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Old 01-09-2016, 10:28   #76
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Re: Battery Voltage in the Morning

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I've been reading this thread with fascination. No wonder us mere electrical mortals get confused. I understand basic physics here. A battery cannot be both charging and discharging. It may be receiving multiple inputs and outputs, but it has a cumulative state. It's like solving a vector problem. There may be multiple forces acting on a body, but there is a single cumulative vector which results in a single specific state.
But in a malfunctioning paralled battery bank both can happen simultaneously so maybe that's just how the state of Ramblinrods batteries are
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Old 01-09-2016, 10:42   #77
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Re: Battery Voltage in the Morning

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I recall some electronics courses from my ancient past taught electrical current in terms of electrons and holes. Never made an physical sense ... protons do not flow in electric circuits (although they certainly do in a plasma).

I've been reading this thread with fascination. No wonder us mere electrical mortals get confused. I understand basic physics here. A battery cannot be both charging and discharging. It may be receiving multiple inputs and outputs, but it has a cumulative state. It's like solving a vector problem. There may be multiple forces acting on a body, but there is a single cumulative vector which results in a single specific state.
That was it holes. I like you it was the ancient past and never made a great deal of sense to me. Thus the ref. to Albert E.. I don't even know why it was mentioned in an electronics course.

As to your second paragraph, yep it is charging or discharging there is no both.
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Old 01-09-2016, 11:30   #78
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Re: Battery Voltage in the Morning

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A battery is no more than a capacitor treat it as such.
Accumulator (electrical) would be more correct. https://en.wikipedia.org/wiki/Accumulator_(energy)

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So the question is whether the supplied solar is raising the voltage even though it isn't meeting the demand.
Yes, the supplied solar influence the voltage but the voltage is not high enough to influence the current flow.
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Old 01-09-2016, 15:16   #79
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Re: Battery Voltage in the Morning

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Originally Posted by Mike OReilly View Post
I recall some electronics courses from my ancient past taught electrical current in terms of electrons and holes. Never made an physical sense ... protons do not flow in electric circuits (although they certainly do in a plasma).
You must have been studying semi-conductors. That's where holes "flow".

Quote:
I've been reading this thread with fascination. No wonder us mere electrical mortals get confused. I understand basic physics here. A battery cannot be both charging and discharging. It may be receiving multiple inputs and outputs, but it has a cumulative state. It's like solving a vector problem. There may be multiple forces acting on a body, but there is a single cumulative vector which results in a single specific state.
Vector sums is a good analogy in this case.
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Old 02-09-2016, 10:10   #80
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Re: Battery Voltage in the Morning

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You must have been studying semi-conductors. That's where holes "flow".



Vector sums is a good analogy in this case.
Holes are involved in all electrical current flow, an electron can't move without one.

The interesting thing about semi-conductors, specifically P/N junctions is the diffusion current flow as well as the drift current flow (the latter as we usually think about).

But regarding the "charging and discharging" at the same time, please excuse the brain fart. I was considering the internal resistance of the battery with the appied voltage of the charger, having to resulting current flow, and also the apparent "absorption" any AC ripple on the charge voltage, forgetting that (somehow, call it a seniors moment or actually day) that a battery post cannot be positive and negative at the same time. Few battery equivalent circuits show it, but correct ones have a "charging diode"'and a "discharging diode" that prevent reverse current flow.

My apologies if my obstinance offended anyone, the theory made sense (to me only) at the time.

Now, as in before this thread, I agree that a battery cannot charge and discharge at the same time.

All I need now is for some physics genius to come on here and explain why we're all wrong. ;-)
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Old 02-09-2016, 10:40   #81
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Re: Battery Voltage in the Morning

With the described -1 amp discharge in this case, the "charging" flow never makes it into the battery.

It joins the discharge from the battery and adds to the total 3 amp load current.

In dc circuits, elections don't flow in both directions. However, the Navy and the Air Force disagree on, an train on opposite understandings of flow direction. Conventional flow theory vs. Electron flow thoery.
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Old 02-09-2016, 10:58   #82
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Re: Battery Voltage in the Morning

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Holes are involved in all electrical current flow, an electron can't move without one.

