24 Volt help, engine room ventilation.


Old 08-31-18, 11:33 AM
Thread Starter
Join Date: Aug 2018
Location: Norway
Posts: 2
Received 0 Votes on 0 Posts
Smile 24 Volt help, engine room ventilation.

Hi to all,
New to this forum and I hope someone can give me some help with regards to wiring up my engine room fan system.
My boat was fitted with 6 flange mounted fan units, 4 blowing air in and 2 extractor.The fans are all the same size and type single speed 24 Volt DC and I am guessing approximately 6amps wired to 1 switch on the console. This fan system has never worked during my ownership and on investigation I found cracked,brittle wiring and what looks to be the remains of a 40 year old resistors (hard to tell with corrosion) and basically a mess.

I have stripped all this out and tested each fan directly from a battery and they all work, so I would like to reinstate these and get this working. I am no genius in electrics but I know I cant wire 6 motors to one switch without something melting so I assume I will need som form of relay ? To get this running again.

Any advice on what will be needed here would be greatly appreciated and thank you for taking the time to read this.

Old 08-31-18, 03:09 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 60,725
Received 1,316 Votes on 1,216 Posts
Welcome to the forums from overseas.

Wiring all the fans in parallel to a single switch is ok. If all the fans are wired to a point near the power supply (batteries) then using a switch to activate a relay would make better sense especially to keep voltage drop down on long wire runs. The resistors are more than likely there to reduce the speed of the fans. If you want to be able to reduce the speeds of the fans now...... use a PWM controller. This is an electronic speed controller designed to safely reduce the speed of low voltage motors without harming or overheating them. I've shown one in the link below.

Old 09-01-18, 12:24 AM
Thread Starter
Join Date: Aug 2018
Location: Norway
Posts: 2
Received 0 Votes on 0 Posts
Thanks Pete,

The controller you mentioned is a good idea and at only $15 and some P&P it's not going to break the bank, so I will give this a try. Quite sure i am going get myself into trouble with some other part of the electrical system in the near future so to quote some famous big guy,

i,ll be back.


Thread Tools
Search this Thread
Ask a Question
Question Title: