running 3 way fridge from tow vehicle red anderson plug

HI - so I can run the fridge on 12 volt whilst the engine is running and it won't run my car battery down?
When I am stopped it will be on Gas
it would be disconnected to the red anderson plug on the car manually
thx in advance
Rea

If you are stopping for an hour or 2, the fridge will stay cold just like an esky, I only use the gas overnight.

The red Anderson plug was a recommendation by Al-Ko to supply their ESC if it was fitted in your van. The reason for this is that the Al-Ko ESC units can misfire when you are travelling in off-road tracks. It has become a bit of an informal caravanning standard. There is no regulation to stop you from using it for other purposes, however if I was doing that I would change to another colour for use with a fridge.

Regarding the use of an ignition switched relay in the line, it is recommended by Electrolux (yes that far back) as a safety measure. The world is full of good intentions. There are also a huge number of those with good intentions who forget to disconnect the fridge when stopping for a rest stop. Many of those require assistance to restart their tug's motor. There are also who forget to reconnect the plug and lose the benefit of fridge 12V operation during the next phase of the journey. Again the choice is yours.

Thank you :-)

There are a number of variations of stability control these days, but the ALKO ESC version we had on our 2013 Jayco van, tandem axle, applied the braking to all 4 wheels constantly when activated.

It only happened to us twice within a few minutes on a very rough and winding bitumen road and you definitely knew it.

thank you, that was great

thank you

thank you that was good info
the van battery is the 200ah mentioned
how do i check how much power the vehicle is supplying?
tar

I'm no expert others will know more but I like to keep things simple so hopefully less problems.
You need to find out how the battery in the van is being charged wether it's wired directly off your vehicles starter battery or if there is a lithium battery charger it the set up which is the more likely scenario. If there is a charger the amp output should be written on it which could be somewhere between 20 to 40 amp for example. It should also have a built-in battery isolator so when the cars engine is off the 2 battery are isolated so if you accidentally flatten the caravan battery it will have no effect on the cars starter battery.
You also need to know the size of the vehicles alternator so you don't exceed it's limit best to stay well inside it. It sounds like a bit unnecessary and maybe over whelming but it's not that bad and can save you a breakdown in the future. An auto electrician might be able to help you should try and add up within reason how many amps everything will be drawing off the alternator from lights to battery charger etc etc which can be a bit difficult with a modern vehicle but a ball park figure is a good start.

Thank you, lithium battery charger in van is 60amp

That's a pretty big charger it will recharge the battery fast so short drive of a few hours shouldn't be an issue but I still would make sure your alternator is going to cope with putting out that much power and still be able to run the vehicle with it's accessories over the long term .

ok - Thanks Batt

Vehicle alternators are self-regulating. If you attempt to draw more than their regulated capacity, they will not deliver it. Get yourself a voltmeter that plugs into a lighter socket, if the alternator does not deliver the full charging voltage with a DC-DC charger attached, look to see if there is a way of throttling back the DC-DC charger. If you can not set the output regulator of the charger to deliver less current, then you will have to find other accessories to switch off or replace your charger.

Thank you for that.
The charger i refer to is a 240v charger
at this stage I don't have a dcdc charger - i was thinking of getting a 25amp one
I am presuming i cannot run the car directly connected to caravan battery via anderson plug :-0

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I agree with what Qldcamper has said and would add further……..

DC-DC chargers begin charging when they detect that the alternator is producing at a sufficient voltage, typically 12.9v and then automatically check periodically and if the supply voltage is less than 12.7v the charger will cease charging. If your charger is attempting to draw more current than the alternator can continually supply the voltage will fall below the acceptable value and the charger will disconnect for a time and only reconnect again when the alternator is producing at least 12.9 volts. This process will repeat ad infinitum and is unhealthy to both the alternator and the cranking battery.
During the time that the alternator is delivering a high current to the dc-dc charger it is likely to be outputting a voltage lower than required to put charge into the cranking battery and it is even possible that the cranking battery will contribute to the dc-dc charger input and thus reduce its State of Charge.

From this you can see the risk of connecting an oversize dc-dc charger to an alternator that is incapable of providing sufficient continual current. The nameplate current rating of an alternator is the maximum current that it can deliver but it may not be the current that it can deliver indefinitely without coming to grief. So the take-home message is to be sure that your alternator can manage the demand of your dc-dc charger.

G'day Allan,
I am only really familiar with the way redarc bcdc chargers operate but can't say for the cheaper ones.
Redarc are designed to overcome supply line voltage drop and will operate down to 9 point something volts but have a low voltage cut out 12 point something. This seemed a bit confusing to me too so I dug a little deeper and found they achieve this by stopping charging briefly every 90 seconds or so, so there is no voltage drop in the supply line and sampling the voltage then, if it is below the threshold it will not commence charging again, but if the engine is idling as soon as the load disappears the voltage shoots up and this is what the redarc sees so thinks all is good and ploughs on for another 90 seconds. I see this on my in dash volt meter quiet often cause it is a cheap meter with a very slow sample rate and now and then captures the accessory battery voltage below its float voltage.
Easy to assume they all work the same but maybe there is a reason for Redarcs price tag.

Rea 58,
Not a good idea to connect directly.
Automotive charging evolved hand in hand with lead acid batteries and lithium batteries are a completely alien being to them. Hence the reason systems have been developed to try to integrate them into the automotive platform but are still far from being perfected.

