Monday, April 16, 2012

Little boxes

Not made out of ticky tacky, but of some mahogany offcuts I have lying about.  These two you see below are nearly ready for installation aboard Herbie.  This first little one contains a piezo beeper and an LED and will be mounted just inside the rear hatch so when it flashes and beeps the steerer will hopefully see and hear.


This second larger box will house Herbie’s Smartgauge battery monitor (it drops over and into the the big square hole)


and the little electronic circuit you see here.  The box does have a base – but I’ve removed here so you can see inside.


We’ve had our Smartgauge for a long time now and it really is good at monitoring battery capacity and state of charge.  However, until now I have not enabled the feature which enables it to trigger an alarm if the batteries go outside of their healthy voltage range.  Most of all I worry about overcharging because we now have sealed domestic batteries and if they boil off water, I can’t top them up.  Since we’ve had the solar panel this is an occasional problem after a few hours cruising on a sunny day.  The Smartgauge flashes “E03” because the voltage has risen beyond 14.5 volts.  However, because the Smartgauge is located where I can’t see it when steering, I don’t see the error message.

So this is what these new boxes are all about.  Thoughtfully, the Smartgauge has a relay switch which closes when the warning condition occurs, so al you have to do is connect a lamp or buzzer to it (and a battery) and the lamp or buzzer will come on.  Just because it’s more fun to do I chose to make this little 555 timer circuit which will pulse the flash and beep about once a second.  There will of course be a cable between the two boxes.

The hardest bit was the little buzzer box –yet to have its coats of varnish..  I didn’t think I could make a good one out of individual bits of wood – too fiddly and I am not a cabinet maker.  So I used a solid block of wood and chiselled out little holes and grooves to hold the buzzer, the LED, a resistor and the wiring.  Amazingly I still have all my fingers.


Halfie said...

A lovely little project. It looks just like one of those where you think it might take an hour or so to knock up, but which, in fact, takes up to a week of solid hard work.

Halfie said...

I should have added: (for me, anyway).

Neil Corbett said...

Dead right John, but that's the joy of retirement. You have time to waste on such projects.

nb.bobcat said...

I too get an E03 error when the batteries are at 100% and the sun is shining. However I am reasonably ok with this now that an electrician had his poky thing on the batteries when the E03 happened and it was not reading 15volts which I had been told was the spike. I think the smartgauge is set too sensitive. At least I hope so! I too have sealed batteries and I normally leave the fridge on when I leave the boat but didn't this month instead I covered the panels over with holey rubber mats. Still got the E03 error so must get bigger mats!