Friday, 19 August 2016

More bits and a solar assumption

First I have to apologise to reader and blogger Andy (nb Centurion).  Andy cruised past us on 9 Aug and spoke to Jan. <link here>.  All I managed to get was a photo of him disappearing and Jan’s comment about the boat name.  I should have realised it was Andy because his own blog appears on our blog list <link here>.  I’m claiming a senior’s moment!

Today I walked to Argos and collected the DC to DC power converter purchased recently from eBay.  The converters are actually cheaper to purchase directly from China but as we don’t have a postal address I needed a UK supplier who would either deliver Post Restante or via Argos.  The converter is a spare because I think the one being used to power the laptop is suffering from intermittent faults which probably means it will shortly fail.


We use two of these little converters on Waiouru.  The first powers the 240V TV from the 12V domestic battery bank.  The Samsung TV has an external power adapter (brick) which converts 240V AC to 14V DC  I cut the power adapter off the TV and wired it into one of the DC to DC converters increasing the battery voltage from 12V to 14V.  Of course the battery bank is never as low as 12V and usually around 13-14V so the converter has a very easy life.  The second converter powers the laptop raising the voltage up to the required 19.2V.  This converter has a slightly harder life which is probably why it’s starting to fail.

I’ve been watching the solar panel input readings over the last four months and noticed something.  The solar system has a monitor displaying the voltage and amps being generated.  I’ve noticed that on a bright sunny day the solar panels might not produce an output, which is a bit of a surprise.  Then I realised this happened when the engine was running.  Waiouru is fitted with a Sterling pro-digital advanced regulator (PDAR) which is hard wired into the large 175A alternator.  Amongst other things, the PDAR forces the alternator to produce a higher voltage.  With our large flooded lead acid traction batteries it is set to produce 14.8V rather than the usual 14.4V.  I suspect the 14.8V is higher than the maximum voltage produced by the solar panel controller so the panels contribute nothing to the battery charging in this situation.


Halfie said...

I bought a very similar-looking DC to DC converter for powering our laptop but it failed after only about two months on the boat. It did get warm while running - perhaps we need to get a higher-powered version. I use a smaller (and even cheaper) device to power the DAB radio. That one hasn't given any problems.

Tom and Jan said...

Ours gets hot. I have ventilation holes drilled in the surrounding case. If it got even hotter I'd probably mount a small cooling fan. What was the maximum amperes output rating on yours? Ours is 10 amps.

Andy Healey said...

No problems Tom, would have been nice to have a look at the Battlefield Line, but we where on a mission.

Halfie said...

Tom, I can't remember what the rating was. The figure of three amps comes to mind. I put it in a shallow plastic box with no lid so the heatsinks wouldn't be too obstructed. Thinking about it now ... the heatsinks got hot, not merely warm.