Category: Tech

Tech

Understanding Fridge Temperature Cont

A follow up for some of the takeaways of the previous post (http://192.168.2.65/understanding-fridge-temperature/). Repeating the experiment in a different part of the fridge showed some cleaner results. In-fact there were oscillations present at a much more realistic interval (30min). This was very surprising as this is a mechanical fridge with a thermostat and the oscillating period was dead on 30min almost as if it was computerized.

The temperature logger was able to go for 4.5 days on the external battery bank.

Power BI Top 1%

One of my Power BI reports has reached the top 1% of all Power BI reports for the whole international company. A few keys to getting my report to this point.

  • Value to users: I tailored many aspects of the report to be more suitable to users in different departments giving them a reason to use it and widening the amount of people interested.
  • Automated Reports: Many daily and weekly status and trends were automated through power automate where users could quickly see top issues and then links were added to go to the Power BI report for further trends.
  • TRAINING, TRAINING, TRAINING: Many users are still new to Power BI and are unaware of what data is available. Training sessions and more commonly training videos were a key in getting users more engaged and involved.

Measuring USB Power Bank Capacity

Unfortunately there are many subpar USB power banks on the market that overestimate there capacity. Many people take the posted capacities at face value but it is beneficial to confirm. I have a cheap USB safety tester that reads the voltage and current coming out a usb port and from that can capture capacity.

I ran a new power bank from 100% -> 0% and for those two trials I got a capacity of 7.080Ah & 7.131Ah. The reported capacity was 26.8Ah and other users also reported capacities less than that. I will also be testing the capacity of charging as the tester itself has some power draw that might negatively influence the measurement.

Understanding Fridge Temperature

Following the basis of http://192.168.2.65/quick-temperature-logging-probe/ I setup a wireless temperature probe to monitor the temperature in my fridge because who knows what the temperature is when the dial is set to 3 😉 (there is a joke about a fridge that goes to 11 somewhere there).

Results were very surprising as the 95% confidence interval was so tight together I though something was wrong. Looking at the trend chart we see that there might be some oscillations if we tracked for longer but this was already a 3-4 day time frame O_o. It would be extremely shocking to me if there were oscillation with a period of 7-8 days.Follow ups.

Follow ups & Notes

  • Trial with different locations as obviously positioning further away from cooling coils will have higher temperatures.
  • Trial with larger battery bank to get large time frame trending
  • This was done on a cheap & old mini fridge so there might be value in testing newer hardware.
  • The fridge was heavily stocked with high heat capacity items so hysteresis may be playing a bit of a part here.
  • Higher polling frequency, though 15s should be more than frequent enough.
  • …

Quick Temperature Logging Probe

As precursors to some of my temperature logging investigations I wanted to go over the hardware. Using a cheap 5$ NodeMCU and a 1$ DS18B20 temperature probe I setup a wifi enabled temperature logging probe that my home server pulls from. Not going to go too in-depth but a quick digital read and processing is all it is. Cable is fairly robust so it can be passed through many places. Code is a basic example (don’t want to include network details).

Server Control & Monitoring

What is the point of running a home server if you don’t manage it?

With a bit of legwork Grafana provides an excellent monitoring and visualization tool. Key stats such as server load, memory, network & disk usage are tracked and alert base on thresholds. I will post some more updates on my home monitoring process over time.

Current Home Dashboard

This is a snapshot of my current dashboard I have mounted in my room. All the key stats for my server and network as well as weather details and time.