternator would see that the batteries can take more (or less) than it was supplying and so react accordingly. This doesn't happen though. Why? Well, it does happen 😀 During Absorption the batteries are demanding less and less input as the plates become saturated. If you add a load such as the fridge then the alternator output will rise to meet that demand in addition to that which the batteries are taking. If you're not seeing an increased output from the alternator then my guess is that the shunt is wired at the wrong point to see that. If the shunt is between the alternator and the batteries it will show charge or discharge current to and from the batteries. If the domestic feed is taken from the alternator side of the shunt then the extra current to feed the fridge doesn't pass through the shunt. Does that make sense? Tony
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Post by tonyb on Oct 26, 2016 10:40:50 GMT
But it does. Typically the alternator will be connected to the batteries on the battery side of the main domestic supply take off so when a demand is put on the domestics the alternator increases its output as you suppose BUT as ammeters are usually connected in between the battery and domestic supply the increase in output is not shown. My ammeter is connected in the alternator's main output so I can see all this happening.
Probably not described very well though.
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Post by tonyb on Oct 26, 2016 10:42:39 GMT
Here we go again. This agreement between us is becoming the norm.
Note to unsure and newer members. The more contributors who agree the more Ilkley any advice is correct.
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Post by tonyqj on Oct 26, 2016 10:44:06 GMT
It's worth pointing out that how your shunt is wired and how TonyB's shunt is wired are purely a preference thing. Neither of them are either wrong or right.
Some folk have a whole bunch of ammeters showing solar, charger, alternator etc.
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Post by JohnV on Oct 26, 2016 10:52:57 GMT
Some folk have a whole bunch of ammeters showing solar, charger, alternator etc. Some people are just anoraks
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Post by Graham on Oct 26, 2016 10:56:21 GMT
It is my understanding that, during absorbtion(sp?), it is the batteries that dictate the alternator output. Is this correct? If so, then why doesn't the alternator react when, say, the fridge kicks in (or vicky vercky)? I would have thought that the alternator would see that the batteries can take more (or less) than it was supplying and so react accordingly. This doesn't happen though. Why? In simple terms yes. Yes the alternator does react it see an increase in demand, but you see no change in the positive flow into the system. The ammeter measures what is flowing in and out of the battery so now it has a flow in the charge current plus the fridge current from the alternator and a minus the fridge current going to the fridge the two fridge currents +- cancel out so what you see is the mean current into the batteries. That is what I think I am sure that can be put better
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Post by loafer on Oct 26, 2016 10:58:14 GMT
It's worth pointing out that how your shunt is wired and how TonyB's shunt is wired are purely a preference thing. Neither of them are either wrong or right. Some folk have a whole bunch of ammeters showing solar, charger, alternator etc. So just what's wrong with that then, eh? Eh?
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Post by IainS on Oct 26, 2016 11:25:28 GMT
As others have said, it does.
However, if the ammeter is connected in the normal way, it will still show the same current flowing into the batteries. The alternator, however, will have upped it's output. The "extra" current flows to he fridge, bypassing the batteries.
On a boat I used to have a share in, I fitted an ammeter in the cable between alternator and batteries*, so that it measured current from the alternator. The increased current when a load was switched on was very noticeable.
* I did it that way because I used an analogue meter, and a centre zero one would have lost precision as only half the scale would have been available to read charge, and half for discharge. The alternator lead seemed the most useful place to put the meter.
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Post by tonyqj on Oct 26, 2016 11:27:48 GMT
Some folk have a whole bunch of ammeters showing solar, charger, alternator etc. Some people are just anoraks View AttachmentYeah but ain't it fun 😀
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Post by tonyb on Oct 26, 2016 12:53:24 GMT
It's worth pointing out that how your shunt is wired and how TonyB's shunt is wired are purely a preference thing. Neither of them are either wrong or right. Some folk have a whole bunch of ammeters showing solar, charger, alternator etc. So just what's wrong with that then, eh? Eh? Actually technically mine is wrong in the as the alternator is earth return so the shunt has to go into the positive lead. That brings the chance of a fire inducing short on either meter cable. I could fit a fuse on each meter cable but then the extra connections and any looseness in the fuse to holder connection may give an incorrect reading.
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Post by tonyqj on Oct 26, 2016 13:02:25 GMT
So just what's wrong with that then, eh? Eh? Actually technically mine is wrong in the as the alternator is earth return so the shunt has to go into the positive lead. That brings the chance of a fire inducing short on either meter cable. I could fit a fuse on each meter cable but then the extra connections and any looseness in the fuse to holder connection may give an incorrect reading. Interesting observation Tony. There again, there's no such thing as 100% safe I guess.
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Post by canaldweller on Oct 26, 2016 16:14:44 GMT
Thank you for all your answers. so, it's not a charging problem but a measurement "problem". I am going to stick with the measuring devices that I have, happy in the knowledge that all is working as it should, even though I can't "see " it working.
Ps seeing everyone agreeing is a bit disconcerting though. Perhaps Gibbo can do something about that (smiley thingy ).
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Post by Gibbo on Oct 26, 2016 16:20:16 GMT
Thank you for all your answers. so, it's not a charging problem but a measurement "problem". I am going to stick with the measuring devices that I have, happy in the knowledge that all is working as it should, even though I can't "see " it working. Ps seeing everyone agreeing is a bit disconcerting though. Perhaps Gibbo can do something about that (smiley thingy ). I would love nothing more than to start an argument but they are right
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Post by Telemachus on Oct 26, 2016 16:22:13 GMT
Actually technically mine is wrong in the as the alternator is earth return so the shunt has to go into the positive lead. That brings the chance of a fire inducing short on either meter cable. I could fit a fuse on each meter cable but then the extra connections and any looseness in the fuse to holder connection may give an incorrect reading. Interesting observation Tony. There again, there's no such thing as 100% safe I guess. It's going to be really tricky with tonyb and tonyqj - the latter could you please get yourself a distinctive avatar so I don't have to reach for my glasses to see who is who?
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