curious loss of main battery power .....

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Re: curious loss of main battery power .....

Post by CovKid »

These days you need bigger batteries. In the 80s most of us still had tungsten bulbs and a simple radio. Now our expectations are that much greater so an 096 sized battery is about right and perfect in the winter months when batteries tend to perform below par.
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Re: curious loss of main battery power .....

Post by ghost123uk »

waltraud wrote: Any ideas how to check westy fridge for 12v function.

Just check with your meter that 12 Volts is reaching the fridge and that it is earthed correctly. Then you need to drive around with it on for at least an hour before you will feel the ice box start to get cold, it takes that long. Also note that it should be wired (via a special terminal on the relay) so that it can only get 12 Volts when the engine is running (otherwise it would flatten your battery in no time). If it still does not work you need to look at the switch on the fridge and the wiring to the heating element, or even the element itself (though they rarely break). I think there will be a thermostat somewhere on the fridge also, but not sure about that, it varies from fridge to fridge and as far as I know, mine only has a stat for use on he gas. If yours has one, test it's continuity (again, with your meter).
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Re: curious loss of main battery power .....

Post by Ian and Lins »

Sorry to butt in; to test for a 'drain' on the battery (either starter of leisure) I assume you disconnect the 12v 'live'/red and put a volt meter in series between the batery post and the terminal. If it reads 12v then someting is taking current? What would the reading be if nothing is taking power/current?
Are we going on anything else?

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Re: curious loss of main battery power .....

Post by waltraud »

Thanks all. I noticed that I had not plugged in the two pin mains plug for the fridge. Obviously it makes no difference for 12v or gas functionality but I did wonder if this was a combined earth for 12v also? I think the 12v functionality runs via a connection with three wires and another with one wire.....or so I have read. If this is the case can anyone help me to identify which wires do what so I can start to isolate what functions they have and test. I will start tracing them to sources.
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Re: curious loss of main battery power .....

Post by ghost123uk »

Edited = double post = see below !
Last edited by ghost123uk on 07 Jul 2014, 08:56, edited 1 time in total.
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Re: curious loss of main battery power .....

Post by ghost123uk »

@ waltraud I have never worked on a Westy fridge but I am guessing it is just the same as the usual "RM some number" ones fitted to most T25 campers. There should be some indication of the model somewhere on it, let "us" know and we can point you to a circuit diagram. Mind you, a person well versed in the use of a test meter set to Ohms could figure it out in minutes. Do you have a friend/workmate/drinking mate that knows about such things ? (though make sure he knows and not that he just says he knows ;)

Ian and Lins wrote:to test for a 'drain' on the battery (either starter of leisure) I assume you disconnect the 12v 'live'/red and put a volt meter in series between the battery post and the terminal. If it reads 12v then something is taking current? What would the reading be if nothing is taking power/current?

To answer your question, it would in theory read 0 Volts. But, in the real world it would still read 12 Volts as there will always be a tiny drain and your meter, if set to Volts, is sensitive enough to read that tiny current and therefore display the voltage present.

However, read on...

That is not quite the way most folk would do it. Normally one would first set the meter to read DC Amps (not Volts). You would set it to the scale for Amps that says 200mA. You would then make sure everything in the van is turned off, radio, interior lights etc. You would then remove the +ve lead from the battery, hold the red lead of the meter onto the +ve terminal of the battery and the black one onto the lead you just took off, so the meter is now "completing" the circuit. You would then note down the reading. You will nearly always get some drain, from say the radio's memory wire, the clock, the alarm system, etc, but a reading of anything over 100mA indicates summat not really right. You then start taking fuses out, one at a time, to find out what is draining the power away.

Note, don't turn anything on whilst the meter is in the circuit or you will either blow it's internal fuse, or even damage it more seriously.

Also note, some (better) meters have a 5 or 10 amp DC Amp scale. If yours has it, you can use that setting and then you can turn things on, but only things that use less than the setting, i.e., less than 5 Amps (or 10Amps). Of course, do NOT try and start the engine or your meter will go up in a puff of smoke !

Last note, the death of most multimeters often comes from folks making mistakes whilst it is set to Amps. Folk forget to set the dial to off and they forget to put the red lead back into the "Volts" socket. Then they go to measure the voltage of perhaps a leisure battery, and as soon as they touch the terminals the meter goes up in a puff of smoke (or the internal fuse blows).
So, best practice = always remove the test leads when you have finished and set the dial to "off".

Here endeth today's lesson.
Last edited by ghost123uk on 07 Jul 2014, 08:40, edited 1 time in total.
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Re: curious loss of main battery power .....

Post by CJH »

^^^ That's worth repeating :rofl
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Re: curious loss of main battery power .....

Post by ghost123uk »

Here is a link to the RM212 fridge, including wiring.HERE. Note, on my computer that pdf did not appear correctly when simply viewed with Firebox's pdf viewer, but it did after I saved it to my "My Documents" and viewed it then.

Here is the same for the RM122 and RM123 Link
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Re: curious loss of main battery power .....

Post by ghost123uk »

CJH wrote:^^^ That's worth repeating :rofl

What, what is, what :|
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Re: curious loss of main battery power .....

Post by CJH »

ghost123uk wrote:
CJH wrote:^^^ That's worth repeating :rofl

What, what is, what :|

Sorry John - facetious comment about the double post, that's all.
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Re: curious loss of main battery power .....

Post by ghost123uk »

Ah, I hadn't noticed the double post, don't know how that happened :oops:

.
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Re: curious loss of main battery power .....

Post by waltraud »

Excellent full and clear info, top dollar Ghost. Thank you.
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