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WS-12-250-DC, firmware 1.5.0, Board Rev F, Power Supply B, Average power consumption 38 watts, Charge Controller Schneider MPPT 60 150, 1 Kwatt of Solar panels with 67 Volt max.

Occasional voltage spikes have appeared in the voltage plots but now it is happening more often and figure I better get to the bottom of this before we get too far into Winter. The spike is measured at 400 Volts, do not know how that can even happen?

Read from this post down in this thread: viewtopic.php?f=17&t=4641#p27199

Is the switch connected DIRECTLY to the battery bank and not the controller and the charger/controller connected to the batteries separately?

Thank You for the quick reply. Yes, the switch is connected directly to batteries (through a breaker). But, sounds like it is time to get back on site and look for loose connections.

I do not see the switch in your diagram?

If the wires running from the switch do not go DIRECTLY to the battery bank (with a breaker) but rather connect to a terminal on the controller this is not directly connected to the batteries.

Thank You and understand. The switch is not in the diagram but is connected to the batteries, not the controller. And to be more accurate, it is not a breaker, we are using an inline fuse on the positive wire.

Do you think the switch is actually seeing 400 Volts and not failing? 400 Volts by far exceeds the maximum input voltage.

This is DIRECT connect, if not like this then it is WRONG.

BaldwinCo wrote:Thank You and understand. The switch is not in the diagram but is connected to the batteries, not the controller. And to be more accurate, it is not a breaker, we are using an inline fuse on the positive wire.

Do you think the switch is actually seeing 400 Volts and not failing? 400 Volts by far exceeds the maximum input voltage.

I do not see how, 400 volts would obliterate the switch?

I do not know that the switch is failing, you could swap it out with a spare and see if the issue stops?

If possible one purchased in the past 6 months as there is a newer boot loader being shipped these days and upgrade it to v1.5.1rcNEWEST.

Another thing that could be happening is ground current. I know people keep saying I blame everything on ground current but the truth of the matter is sending a lot of ground current through the switches cause weird things to occur and ultimately will damage something.

Is there an electrical service on site?

If there is an electrical service on site are the service ground rods BONDED to the tower ground rods with #2 wire.

If this is an off grid site make sure that tower ground rods are bonded to any equipment box rods.

All ground rods must be bonded or you get 2 different ground potentials and often the Ethernet cable becomes that bond.

Since most lower cost radios used by WISPs have their DC negative rail bonded to chassis/earth ground we were forced to also bond our DC negative rail to chassis/earth ground so then if you do not have the tower ground rods bonded to equipment/service ground rods eminent damage is going to happen at some point when ground potential shift most often caused by rain events or electrical surges.

When you can not bond the rods maybe because of distance then make sure you add additional service rods (more than you think you need) and possibly consider only bringing the Neutral and Hot wires and use the tower ground at the receptacle.

I do not think the switch is failing, if so it is really taking its time - a year or so. In that time it has seen hundreds of these 400 volt spikes.

I think grounding has to be reviewed at the site, it is off grid, and was built 4 years ago. There are 4 ground rods in a 12 foot square connected with 6 gauge stranded copper. And then those 4 rods have two wires from the corners going to a ground bus. And all components have their own ground wire to that bus. Won't hurt to retighten all connections. The "soil" at this location is basically tundra - it is at 9700 feet. We also have a metal conduit running about 50 feet away from the solar shack that is grounded with rods in three places and connected to the shack ground.

A perhaps important fact is that the spikes occur day and night. The controller is basically off at night.

Interesting.

Even if you have poor ground so long as all grounding bonded ground current damage does not occur (when off grid as ground current can come from service provider).

Could it be a lose connection......maybe.

So possible issues:
LONG SHOT - grounding - do not think so with your description and being totally off site and all grounding bonded
Defective unit - POSSIBLY
Software - possibly but would think more people would see this?

I would say swap unit out with spare next visit but up to you.

Will ping engineer to review this issue. @Dave

this is some sort of weird software bug...by equation (if equation is correct...I need to verify with Eric), the maximum voltage we should be able to read/display is around 75 volts.....I will discuss with Eric....