Battery disconnects and Freezer fridges......

[xcmountain80]

Expo,

I saw a build thread or article in OJ perhaps that had a very clever battery disconnect (low voltage disconnect) being used with a freezer fridge. I though now why didn’t I think of that. I can’t tell you how many time my fridge has almost disabled the vehicle. What are others using for this purpose?

Thank you

A

 

[Mike S]

I have dual batteries on both my vehicles. That said, I have run the Engel 45 for a LONG time and never had issues with it drawing down a battery.

 

[RMP&O]

When I had my 04 Taco.....I had a red top for starting and a yellow top for the 45L Engel. I had the yellow top on a National Luna dual battery set up. It seemed to me if I didn't start the truck for 2-3 days the Engel would drain the yellow top down dangerously low. Once this happened once or twice the yellow top was weaker and could go one to two days tops. By the time I got rid fo the truck, 12-16hrs is all it would take for the National Luna to warn that the yellow top was low. I think this is all due to the batteries though, ie Optimas. The National Luna system worked great as did my alt. upgrade and the Engel also worked very well.

I was never in danger of being stranded though as I had the red top for starting.

I have never heard of an auto low voltage disconnect system and I take it you are on a single battery?

 

[Ryanmb21]

I think they were referring to the low voltage disconnect built in to the fridge. I think its a feature that many of the new fridges have these days.

 

[xcmountain80]

I had dual batteries and it was alright I opted for less weight and went back to 1, the NL dual batt system is still in place and currently serving a differnet purpose. I'll have to scour OJ again as I swear I read it somewhere. It wasn't an integrated feature either, it was standalone IIRC. I found one that would work just looks kinda no frills.

The 12V Smart Switch is an adjustable LVD (Low Voltage Disconnect) that includes on/off and over-ride features. The 12V Smart Switch is the perfect way to protect your battery investment from a destructive over-discharge condition. The 12V Smart Switch will constantly monitor your battery and disconnect the attached DC load(s) if voltage drops below an unsafe level. The 12V Smart Switch will directly switch up to a 40 Amp load and can easily be configured to switch much higher loads with the addition of relays or solenoids (sold separately). The 12V Smart Switch also has a handy low voltage signal output that can be used to switch on a light or buzzer to notify you of the low voltage condition or could switch on a battery charger so that the batteries do not sit discharged for extended periods if unattended (light, buzzer, and battery charger not included). The 12V Smart Switch is epoxy encapsulated and ready for marine or tropical environments.
Factory Set Disconnect Voltage is 10.5 Volts
Factory Set Reconnect Voltage is 11 Volts
Voltage must remain below disconnect threshold for at least 5 seconds before disconnect will occur.
Voltage must remain above reconnect threshold for at least 5 seconds before reconnect will occur.

http://www.powerplanted.com/12vss.html

I figured the unit could be wired to the rear cig outlet or independant of it whatever was preffered and the fridge run through it so that when it reached a low threshhold the circuit would kick off.


A

 

[hoser]

Engel and Waeco/Dometic both offer automatic low voltage cut-off devices.

http://www.engelaustralia.com.au/cgi-bin/products.cgi?any=low+voltage+cut+out
http://www.waeco.com/en/3772_724.php

 

[cnynrat]

The new style ARB fridge also has a low voltage shut-off that is programmable so you can prioritize keeping your food cold vs. keeping your battery charged. I have dual batteries, and the fridge runs off the secondary battery, so I set it to prioritize keeping my food cold.

 

[CYi5]

I'm in a similar boat, although i'm pretty sure my Edgestar has this function built-in. I want to start taking more solo trips but am worried about a battery discharge out in the middle of nowhere. I hadn't seen the company you mentioned Aaron, but have been looking at the battery brain...still haven't decided on an affordable low voltage cutoff product that can go inbetween my battery and my many potential power drawing toys.

 

[Rovertrader]

Is it just me, or why not do a manual switch- at least on the second battery when parked? I appreciate the safety knowing the second battery is off the loop. You can still use the whole auto charging deal, but simple add a cutoff switch to use only when parked/camping beyond a day, or whatever time frame suits.

 

[xcmountain80]

Mine has gotten to the point (especially now I'm back to 1 battery) that I keep a 10' extension cord under the fridge slide to plug in whenever I'm parked. I envisioned something that would kick off around 10V, and not come back on until the level hit 10.9 or 11.5. I'll keep looking or research how to make such an apparatus I don't think it would be all that difficult.

 

[Jay H]

Yes every one absolutely needs a low voltage cut out circuit enabled if running a fridge off of battery power all the time. Running a battery down to 40% charge gives you hundreds more cycles than running it down to 10%. Running a battery to 10.5 volts(darn near 0%) will place a huge amount of ware on a battery. Your battery will likely not make it to 2 years if you run it to 10.5 all the time and likely even if only a few times. I am talking about 1000 cycles vs 400. If you keep it at or above 11.9v ie 40% charge it could easily go 5 years. 10.5 may still start your rig but it is not an appropriate cut out voltage for the long term health of your battery. Here is some of the best battery info I have ever seen. http://www.windsun.com/Batteries/Battery_FAQ.htm

If your using a fridge with a danfoss compressor you can download the data sheet and by changing one resistor you can set the cut out voltage. Mine is set for about 11.60 volts which is much better for the battery than the default 10.5. I put two resistors on a toggle switch so I can switch between solar mode which runs from any where between 10-27V and cut out at 11.60V.

I know fully sealed batteries and especially optima's are all the rage around here but for a low current application like powering a fridge a good old lead acid marine battery will last longer and run the fridge a little longer on each charge cycle. Those huge thick lead plates are jsut solid. I have a 4cyl Toyota that came with a very small starting battery which I replaced with a run of the mill 27 size marine battery from napa. I could have gone with dual batteries but that's a lot of extra expensive wring and weight. By replacing with an up sized battery it has more than enough cold cranking amps to start even in arctic temps.

I wish Oatley electronics sold there kits in the US, well they probably do I am not paying shipping from Australia. Thy have an awesome looking kit that would manage a second battery or provide a low voltage cut out. By using two of them you could have a dual battery set up and have it cut out when the voltage gets low.