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Battery Charging/refrigerator Problem


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#1 Steppenwolf

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Posted 10 June 2012 - 08:27 PM

We've recently got back from a full shakedown trip with our new 2012 Lunar Delta RS. Everything worked perfectly apart from the refrigerator clicking on and off when running from the car with the engine running.

I have now completed a full check of the system and as I had suspected that the largish refrigerator was drawing too much current from the car's original split relay charging system, I doubled up the 12v supply cable in the car. However, not only has the refrigerator stopped working but I now note that the caravan battery isn't charging either!

I have checked the wiring from the battery/split charge relay all the way through to the fuse panel in the caravan. With the engine running, the split charge relay definitely switches over and I am getting 14.28v right to the back of the fuse unit in the caravan. However, from there onwards the voltage on all relevant fuses (and the caravan battery) is reading only 12.5v - this is clearly the voltage available currently (ooops pun!) from the caravan battery and not the split charge relay.

When I connect the 12S plug, the ATC unit cycles (as it should) and a relay can be heard clicking over once in the PSU module in the caravan (as it should).

I know the 'van is under warranty but if I can sort this myself, I'd like to do so. Is there a second relay that should have tripped when a charge voltage is detected? Does anyone have any thoughts on what the problem could be as it is clearly not limited to just the refrigerator? And, yes, I have checked the relevant fuses!

#2 Ich

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Posted 10 June 2012 - 08:31 PM

Possible loose connection in that area? Or a fuse that you don't know about

#3 BrianI

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Posted 10 June 2012 - 08:44 PM

I have now completed a full check of the system and as I had suspected that the largish refrigerator was drawing too much current from the car's original split relay charging system, I doubled up the 12v supply cable in the car. However, not only has the refrigerator stopped working but I now note that the caravan battery isn't charging either!

The problem is most likely in your car. If the fridge is not working, neither will the caravan battery charge as there is a relay in the caravan that swiches the caravan battery into circuit once it detects a supply going to the fridge. It was certainly a good idea to double up on the wiring but you must have done something to stop the power getting to the fridge. Pin 6 on the 12S should be live with engine running.
Pin 4 supplies the ATC and battery charging and is permanently live but the battery needs the relay to operate. If you sort out the frideg supply everything should work.
Brian

#4 Steppenwolf

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Posted 10 June 2012 - 09:33 PM

If the fridge is not working, neither will the caravan battery charge as there is a relay in the caravan that swiches the caravan battery into circuit once it detects a supply going to the fridge. It was certainly a good idea to double up on the wiring but you must have done something to stop the power getting to the fridge. Pin 6 on the 12S should be live with engine running.


Brian, thank you, this is very useful information about the fridge 'controlling' the caravan battery charging. I have a 12n +12s to 13 pin adapter (caravan is 13 pin, car is twin socket). I have tested for 14.28v on pin 10 of the adapter and at the caravan cable end (at the PSU inside the caravan locker) which is a red/brown cable on the Lunar. The 14.28v is there all the way to the fuse board printed circuit board from where I can see and test the circuit board side of the fuses and the voltage on both the refrigerator and battery fuses is 12.5v.

Is the relay that is switched when the refrigerator receives the correct voltage in the refrigerator wiring compartment or in the region of the caravan battery compartment (the two are on opposite sides of the 'van).

Your input much appreciated.

#5 BrianI

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Posted 11 June 2012 - 06:05 AM

Caravan relays are normally in the area with the charger/fuseboards, not near the fridge. There would be a wire coming from the frideg supply to the relay coil to trigger it.
Brian

#6 carabiker

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Posted 11 June 2012 - 06:21 AM

Hi
the best option is to covert the 2 X 7 pin sockets to 13 pin
The 7 pin sockets amd plugs are only rated at 7 amp
The fridge will draw about 12 -14 amp charger upto about 15 amp if the battery is low

The voltage readings you quote will be "no load " volts " these readings will drop under load ie the fridge on


Make sure the cable sizes from the car battery to the split relay are minimun of 2-5 mm cross section and individual earths from the socket to the car body Same applies to the constant live feed from the car battery to the 13 pin socket both fused at 15 amp each

Edited by carabiker, 11 June 2012 - 06:26 AM.


#7 Steppenwolf

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Posted 11 June 2012 - 08:18 AM

Thanks Brian and carabiker. The twin cables from the car battery to the split charge relay are 44/0.30mm, 3mm2, 27.5amp cable so I would hope that this was more than adequate.

When the battery was charging a few days ago, the on load voltage was 13.35 as measured as the caravan battery terminals using just the single cable run in the car but this was without refrigerator running as that was the original problem.

Moving over to 13 pin is tempting but I tow other trailers for other hobby pursuits so need to think carefully about that first.

