can you disable voltage protection on fridge?

[89gqpatrol4x4]

I have a 65 ltr dual zone iron man fridge and it has a three stage voltage protection with the lowest being 10.5 volts or the like can't remember/find. Question is can I bypass this in some way to get the most from my second (deep cycle) battery? My dads engal you can turn it off all together meaning you can keep running the fridge untill the battery is dead, but mine the fridge stops at set voltage thus leaving considerable charge still in the battery. Any help appreciated.

[MudRunnerTD]

I think the problem is the lack of efficiency at 10.5v for the fridge. You will find that although the fridge is cycling it is almost certainly not maintaining a good temp when it's supply is below 10.5v. It does not do your battery much chop either to be honest. Some alternators will struggle to pull a battery back up from below that too hence the protection .

Your better off buying a solar panel and boost the batteries every 2 days when camped for a while.

[89gqpatrol4x4]

That was my other thought! Thanks

[Bob]

I have a 100 AH Deep Cycle Battery which runs my 60Litre Fridge Freezer for 2 1/2 days quite easily and will cut out at 10.5V.
As MR stated I run a Solar Panel and top up the Batteries continously whilst there is Sun and I am Camping and I am yet to have the Fridge cut out due to low voltage

[89gqpatrol4x4]

ok then, what size solar panel do people use and is it just hooked to the battery when stationary? By the way everything except the starter, winch and compressor run off the second battery. Spot lights, light bar, cb radio, fridge, camp lights, 12 volt plugs for charging phones etc.

[Cuppa]

Mudrunner is correct.
If you care about your battery lasting you will not discharge it to 10.5v. When fridge manufacturers refer to such settings as ‘battery protection’ they are simply telling porkies to help them sell their fridges. They all do it. To get maximum life from your battery you do not want to let it go below around 40%. (12.0v) Those settings are more about protecting the fridge.
To determine how much solar you need you first need to add up how many amp hours (or watts) your various accessories will use. Also depends on how the second battery is currently charged (at home via mains, in car via solenoid or in car via dc to dc - all will make a difference, as will how long you drive). Hard to decide what you think YOUR needs will be, but doing so & getting it right will be really worthwhile, whereas doing what many do, & just guessing & hoping is more likely to result in disappointment & frustration, or wasted expenditure.

Running all that stuff, particularly the spotlights, light bar & fridge is asking an awful lot of a single battery & I assume that the reason for your intial post is that you have found this out the hard way.

Note the voltages on the following chart. Take your battery down to 10.5v on a regular basis & you’ll be lucky to get 12 months out of it.

http://www.nissanpatrol.com.au/forums/attachment.php?attachmentid=49101&stc=1

[89gqpatrol4x4]

Thankyou cuppa, I will look into what my needs are in more depth and see what I need to do to make it work then. This sort of advice makes you look at the bigger picture when sometimes you have blinkers on!

[megatexture]

Are you running the batteries that low !?? Testing the battery with a multimeter Or is the fridge saying the battery is low? I'm just wondering if it could be insufficient cable size and suffering voltage drop

[Bob]

My set up is as follows:-

Caravan
100 AH Deep Cycle Battery
Useuage
1. Approx 10 Metres LED Strip Lighting both inside & outside Van
2. Computer Fan to aid in dispersing Heat from Van Fridge
3. Runs Shower Pump
4. LED Spotlight for Camp Fire whilst Cooking
5. Recharging Phone's (Not very often)

Second 100 AH Deep Cycle Battery running :-
Evakool 55 Litre Fridge Freezer
1.2 to 1.6 Amp Hours running Fridge at 4 degrees with Ambient temp of 32 degrees

Both Batteries are connected to a 140 Watt Solar Panel with a Redarc SRP0240 20 Amp Solar Regulator
The Battery running the Fridge gets 80% of the Charge and the Van Battery the remaining 20% (This can be set on the Regulator).
By disconnecting the Van Battery the whole of the Charge goes to the Fridge Battery.

This set up works quite well

Forgot to mention that Caravan Battery is charged via a DC to DC Charger whilst travelling

[threedogs]

Are you running the batteries that low !?? Testing the battery with a multimeter Or is the fridge saying the battery is low? I'm just wondering if it could be insufficient cable size and suffering voltage drop

Good call Mega wire size plays a big part in how your fridge operates

[Cuppa]

Good call Mega wire size plays a big part in how your fridge operates

Yes it is a good point. However if the fridge is cutting out when set at the 10.5v threshold, even with thin wire induced voltage drop, there is still every chance that the battery is is being discharged lower than is good for it if a long life is desired. But yes quite possible it won’t be as low as 10.5v at the battery. As far as the battery goes the voltage drop could be seen as giving it a little more protection. ;) If good heavy cable has been used the news is worse for the battery.

[89gqpatrol4x4]

Are you running the batteries that low !?? Testing the battery with a multimeter Or is the fridge saying the battery is low? I'm just wondering if it could be insufficient cable size and suffering voltage drop

6mm cable was used as supplied by my local auto electrician. Don't know if this is correct just went with his advice. Basically I was just trying to squeeze more life out of my battery without having to purchase solar panels etc, but it sure seems that this is the way to go. I don't want to run a third battery as they are expensive and heavy!

[megatexture]

Replacing batteries regularly will be costly and it potentially could drop a cell or die while your needing the fridge? You can buy decent panel's on ebay for under $200 and in the long run be cheaper then replacing batteries.

Use a panels and if its cloudy run jumper leads to the battery and run the car with idol up if you have it if you get desperate

[Cuppa]

In most instances 6mm2 cable is sufficient if the fridge is not too far from the battery. If in doubt go heavier. Or if you have a multimeter measure voltage at battery terminals & then again at the fridge end of the cable.
A common trap folk (including auto electricians) fall into is assuming that 6mm cable means cable with a 6mm core. 6mm auto cable includes the thickness of it’s insulation & it’s copper core is only about 4.5mm2. Usually in solar & low voltage installations recommended cable sizes given are the size of the core. It is not uncommon for fridges, including those installed by some RV manufacturers, to not work as they should because their supply cables are not heavy enough.

[89gqpatrol4x4]

Thanks cuppa, I have learnt that trap and now make sure it is mm2 not just Xmm cable.

[the evil twin]

Not a great idea to be disabling the low voltage cutout for many reasons.

Quite a few have been mentioned already.
Yet another is that the lower the voltage the more current a given load will draw so voltage drop gets exponentially worse and can possibly damage the fridge.

Exotic technologies aside there are bugger all batteries that can handle regularly being drawn down to 10 volts and survive very long.
If the battery terminal voltage is getting that low then you need more capacity or more frequent charging
If the battery voltage is staying up but the fridge voltage is that low then you need to sort out the voltage drop issue