toftat's blog

As I mentioned in the previous post, I was going to design and build a solar tracker. As time has gone by, this has become more necessary.

When I first set the panel angle I was getting great performance (fairly consistent 1.1A off the panel). Now, 3 weeks later, not so much as the angles are all wrong again, and I am back to getting about 20 minutes of runtime in the evening.

So, what a difference that made!

After changing the angle on Sunday, we had a couple of fairly cloudy days, so there was no opportunity to see what a difference it had made. That was until today.

After the last post, I monitored the charging system and battery more closely to see if changing the angle made any difference...

It had not.

As mentioned I thought I had got the angle wrong again, so I decided I needed to make adjustments. I used the principle that something pointing directly at the sun casts its shadow directly below itself (it looks like there is no shadow at all). My tri-square has an edge that is nominally square so it will stand perpendicular to the surface it is on.

So the battery is not getting charged during the day, again. As the battery is new, I decided that it must be either the charge controller, or the panel is at the wrong angle.

Last weekend I took my weather station of the dock post and put it on the chimney on top of the house. This should give me significantly more accurate measurements especially when it comes to wind speed and direction.

So a week or so ago, someone invited Irma to Orlando. She huffed and puffed and did not manage to blow the house down, nor did she blow SolarDock into submission.

Essentially all that happened was the post caps came off the tops of the posts (they are not permanently attached yet). The power cables acted very effectively as tethers so they didn't go into the lake or otherwise get lost.

So over the last few weeks, I have noticed some strange graphs from the monitoring system.

You get a disco!

After faffing around with trying to eek the last bit of charge out of the battery, this weekend I decided there _had_ to be something wrong with it. I took it (and a bunch of old UPS batteries) to batteries plus, UPS batteries for recycling and the solar dock one for testing.

I did some measuring of currents in the various fuses, as well as some open circuit voltages...

At the time it was sunny, and the panel was producing an open circuit voltage of 19.5v.

By removing the load fuse and putting the meter in its place, I could measure the current of the load in various configurations... Bearing in mind we are referring to the gazebo and 5 post caps, here are the numbers...

Full on (255,255,255) = 5.8A, so I replaced the 10A load fuse with a 7.5A one. On the bench, one postcap at full bore was measuring between 400mA and 450mA.

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