I suspect that the refrigerator relay has burnt out but the only relays that I can currently locate appear to be soldered to the fuse board circuit board so I cannot remove them for testing.

#8 BrianI

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Posted 11 June 2012 - 08:40 AM

Your earlier post said your fridge was not working. The relay that switches the fridge on with engine running is in the car. Maybe you know this but I just thought I would clarify.
Brian

#9 Steppenwolf

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Posted 11 June 2012 - 08:56 AM

That's fine, Brian, I know that (it's the split charge relay) - the relay that I am now talking about is the one that you alerted me to that switches over when the refrigerator gets 'alternator level' voltage and allows the battery to be charged.

#10 carabiker

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Posted 11 June 2012 - 09:21 AM

Hi

To clarify
The relay in the rear of the car is the split relay this operated / switch by the increase in volts from the alternator

The other van relays are the habition relays , The operation of the habitation relay are determined by the van selector swicth
In the off mode and the van connected to the car with the engine running at about 1000 rpm the split relay in the car turns on the fridge circuit inturn the habitation relays switch to allow the fridge and van battery charger to function also turns off the other circuits in the van ie lights pump

The only way to determin if the fridge is working is to measure the voltage at the fridge under load and test to see if there is a volt drop and then work backwards towards the car socket and then the split relay

with the requirements and total load for the fridge , battery charging and ATC I would concider a 6 mm feed fused at 30 amp from the car battery to the rear of the car a better option to avoid volt drop


re the 7 pin sockets
install a 13 pin for the van and wire a 7 N pin socket for the other trailer lighting

Need a spell checker
dyslexic
Dave

#11 DeeTee

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Posted 11 June 2012 - 09:27 AM

I would suggest that the car is converted to a 13 pin socket and either use the other trailers with a 7N to 13pin adaptor or fit the other trailers with a 13 pin plugs.

#12 Dorchester

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Posted 11 June 2012 - 09:51 AM

As Dee Tee suggests above, I strongly recommend the switch to a 13-pin socket on your tow car. The 13-pin connector is of a far superior design and does not suffer from any of the disadvantages of the 7-pin connectors. It is also rated at a higher current then the 7-pin units.

The easiest way to cope with your other trailers (assuming that they require only a a 12N connection) is to obtain one of these, which simply plugs directly into the car 13-pin socket and instantly converts it to a 12N. I always keep one of these adaptors in the boot of my car>

Hope that this helps.

Regards,
David

#13 Steppenwolf

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Posted 11 June 2012 - 08:29 PM

OK folks, thank you very much for your input. Sadly, I think I am going round in circles now as I understand the wiring system OK but it is not doing what it should do!

To recap and clarify:-

1. I have an ample current capability, direct permanent 12v supply from the car battery to pin 4 (12S) and I know that it enters the caravan. I know this is working:-

( a ) using a test meter (it measures about 12.7v)

( b ) because the ATC LED lights up and the unit cycles through its test procedure

2. The voltage on the two outputs of the car's split charge relay in the boot is 0.8v approx (must be some kind of residual)

3. If I start the car engine, after a few seconds, I can hear the split charge relay click and the two outputs read 14.28v as indeed does the permanent 12v feed (as one would expect)

4. I can trace 14.28v all the way through to the fuse board in the caravan but the battery and refrigerator fuses immediately adjacent both show only 12.5v (the voltage that I have measured independently on the caravan's 12v battery)

5. With the engine running, the refrigerator shows an error message 10 which means 'engine not running!

6. With the engine running, the caravan battery still shows a voltage of 12.5v so it is not charging

Soooooo I have now checked out the habitation switching and have discovered the following:-

1. With the caravan master switch set to 'ON' and the car disconnected, the caravan internal lights work as normal.

2. With the caravan master switch set to 'OFF' and the car disconnected, the caravan internal lights do not work.

3. With the caravan master switch set to 'OFF' and the car connected but not running, the caravan internal lights still do not work even though the ATC is working!

4. With the car disconnected and the master switch set to 'ON', the built in control panel test meter shows approx 12.5v

5. With the car connected but not running and the master switch set to 'ON', the built in control panel test meter shows approx 12.5v

6. With the car connected, the engine running and the master switch set to 'ON', the built in control panel test meter shows approx 14.3v

I must, therefore, conclude that there is a problem with the refrigerator circuit or the habitation relay(s).

I will give serious consideration to upgrading to a 13 pin socket on the car and one of the adapters that David suggests but currently do not feel that this is the immediate problem as previously, the caravan battery has charged correctly.

Again, I appreciate your kind input.

Edited by Steppenwolf, 11 June 2012 - 08:29 PM.


