How to carry out a load test?
 

I would like to see what amperage I can get at the 13 pin socket of my cars towing electrics. I can measure voltage but don't knowingly know how to test amperage without plugging something into the socket and I don't want to plug the caravan in. I may have known and simply forgotten how, so could find myself being embarrassed.
The fuse is 20 amps and would like to get perhaps 12A.

Can you tell me how?

macafee2

Hello Ian,

I'm afraid it's not possible. The available current will depend upon the alternator's output (and whatever other equipment is operating at the time) but 12 amps shouldn't be a problem. :D

Simon

Thanks Simon, is there an easy way to create 8-12amp load, in 1 amp steps?


macafee2

Hi Ian,

Is it the 13 pin towing socket that you're worried about? Do you want to be sure that the wiring can carry 12 amps?

Two car headlamp bulbs connected in parallel with draw just over 8 amps; a single one 4 amps. That's about as easy as it gets! :}

Simon

cheers Simon, I can do 4 amps, I have a headlight with some wires on for testing, thank you. If it melts, it cant carry 12 amps :)

macafee2

You don't really need to set up any practical experiments to answer your question on the suitability of your caravan connector wiring. Standard auto electrical cables/insulated wires have current ratings directly related to their thickness/cross sectional area. A simple Google search will provide lots of info that will indicate what size wire you need for what ampage and any associated factors.
Click: https://www.google.co.uk/search?safe...4dUDCAg&uact=5

EDIT: Of course you'll need a vernier caliper of some kind to measure the wire size.


TC

Wiring is already in. On a caravan forum, it has been said that sometimes there is not enough power getting to the caravan fridge when being towed to keep the fridge cold. I was curious to know how my car was doing. This may be a problem of smart alternators of which our cars do not have.

macafee2

It's been 2 years now since I last hooked my van up, when i did I found that the fridge didn't work on 12v you could just hear a clicking behind the fridge (relay?). I had fitted a new alternator so assumed this had caused a change in power supply and I was given to understand that the towbar electrics should have a relay fitted that is adjustable to compensate for any power difference. I haven't sorted the problem because of lack of use and will likely sell the van in the spring so might not get to the bottom of the issue.
This of course may be a completely different issue to what you are trying to resolve but thought I'd throw it in just in case it has any relevance.