I used to work for a very small company that had to go each year to this big exposition to show our new technologies.
Our demo units were all battery powered, and their consumption was so low that with a single fully charged car battery we could easily run everything for the 3-4 days of the show without recharging.
However, we also had to show a short video and we needed to also have a laptop always on, so we did need to have power.
The first year I went I discovered only at the end of the show how much we paid for that little power.
The next year, maybe couple months before the show, I brought to the office my home UPS, which while not super big, is definitely bigger than the average consumer model.
I convinced my boss to try running the monitor with the video and the laptop to see for how much time we could have them running only with battery power.
Not enough time.
My former boss was already too much happy about the idea of not having to pay for power that didn’t want to abandon my idea... yet.
Our engineering guy suggested to buy spare batteries and change them during the day, and so we did.
We calculated that we needed about 2 extra batteries, and so we got 3.
We did the test again, and it worked!
We could run everything with just the UPS, and so we didn’t ask for power at our booth.
First day went super smooth. I didn’t even need to use the third extra battery.
At the end of the day we brought the ups and all the batteries back to the hotel where we had a small “charging station” to ensure that everything was at 100% for the following day.
Before the beginning of the second day we had a little inspection from the venue staff to make sure that everything was exactly like what we said on the paperwork.
The crewman after a minute noticed the monitor running the video, and after checking a couple of times his own papers...
“Here it says that you didn’t pay fo power and so we didn’t give it to you, if you plugged your stuff to the power of another booth you need either to pay or to unplug everything”
My boss giggled and said “do you want to explain it to him?”
I did, and the crewman was clearly confused. I’m not sure what he was thinking, but his face was like “what is this bullshit”.
Do note that this exposition is usually filled with companies with A LOT of money, companies that have big, expensive booths.
We were the outsiders: a company of 3 people with no money, that took the smallest booth possible, brought his own flooring (and when I say “flooring” I mean fake persian carpets, which I can assure made the trick at making our booth stand out) and that instead of getting proper walls used wooden frames covered with cheap blue velvet.
Oh, and we had a couple of old fake plants.
So, the crewman was already busy processing our... particular booth, imagine having to add “we run everything with 4 batteries instead of paying for power like everyone else”.
But then he left, and the day went fine.
Third day.
He came back with another 2 crewman, what I think was the crew master and a manager of the venue.
The crewman explained to the others the situation in the local language (we were abroad)I think, and then they started looking around our booth while the manager and the crew master talked with us.
The crewmen were searching for cables leading to a plug from another booth.
I explained again our setup, that everything was running on battery power, and that the UPS had its own protection circuitry and breaker, so that they could see we weren’t completely crazy.
The crew master said “I’d say you are crazy judging by your setup and the style of your booth, but this expo needs a bit of crazy”, and gave his formal blessing to everything.
The 3 extra batteries together costed a bit more than half what we would have paid for a regular power supply, and of course we could reuse them.