#14 carabiker

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Posted 12 June 2012 - 06:36 AM

1. With the caravan master switch set to 'ON' and the car disconnected, the caravan internal lights work as normal.

Correct
2. With the caravan master switch set to 'OFF' and the car disconnected, the caravan internal lights do not work.

Correct
3. With the caravan master switch set to 'OFF' and the car connected but not running, the caravan internal lights still do not work even though the ATC is working!
Correct

4. With the car disconnected and the master switch set to 'ON', the built in control panel test meter shows approx 12.5v

Van battery voltage
5. With the car connected but not running and the master switch set to 'ON', the built in control panel test meter shows approx 12.5v Van battery voltage

6. With the car connected, the engine running and the master switch set to 'ON', the built in control panel test meter shows approx 14.3v
Correct Car battery / alternator voltage

I must, therefore, conclude that there is a problem with the refrigerator circuit or the habitation relay(s).


Have agree looks like the habitaion relays or some form of over load

Quick general check is to set the van panel to "on " and turn on the interior lights , connect the car to the nan start the car and increase the revs
The internal van lights should go Out and van battery charge and fridge function

I assume the elec system is by Plug in Systems
I have
1 ) the Bailey factory wiring diagrams with fault finding (by P i S )
2) a diagram that discrbcribes how the habitaion relay function

If required PM me with a direct addy


The other option is to try an other car connected to the van and see if the test results are the same
May be worth looking at the Lunar web site to see if a mobile caravan Tech has aurtherization to carry out warranty work

#15 TD 42

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Posted 12 June 2012 - 07:11 AM

If you are testing with the car on tickover only you may find that you need to increase the revs to around 1000/1200 in order to energise the habitation relay properly in order for the charging & fridge systems to operate properly

Edited by TD 42, 12 June 2012 - 07:12 AM.


#16 Steppenwolf

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Posted 25 June 2012 - 09:15 PM

I have had the twin electrics replaced with a new single 13 pin socket - a much neater and far firmer connection. However, the refrigerator/habitation relay problem persists so the 'van is going in for a warranty repair this Wednesday.

Thanks all for your help.

#17 Dorchester

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Posted 25 June 2012 - 09:47 PM

Well, I think that you have done all of the checks that could be done on "your" equipment, and it could well be a high resistance contact on the habitation relay or its terminals. Anyway, I do hope that they get it sorted for you under warranty.

Incidentally, I believe that you have done the right thing in changing the car sockets for a 13-pin socket, for in my opinion it is of a far superior design to the 12N & 12S (but that's just my opinion - others may disagree!).

Do please let us know the outcome when the matter has been sorted.

Regards,
David :)

#18 Steppenwolf

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Posted 27 July 2012 - 12:31 AM

I have an update and good news!

The caravan was returned to the dealer under warranty and while I was there, they connected my car up to another caravan which confirmed that the car electrics were working fine (more about this later!)

They confirmed that they were unable to power the refrigerator or charge the caravan battery with their own test equipment as there was a fault with the Habitation relay circuit. This problem turned out to be an earthing issue - there wasn't one!! With a new earth circuit installed the system appeared to be working just fine but after a 5 minute test the internal lights came on with the engine running indicating that the habitation relay had released again! A quick test with their diagnostic set confirmed that the caravan was now not at fault so with one problem resolved, I had to find the second fault.

Whilst checking the voltage on the input and output of the split charge relay, I heard the relay click and the output voltage dropped to zero! I had found the second fault, the voltage sensor threshold was too low so over a five minute period, the high current draw was either warming the cabling and thus increasing the resistance or the split charge relay's sensor was overheating and tripping - in any event, the solution was to tweak the threshold setting a fraction and all is now well.

Two faults, who would have believed it? At least I now know why I was going round and round in circles with my testing .....

The reason why the split charge realy had not failed when testing my car on their caravan was that we didn't test it for long enough for it to trip.

#19 Dorchester

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Posted 27 July 2012 - 08:14 AM

I am so pleased that the problems have now been sorted Stephen. What an unfortunate so-incidence to have two separate issues contributing to the 'fault' - but al least you managed to locate them and cure the problem :)

The other benefit is that you now have the ISO standard 13-pin plug and socket fitted, which in my opinion is far superior to the 12S/12N set-up.

Regards,
David

#20 FlyingTog

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Posted 27 July 2012 - 08:40 AM

If you are testing with the car on tickover only you may find that you need to increase the revs to around 1000/1200 in order to energise the habitation relay properly in order for the charging & fridge systems to operate properly


Unless you have a dynamo fitted, modern alternators produce the correct charging voltage at the engines idle speed.

The "rev it to charge it" is a hangover from the days when dynamo's were fitted to cars.

FT

PS... I wrote a bit about charging circuits, alternators and dynamos a while ago... http://caravanchroni...arging-circuit/




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