That is similar to my thoughts much better organized though. Thank you for some verification of my learning...
No I was looking at a sketch from another contributor that looked easier to convert to an LCD module as that was why I boughta gps unit, cheap accurate always on time keeping, this and some more functions to be combined for my little bedside look at the world a weather station, clock and X10 controls blended carefully with some of those cheap nRF24XX series modules and an 8 digit 3208 scrolling display for casual time display will be all included and a 3.2" touch screen to control most of it it will monitor a car and my garage as well... for now. Mostly a project to keep an old man busy, learning and doing after I retired. That was my single challenge to keep busy at something I love... dearly. I do thank you for your help as the language is very new to me, I read a lot and that 'line' really jumped off the screen when I tried to figire out why it didn't work, that after all is half the learning. IMO

Doc

Try as I can something in this single line just doesn't make sense to me, or work for that matter.
tlcd.print(static_cast<int>(hour + 7)); tlcd.print(":"); tlcd.print(static_cast<int>(minute));
Where did I miss it in the books, I try hard not to waste time here If I can avoid it...
I know what both terms are, more or less but why a static cast inside a function when the data changes outside of
the function once a second. GPS Time is being displayed here, and a 2 second delay after the function ends before the closing brace.

Doc

The Adafruit module looks easier to use... 1.8" display and 10 jumper wires and load the demo's and libraries restart the ide and compile and run the samples also has an SD card slot that can be read using the same interface as the TFT, for a Tiny display mine looks pretty good... Easy to use the samples to really use the display with your own sketches too...

Doc

Buy a good one and buy it once, my Fluke 179 has been used continually for 4 years, had to replace the fuses once and only once as the set from anyone including Fluke is $20 + Dollars but Never anything except a battery once every year or so have I done to it... Calibration is still factory good as well. My previous meter was a Fluke 77 it worked for 10 years until someone needed it enough to steal it. That one was a great meter too took several falls of 30 - 40 feet and still was ok, case a little worse for wear as I was a field engineer for a couple of communications outfits for about 5 of those years repairing high power uhf and vhf transmitters and low density microwave comm links.

Doc

yes and did you know that an 805 size resistor solders neatly between 2 .1 in Ctr pads or traces???, even with pins in the holes???.

Doc

The leakage current specification is upto 0.8uA for switches in the off state, plenty large enough to explain your readings.

only if the source impedance was as high as the input impedance of the processor. what does the spec sheet say about output impedance or available load current? since you didn't see fit to post the sensor information anything beyond power supply bypassing is a waste of time... My Crystal Ball has been broken since it told me I was ugly...

Doc

5 X 1.5 = 7.5 V and the Arduino Uno has a 5V Vcc........ ? Quite frankly I don't see how it could have worked at all, unless the batteries were dead ( a battery is usually considered used up @ .9V) so 5 X .9 = 4.5V good except it would go away when the device motor was powered up. should have displayed garbage text then...

Doc

Not impossible, the picture clearly shows well soldered joints...
I think the person attempting to do the soldering needs some soldering experience or someone who has that experience to do it for him, there is nothing in the picture that looks at all difficult. From the description he gave of his less than successful attempts it sounds like he is not heating both surfaces equally hot enough to melt the solder. Heat both the pad and the pin equally hot enough to melt the solder (place them together first)  put the solder on the work, not the iron, you can touch the iron with the solder a little, just enough to start to melt the solder but you must heat both pieces equally, apply the solder and NOT MOVE them until the solder cools or you will have a bad solder joint, just a couple of seconds is all it takes.

Doc

an ohm meter has a battery and a measuring device of some kind and some resistors to scale the current correctly for the measured device. External voltages are generally not good to try and pass through those resistors... You usually let the magic smoke escape from them when you do that, especially on low ohm ranges.

Doc

No because it takes a threshold current to begin to move the armature/rotor which can be several times the stall current or at any rate this is my experience. I designed a solenoid driver for a bi-polar or latching solenoid about 20 years ago. It was a 4700 uF cap "Dumped" into a 3 ohm coil @ 12V dc from a Yuasa NP1.2-12 battery and I measured currents in excess of 10A for 20 - 30 uS... The current was Max until the magnetic field built up that it was that high is perfectly normal. the coil should have drawn 4 A and did in steady state conditions but REQUIRED the large pulse to overcome the hysteresis imposed by the magnetic material (the core or solenoid shuttle) on paper with a 2200 uf cap the device was supposed to work and did only if one charged the cap and connected it directly yo the solenoid 6feet of 16 Ga 2 conductor wire was anough to prevent the operation of the solenoid under 2 ATM. or 30 PSI water pressure on the valve controlled by the soleniod. I also found that it 'required' a Mosfet with under a tenth of an ohm Rds_on or it was unreliable with more than 10' of wire. I used a flipflop (7474) and that part has a 40nS rise time it was coupled to the FET gate with a 100 ohm resistor so I wouldn't loose energy charging the gate, I used the edge of the FF output to trigger my scope and typically it was about 5 uS to peak current, reached a plateau 30 us later and was done completely in less than 100uS and the peak was in excess of 10A... Why with a 3 ohm coil (DC resistance). Like the electrostatic field in a capacitor the electromagnet has a magnetic field that must be built up before the rotor/solenoid/armature can begin to work.

Doc

variations in leds will require different current for the same amount of light output... Even in the same batch or type

Doc

One real issue could be the Grounds... If the Arduino is connected to a computer that is also connected to the vehicle 12V there is a high current common ground path from the charger that will slightly raise the Arduino's ground potential relative to the ground of the sensor and this voltage is also common to the analog input as well.If for example if the ground lead from the 12V to the computer was part of a 1A load and perhaps there was a quarter of an ohm of resistance from the charger ground to the car ground there would be 1A X.25 ohms or .25V difference between the 2 grounds this voltage or a part of it will show up on the input pin as an offset voltage it's called 'common mode' offset or differential offset and frequently seen as noise... It is noise as any signal added to a desired signal is noise.

Doc

Required because even though Vcc and AVcc are connected to the 5V source, they are different pins. and ANY Vcc supply pin of any kind Must have it's own bypass capacitor, Not for the board, for the chip internal connections.

Doc

 no it is the Junction Voltage much like a simple silicon diode will have a .6V drop across it, an LED will have a 'forward voltage' that can range from 1.8 to about 3.8V depending of material (color) and manufacturing process. it will also have a recommended current above which you will be exceeding the recommended power dissipation as well If you truly would like a real answer to your several questions over the past week or so then post a COMPLETE circuit or design requirements and someone will provide an answer for you. If I see it and feel that the answer given you is wrong or inadequate, rest assured I will add my $.02 to it. What you are asking has no real answer I feel, beyond what you were given so far.

Doc

I had a techie trainee do just that once... he asked me what I thought of that and I replied that he hadn't given it much thought, why should I?. He did as his thoughts directed and powered it up... it took about a minute for it to be over, was interesting to watch... much like popcorn they went off each brighter than the one before randomly (they were in a circle), I had his check ready for him when he went on break... because he plugged in 10 more led's and tried it again. I asked him why and he replied that he thought he had some defective led's... the first time, he hand't an answer for the second attempt.
Insanity can be defined as doing the same thing repeatedly, expecting different results.
I see a lot of that here too... LOL

Doc