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Connect fridge directly to Victron MPPT Charger

kave

kave

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1,601
Location
Boras Sweden
Vehicle
T6 Beach 4Motion
I have the Victron MPPT 75 I 10 charger with two 120w panels on my California.
I have installed the kit from @Roger Donoghue .
Very often our fridge, Waco CFX28, is disconnected from it's outlet.
I am considering connecting the fridge directly to the Solar charger to also have a number on much energy the fridge takes.
The fridge is rated at 40w.
Good idea or should I just hard wire fridge directly to the battery?
 
I have the Victron MPPT 75 I 10 charger with two 120w panels on my California.
I have installed the kit from @Roger Donoghue .
Very often our fridge, Waco CFX28, is disconnected from it's outlet.
I am considering connecting the fridge directly to the Solar charger to also have a number on much energy the fridge takes.
The fridge is rated at 40w.
Good idea or should I just hard wire fridge directly to the battery?
What will happen if it is cloudy or at night. Wiring the fridge to the Leisure Battery would be a better alternative, smooth out the fluctuations. Just my opinion.
 
I have now studied the Victron forums, it seems it does not work reliably using the Victron output connectors with a fridge. When solar input is low it seems the MPPT will just kill off the power to the coolbox. I will wire it directly. A pity though because it would have been nice to use the energy monitor of the Victron for the fridge.
https://community.victronenergy.com/questions/1558/mppt-load-output-switches-off.html
 
I fitted another 12V socket to the back of the passenger seat and wired that to the battery with an inline fuse. I used a good 6mm cable and quality socket. The short cable run and good socket provides a decent amount of power for pumps and freezer etc.
 
I have the Victron MPPT 75 I 10 charger with two 120w panels on my California.
I have installed the kit from @Roger Donoghue .
Very often our fridge, Waco CFX28, is disconnected from it's outlet.
I am considering connecting the fridge directly to the Solar charger to also have a number on much energy the fridge takes.
The fridge is rated at 40w.
Good idea or should I just hard wire fridge directly to the battery?
I have hardwired mine. I now have a choice of three sockets for the fridge:
  1. behind the passenger seat - fridge gets strapped to the passenger seat
  2. in the boot tool compartment - fridge will sit under the shortened multiflex
  3. under the awning cover - fridge can go under the awning or with a driveaway awning I can use an extension lead to place the fridge where I like.
Full explanation on this thread:
https://vwcaliforniaclub.com/threads/hard-wiring-cfx28.27239/
 
Not a good idea to connect fridge to the charger. Connect fridge directly (fused) to second battery.


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The load terminals on the Victron, much like nearly all solar regulators, are acually designed exactly with this kind of use in mind.

The "load" terminals on the Victron, are , in effect , direct connections to the leisure battery/s that the Victron is charging, but with two key advantages.....

Because the load terminals pass power through the Victron, it can

a) show you how much power you are consuming
b) shut the load terminals down if the battery/s become too low.

The Victron won't shut the load terminals down when there is low/little solar power. It will shut them down if your battery/s get too low (this is what you've been reading about Kave). This actually saves you a lot of money, because one sure fire way of wrecking batteries is to take them below 10v and leave them there . It kills them. Hence this shut off feature is called low voltage battery protection. It prioritises two very expensive batteries (Calif Ocean) over a small fridge contents.

With healthy batteries, and good solar, this protection should rarely , if ever , kick in anyhow. You can also adjust the cut off voltage on the Victron app.

It may well be that the Cali has it's own low voltage cut off built in to it's electrics. I don't know.

Ciki is right in as much as your fridge should have a short, thick, fused cable run to your battery - this is because they have a high current surge start up each time the compressor fires up. Inadequate wiring leads to a higher voltage drop, and this will kick in the fridge's own low voltage cut off, and it won't run efficiently. Also, with thin wire, you lose voltage, and again, lose performance.

However, as long as you wire your Victron's battery leads up with thick, short cable, the same thickness that the fridge requires, and then use the same type of cable to connect the fridge to the load terminals on the Victron, then it's only a win situation. You gain good low voltage battery protection (better than the fridge's inbuilt protection), and you can see power usage (though that novelty will soon wear off!).

It's kind of academic in an Ocean, as it's a pain to rewire things, and they already work well, but in a a Beach, with a portable compressor fridge, I'd use thick battery cable to the charger, and hang the fridge off the charger.
 
After much problems with our CFX28 this year where it basically wont start after our panels have stopped giving solar energy I decided to hard wire the fridge. Since our Victron is closer to the fridge than the battery I took apart the fridge cable and just connected it to the Victrons out terminals. I set the fridge to -22C and started and old phone with display sleep turned off so I could monitor the batter over night. It seems the Victron app only shows the last two hours in this case. In the morning at 6:45 battery was down to 12.1V. Fridge seemed to have been running the whole night :) I measured the voltage at another 12V outlet and that was in fact lower than what the Victron reported so I guess I dont need to change cables between Victron and the battery.
I think I win three things with this setup:
1 Less cables to and from the batteries
2 I can remotely turn off the fridge from my phone if I so desire, we often turn it off between 22 and 6 to sleep bettter
3 I can keep an eye on how much energy the coolbox takes.
 
Just bear in mind that the danfoss compressor fridges (the compressor in virtually all camping fridges) measures voltage at startup to "decide" if there is enough in the battery/ies to run.

When it fires up the compressor there is quite a surge of current demand, and this drags the battery voltage down lower than it will be once the fridge is up and running. This is why, when real time monitoring, you'll see 6-7 amps current draw for a second, then it settles to 4 or 4.5 amps continuous when the pump is now running.

A battery that is say, 12.4v volts, might drop to 11.8v for that second, then settle at 12.2v once up and running. This voltage drop is affected a lot by cable resistance. i.e. how thin it is. If this drop goes under a certain threshold then the compressor will switch straight back off again to protect the battery. This is why you get fridges "hunting" on and off again and again when the battery gets low.

Use too thin a cable and you'll get enough of an increase in voltage drop that the fridge will start "hunting" (going into battery protection mode) a good bit earlier than it would with thicker cable.

It's all about startup load and cable resistance.

The 2mm square cable I supply in the kits is fine for a fridge, and is the most common size cable used in camper conversions. If I was running more than a couple of metres I'd go up to 2.5mm squ, or even 3mm squ.

If, however, you never run your battery very low, you won't notice the difference between the cables, as you'll never run into the low voltage battery protection of the fridge.

The victron load terminals have the same battery protection built in. The charger will turn off the load terminals when the battery gets too low.
 

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