Friday, August 20, 2010

AVR Micros

So I ordered some AVR microcontroller kits from and and of course the odd parts from Mouser and Digikey. It was easy in Majuro, MH. They have a US Post Office and a state like abbreviation. Parts came in 7 days priority mail.

A programmable DVM looked just the ticket and TuxGraphics has a 3 digit meter that can easily be expanded to 6 analog inputs and sufficient code space to make it smart.

Planning ahead I also got a Data Logger shield for an Ardunio.

Of course my soldering is not this neat.

After only a few tests with misleading results and lots of other problems, I put the pieces on the shelf and have been monitoring the batteries with a simple voltmeter for the past year.

Thursday, August 12, 2010

A Back Dated Poet to Set the Stage

We live on our 45 foot sailboat out in the Pacific. We were in Majuro, Marshal Islands when the battery charger controller and electrical system failed. A cruising boat is an 'off-grid' energy system.

For the supply, we have 880 amp hours of battery storage, 200 watts of solar panels, a small wind turbine and two large alternators mounted on separate diesel engines. And for the consumption we have a refrigerator, lights, computers, TV, DVD player, radar, radios, GPS and various other navigation instruments. Not to mention the need to re-charge all those little re-chargeable devices and their 'wall-worts'.

With all this, we have spent only 12 days from the past 3 years plugged in the grid. The rest of the time we monitored the batteries and charged them as needed.

The primary monitoring device has been a sophisticated volt meter that accumulates the amp/hours used from the battery or the amp/hours put back in through charging. It also controlled the rate of charge from the high amperage alternators to ensure long battery life. It was an integrated system. Integrated systems are not normally desireable on cruising boats because if one part fails it usually renders the remaining integrated functions inoperable. ANd when you are 1000 miles from shore, it is a long swim back when it all fails.