Notice: We request that you don't just set up a new account at this time if you are a previous user.
If you used to be one of our moderators, please feel free to reach out to Chris via the facebook Outerlimits4x4 group and he will get you set back up with access should he need you.
Recovery:If you cannot access your old email address and don't remember your password, please click here to log a change of email address so you can do a password reset.

12v circuit breaker question

For all things Electrical.

Moderator: -Scott-

Post Reply
Posts: 2732
Joined: Fri May 28, 2004 11:50 pm
Location: Perth, WA

12v circuit breaker question

Post by stuee »

Hi all,

I have a question regarding this type of circuit breaker
Image

Do these operate with current travelling in either direction? They are marked with a positive terminal and negative terminal. Reason for this is that I have a 2nd battery in the back and want to have a breaker at each end so that if the cable were to break half way then the spare battery wouldn't cause a fire if the cable were to short circuit (this is opposed to having a breaker at only one end).
-Scott- wrote:Isn't it a bit early in the day to be pissed? :finger:
Posts: 558
Joined: Sat Dec 11, 2004 4:38 pm
Location: Gold Coast

Post by drivesafe »

Hi stuee, sure their note marked “BAT” next to the short stud and “AUX” next to the long stud.

Away, they are not polarised, in other words they do not have to be fitted in one specific direction.

They have a short stud for the battery side because there is usually only one cable to be connected on that side while on the other side there is a long stud so that you can connect a number of cables to it.

So in your case, you can fit them any way that suits you.
2007 TDV8 Range Rover Lux
2009 2.7 Discovery 4
Posts: 2732
Joined: Fri May 28, 2004 11:50 pm
Location: Perth, WA

Post by stuee »

Cheers Drive Safe,

I just picked this unit up when I saw it in Jaycar while picking up some distribution blocks. Got a plus and minus sign but different length studs like you say. I was just concerned that perhaps the breaker mechanism might only work in one direction as I have no idea how these particular breakers work.
-Scott- wrote:Isn't it a bit early in the day to be pissed? :finger:
Posts: 3523
Joined: Fri Aug 27, 2004 12:27 am
Location: Fairfield,Sydney

Post by pongo »

If in doubt bench test it and let us know, Better to be safe
Posts: 2732
Joined: Fri May 28, 2004 11:50 pm
Location: Perth, WA

Post by stuee »

pongo wrote:If in doubt bench test it and let us know, Better to be safe
Unfortunately I don't have any equipment that can suck up over 50 amps. I guess I could always try shorting the lead but that's a bit dodgy.

I'm happy with drive safes opinion at present.
-Scott- wrote:Isn't it a bit early in the day to be pissed? :finger:
Posts: 558
Joined: Sat Dec 11, 2004 4:38 pm
Location: Gold Coast

Post by drivesafe »

Hi stuee, I’d be a little cautious of anything bought from Jaycar unless it was specifically labelled as being intended for automotive use.

This may be the reason for the strange stud markings.

See if there is some info about the device on their web site because while the quality of the product is not in question, how it performs could be.

There is a specific paten for how an automotive circuit breaker must work but circuit breakers made for other uses may not ( and in most cases do not ) perform in a way that is suitable for automotive use. It might mean that your 50 amp CB will perform more like a 20 amp automotive CB.

This may sound strange but there are some very big differences in the way CBs operate. A CB intended for use in a sound system may trip if the applied current exceeds the marked CB maximum by just 10% while an automotive CB is designed to tolerate up to 45% above the marked maximum for 1 hour.

This shouldn’t be a major problem other than it may trip every time a high current load is switched on, like driving lights or your fridge motor and so on.
2007 TDV8 Range Rover Lux
2009 2.7 Discovery 4
Posts: 2732
Joined: Fri May 28, 2004 11:50 pm
Location: Perth, WA

Post by stuee »

The CB part number was labeled as being an automotive 12v CB.

Mind you that's not to say that they haven't been mixed up with others or placed there incorrectly. I'll look into it. Worst case I'll take it back. Still a while of putting the battery in anyway.
-Scott- wrote:Isn't it a bit early in the day to be pissed? :finger:
Posts: 558
Joined: Sat Dec 11, 2004 4:38 pm
Location: Gold Coast

Post by drivesafe »

Hi stuee and this may sound like nothing more than splitting hairs but if it’s a genuine AUTOMOTIVE circuit breaker, it shouldn’t have 12 volts marked on it because Automotive circuit breakers can be use in 6v, 12v and 24v vehicles.

That one just may be the way the Chinese mark them but it’s not common to have the voltage marked on them and it should not matter what voltage they are use with, the current rating is the same, I just have come across voltage specific automotive circuit breakers.
2007 TDV8 Range Rover Lux
2009 2.7 Discovery 4
Posts: 2732
Joined: Fri May 28, 2004 11:50 pm
Location: Perth, WA

Post by stuee »

Well I took the easy option, took the jaycar unit back and found one marked with the batt and aux. All good now :D
-Scott- wrote:Isn't it a bit early in the day to be pissed? :finger:
Post Reply

Who is online

Users browsing this forum: No registered users and 0 guests