Now why would you do THAT?

    OK, so we are getting closer to reality here.  Since the last article , I have made some small changes, which helped things out. Firstly, I added a 1000uF/63V filter capacitor to the battery output.  This practically eliminated the serious "hunting" issue that caused the software to rapidly ramp PWM values up and down almost constantly. Next I added two relays to the control circuit. The first is a battery cutoff, which will disconnect the battery if it is above 15V or below 9V, as these would indicate some kind of fault has occurred. The other relay disconnects the solar panel on the same principal.  If either of these events occur, the LCD indicates the nature of the fault. In order for battery monitoring to work effectively, the voltage divider must be located between the relay and the battery .  This way the battery can be reconnected automatically when the fault clears.  I have elected NOT to do this on the solar panel side as an over-voltage...

Last time I introduced my new solar power project.  By the end of that post we were monitoring the power flow from the solar panel to the battery in a simple test environment.  This time we're going to dive in and start trying to control the charge power. What's MPPT? Maximum Power Point Tracking (or Transfer , depending on whom you ask) is a condition where we can transfer the highest power from the solar panel into the battery.  The key here is power, rather than voltage or current on their own.  Remember that power is the product of voltage and current, so it is possible that you will find that perhaps higher current and lower voltage (or vice versa) is the most efficient. What makes this a little problematic is that the peak power point varies constantly depending on the battery state of charge and temperature, so it is not a set and forget operation. This is why the first thing we did was to build a power monitor.  Now we can determine at any point of time...

I've got a new shed... And even though it's wired for power, my 16x9m shed is going to be powered as much as possible from solar panels and batteries.  Given that I have more than a few computers and radios in there, this is going to be a challenge. The house already has a set of panels and a big inverter, so this is really my own personal R&D project.  For safety, I am not attempting to connect my work to the house wiring, or feed into the grid.  I will be running separate wiring to power this gear. A note on safety Electricity is dangerous.  Contact with live wiring or components can be fatal.  I can't state this clearly enough, electric shocks can, and do kill people.  Batteries contain dangerous chemicals and can give off flammable gasses, which in a confined space can be explosive.  Connecting or disconnecting batteries can cause sparks, which could have very bad side effects. I will detail steps to mitigate these risks, but ultimately it is u...

  I am not 100% sure where this is going, but it's going to be a fun journey...   I own an iRobot Roomba 630 floor cleaner, and it works well enough for our house.  But I discovered the iRobot "Create" which is designed for teaching and hacking in general.  As you can imagine, repurposing our cleaning robot for my hobby might not sit too well. Using the local social networks, I picked up an iRobot "Scooba" for nothing.  According to the previous owner, it won't charge and the power light glows red when you plug it in. I downloaded the service manual from one of those manuals websites, and learned this is likely to mean that the battery has failed and won't hold a charge.  I figured I could probably re-pack it and things would be sweet. As with so many of my projects, the problem was a little more complex than I expected.  The reason why it won't charge is that the battery was missing, rather than simply faulty.  Given it's a specialised package, ...