The interesting thing about semi-conductors, specifically P/N junctions is the diffusion current flow as well as the drift current flow (the latter as we usually think about).

But regarding the "charging and discharging" at the same time, please excuse the brain fart. I was considering the internal resistance of the battery with the appied voltage of the charger, having to resulting current flow, and also the apparent "absorption" any AC ripple on the charge voltage, forgetting that (somehow, call it a seniors moment or actually day) that a battery post cannot be positive and negative at the same time. Few battery equivalent circuits show it, but correct ones have a "charging diode"'and a "discharging diode" that prevent reverse current flow.

My apologies if my obstinance offended anyone, the theory made sense (to me only) at the time.

Now, as in before this thread, I agree that a battery cannot charge and discharge at the same time.

All I need now is for some physics genius to come on here and explain why we're all wrong. ;-)
You are right. Charge and discharge at the same time can't happen. I wouldn't even go into that again because some has expressed it better than I.
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Old 02-09-2016, 12:17   #83
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Re: Battery Voltage in the Morning

guess I'm not crazy or an idiot after all (at least far as this thread)

almost, ................... almost heard an expert say they were wrong (that will start a whole new post)
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Old 02-09-2016, 12:35   #84
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Re: Battery Voltage in the Morning

Someone already mentioned this, but look at any circuit diagram showing a battery with a positive and negative charge and the current flow is represented as going from the positive post to the negative. However the current is merely a flow of electrons which are negative charged. A negative charge is attracted to a positive battery post while being repelled by the negative post so the standard representation of current flow is opposite of what is happening. My 2 cents
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Old 02-09-2016, 13:24   #85
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Re: Battery Voltage in the Morning

I must correct something.

When I learned electron flow in the Air Force they said the Navy teaches conventional flow (Ben Franklin's mistake), but that is not true.

Both the Navy and Air Force teach electron flow theory.

There are some nostalgic old training films on YouTube that are interesting if you search electron flow vs conventional flow.
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Old 02-09-2016, 16:08   #86
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Re: Battery Voltage in the Morning

Interesting bit of trivia, one will never see battery posts marked anode and cathode because it changes depending on whether charging or discharging.
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Old 20-12-2016, 14:14   #87
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Re: Battery Voltage in the Morning

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The other morning my solar panel was supplying about 2 amps into the system, the battery was discharging about 1 amp, the batteries were 30 AH out of a 460 AH bank, the voltage was reading 12.6V.

Can the voltage be believed?
I'm going to give the real answer. After 3 months of cruising and watching what goes on with my system I can say the answer is, NO you can not believe that voltage.

It doesn't seem to really matter what the net amp use is between the solar and the batteries. If the solar is supplying anything into the system the battery voltage will be high. And by this I mean it will may be higher than a fully charged rested battery, which of course can not be believed at all.
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Old 20-12-2016, 15:34   #88
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Re: Battery Voltage in the Morning

I would have figured this was fairly self evident. Any time you have a net charge going into a battery, the voltage will be elevated in relation to it's natural zero amp resting state. The reverse is also true - any time there is a net discharge, the voltage will be lower than the zero amp resting state.
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Old 20-12-2016, 16:37   #89
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Re: Battery Voltage in the Morning

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I would have figured this was fairly self evident. Any time you have a net charge going into a battery, the voltage will be elevated in relation to it's natural zero amp resting state. The reverse is also true - any time there is a net discharge, the voltage will be lower than the zero amp resting state.
Read it again as you didn't understand the first time
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Old 20-12-2016, 17:37   #90
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Re: Battery Voltage in the Morning

Oh but I understand just fine. Unless you have the batteries isolated and doing nothing at all, the voltage reading cannot be relied upon to give much indication of state of charge. Some broad brush information might be discernable once you know your boat's characteristics, but it's entirely dependent on what you are measuring and whereabouts in the circuit the measurements are being taken.
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