Q&A - How do I find the problem with consumer unit?
The 12v system is not working in my 1999 Countryside 500-EB and I am having a problem with the electrical consumer unit. Do you have a circuit diagram and list of spare parts please?
Response
You'll have a Power Centre 11 - 240v/12v distribution/charger unit. The 12volt system comes from the internal charger, which not only charges up your caravan battery when connected to the 230v mains but also supplies 12v to the lighting and pump etc.
The 12 volt system is limited to 10amps. If there is a greater requirement for 12 volt power the charger has an inbuilt limiter and will shut down all 12 volt systems. This I think is what has happened in your case. It will not come back on until the overload is removed!! Try the following:-
- Remove all 12v fuses on the side of the Power Centre11
- Open the 230volt switches (all 3)
- Connect the 230v mains to the caravan
- Switch on the mains switch on the other 2 breakers and check that the 230v systems work OK.
- Replace the12volt fuses one by one, (Leave the lighting until last) checking that each appliance is off before you replace that circuit fuse then turn that appliance on.
Let me know how you get on.
Reply
I have had a further look at this electrical problem after your previous email.
| This diagram shows all the major components inside the electrical panel. |
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- The 12v power unit is giving out at least 13v
- The circuit breaker and the other 230v switches are all working correctly
- The fuses are all working and 13v is going through them all.
The relay I have marked as relay 1 is switching over when given power but the other relay (relay 2) contacts cannot be seen.
I am assuming since it is the only item I can’t see working that it may be at fault.
When "hooked up" to an outside 230v system everything works except there is no 12v going to the leisure battery.
When the 230v is removed nothing works and the battery voltage doesn't come back into the caravan.
Can you please advise if this "RELAY 2" is the relay that connects the charger to the battery and allows the voltage to return when the leisure battery is "in use"
Response
The two relays you refer too are the 'Auto CAR/CARAVAN battery changeover relays.
Their purpose is to provide isolation of the 12 volt systems in the caravan when the car is connected to the caravan via the 12S plug/socket, and allows the caravan battery to be charged while the car engine is running.
Sounds to me as if one of these relays has failed (or its contacts have welded together) either way it's non-operational.
To test the system, disconnect the wiring to the contacts of the relay, and you should have the 12 volt back on within your caravan. If that is the case you'll need to replace the relay.
A couple of other thoughts!
I assume your battery is in tip top condition, with nothing connected the terminal voltage should be above 12 volts.
An easier way of checking the relays is to connect the caravan's 12S plug into the car and start same while someone is observing the relay operation. Check the battery voltage with the car's engine running, What is the voltage?
One last thought!!
There should be an in-line fuse from the battery to the 12volt distribution unit.
- This could have blown, think it's a 20 amp fuse.
- You'll need to check the physical wiring from your battery to the distribution unit to find it.
Also check the battery connections and those in the distribution unit are tight.
The more I think about it I'm leaning towards the battery/wiring end of things so check these first.
Reply
The things you have mentioned.....
- Relay .. upper one operates but can't see the lower one because it's obstructed .. would have to remove it from its fixings
- Battery wiring/condition .. looking good
- Fuse from/to battery .. I can't see one, is there another distribution box or holder or would it just be in the cabling?
There was a sort of clicking sound before things went wrong which makes me think the relay contacts have welded themselves together!!
Can you tell me where to get the relay from?
Response
The fuse would be in the cabling, if you can't see it maybe they didn't fit an in-line one for your year. Can you see where the cables go into the distribution box? Is there a fuse in there????
This fuse provides for reverse polarity protection if you should flash the battery leads on the wrong terminals in error. If this has occurred and your unit does not have this protection you could have damaged more than the relay, hopefully not.
With regards to the relay can you see a manufacturer on the distribution box, it should be one of the following:- Plug in systems; Zig; MCS or BCA Leisure.
The easiest way to match up the relay would be to take it to Maplins and get the nearest equivalent elect spec and physical size.
Alternatively you could get an electronics engineer who specialises in the repair of caravan power supplies to do it for you.
Update
Found another fuse box under one of the front seats - near to where the leisure battery is stored. So there is more than one fuse panel - silly idea not keeping everything together!
So the caravan is working again, thanks for your help.
