Arduino spot welder v3 displays zero voltage even though 12v battery voltage is detected at electrode pen.
Mmmmmmm.....
I bet it's the code, or the wiring. But you have supplied nothing to go on.
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You might want to look at this How to get the best out of this forum before you proceed any further.
We only know what you tell us, and without knowing what you have, we don't stand a chance.
@reh245
Check the voltage at A0
Thank you for all the quick responses. The voltage at A0 is 12.86. Read “How to get the best out of this forum” as suggested. This is my first Arduino, so newbie, do not even know what info to add. I got the spot welder from someone who said it worked. This may be really dumb. Do not know if software, or lack of, would cause a “Battery low volts” error. Am figuring out now how to install/reinstall it.
A0 MAXIMUM input is 5V, so that may be your problem!
Yes you do. You had to read and submit answers to get to the forum. Then you saw this: How to get the best out of this forum and acknowledged you had read it. You ignored it each time. Attention to detail is affecting your project.
While you're sorting this out, consider ordering some more Arduinos, you’ve likely fried A0, the Arduino and possibly other components. Post your annotated schematic, and we'll check it for you. While waiting for the new Arduinos to arrive, take a look at the Arduino Cookbook, it will be a big help.
Hi, @reh245
Welcome to the forum.
Can you please post a copy of your circuit, a picture of a hand drawn circuit in jpg, png?
Hand drawn and photographed is perfectly acceptable.
Please include ALL hardware, power supplies, component names and pin labels.
Can you post some images of your project?
So we can see your component layout.
Thanks.. Tom.. 
Did you try V4?
@reh245 there have been 12 posts so far and you have only two of them. You need to answer more question asked of you. Otherwise this thread is going nowhere, and people will not bother posting and you will never get the help you need.
Maybe you don't understand the questions, if this is the case then ask specifically what you don't understand about them.
When I search for "arduino spot welder" I get a host of different boards. So do that and report back which one you have, in the form of a link to where it can be bought. It doesn't matter if you bought it there or not, at least we can see what it is.
Next we want to see how you wired it up, the best way of doing that is a schematic. You must have some sort of schematic because you wired it up, so I assume you were following some instructions somewhere. We need to see those instructions because only you know what they are.
Finally we need to what code you are trying to run to get it to work. Did you write this code yourself? If not who did?
Something wrong with the circuit. That voltage should not be over 5V. The Nano now could be damaged.
Attached are pictures of the Arduino Spot Welder V3.3
I reinstalled the code (after a whole bunch of errors) but the display totally disappeared and was blank. This might have been because of the final error “setTextProp” I did not resolve and just commented out.
The upload was successful so I tried a weld without the display. It worked. I created a weld. Bad idea though. After a second test weld a mosfet burnt out.
Since I uploaded “HelloWorld”, it displays and peculiarly I now have 4v at A0 I believe the Nano works.
I have been working on it and have learned a lot. Now I need to restore the spot welder menu, replace the mosfet and get back to square one. I am really impressed by the expertise, accountability, response and goodwill of this forum.
Following is the software error:
In file included from C:\Users\palace\Documents\Arduino\asp\asp.ino:1:0:
C:\Users\palace\Documents\Arduino\asp\Arduino_Spot_Welder_V3_3_3.h:229:35: error: variable or field 'displaysetTextColor' declared void
void displaysetTextColor(WHITE);
^
C:\Users\palace\Documents\Arduino\asp\Arduino_Spot_Welder_V3_3_3.h:229:30: error: 'WHITE' was not declared in this scope
void displaysetTextColor(WHITE);
^~~~~
C:\Users\palace\Documents\Arduino\asp\Arduino_Spot_Welder_V3_3_3.h:229:30: note: suggested alternative: 'WDIE'
void displaysetTextColor(WHITE);
^~~~~
WDIE
C:\Users\palace\Documents\Arduino\asp\Arduino_Spot_Welder_V3_3_3.h:230:60: error: 'WHITE' was not declared in this scope
void setTextProp(uint8_t, uint8_t, uint8_t, uint16_t = WHITE, boolean = false);
^~~~~
C:\Users\palace\Documents\Arduino\asp\Arduino_Spot_Welder_V3_3_3.h:230:60: note: suggested alternative: 'WDIE'
void setTextProp(uint8_t, uint8_t, uint8_t, uint16_t = WHITE, boolean = false);
^~~~~
WDIE
exit status 1
Compilation error: variable or field 'displaysetTextColor' declared void
