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.

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

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

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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.

4 comments:

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!