solar panels

[TigerMK1]

One day I'll get someone to explain how a shunt works. Sounds rude to be......
Comeon Bernie, tell us the brand of controller?
I thought they all have a display?

As far as I am aware, a shunt takes (passes) all the current being supplied by the battery or fed into the battery. There is an electronic box that has 2 very small leads from it to either side of the shunt. It reads the small difference in voltage and translates that to amps in and amps out. This info is then sent to the solar regulator for display . In that way my 20A solar regulator can show over 90A if needed and it doesn't get hot.

There is also a high speed relay controlling the 240W of solar I have, but thats another story.

[T1 Terry]

One day I'll get someone to explain how a shunt works. Sounds rude to be......
Comeon Bernie, tell us the brand of controller?
I thought they all have a display?

a shunt is just a way of measuring current flow with a mini volt meter. the material used in the shunt has a known voltage drop across it that increases as the current increases. In the good units,a small translater board reads the voltage across the shunt and which direction from zero it is, to determine charge or load, then sends the information to the display unit. That way, the meter is isolate from the battery voltage and potential current, a short wouldn't see the whole battery trying to discharge through the little leads going to the meter.

[BruceS]

See I did what I was told & found this answer.
[QUOTE: A low-resistance connection between two points in an electric circuit that forms an alternative path for a portion of the current. Shunts allow meters to produce accurate readings in a much wider range. ENDQUOTE]
So if a portion is going via a different route how can measuring the remainder tell you what 100% is?
If you KNOW that 80% bypasses the measuring devive or switching device then I can understand how it could be used.
Does each shunt tell you it's 'performance'?

[T1 Terry]

None of the current is bypassed, because there is resistance across the shunt, the voltage is less on the out going side than the incoming side, only millivolts, but a voltage difference all the same. The meter just shows very small voltages, but the display is marked in amps, a 75mv 200amp shunt would produce a voltage drop of 35mv if 100 amps were passed across it, causing a volt meter scaled to 75mv to read halfway, the scale would be marked as 100 amps at this point, more or less current will cause more or less voltage difference across the shunt, so the meter would read accordingly.

[oldtrack123]

Hi, all.

BernieQ - my current understanding is that the charge rate showing on a regulator indicates the amperage required to bring up the battery voltage.
1]Therefore a high charge rate indicates low batteries or substantial draw. As a test, the Apple(rated at 6.5amps) was switched off,the battery voltage was way up there, and the charge rate was 2.5amps. Turned the Apple back on and the rate shot up to about 8-9amps.
Some time ago the system installer, upon being told the two 7amp rated panels were kicking out 15.5amps, stated the panels were working very well indeed, not that the batteries were flat. Hmmm.

Current understanding, get it??

See you on the back roads,
shonky, his Imac 21, et al.

HI Shonky
The charge current into the battery depends on many things
[1] the applied voltage
[2]the output characteristics of the supplied source
Some are constant current ,some are constant voltage
The actual method of voltage regulation once the battery approaches full charge
Solar PANELS are essentially constant current under constant light conditions until the regulator starts regulating
At that stage the current will generally be pulsed
The panels out put will still be the same what you will then see is an AVERAGE current
of "on" time &" off "time
That applies even with a MPPT reg when it starts to control
A PWM reg can only supply the current as shown on the input side
A MPPT reg can juggle the available WATTS input to to pump out a current in excess of the panel input amps & does react to battery voltage with possible higher currents still into a battery with low Soc

What you saw with your panels giving 15,5 is not unusual .
it simply meant the panel were receiving a higher than "standard" light

PeterQ

[BernieQ2]

My shunt is not apart of the solar controller, its a stand alone shunt that I have installed, my battery positive goes to the shunt then to the circuit breakers
then to what ever appliance I have.
I will install the ammeter just above the solar controller along with a volt meter When I buy them..
My controller does have a remote doodah that tells me all that in and out stuff (careful Dot) but I didn't buy it.
As far as I'm concerned the two gauges are all I need.
Mr/Mrs. Boss it a Tracer MPPT controller.
Bernie.

[T1 Terry]

Lucky you saved some $$ with not buying the Tracer gauges, they are not in the slightest bit accurate.

[oldtrack123]

My shunt is not apart of the solar controller, its a stand alone shunt that I have installed, my battery positive goes to the shunt then to the circuit breakers
then to what ever appliance I have.
I will install the ammeter just above the solar controller along with a volt meter When I buy them..
My controller does have a remote doodah that tells me all that in and out stuff (careful Dot) but I didn't buy it.
As far as I'm concerned the two gauges are all I need.
Mr/Mrs. Boss it a Tracer MPPT controller.
Bernie.

HI Bernie
Just to confuse you a little
The Ammeter used with a shunt is actually a voltmeter asT1 has pointed out
THe current flowing through the shunt produces a voltage drop
The Shunt & the Voltmeter are matched ,with the VOLTMETER calibrated in AMPS
Within reason they can be wide apart as the very small current needed by the voltmeter doed not present a problem .
The voltages required are only in milliVolts[ even microV with higher quailty ones ],so shunts are made to produce as little voltage drop as practical so asto not affect connected equipment
Digital units are normally in the microV range no matter what the actual current


PeterQ

Confused

[BernieQ2]

Not confused Peter, its not all that inporTant to me, the large T is for all those out there that think the word has a D in it ( one of my gripes) news readers as well say it wrong.
Whats a smidgen of a AMP in the real world it don't matter, to me any way.
I just like to watch the needle jump when I flick a switch (gives me a reason to yell at Carol about wasting power), and the volt meter gives me a clue as to whats in the battery with a single glance.
Without all that technical hooha.
Its raining here now.
Bernie.

[TigerMK1]

, and the volt meter gives me a clue as to whats in the battery with a single glance.
Without all that technical hooha.

Not quite right, the battery voltage does NOT give the battery capacity, only the terminal voltage of the battery. EG a small capacity battery can read 13.8V, fully charged. And a huge capacity battery can read 13.8V, fully charged. Guess which provides more power over a longer period?