Just got an Adria and it is fitted with a battery in the gas compartment, I'm sure this is wrong and I plan to move it to the compartment next to the electric devices, under the left hand bed compartment. Who ever fitted the battery has not fitted fuses. Anyone know what size fuse should be used in the supply to the battery and the size of the fuse at the battery end.
On my Lunar, the main inline fuse from battery is 20A, and fitted between battery and Power Supply Unit. All the other various output circuit fuses are integrated into the Power Supply Unit.
If you have a motor mover fitted, that should be supplied direct from the battery terminals via it's own isolator switch and it's own supply fuse, NOT taking it's supply after the main fuse above or using same cable feeding the main fuse.
Never seen a battery fitted into gas locker, always in their own locker, sealed from interior of van and venting any charging derived hydrogen/oxygen gases and acid fumes to outside. No electrics in my gas locker. Wise move to shift it even if not required by regulations (which I would have expected).
Weight of it must do horrible things to your nose weight on the hitch!!
I agree, I would move the battery out of the gas locker.
I had a problem with the battery fuse holder shortly after I bought my caravan, so I replaced it with a small 20 amp circuit breaker. Saves having to carry spare fuses, and a simple press resets it. Not that I've needed it so far. Of course, my motor mover doesn't go through it, as it runs direct off the battery with its own isolator.
Hi Colin, I'm not sure if a circuit breaker is up to that job. Maybe a bit technical but here goes.
A battery has the potential to deliver a very high short circuit current if the terminals were to be connected directly together. Circuit breakers have a short circuit breaking capacity which may not be very much on some. In other words it might not trip and may suffer some pretty serious damage.
Unfortunately I dont know the short circuit current of your battery or the breaker, I normally deal with mains electricity.
Quote: Originally posted by navver on 30/6/2020
Hi Colin, I'm not sure if a circuit breaker is up to that job. Maybe a bit technical but here goes.
A battery has the potential to deliver a very high short circuit current if the terminals were to be connected directly together. Circuit breakers have a short circuit breaking capacity which may not be very much on some. In other words it might not trip and may suffer some pretty serious damage.
Unfortunately I dont know the short circuit current of your battery or the breaker, I normally deal with mains electricity.
Shouldn't be any problem, there were no fuses on my boat, only circuit breakers. That was all 12 volt circuits and 220 ah leisure batteries.
I could have replaced the fuse-holder, which was suffering from corrosion, but I decided to go with a circuit breaker instead. A short circuit at the battery is highly unlikely and the circuit breaker is probably more sensitive to an overload than a fuse.
I have worked with both mains and low voltage circuitry, but I must admit not for a good many years, except for my own equipment.
An AC breaker has different requirements to a DC breaker, AC breakers might not break a high short circuit DC current and may suffer damage and potential fire risk.
A DC breaker, as the voltage is constant, needs different tripping characteristics,a DC arc, created as the contacts separate, will maintain the arc due to the voltage being constant whereas AC voltage goes through 0 volts 50 time per cycle so the arc is easier to interrupt,as a result the DC contacts need greater separation to safely extinguish the arc.
As Navver has pointed out,for the above reason, it is necessary to ensure that if an AC breaker is used it has a DC rating as well.
saxo1
Quote: Originally posted by navver on 01/7/2020
I think you just need to make sure the breaker has a DC rating. If it's just an ac breaker it may not do the job on DC.
Not an AC breaker Navver, a purpose-built DC one like the ones on my boat. My boat was a sea-going one originally, and I have always thought that they used circuit breakers so that you don't have to carry hundreds of fuses at sea. That my be completely wrong though, it's just my guess. I did think though that if they are good enough on a sea-going boat, they must be good enough in a caravan. I only ever used the boat on the river though.
That sounds OK Colin. I think you're right, it's better to have a resettable breaker than a fuse, just needs to be up to the job. Sorry but it just rang an alarm bell with me.
Quote: Originally posted by navver on 02/7/2020
That sounds OK Colin. I think you're right, it's better to have a resettable breaker than a fuse, just needs to be up to the job. Sorry but it just rang an alarm bell with me.
I can quite understand your concern Navver. Some people might not realise the difference and use the wrong thing.
Thanks Colin. We always had to calculate the fault levels in the networks and ensure all switch gear fuses, breakers etc were up to the job and could operate avoiding damage. This was all theoretical of course.
However, many years ago when I was a very young engineer I worked with a very old engineer who had worked all his life for a major British switchgear manufacturer. They had their own ASTA testing station which would test and certify switchgear made either by them or other manufacturers. (ASTA = Association of Shortcircuit Testing Authority)
I was very privileged because the old engineer arranged for a couple of us to go there and witness a short circuit taking place. They set up some copper bus bar and passed 50kA (50,000amps) through it.
We went about 30 yards away behind a very thick glass screen while they did it. There was a huge explosion and a great thudding of the ground. The copper bars violently threw themselves apart under the extreme magnetic forces. I have never forgotten it.
I have a similar working background to yourself Navver,I worked for SWEB as it was for just under 40 years.
I remember when we I was attending a re-authorisation course at Redlands training centre in Bristol we saw a film, possibly of the short circuit demo
you describe it gave me a healthy respect for the force of electricity.
saxo1
I've had a couple of experiences of the power of electricity. First one was when I was in my first job, which was with a company making custom-built battery charging equipment. I saw quite a large screwdriver roll off a bench and drop neatly across the terminals of a rather large 12 volt battery. It blew it apart like a piece of fuse wire, along with both battery terminals. Second time was while I was training with London Underground at the end of the 1960s. I had to learn how to put down an SCD (short-circuit device) across the live rails to take off the traction current. This is 630 volts DC at goodness knows what amperage. You had to grab the device by its wooden handle, hook the other end over the negative rail, turn your back, and slam the SCD down onto the positive rail. I don't think I've ever heard such a bang or seen such a flash apart from lightning! What that would be like in a tunnel I don't know, I was out in the open.