Let me first tell you my layout. Batteries are in the back of the boat. Starter battery and utility battery connected with a Cyrix.
Wires (3m max) going from the utility battery (fused, 40A) to a positive and negative terminal at the console. At the console I have a Phoenix 12/250 and navigation lights connected to the terminals.
Also, my MPPT 75/15 is there, but wires going all the way back to the utility battery, to charge it.
I have some questions:
should I put a fuse in the wire from MPPT to battery?
or could I connect the MPPT to the positive and negative terminals thereby using the existing 40A fuse? I have a gut feeling this means the Phoenix would take its current from the MPPT instead of the battery…is that correct?
If your MPPT positive wire goes direct to the battery then this MUST have a fuse in close to the battery. This is to protect the wire if it shorted to a negative cable.
You could connect the MPPT to the fused terminal with the other equipment. As everything is connected together to the battery it makes no difference to how the power is used. In fact, if you ate producing solar and running the Phoenix then there will be less voltage loss in the system.
Thanks! So connecting the MPPT to the terminals this would automatically secure the connection to the battery.
However, there will be no fuse between the MPPT and the Phoenix, would that be a problem? The Phoenix is also connected to the terminals directly.
The battery is the unlimited source of power so wires connected to a battery need fusing in case there is a short circuit to stp 1,000+Amps flowing into a 50A wire or piece of equipment. Your solar can not produce more than 15A so it can not overpower the cables or Pheonix as long as the cables are rated for more than 15A.