Fuse or switch or not?

[Strider1]

Hi All
Got Dokio 200 w portable panels. Seem to work fine to charge house battery in driveway. Also got extension cables so I can park in shade and have panels in sun. Any thoughts in need for a fuse or disconnect switch? Good idea or not necessary?
Thanks!
Strider

[mkguitar]

I always fuse anything i add


it's cheap protection


use ohms law to calculate the max A you should see and add a bit


not so concerned about an overload, but a short


mike

[booster]

Normally, I would say that controller should be connected to batteries with a fuse that is easily removable or a switchable circuit breaker and panels to the controller with a fuse and a switch.


The reasoning is that you never want to have the controller getting output from the panels when a battery in not also connected to it. With no battery in the circuit the panels can drive the controller to pass through higher than nomal voltage. Worst is if the panels are not connected and sitting in the sun and you plug them into a controller that isn't attached to a battery. Big spike possible.


In use, you would normally leave the controller connected to the batteries all the time and only disconnected for storage or maintenance if needed. Any on/off function is done on the panels only so the above bad things don't happen. Totally safe to turn the panels on and off as long as the battery is connected to the controller.



Portable panels and ciip on controllers are more difficult to make sure this doesn't happen, but it sounds like yours are going to be hardwired with a long cable.

[Strider1]

Thank you all! Very helpful.
Strider

[SteveJ]

Before plugging in our portable panels I either cover them or have them face down so there is no output. The controller is hardwired.

[booster]

Originally Posted by SteveJ

Before plugging in our portable panels I either cover them or have them face down so there is no output. The controller is hardwired.

That makes it totally safe, but probably isn't necessary from what I have gotten from manuals for controllers. Many of them show a switch in the line to the panels which is really the same thing. There big concern is having the battery in the system whenever the panels are connected and seeing sunlight. Worst case, as mentioned earlier, would be to plug in or flip a panel switch on with no battery in the circuit and bright sun on the panels.


Since with portables it is easy to do, no reason not to, though, as it is foolproof and depending on the plug style you might see some arcing.