Quick question:
Do I need a fuse in the red wire from the battery to the red kill-switch?
If yes, what value? My guess is 100A.
Yes, you need a fuse. As close as possible to the battery.
The rating if the fuse depends on the wire thickness. Ist the cable a 13,5mm² ?
If yes, than a 40A ist recommended. Max would be 50A.
Thanx. The wire thickness is 16mm2.
Then 50A is recommended.
And according to the loads I see, this should be fine anyway as the 12/500 Inverter is the biggest load.
The concept regarding fuses is they are there to protect the source and wiring should a short occur anywhere in the wiring path. So yes, a fuse near the battery is recommended. Batteries are a perfect example of a source with nearly unlimited current. A short in an unfused conductor will likely heat and burn. Sources like the charge controller have a defined maximum current so fusing AT that source is less of a concern. So the fuses shown in your diagram should be as close as possible to your distribution block since it is the battery current that could heat/burn the smaller conductors running to the charge controller and inverter.
Note that a fuse (again located at the distribution block) should be added to the small red wire going to your fuse block.
Solar panels are also current limited so the circuit breakers in these lines are there mainly as a disconnect, not wire/source protection.
When choosing fuses look further than the power rating. Look also to the short-circuit-current the battery can deliver and the maximum voltage. If you don’t understand why: Please consider yourself unqualified and some sort of hazard or potential rootcause of a catastrophic fire/electrocution/spark blindness when it comes down to handling high DC current circuits. It’s good to take technical challenges but no other technical field has more specific law’s written for it than electricity. Asking is much better that not asking at all offcourse and 40A circuits are well withing the lower side of the range. Once you start going over 63A please ask a lot more questions! To anwser your question I must advice you to put a fuse so close to the positive pole of the battery that it is impossible to let the unfused part of that fuse(holder) to touch the negative or vihicle chassis if it is connected to the negative. Also count in all scenarios that are related to car crashes.
Thank you Gerd.
A bit of strong language there, but I catch your drift and appreciate it.
I am a DIY and beginner in the field of solar power, correct.
Hence this small little setup in my living room (see my post about Offgrid desk ) .
Learning the basics in a hopefully good way by studying, classes and input from you and others on this forum.
So, yes, I will be asking a lot more in the future.
