Hummm...
that's not going to work.
what are the fets doing anyway? i see no way to turn then on or off, since the gate of both are being turned on by the output of the two regulators. And while i did not look up the specs for the fets you're using, the 6 volt output is not enough to turn on the fet anyway (unless it's a logic level fet)
and the negative side of your battery pack is connected to the input of the third regulator. It's not going to be happy with a neg input voltage.
and what's the load resistor for?
mike
There's still trouble.
How are the gates being switched?
unless the solar panel is in the dark, it's output will always have some voltage to it as a solar panel is a constant voltage source.
the input to the second lm317 with the negative side to the battery is not going to fly either. the adjust line is at ground.
Grab a hunk of perf-board and build just the battery and u2 connected to each other, then apply voltage with your power supply to the + side of the battery. see what happens in the real world.
if you are only after a charge controller, use one lm317 set up for a constant voltage source. set the output of the lm317 to whatever the full charge voltage of the battery back is. Let's say your charging a small lead-acid battery. A 12 volt pack is fully charged at 14.3 volts (depends on the company) so set the output of the regulator to 14.7 volts and then insert a diode between the output and the battery to prevent discharge at night.
when the battery voltage reaches the voltage set by the lm317, charging current stops or drop to a very small amount to keep the battery fully charged.
why do you want to complicate such a simple process?
your battery will NOT charge when the negative side is connected to the + side of a regulator.
the regulator you have with the negative side connected to the regulator + input simply won't work!!!!
THere no way you can turn the fets on or off.
"Vinput starting drop below to voltage battery"
the only thing I see here is you're going to cook the fet as you have it in an not linear region instead of either fully off or fully on.
you need a clean sheet of paper.
Get rid of the fets unless you have some logic to turn them off and on as the battery requires. Depending on solar panel voltage to switch fets is not going to work.
There's no need for a load resistor either.
have you actually sat down and built any of this?
Wrong.How's this for simple?
Input from the solar panel is sent to the lm317. Its output is set to the final fully charged battery voltage with the pot.
input from the solar panel is sent to the lm317. Its output is set to the final fully charged battery voltage with the pot. The diode between the battery and reg prevents the battery from discharging at night.
when the battery is fully charged, current flow is drop to a very low level.
If you want I can supply you photographs of several commercial versions of the very same circuit. All are used as battery chargers in the form of a LM317.
I don't put much faith in multisim. I downloaded the 30 day version and hell I can't even get a led to flash..
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