MrWizard wrote:
red31 wrote:
MrWizard wrote:
...OUCH
ain't that one of the controller's job, to limit panel energy production when it is not 'needed'.
controllers JOB .. is to control Voltage
the amount of current in the circuit is a function of voltage/resistance
as the battery charges, it's internal resistance increases, so current flow will drop, increasing to voltage to set limit allows the battery to keep accepting charge current
the OP asked if the 7amps being shown on the controller was all the batteries would take, or what the panels were putting out
the answer is YES to both questions
it is NOT an either or situation
it is "that is it" situation
it might be the middle of the day, and the batteries nearly fully charged, so that is ALL they will accept (aka all that battery resistance will let flow thru the circuit into the batteries) so that IS what the panels are putting out , until the circuit resistance changes, by turning on some power using device (aka load), when another load is added, circuit resistance is lowered and current increases up until it reaches the limit that the Solar can provide
or the other possibility is that the batteries are Not yet charged, but the sun is low and that is all the solar panels can produce, and the batteries are taking all of it
but it is still the same answer
yes that is what the panels are producing, yes that is what the batteries are getting
example
in the morning, my batteries are low (all eight of them) and can easily accept over 100amps
but the solar conditions can only supply a few amps, and that is what the controller will show
i can start the generator put my clamp on meter on the converter charge wires and read over 100 amps
the solar will still show the same few amps because the batteries can take all that can be supplied, and that is all the solar can produce until the sun gets higher, as the sun gets higher the solar increases until it reaches the limit the solar can produce or the limit that the batteries can accept,
but what ever is on the meter IS what is being produced and going to the system, it is voltage vrs resistance
and the meter will change reading every time the fridge cycles something is turned on or off
I have observed this time and time again, with my RC watt meter in line, it is correct. Doesn't matter if your solar panel or panels make 8 amps, or 800 amps, if it's a lead acid battery or a AGM battery, it is correct.
It might be considerably different with a Lithium ion battery, only because Li batteries have so little internal resistance to slow the charging rate in amps being taken on down from what the the solar panels are capable of producing, until perhaps the last 1 or 2% of charge being added to the Li battery. Of course, it's very very hard on Li batteries to continually charge them to 100%, it shortens their life greatly.
Generally speaking, if the state of charge of your battery is somewhere between 30% SOC and 80-85% SOC, unless you have a huge overcapacity of solar panels, in most engineered systems, your batteries are going to take all that your solar panels are capable of producing.
By the time mid to late afternoon comes around, your batteries, on a normal sunny day, with no clouds, might be getting close to topped off, and then your amps will start dropping, as the battery resistance goes up, closer and closer to full charge. It's this resistance that makes solar panels so much better at saving you money top charging, vs burning all that gas with the generator to get to a top charge.
