Tuesday, Sep 17, 2013 at 19:35
PeterD
Interestingly OP has never actually stated the charger didn't charge when the fridge was running on 12V. Everyone just seems to have jumped to that conclusion.
He did write as you pointed out:
The problem occurs when the fridge is running on gas or 240V. The fridge requires a 12 V input at all times to run the control system. If I connect the fridge to a small 12V battery that I use for my fish finder the problem goes away and the charger charges the house battery as normal."
This could also imply the charger did not work when Gas or 240V was manually selected, before he resorted to using the battery. Assuming you can do this, if fridge is wired incorrectly which it probably is, why didn't the charger fire up when the fridge is running on gas or 240V
without the addition of the extra battery?
One could assume the OP indicating the charger is not charging means exactly that the charger is not charging, not can't supply the load. As he has enough brains to understand and power supply is required and where to connect it to one would assume he can tell if a charger is charging or not.
You wrote:
"An AES fridge has two 12 V inputs. A light duty one that should be connected to the house battery to power the logic board. The other, a heavy duty high current one, should be run to the alternator/starter battery in the tug and no where else.
If the fridge is wired this way, when you have mains supplied to the van to power the C-Tek Multi XS 7000 the fridge should run on 240 V power by default."
Note: as the heavy is connected to the tug it can't be used to sense the charge voltage being detected in the van as you state later.
"It should not matter what charger you apply to the house battery the fridge should remain powered from 240 V power. If as the OP says starting the charger up also starts the 12 V power operation, this indicates to me there is a wiring problem."
Where did OP state the above?
"When the OP says "If I connect the fridge to a small 12V battery" which of the two 12 V inputs is he connection to this additional battery? Is it the light duty one, the heavy duty one or both? If the heavy duty one is normally connected to the house battery then there is no problem with the logic board. The logic board is doing its job correctly. It is working normally. That connection is probably the one that is used to trigger the 12 V fridge operation."
You have contradicted yourself above, if the heavy goes to the tug it can't be used for charge sensing.
"What is happening is that when the battery charger is switched on, the logic board sees a rise in voltage and thinks it should switch the fridge to 12 V operation. When the fridge is wired to the external battery the logic circuitry does not see this rise in voltage and stays on gas."
The above doesn't make sense, according to this theory if you didn't have a charger in your van the fridge would never switch to 240V!
Form a self proclaimed expert your deductions leave a bit to be desired:)
Still a few answered questions but as the OP will probably never return we will never know.
Cheers
Leigh
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798104