Correct, but it is important to note that if you’re drawing 5v (USB) from a 12V battery, 1A at the camera effectively becomes less than 1/2A at the battery (after passing through the transformer), so you end up with double the runtime (roughly).
This is actually a case where watt-hours is a bit easier to deal with since it takes voltage into account and removes it from the equation. But you still have to factor in the inefficiencies in the system which are probably going to be in the 10 to 20% loss range, possibly more if the battery does not charge to full capacity.
P=IV (watts = current x voltage). Similar to those high up power lines on the pole that carry a fraction of the current that the low voltage lines do, since they send it at a much higher voltage, then use the transformer to step it down (convert voltage to current effectively). That’s an AC system but same applies to DC. The opposite is true too, you can technically use a 3.xV lithium battery to put out 5v, with a step up, you just draw more current from the battery. WH accounts for that, AH doesn’t. AH spec is at the battery’s “native” voltage.
The former is Watt’s law, Ohm’s is V=IR but also a very important one.
I just want some Pi now.
I rarely see Watt’s expressed as P=IE anymore, but considering Canada is involved here, never know. Probably manage to put a “U” in there somewhere too
We always considered it as Ohm’s law but memories fade.
E was a common reference to voltage back in my day. Electromotive force or E. That was in College and Navy Electronics school. E is the same as V.
We also had a funny g-rated phrase and and r-rated phrase for resistor color codes and transistor configs. Also Oscar Had a Heap of Apples or Eli the Ice man for others.
Yeah I recall seeing it here and there but by the time I was in college we were pretty universally using V. But like anything, it can be a regional thing or based on who is teaching stuff.
I have many mnemonics for electronics and networking, and many of them are not family friendly. But they stick, so it works.
The one law that is universal is that when it comes to electricity, nothing ever follows the simplified equations perfectly. And I don’t care to even try to remember the complex equations that draw all the other relevant factors, plus a dash of physics into the mix.
Most of us just calculate using the basic rules, add some extra overhead, and “ship it”.
When I need a capacitor, I double the voltage and buy one rated for that. Pretty good rule of thumb for just about every component, though 50% is usually enough when cost becomes a factor.
I have two engineering degrees, and the only time I ever used E (or more frequently ε) was in electronics diagrams in college. Yet oddly the formulas always used V. Perhaps part of the confusion was that Einstein used epsilon to describe energy as a totally different kind of force so they started changing to V for Volts? Who knows. From what I recall E was nearly always used to denote a power source and V was used when you were listing a voltage at a particular point in the circuit on the layout.
Of course lower case v is for velocity so that’s another confusion with physics. I guess I for Intensity and P for Power didn’t conflict with anything so they stuck around. Probably one of those things that has no concrete explanation, like “Jerry Rigged” vs “Jury Rigged” or any number of those ages old arguments of which one is correct or what the origin is. Here in good ol’ New England, electricians (which I dabble in) and electrical engineers both use V pretty consistently. Power source is nearly always denoted by an icon of a battery or waveform these days.
Worth noting that especially when AC becomes involved P can be expressed in VA or Watts. Watts typically incorporates the power factor and is more of an “input” or “consumption” where VA is more of an output or “potential” in ideal conditions. So in a way it does make sense to have both P and W, but in reality they aren’t used that way in calculations.
That’s why you’ll see UPSes rated in VA instead of Watt. Technically they are the same thing but the power factor on the setup is very inefficient so you end up with far less watts than VA.
Finally able to some testing now that we have sunshine.
To recap :
I have three Wasserstein solar panels with connectors meant for a WOC.
The solar panel is out in bright sunshine, and the USB meter is connected to the solar panel. The WOC is connected to the USB power meter. No reading at all. I have tried all 3 solar panels. These panels were in the sunshine for 3 hours today. Two have not been disassembled and were working when pulled from service.
The USB meter is working because I can plug in a power bank and it shows voltage.
The one solar panel I took apart has voltage right at the board where the panel connects.
I see this comment in an old thread related to the same panel and camera
I didn’t realize the Wasserstein had it’s own embedded battery as well for charging off solar panel. Instructions say to give it a good 8-10 hours in sun before plugging into a fully charged WCO. There isn’t a separate USB charging port so have to go with the sun.
Not sure if that is accurate or not, but maybe it will not turn on the output until it is charged up fully?
Maybe put some other load on the panel, like your battery bank charging port, see if that causes it to switch on, maybe the camera is dead and not trying to draw power?
The 18650 battery has a full charge. For grins I tested it with my Opus https://a.co/d/cMYTCfU expecting to see less than 1000 mah but it tested at 2150 mah
I get disgusted easily in my old age. Everything went to the basement. Perhaps I will get a bee up my butt someday. Right now I will continue to swap batteries.
