my Cotek inverter SP3000 48VDC sulfates the circuites

mauricio

English and Spanish

A year ago I bought 1 Cotek sp3000 48vdc inverter, it worked  for about 3 months, while trying to get Northern Arizona Wind & sun to process its repair, I bought a new one. This also worked a little less than 2 months. I made the corresponding claims, and sent the 2 investers for repair or exchange and they never explained to me what was happening. on the contrary they told me that they didn't know why they stopped working, but that it should be my responsibility because they never got damaged. They finally gave me a SP400 48vdc in replacement, and for an additional payment they replaced the other one, but they voided any warranty. The replacements came to me, and I installed the first one, was 45 days working, and I changed it for the second and also worked a little less than a month. As I had no guarantee or any response from Cotek for the cause of the damage, I took them to an electronic engineer, and we discovered that the equipment is sulfated at the bottom of the cards, apparently close to the fans the humidity allows to produce sulfate. The unfortunate thing is that new equipment in less than 30 days is sulfated, which indicates that the quality of the investers is very low. I want to clarify that I am about 40 miles from the sea, and that the only thing that is sulfated, is the inverter circuit, but neither the batteries nor terminals have that problem. 

BB.

Welcome to the forum Mauricio,

Just to be clear, other than Northern Arizona Wind & Sun founding this forum years ago, and kindly supporting the software and paying hosting fees, the forum itself is pretty much run by the folks that post/read here. None of us work for NAWS, and we have no insight into NAWS operations.

So, to your question(s). In are you sure that this is a sulfate (i.e., sulfur and copper as an example)? From my little experience, if there is a build up of sulfates, that would seem to suggest that (possibly) there are "fumes" from flooded cell lead acid batteries circulating into the AC inverter (i.e., inverter near the battery bank/bank venting, inverter fan(s) drawing fumes from the battery bank into the inverter ("fumes" typically being electrolyte mist from FLA battery charging, and getting on the circuit board).

If you smell sulfur (aka "rotten egg" smell around the battery bank/AC inverter installation), that would suggest that venting the battery  bank outside (bank in box, draw/push from box inlet vent(s) outside).

Other possibilities... If you have a very humid (possibly ocean salt air) getting into your power room, that could cause issues too. For humid environments, there can be temperature issues... For example, everything is "cold" in the morning, and as the sun heats the walls/shed, the moisture from hot areas, and then condenses on the cold areas (aka, the cold metal).

And some companies will "conformal coat" (basically a tough plastic that is poured over or electronics dipped into) the electronics to help prevent moisture from getting to the circuitry.

MorningStar is a company that conformal coats some (much, all?) of their equipment for marine use. Many companies hate conformal coating as it adds cost and makes any repairs very difficult. Here is an example of their inverter (a 300 Watt unit):

https://www.solar-electric.com/lib/wind-sun/SureSine.pdf

If the inverter (for example) runs 24 hours per day and is always "warmer" than the rest of the shed, generally, moisture will not condense on the internals.

For very tough environments, there is installing the inverter (and other electronics) in a sealed metal cabinet, and installing heat sinks (metal fins) inside the box (to take heat from inside the box) and another set of heat sink fins on the outside of the cabinet (to move heat from inside the box to outside the box).

Those are my initial suggestions/comments. I too am just a volunteer here and I do not have any direct experience with these products.

And perhaps, some others have suggestions.

Your thoughts?

-Bill