# Fuse Question



## MoonRiver (Sep 2, 2007)

I have 2 100 watt solar panels connected in parallel. They connect to a 30 amp charge controller. This is for my RV. Cable run (10 awg) from charge controller to 12v battery is about 8'.

What size fuse do I need between the charge controller and battery?
Can the fuse be installed on the charge controller end of the cable?

Thanks


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## wy_white_wolf (Oct 14, 2004)

You can get by with a 20A as that will handle all the current that the panels can put out. If you want expansion room it should be:

30A *1.25 = 37.5 Amp so a 40 amp.

It should be mounted as close to the battery as possible. If you put it next to the charge controller what happens if the wire to the battery happens to short out? 

WWW


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## MoonRiver (Sep 2, 2007)

wy_white_wolf said:


> You can get by with a 20A as that will handle all the current that the panels can put out. If you want expansion room it should be:
> 
> 30A *1.25 = 37.5 Amp so a 40 amp.
> 
> ...


Thanks. My cables showed up today so I'm ready to go. The reason I wanted it by the charge controller is the charge controller is in the closet in my trailer, so it would be convenient if I could check the fuse without having to take the cover off the batteries.


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## Peasant (May 18, 2013)

wy_white_wolf said:


> You can get by with a 20A as that will handle all the current that the panels can put out. If you want expansion room it should be:
> 
> 30A *1.25 = 37.5 Amp so a 40 amp.
> 
> ...


Yep on all of the above. Closer to the battery is better. If a short occurs, current will flow from the battery to the charge controller. You don't want it traveling through 8' of wire.

Consider a circuit breaker like this or this instead of a fuse. Easier to reset and you can use it as a switch. A circuit breaker like this doesn't have a switch, but it's cheap and easily reset.

FYI, if you don't already, you should have a switch between the panels and charge controller. Turn this off before working on the charge controller. You don't want to disconnect the charge controller to battery circuit while the panels are still feeding the charge controller.


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## MoonRiver (Sep 2, 2007)

Peasant said:


> Yep on all of the above. Closer to the battery is better. If a short occurs, current will flow from the battery to the charge controller. You don't want it traveling through 8' of wire.
> 
> Consider a circuit breaker like this or this instead of a fuse. Easier to reset and you can use it as a switch. A circuit breaker like this doesn't have a switch, but it's cheap and easily reset.
> 
> FYI, if you don't already, you should have a switch between the panels and charge controller. Turn this off before working on the charge controller. You don't want to disconnect the charge controller to battery circuit while the panels are still feeding the charge controller.


Thanks. 

I don't have a switch between panels and charge controller, but I have MC4 connectors right there I can disconnect.


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