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RFC Solar Cgarge Controller

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MrUmunhum

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RFC Solar Charge Controller

Hi group.

I put together what I like is a simple Solar Charge Controller. I would like you to examine it and tell me if you think it will work?

The therory of operation is:
  • Power comes from the solar panels
  • The TIP2955 pass power when they are grounded
  • The LM317 creates a reference voltage of 13,7 volts
  • If the battery voltage is over 13.7 volts the LM741 shorts the TIP2955 ground
I am concerned about R1, is it placed correctly and is it the right value?
What do you think?
This is another one of my "Monkey See. Monkey do" projects.:)
 

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MikeMl

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What is the max base current will ever get to the power transistors?(Hint: Ohms law)
How do you guarantee that current is shared equally by the power transistors?
Why regulate the supply pin on the 741? (Hint: look up PSRR).

How much current is your panel capable of?

I can show you how to do this with about 5 components, but first you have to answer my questions.
 
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MrUmunhum

New Member
What is the max base current will ever get to the power transistors?(Hint: Ohms law)
How do you guarantee that current is shared equally by the power transistors?
I forgot the resistors. A 0.1 ohm 5W resistor in each input leg of the TIP2955. So is that the answer you are looking for? Remember, I'm a software guy not a double E.
MSMD( Monkey see, monkey do ).

Why regulate the supply pin on the 741? (Hint: look up PSRR).
I though that a lower voltage would be better to keep the heat down?

How much current is your panel capable of?
Dead short, 3 set of 3 panels produce appox 18 volts at 18 amps. Monitoring the charge current the most I see is 11 amps. Have not monitored the input voltage.

I can show you how to do this with about 5 components, but first you have to answer my questions.
I'm listening! :)

My web resources:
 

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MikeMl

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Here is a variation of regulator I came up with for a linear power supply/battery charger. When I said five parts, I thought you could use a shunt regulator, but at 12A and 14V (168W) that is not practical. I know this series regulator works because I have already built it.

For your solar panel, I crudely modeled it as a current source of 12A, shunted by a voltage to clamp it's open circuit voltage at near 18V. I modeled your battery bank as though it is a 12V flooded-cell lead-acid battery which is charged at 14.25V. I included a realistic series resistance. For simulation purposes, the 50 Farad capacitor charges about a factor of 100 times faster than your actual battery will charge. So in the real world, seconds become hours :D

Note the power dissipation in the PFET. It has to be mounted on a very large heat sink. Or you may mount it on a surplus CPU heatsink with integral 12Vdc fan.
 

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tcmtech

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damit! now I am stuck in a loop!

I think what he ment was to start a new thread in the main area not in an older thread.
 
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