chrisoverson
Member Since: 10 Dec 2020
Location: Bideford
Posts: 29
  
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| Wiring cubby fridge to aux battery |
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Hi all, two quick questions, if I may:
1) What is the easiest way to access wiring going to the cubby fridge? I wondered if they ran past somewhere else so I don't need to remove the fridge itself.
2) Does anyone know what the rough current draw of the fridge is, over a long period of time?
I've got a Optima Yellowtop 55ah Aux battery and would like to just keep milk cold over a 2 day camping weekend, so hopefully wiring the fridge that way will do it. 
Planning on using a boost converter to trick it into running when the ignition is off. It's a 2006 HSE.
Thanks!
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 31st Aug 2022 11:29 am |
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chrisoverson
Member Since: 10 Dec 2020
Location: Bideford
Posts: 29
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Okay, self reply.
I have successfully now got the fridge on a switch to run all the time. There may be more efficient ways to do this but I'm happy with the solution I went for.
I'm using a 8-40v to 13.8v DC to DC boost converter, which will take an input and give 13.8v output as long as the input is between 8 and 40v DC. This is rated to handle 10a and was sourced from amazon: https://www.amazon.co.uk/gp/product/B07WFM...&psc=1
Then I'm using a pair of relays, both wired to the same toggle switch.
The first relay switches the power on/off to the boost converter, which is running through a 10a fuse from the aux battery.
The second relay switches the fridge from running on the standard D3 power feed to running from the boost converter. The fridge's built in voltage sensing will then turn the fridge on when it sees the correct voltage.
The reason for a relay turning the power on/off to the DC to DC converter is because it will always use a (very small) input current even when I don't need it, if it was left connected to the aux battery. I didn't like this, and wanted it totally isolated when not needed.
To access the cable, I removed the centre console around the gear lever. It wasn't necessary to remove the fridge itself. There was enough room in there to hide the two relays, DC converter and the wire connections easily. I used VHB tape to hold the bits in place. I cut the wire going to the fridge and used WAGO connectors (for now) to connect to the output/input to my relays.
The result is that now the fridge runs by default exactly like normal in the D3, on with the engine and off with battery, or always off if the switch under the lid is off. When the toggle switch is flicked, and the fridge switched on, it will remain on until the voltage on the aux battery falls below 8v.
I haven't yet conclusively measured the current consumption over a long period but that's to come. Another thing I've done is taken some soft insulation I had from a hello fresh delivery, and I can put the items in the fridge up against the front where the Peltier module is, and stuff the insulation behind and on top to help reduce power consumption .
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| 21st Sep 2022 1:40 pm |
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V8man
Member Since: 01 Jan 2021
Location: Dunno i was just following the satnav😳
Posts: 288
 
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Very smart solution  1996 Defender -died (now in landrover heaven😇)chassis to ashes , rust to dust !
2004 Defender td5 gone
2012 Evoque gone
2007 D3 V8 HSE
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| 22nd Sep 2022 7:35 am |
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Motolab
Member Since: 18 Oct 2019
Location: Sleen
Posts: 1820
 
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chrisoverson wrote:it will remain on until the voltage on the aux battery falls below 8v.
Since a battery on 12v exactly = 100% EMPTY (12,7 is 100% full) everything beneath 12V is Deepcycle…
And therefore killing your battery….. (sulfatating of the lead)
Yes deepcycle batteries like yellow top are more resistant to deepcycle than standard starters
But “more” not 100% resistant
8v is far far far too low…. 11v or above can be acceptable IF it is charged again within a few hours after getting empty (=12v)
There is a lot of wrong thinking regarding batteries and the chemical process inside.. Best regards
Harold
Always looking for Pre '55's & Pre war British Motorcycles! knowing or having one for sale? PM please. I visit the UK 6 times a year
Ps. I edit my texts quite often, english is not my native language, so I will edit My “typo’s” etc. 
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| 23rd Sep 2022 7:10 am |
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