Yes, totally new to all this, but have been tinkering for a month or so and getting there, but gee I’m getting confused! My project is a Polly-tunnel irrigation system that works faultlessly when attached to the laptop on the pc, but when I hook it up to the 12v car battery and solar system it damages the voltage regulators on the boards. It also requires me to adjust the LCD frequency screw to see text.
I know it will be something I’ve missed, but even if I mimic the power supply from my laptop with a voltage regulator nothing works!
There has been a lot of colour full language of late!
Sounds like the ol' "overloaded 5V regulator after being forced to drop 12 volts to 5" syndrome. What all is connected to the 5V pin? 5V power from the laptop's USB does not come through the onboard 5V regulator.
Sorry for being so vague! OK, the setup works perfectly when hooked up to the PC /laptop as I’ve tested it over 1wk, so I was happy to test outside, but I also tested on a standalone 12v battery the voltage regulators and system seems to run ok apart from having to tweaks the LCD, but no over heating or smoke with a pop when connected to the load, which according to the spec and physical tested load output it shouldn’t cause this! The load spikes 14v very rarely, so I thought it would be ok due to the spec of the reg max 20v.
The funny thig is I’m ok with this area, but I was mostly design and never on shop floor trouble shoot errors like this.
I think its another complete strip down as there must be a wire wrong, but its not a big set-up to get wrong twice with the same probs.
SET-UP: Solar panel, to consumer box (input/battery output/Load), voltage stepdown to 8.7v, board mega fitted with 20x4 lcd ic2 connected to SDA/SCL/VCC & GND, DS3231 SDA/SCL/VCC & GND, DHT22 Data pin D06/VCC & GND, 2ch relay VCC & GND ch1 to pin D11 & Ch2 to pin D09. The relays are activated by DHT22 data parameters and timer to switch on a 12v valve (water supply)
JCA79B:
Sounds like the ol' "overloaded 5V regulator after being forced to drop 12 volts to 5" syndrome. What all is connected to the 5V pin? 5V power from the laptop's USB does not come through the onboard 5V regulator.
Ha that sound about right, but ive used the jack plug in too with the same result!
Yes, got one and all the outputs seem to be good 4.8 to 5v! Never checked the input of the board around the jack or reg as thought they’d be up to spec. More fool me for trusting, but The thing is when I started, I bought cheap boards, so it might be that. It’s the working when linked to PC, but not or in the process of failing when stand alone. Looks like a little homework required on the boards
So you are using an external regulator to step down from the battery 12V to 8.7V before going into VIN of the Mega, which onboard regulator drops down to 5V?
When you are plugged into the laptop, are you powering the mega by USB?
If so, I'm thinking your 8.7V step-down regulator is a potential issue.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Label your terminals and battery and PV terminals please.
Can you post a picture of your project so we can see your component layout?
Might seem quirky at first, but consider using a voltage divider on your input.
I would much rather have the “waste” voltage dumped into suitable resistors before going into the Arduino vs having the regulator trying to do all that work.
Either way that excess is being turned into heat..
Pic isn’t possible due to tear down!
I’m on the AutoCAD Computer tomorrow as I’ve got a job to get out, so I’ll try and get a schematic drawn up if I get time, but when the kids get home I’m not allowed to work!
I’ve just ordered up a good stepdown regulator, so I can rule that out, but I was thinking maybe it’s the solar controller unit. Not had much experience with them, but the load will rise to 14v during the day and drop at night to 12.4volts but didn’t think that would be a problem. What I might do is get a small pure sin 12v inverter and run the setup through its USB output.
Pic isn’t possible due to tear down!
I’m on the AutoCAD Computer tomorrow as I’ve got a job to get out, so I’ll try and get a schematic drawn up if I get time, but when the kids get home I’m not allowed to work!
I’ve just ordered up a good stepdown regulator, so I can rule that out, but I was thinking maybe it’s the solar controller unit. Not had much experience with them, but the load will rise to 14v during the day and drop at night to 12.4volts but didn’t think that would be a problem. What I might do is get a small pure sin 12v inverter and run the setup through its USB output.
Robin
You might also consider using a 12V buck/boost converter to clean up the signal before starting the reduction process. That would give you a window of ~8V to 15V of battery voltage.
magnethead494:
You might also consider using a 12V buck/boost converter to clean up the signal before starting the reduction process. That would give you a window of ~8V to 15V of battery voltage.
I was thinking just that!!! I've got a step-up boost attached directly to the load now and taking measurements from it to see what’s happening, but its solid and constant with its output of 14 volt that it was sent to.
The step-down unit I’m getting also has a USB output, so I’m covering as many bases as possible.
The thing is the poor polytunnel is the test bench for my snake’s vivarium’s and fish as looking to make them all run of solar energy to maintain their habitats.
I had a similar problem with a 12v wall wort that outputted 12.3v. I assumed it was cheap Chinese knockoff boards. I ran the 12v through a 7805 circuit. I stayed with 12 v because I am powering some 12v valve through a relay. My board is a 3.3v mini pro and the onboard regulator knocks the 5v to 3.3v
