Raspberry Pi Current SensorAfter constructing a solar panel and battery system to power a Raspberry Pi, I wanted to find a way to monitor how the battery and charger was performing.  There are several ways to accomplish this task, usually involving a voltage sensor, a current sensor, or both.

A voltage-based sensor can be used to monitor the charge of the battery.  Over a typical day, the battery voltage should rise as the solar panel charges the battery, and then discharge at night while the Raspberry Pi consumes power from the battery.  A common technique for monitoring voltage is to use a voltage divider.  If appropriate resistances are chosen for the voltage divider circuit, the drain on the battery from the sensor is negligable.

Another option is to use a current sensor.  A current sensor placed off of one of the battery terminals will measure how much current is flowing into or out of the battery.   Continue Reading

Temperature ImageUnless you have been living under a rock, you can’t help but notice that lately everyone seems to be eager to conserve or reduce their energy consumption and increase the efficiency of the items they purchase.  Not only is it the popular thing to do, most consumers expect substantial savings by spending less on the energy needed to power our lives.  I suspect, however, that very few people actually measure how much energy they are saving.

In fact, there is an effect called the Jevons Paradox that states that as consumers save energy, this naturally results in the cost of energy becoming cheaper.  This then causes economic growth and consumers use even more energy than before!  Still, the argument exists that you cannot understand or begin to control your energy consumption until you actually examine the data.  Knowing your usage will lead to, hopefully, more responsible choices going forward. Continue Reading

WELLike any good do-it-yourself project, this one started with a need.  I have a home which has a radiant floor heating system.  I’ve never had a heating system of this type, and as such, I tried to learn everything I could about the operation of this system.  My biggest concern was the operation of the system when I wasn’t at home.  What if the house temperature dropped and the pipes froze?  How would I know?  Clearly I needed a way to monitor the performance of the system without actually being at home. Continue Reading