Bavaria 32 - Problems with cable size when wiring a shunt

[Duncancw]

Hi

I have a Bavaria 32 and would really appreciate it if anyone can help?

I've recently purchased a shunt to start monitoring my battery before installing solar panels. The wiring diagram (Panel 424) that comes with the owners manuals for a Bavaria 32 states that the cable running to the earth on the domestic battery is 95mm sq. (see attached for details). Having used my callipers the actual width of the cable is only 10-11mm which equates to a 35mm sq cable and is considerable smaller than the approx 16mm cable which is standard for a 95mm sq cable.

I need to make up a spare cable to run between the earth on the domestic (140Ah) battery and the shunt.

I want to keep the electrical system as uniform as possible. If I purchase a 95mm sq cable it will be considerable larger than the cable(s) that are current in situ. If I purchase an 35mm sq cable then I will potentially introducing a different amp rating into the system.

I should point out that I only have one domestic battery rather than the two that is in the original Bavaria 32 wiring diagram, so some modifications has taken place (previous owner of the boat).

 

[simonfraser]

going to depend on the length of the cableand amps drawn
you are likely to be interesting in the domestic side, which should work fine with either side
if it is short, less than 1m there is not going to be a significant difference in the voltage drop due to the cable size

 

[Moodysailor]

It won't hurt to go larger, at the end of the day you are already changing the electrical system, and have indicated an change has already taken place, so use the largest size cable that is practical and affordable - it's rarely a bad investment when it comes to primary cabling as the loads only ever increase, not the other way.

If you feel like keeping all in order, make a drawn (computer or hand) update to the relevant section of the electrical system and insert it into the manual. You can note the new cable dimensions there.

 

[PaulRainbow]

Hi

I have a Bavaria 32 and would really appreciate it if anyone can help?

I've recently purchased a shunt to start monitoring my battery before installing solar panels. The wiring diagram (Panel 424) that comes with the owners manuals for a Bavaria 32 states that the cable running to the earth on the domestic battery is 95mm sq. (see attached for details). Having used my callipers the actual width of the cable is only 10-11mm which equates to a 35mm sq cable and is considerable smaller than the approx 16mm cable which is standard for a 95mm sq cable.

I need to make up a spare cable to run between the earth on the domestic (140Ah) battery and the shunt.

I want to keep the electrical system as uniform as possible. If I purchase a 95mm sq cable it will be considerable larger than the cable(s) that are current in situ. If I purchase an 35mm sq cable then I will potentially introducing a different amp rating into the system.

I should point out that I only have one domestic battery rather than the two that is in the original Bavaria 32 wiring diagram, so some modifications has taken place (previous owner of the boat).

If the current battery cables are 35mm, the shunt cable can also be 35mm.

35mm cable for your boat is more than adequate for the domestic loads or even for starting the engine. It's rated at 240A, you'll most likely never see more than 12A drawn from the domestic battery.

 

[Jodel]

Are you sure you have your calculations correct? Google suggests that 11mm diameter gives 95sqmm area.

 

[pvb]

Are you sure you have your calculations correct? Google suggests that 11mm diameter gives 95sqmm area.

You're ignoring the insulation, which increases the overall diameter. 95mm² cable is typically about 18mm overall diameter. 35mm² cable is typically about 12mm overall diameter.