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Hi Qldcamper,

I have used Redarc chargers for a long time and was aware of the technique of charge interruption to enable measurement of battery terminal voltage. I think a number, if not all, dc-dc chargers are employing that method. Certainly the OP's Intervolt charger does, see below:

"Input Voltage control: This function is incorporated to compensate for Voltage
drop caused by undersize cable, poor connections, improper termination, etc. by
comparing the input Voltage at the main battery terminal with the Voltage at the
Charging Device itself. It does this by momentarily disconnecting the auxiliary
battery, thereby removing the load. At this time it measures the Voltage without
load to determine the true Voltage. It will then establish if the true Voltage is high
enough to continue charging or to implement low Voltage shut down."

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Hi Pinko,
Do I understand that your Intervolt dc-dc charger is located in the car and the battery it charges is located in the camper?
As the norm is to locate the charger close to the battery it charges I wonder why-so your arrangement.

Hi Pinko,

I have looked at the Intervolt charger instructions and can see where they say that the product can be positioned either in the car or in the caravan/camper. But they also say……

"if the DCC Pro is required to charge a battery in a caravan it may be better to mount the Charging Device in the caravan itself rather than the vehicle but this may depend on where the Remote Display needs to be located."

What the Intervolt instruction do not address is as follows:

The main reason to use a dc-dc charger is to overcome the problem of volt-drop in the cable between the alternator and the battery in the caravan/camper.
The regulation of the charger's output voltage, and hence the voltage that the battery receives, is measured and controlled at the output point of the charger. Inevitably, there will be some voltage drop in the cable to the battery which will depend on the distance and cable size. If the auxiliary battery is installed in the car close to the charger with short cabling, then the inherent voltage drop will be small and tolerable. If however, the charger is in the car and the battery in the trailer, the battery will receive a depleted voltage and probably not become fully charged. With a lead-acid battery this can result in premature ageing of the battery. However, if it is working for you, then it is working!
If your cabling is large enough there may be no problem and measurement of the charged battery voltage at its terminals will reveal this.

Pinko, why don't you use the "Follow Up" button when replying to something in a reply? You are making this thread very disjointed by starting a new Reply each time you are really adding a Follow Up. It's not too hard to follow in this case, but if there are a few things being posted to the thread, it can make a thread very disjointed.

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That is the very situation that I described. The monitor is reading at the charger and the charger is seeing this same output voltage at its terminals and makes the assumption that is the battery voltage which it is NOT. So the charger is moving from Boost mode (14.2v) to Absorption mode (13.2v) prematurely with corresponding reduction of amps. It will similarly terminate the Absorption mode prematurely and move to the Float mode where, with time, possibly raise the battery voltage, but NOT if the fridge is drawing current at the same time.

"So the charger is moving from Boost mode (14.2v) to Absorption mode (13.2v) prematurely with corresponding reduction of amps. "

I don't think so. A charger switches to the float mode when the supply current drops to a couple of amps. That is the trigger that the battery has received sufficient current to fully charge it. If you have something else connected to the charger, this will continue to draw enough current to prevent the charger switching to float mode. That extra current being drawn by the fridge prevents the charger going through its cycle properly, that will ensure that the battery will be receiving an overcharge if you have something else connected to its output.

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Well I didn't just guess at it Peter. Not all chargers are the same.
The user manual for this charger says…..

"The boost/CC stage is completed or terminated under the following conditions:
• when the auxiliary battery reaches terminal Voltage
(pre-determined by the battery type selected) ; or
• the maximum boost/CC time has expired before the battery has reached terminal Voltage."

A cut&paste of the full section on charging is below:

"CHARGING METHODS
Boost/CC:
The boost/CC stage (also known as bulk charge) is the stage when
the Charging Device is operating in constant current mode. In CC mode is
producing the heavy current required to re-charge a depleted battery as quickly
as possible. The boost/CC Voltage is determined by the battery type selected in
the initial set-up phase. The boost/CC stage is controlled by an algorithm of
time vs Voltage to ensure that the battery is charged optimally under the given
conditions. In boost/CC stage the charger will produce up to 25 Amps
(maximum) subject to the aforementioned conditions. When the Charging
Device is powered up and the auxiliary battery measures 12.6V or below the
boost/CC stage is then initialised. At this point the ‘soft start’ function is also
enabled (see page 38 for detailed information) and current flows. The boost/CC
stage is completed or terminated under the following conditions:
• when the auxiliary battery reaches terminal Voltage
(pre-determined by the battery type selected) ; or
• the maximum boost/CC time has expired before the
battery has reached terminal Voltage.
In the instance where the boost/CC time has expired before reaching terminal
Voltage, the charging process will skip the next (absorption/CV stage) and
progress directly to the final (float) stage. Generally this occurs when the
auxiliary battery is damaged or no longer serviceable.

In order to prevent further damage due to overcharging, the DCC Pro is
programmed for the safest option which is to reduce the Voltage by switching
out of constant current mode into float stage. There is also the possibility that a
heavy load permanently connected to the auxiliary battery is responsible for the
charging cycle to time out in boost/CC stage before terminal Voltage is achieved.
If this is the case the DCC will continue to monitor the Voltage and if the Voltage
drops below 12.0V again (during the two minute check period), the boost/CC
stage will re-initiate and the whole process will start over.

Absorption/CV:
The absorption/CV stage, the next step in the charging cycle,
is initialised when the boost/CC stage is completed. In absorption/CV stage the
charger is operating in Constant Voltage (CV) mode and is also time limited. The
time is calculated from the boost/CC cycle and is based on a maximum of four
times the actual boost/CC time (subject to the battery type selected). As with the
boost/CC stage the current is limited to 25 Amps. The absorption/CV stage is
completed or terminated under the following conditions:
• the programmed time cycle has finished
(pre-determined by the battery type selected) ; or
• the charge current is reduced below 4 Amps
(approximately 15% of maximum charge current).
Float/CV: The final process in the charging cycle is the float stage."

The complete manual can be found here.