power up the trailer
Submitted: Monday, Sep 26, 2005 at 23:28
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Spade Newsom
I am planning to run a parallelled cable from my auxillary battery to an anderson plug at the rear of my vehicle. This can then be connected to a battery bank in the trailer to run fridge lights etc. I know that battery compatability / voltage drop will make this not overly efficient however......
A couple of questions if some educateds could assist;
1. I understand that a circuit breaker rather than a fuse should be mounted close to the vehicle auxillary. Why is this so? I have a 30 amp (sufficient????) 12v circuit breaker from Autobarn. How do I tell when/if it has been tripped and how is it re-set. It came with no info. (They assume buyer knows what he is doing I guess). Should the cable from trailer battery bank to the plug into the car also have a circuit breaker?
2. Should the trailer battery bank be earthed or should the negative be fully cabled. Noting that the trailers electrics (tail lights etc) are already earthed. If both electrical sources are earthed is there any interference?
3. Can the cable from car auxillary use vehicle as earth or will this interfere with the cars normal electrics.
4. Inline or blade fuses. What is better?
Apologies if my jargon is wrong here. Feel free to correct.
Spade
Reply By: Well 55 - Tuesday, Sep 27, 2005 at 07:16
Tuesday, Sep 27, 2005 at 07:16
As I see it most circuit breakers are self resettable, and 30amp will be sufficent. i use a 30amp blade fuse in place of a breaker, and carry a couple of spares.
Run both wires from the battery, earth and positive.
Blade fuse is the better one to use.
AnswerID:
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Reply By: drivesafe - Tuesday, Sep 27, 2005 at 07:26
Tuesday, Sep 27, 2005 at 07:26
Hi Spade Newsom.
The reason for using a circuit breaker is that, depending on how the wiring is set up, there are a number of circumstances that can arise that will regularly blow fuses. By installing circuit breakers, it won’t matter if these same circumstances occur as the circuit breaker will trip and reset ( depending on the type circuit breaker used ).
If the circuit breaker you have, has two cable mounting bolts, one slightly longer than the other, then this is an automatic reset type and will simply reset itself, if it is tripped. This is the recommend type to use for you set up.
If it has a button of some sort on it, then it is a manual reset type and if it trips, you have to reset it.
The cables running between the tow vehicle and the trailer should be at least 10mm2 or 6B&S ( 13.5mm2 ) to reduce the amount of voltage drop and you should run both a positive and a negative cable of the same size, between the two batteries.
You should still earth the batteries at each location because, ( besides other reasons ) this will actually reduce the chance of electronic interference although this is not a normal problem.
Circuit breakers should be installed at each end of the positive cable running between the two batteries and they should be installed as close as practical to the battery’s positive terminal.
Blade fuses are more reliable because of the way they mount.
Cheers and hope this helps.
AnswerID:
131939
Follow Up By: geocacher (djcache) - Wednesday, Sep 28, 2005 at 00:05
Wednesday, Sep 28, 2005 at 00:05
Footnote
The reason that the two circuit breakers are a good idea and close to the batteries is that should cable damage occur either while plugged into the vehicle or not, there won't be a fire.
The capability of these batteries to deliver current is huge. Heavy cable hooked up to them could pull hundreds of amps if shorted which quickly generates heat and melts and sets fire to plastics and the like that it is in contact with including the insulation.
Dave
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