Solar tracker voltage

[Peter Klaassen]

I am looking for some advice on a DC-DC voltage limiter. We have a Sunlink tracker which operater via a DC motor that is designed for 24-48 V. I have wired it to a 48 V battery bank which can go to 63 V during equalization. There are apparently DC-DC transformers which could keep the voltage closer to 24 V. Can anyone recommend a distributer of such a transformer and a ball park cost? At the moment I am replacing a fuse now and then.

Thanks for the help!
P Klaassen

[Rob Beckers]

Hi Peter,

A DC-to-DC converter does what you're looking for, however, a little search shows they're pricey. I possibly have another (cheaper) idea. For that I need to know what the current of the motor is.

-RoB-

[Peter Klaassen]

Thanks for your response Rob. The tracker motor is protected by a 5A fuse. It is a motor similar to those used for the old style of satellite dish. ( the 8 ft. diameter ones). I am out on my ship at the moment so I can't read the nameplate data on the mechanism. I looked at a transformer that was about $200 and wondered if there was a cheaper alternative.
Pete

[Mario De Castris]

Hello Peter,

I may have something here that will do the job for you, as we're not very far from each other, also I am using a similar motor for my tracker and you might want to have a look how mine workers.

Mario

[Rob Beckers]

Hi Peter,

5A is a bit too much to do with a zener diode (my initial idea).
You should be able to use just a few regular resistors though (of sufficient Wattage). They're cheap. Sounds like the motor will work on anything between 24 - 48V, so if dropping 10 Volt or so will keep the motor happy and the breaker from popping a resistor might do that.

-RoB-

[Dan Lenox]

Peter,

Rather than hanging the tracking motor onto the 48v battery bank, why not connect it across 2 or 3 batteries (24v or 36v)? That is the way that I have my tracker wired.

It is not like it creates a huge imbalance on the battery bank, and keeps the max voltages in line with what the DC motor actually wants to work with.

Dan Lenox

[Peter Klaassen]

I had consdered that solution Dan, thinking the same thing. You have had yours like that without battery issues? The batteries I have are the heavy Surrettes.
Mario, when I'm home in August I will give you a call / visit to have another look at your set up.
Thanks for all the suggestions, gentlemen.
Pete

[Dan Lenox]

Pete,

Have had mine connected this way for over a year now.

The thing is that the draw for literally a couple of seconds to power a tracker is such a light load that the battery hardly even knows that it is there.

I am using strings of 110ah batteries and have my tracker connected across 2 (or 3 - I can't remember) batteries. Nothing like your Surrettes, so I would not hesitate to connect the tracker this way.

Dan Lenox