Tim Nolan's Arduino MPPT - now with LCD

[mega-hz]

Hi,

the power for the nano is taken via Diode from +Batterie going to Nano-Vin, the Nano has a 7805 regulator...
i use the ad8217 with a small piece of thick wire to get 0.005Ohm, the showing resistors are those wires...
if you make a click on the eagle-files you can download them directly!

here the eagle-files:
http://www.mega-hz.de/solar_mppt_charger/arduino_solarcharger.brd
http://www.mega-hz.de/solar_mppt_charger/arduino_solarcharger.sch

and the Arduino Code:
http://www.mega-hz.de/solar_mppt_charger/solar_regler_wf.ino

looking forward to see your tests!
next week the pcbs should be here... can't wait... 

you are welcome to contact me with email too. I am in Germany...

regards,
Wolfram

[mjeanne]

I think I will not use a regulator for the µC, as I'm looking for better efficiency. A 7805 will lost energy in heat from a 12-14V battery (because I want to have a 5V/3A output for my phone and some other devices).

[SeanB]

Cheap MC6403 based switchmodes will drop the voltage down with reasonable efficiency, but you will need a better step down regulator to get 5V at 3A for a cellphone charger. I would recommend having 2 so the micro is always powered by a device with good efficiency and low consumption, and the high power output is only turned on when needed. You probably will want the high power one to have an output of around 5V2 with no load so that you compensate somewhat for cable voltage drop during charging. Not more than 5V25 as this is the limit for a 5V nominal rail.

[mega-hz]

it's no problem to use one of these step-down converter, i also thought about it,
but i only need the 5v for the nano+lcd.
of course it has more power to heat, maybe later i change that too.. but thats only a small nice feature...

note if you want to use the arduino-sketch:
the values for UBat,IBat and so on are not yet the right values!
i firstly have to get the pcb and assemble one, than i adjust those value.
i hope there is no bug in the schematics/layout...

wolfram.

[mjeanne]

Hi,

I don't understand the schematics for D1. Is it one schottky or two ? (and how to choose the model ? )

For information, this is my project:
For the output, I need 12V for 4 lights (12V/3W) and 2 USB port for charging phones (at 1A each).
Actually, I've a 12V/50W solar panel, a 20Ah battery and a cheap PWM regulator (cmp12).
I'm using the 4 lights every night for the outside of my home. It work great from may to october, but in winter battery is empty (<10.5V) after 5 days.
I've try a mppt controller from a friend, and I get about +30% efficiency during morning and evening or poor solar conditions.

My project will use a atmega328p (because I already have lot of them), and ACS712 for current sensor (because I already have them too). So your schematics is a very good starting point for me, very few modifications.
I won't use RF for the moment, I'll use the serial port of the arduino for debug.
LCD will be use during debug, but will be remove too.

[mega-hz]

no no
D1 is a bipolar Overvoltage-protection diode!
Just in Case the Solar-Panel gets static charge or so.
D1 should be (in my case) a 47V Version. (P6KE47CA)

[kibi]

Excellent work mega-hz.
It's nice to someone doing some work to improve this. I, unfortunately, don't have any time to spend on this project at this time, but you seem to be making some good improvements.
Thank you.

[mega-hz]

Thanx,
yes, i want a complete system for my (or yours) solar-panels and windmills.
I have tried to contact Tim Nolan but after i wrote a mail his website went down.
It looks like the worst case (wich i don't hope!) that he has gone...
Can't explain that, but i have a bad feeling about Tim...
So whatever happend, keep in mind, the most of this project is not from me, it's Tims Devolepment!

Wolfram.

PS: Got a mail today, the PCBs are shiped!
They should be coming soon...

[mjeanne]

Hi,

don't you need pull-down for the 'in' pin of BTS432 to secure at first start (so output is off while µC is not ready) ?

[mega-hz]

i don't think thats a problem, it normally happens only once, because the system will be running all the time.

but good idea!

[mega-hz]

Hi,
on Monday the pcb's have arrived, but i had to go to hospital for an operation on my right shoulder..
they look good and i am coming home on Saturday.
Will assemble one next week and see how it works.

Wolfram

[mjeanne]

strange coincidence, I've break my left shoulder two week ago..

[mega-hz]

Hello Folks,
after i made one pcb assembled i try to set it up...
firstly my shunt-resistors (0.025OHM) between mosfet and battery burned...
When the PWM starts, the coil make some strange sounds, about 1Khz and the 5V of the arduino is pulsing.
LCD shows garbage than...
if the solar-volts are smaller as the battery-volts, the system (lcd) shows everything well.
I think there is a need for a seperate 5V, not of the battery.
And there must be an improvement with the mosfet to GND, i dont think this one is needed, it should run also if one takes a diode...
There must be some work on it to do.
At the end my 7805 on the arduino-nano burned too.

So sadly ... but i must stop here!
If anybody is interested in the hardware, i can sell it!
I have another 4 empty pcbs here and the one completely assembled with 4x20 white lcd.
the only thing i need and cant sell is the RF24 Module.

So, who is interested taking over this project?

Regards,
Wolfram.

(Meanwhile i have an Grid-Tie Inverter and have no use for Batteries)
[time... i have not so much time as i would like to have for this project.]

[jam770]

Hi everyone !

I am doing a similar project using tim nolan design. i designed my prototype pcb an all is well . now i am doing the second version with larger current sensors.

here is the pic in 3d of the first design.

the design will be available for sale as a kit also !!

Look here !! http://freesolarenergy.1colony.com/whats_new_2.html

regards

[mjeanne]

I'm still working on my own version, but with only one arm working, I'm going very slow...