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Old 13-02-2018, 11:12   #151
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Re: Battery problem thoughts much appreciated!

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Originally Posted by a64pilot View Post
See, this is exactly the gist of what a I am saying, and where you and I disagree, and one of us is wrong.
I believe that an alternator and a battery charger controls voltage, not amperage. Amperage or current fluctuates as a function of voltage.
....
You could compromise by calling it a voltage source that is current limited.
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Old 13-02-2018, 12:07   #152
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Re: Battery problem thoughts much appreciated!

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You could compromise by calling it a voltage source that is current limited.
Which seems to better fit the description of a "power supply".

A basic voltage regulator is a simple voltmeter that measures the battery voltage, and increases or decreases current to the rotor (field), which directly increases or decreases current at the ouput of the alternator (whatever voltage there is there).

It is by limiting the ouput current that an alternator can keep a battery at a specified voltage. Explaining it the other way round is nonsense IMHO.
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Old 13-02-2018, 14:14   #153
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Re: Battery problem thoughts much appreciated!

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It is by limiting the ouput current that an alternator can keep a battery at a specified voltage. Explaining it the other way round is nonsense IMHO.

Yes that is how it works, but itís adjusting to voltage, voltage, not amperage is itís set point. It varies current to maintain a constant voltage.
Adjusting to amperage is when I adjust one of my chargers to be limited to 20 amps, which I can do, they then hold a steady 20 amps by allowing voltage to vary.
There are constant current chargers, go to Walmart and buy a cheap battery charger, hook it up to a battery and leave it, it will eventually kill the battery, reason is itís supplying a constant current and allowing voltage to rise above the batteries ability to absorb it, just hopefully there are very few of us that charge our banks with such a primitive charger.
I think the original charger in my boat was such a charger though, I donít think it was a three stage. Just on and off
That is why early in I said they were interrelated, one changes the other.
I have yet though to see a battery charger or an alternator controller where you set Absorption and Float amperage though, you set voltage.
Look at it this way, you can hook a huge 6 V charger up to a 12 V battery and there will be no current flow, even if itís a huge charger. In order for there to be current flow, the charger has to have a higher voltage than the battery, the higher the voltage differential, the more current that can flow, too high of a voltage will have too much current flowing and will cook your battery, that is why Float is a lower voltage, not a lower current.
If I have not convinced you by now, then Iím not going to, no point in beating a dead horse, we are actually saying similar things.
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Old 13-02-2018, 18:49   #154
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Re: Battery problem thoughts much appreciated!

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Originally Posted by a64pilot View Post
I believe that an alternator and a battery charger controls voltage, not amperage.
Internally voltage is controlled by adjusting **field current**, hundreds of times per second.

From an outside "black box" POV, the charge to the battery is being voltage regulated only.

It is the battery that controls the actual **charging** current.

So you're "more right" if that matters, but he scored a technicality 8-)
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Old 15-02-2018, 04:03   #155
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Re: Battery problem thoughts much appreciated!

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In order to have a charger that can be programmed to drop to float at a certain battery acceptance rate, that requires a shunt at the bank, and requires ALL negative grounds to be connected to this shunt, which usually means a bus bar of course.
...
Of course it can, it just requires more equipment than a charger.

Hi Pilot!

Do you mean it in order to charge each and every battery on its negative, other than through the bank (that which affects individual voltage), or for any other reason?

Thanks
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Old 15-02-2018, 04:12   #156
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Re: Battery problem thoughts much appreciated!

Voltage is a pressure, a height of water (V)
Current is a flow, quantity over time (l)
As far as battery is charged, its internal resistance gets higher. As V = RxI then l goes down.

Think of water, it flows down, I.e. From higher to lower Voltage
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Old 15-02-2018, 06:07   #157
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Re: Battery problem thoughts much appreciated!

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Hi Pilot!

Do you mean it in order to charge each and every battery on its negative, other than through the bank (that which affects individual voltage), or for any other reason?

Thanks
I don't understand that question, but nothing to do with the charge process.

Think of the shunt as a flow meter. For a BM, all return negative current must route throught it to get measured, let some circuit bypass it then that flow is missed.

If you put it on just one source or one consumer, that's all it measures.
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