New Fridge

[KarwashD2V8]

Hi all,

Ok so I've just bought a new fridge and wired a dedicated merit socket in the back for it. Really pleased with the job, used 6 B&S cable + & - through the cabin, 30 amp circuit breaker at the battery, earthed it all the way back to the battery and used a 50 amp anderson at the socket to reduce the cables down in order to connect to the merit socket. Tested voltage at the fridge end and getting no voltage drop. The reason I used such heavy cable is I intend to use the same cable for my dual battery setup which is coming shortly.
Anyway to the point in hand. My fridge has three stages of battery protection. Low cuts out at 10.2V and back in at 11.2V, Med out 10.7V in 11.7V and High out 11.7V and in 12.7V. While the fridge is running off the starting battery, is it safe to use the high level protection and will my D2 V8 start with 11.7 volts? This sounds too low to me! I think a full charged unloaded battery usually sits at 12.2V?
Cheers.

[PhilipA]

High out 11.7V and in 12.7V. While the fridge is running off the starting battery, is it safe to use the high level protection and will my D2 V8 start with 11.7 volts? This sounds too low to me! I think a full charged unloaded battery usually sits at 12.2V?

A fully charged lead acid battery will show 12.7 volts. 12.2 V is generally considered 50%.

I think it would be a bit brave to leave the starting battery drop to11.7,especially in cold weather.

Maybe invest in one of those mini jump starters prior to fitting a second battery.
Regards Philip A

[Pedro_The_Swift]

Will a D2V8 start on 11.7V.

No.

sounds like your fridge is set up for a storage battery;)

[Fluids]

Hang on guys ... remember, that under load, a batteries voltage sags. So when the voltage is drawn down to 11.7v and the saftey disconnects the power, the batteries voltage will recover ... probably dam close to 12v.

The LVD will be affected by the size of the load connected to the battery. The bigger the load, the more the batteries voltage will be drawn down ... disconnect the load, voltage rises.

[Pedro_The_Swift]

can I assume you are not talking to me Kev?:angel:

[ozscott]

It doesnt quite work.as literally as that and the reading is taken under load. I have my 40l Ironman in the back set up like yours with HD wiring and narva plug. I tried all 3 levels of protection....i found the best is the lowest and allows the fridge to run for longer before cutting out. I have a stock size single D2 lead.acid battery and my fridge will run for over 2 days at 2 degrees c without charging. As soon as it cuts out for low voltage there is plenty in reserve to start the 4.6. You simply dont know from the sound and urgency that the battery has been drained somewhat. Dont forget too that batteries in good condition will cycle back up pretty quickly once the load is removed.

Like PhillipA has noted i carry a little lithium jump pack just in case but have never required it. A dodgy batterys at the end of its life might be a problem but my Interstate at 2 years doesnt show signs of suffering yet.

Cheers

[Fluids]

can I assume you are not talking to me Kev?:angel:

... depends ... :cool:

My Td5 will start at 11.7v ... just ... on the Optima Yellow D31, but they have a lot of reserve still at low voltage.

As far as the OP asked, using 11.7v shut-off setting, the battery voltage should rise somewhere back to or above 12v when the fridge is disconnected by the LVD setting ... and that should be enough to restart the D2 V8 ... as long as your starting battery is in good condition ... If it has a lot of age on it, maybe not.

Remember the sagged/loaded voltage is what the fridge will see and use to trigger the disconnect ... NOT the "at rest" voltage.

An at rest voltage of 11.7v is not good for a battery .... especially if left in that state of charge for any considerable length of time.

[PhilipA]

One thing to remember is that the fridge will not be the only draw.

It may be that the doors are opened or the radio on after the fridge has cut off and the ECU may wake up.

This may drop the voltage down further. You will have to constantly be on your toes that spouse or progeny do not excessively open doors etc.

Regards Philip A

[ozscott]

Bottom line. Good battery well looked after....stick the fridge on the lowest voltage cut off and enjoy very cold beers.

Cheers

[Pedro_The_Swift]

As far as the OP asked, using 11.7v shut-off setting, the battery voltage should rise somewhere back to or above 12v ... and that should be enough to restart the D2 V8 ...

and again, no.
ask me how I know this--;)

[Homestar]

Agree with Pedro here - you're not going to see the voltage rise much when the fridge shuts off as it's only drawing a couple of amps while it's running. No way I would risk running my cranking battery down this low. You got room for a second battery and a battery isolator? The low battery cutoffs are designed to protect your house battery from being overly discharged, so a good life can be got out of them, not designed to ensure your car starts when you've been out all weekend. Either that or get a solar panel IMO.

[vnx205]

The following is not actually helpful information; just a bit of gratuitous gloating. :)

When the battery in my Defender was on its last legs and needed to be topped up with the battery charger if left unused for more than a couple of days, I tried measuring the voltage before attempting to start it.

It seems that the 300 Tdi doesn't need as much as some other engines. I was able to start it with just 10.5 volts. The weather was quite warm at the time and I realise that helped.

In the Series III, low battery voltage was even less of a problem. On a couple of trips to the NT with an old 15 litre Engel and just a single battery, it coped if I drove every day. On the occasions when I stayed two nights in one place, I simply got out the crank handle. :)

I know that running the battery that low is not good for it, but in both cases, the battery was due for replacement anyway.

It seems part of the price of progress is that a higher voltage is needed to get started in the morning. :)

[ozscott]

Ok i will do an experiment and run mine down for the sake of science and cold beers...my bet is that 10 mins after fridge shut off it will be 12.5 or more...we will see though.

Cheers

[Homestar]

If the voltage recovers to 12.5 volts, would the fridge not simply restart? Let us know your test results when the fridge has turned off - and stays off due to low battery voltage.

[Pedro_The_Swift]

Ok i will do an experiment and run mine down for the sake of science and cold beers...my bet is that 10 mins after fridge shut off it will be 12.5 or more...we will see though.

Cheers

need a hand?:angel:

I'm all for science:p

[Fluids]

and again, no.
ask me how I know this--;)

That's surprising ... no where near the compression of a Td5. Should take less to turn over the V8.

Lets see how Ozscott's test shape up ....

[KarwashD2V8]

Thanks all for the input!
As I said in my original post, this is just a short term measure for a xmas & new year camping trip, until the dual battery system goes in in the new year. Would have liked to do it before the trip but time and funds just don't allow me to do it the way I want before, without doing half a job and then going back to finish it off later.
The lithium jump pack appears to be a useful bit of kit in general. Can anyone recommend a good unit at a good price?

[Don 130]

Thanks all for the input!
As I said in my original post, this is just a short term measure for a xmas & new year camping trip, until the dual battery system goes in in the new year. Would have liked to do it before the trip but time and funds just don't allow me to do it the way I want before, without doing half a job and then going back to finish it off later.
The lithium jump pack appears to be a useful bit of kit in general. Can anyone recommend a good unit at a good price?

This sort of thing?
Upgraded 68800mAh 12V Multi function Jump Starter Car Emergency Power Bank-in Car Batteries from Automobiles & Motorcycles on Aliexpress.com | Alibaba Group (http://www.aliexpress.com/item/Upgraded-68800mAh-12V-Multi-function-Jump-Starter-Car-Emergency-Power-Bank/32374858794.html'spm=2114.10010108.100009.23.Q3I6W 6)
Don.