Advice on Interim Fridge Power

[Roaming Robertsons]

As I continue my build up of my Titan, I plan on getting an ARB 50 fridge before I have the dual battery system. I'm trying to figure out the best way to power the fridge until I have the second battery. When we camp, we generally drive every day so my truck battery should be able to recharge on a daily basis, I'm just a little concerned about the overnight draw and starting it in the morning. The truck is a 2004 on the original battery which still seems strong.

I have a fairly big power device for emergency jump starts that I bought from Costco a few years back. It is a PowerStation PS5000M and has a compressor and built-in inverter. Looking at the manual, it doesn't indicate an amp hours for 12v use but it does say it will power a mobile telephone in standby at about 4 watts for about 40 hours as an AC inverter. It recommends recharging itself via 12v socket on if AC is not available since it does not have an overcharge shut off switch when charging from DC power. It recommends charging for no more than 2 hours in this manner. A picture and brief write up can be found here: http://www.costcob.com/Powerstation-PS-5000M-portable-power-station

One last option is the same as the first but to buy a new battery for the truck, even though the old one seems fine now. I'd get a Sears Die Hard Platinum and it would have 100 minutes of reserve capacity. I'm not sure when I'll need a new battery and would prefer not to drop $210 on one until I have to.

So my question do I run the fridge off the truck battery (new or old) and just keep the powerstation for its more intended use of jumping the truck if it does die overnight? Or do I run the fridge off the powerstation and just recharge it in the morning via 12v plug? I cannot run the fridge and powerstation sequentially while the power station is charging, so I'd have to plug them both into the truck's power outlets. I'm leaning towards just using the truck and keeping the powerstation as a back up but thought I'd seek the wise counsel of the Portal. What say ye?

 

[dwh]

Batteries have a rating for how many cycles they are good for. The deeper they are discharged, the less cycles they will do. True deep cycle batteries might go 3000 cycles if they are only taken down 10% (90% full) and then recharged. Taken down to 50% regularly they might only do 1000 cycles before they are toast. Taken to fully dead they might be toast after as little as 100 cycles.

Engine start batteries are designed to be taken down 5% or so (start the engine) and then recharged. They can do that thousands of times. But take an engine start battery down to fully discharged and it might survive no more than a dozen or so cycles.

So if you plan to run your engine battery dead and then jump start it - you're going to ruin it - quickly. Even if you only drain it 50% regularly, you are still going to ruin it - just not as quickly. Engine batteries are not designed for that.

Reserve capacity is a red herring with start batteries - they have very thin plates inside designed to dump a lot of amps in a hurry, i.e., starting an engine. Cranking amps is important. If you're looking at the reserve capacity of an engine start battery - the you are probably doing something that really should have a deep cycle battery instead.

Your fridge might do a good job of keeping food cool overnight, so it's possible you could just unplug it and not deal with the problem.

Failing that, I would run it off the portable battery pack and stay strictly away from the engine battery. That power pack probably says to only charge for 2 hours from 12v because some people will plug it into their lighter and charge it, and kill their engine battery doing so...

But even if there is some electronic reason why it can't charge more than 2 hours from 12v you could plug it into an inverter and charge it that way.

Best to get another battery to run the fridge. You could hook up a lowbuck inverter to your engine battery, and plug a lowbuck battery charger into that to charge the aux battery and have a quick and dirty dual battery setup. Just remember to switch off the inverter when the engine is off.

For that matter you could hack open a powerstation jumpstarter doohicky and unhook the battery and hook up a cheap rv/marine battery which, while not really deep cycle is still better than using the engine battery.

 

[wrcsixeight]

Even if your 6 year old battery 'seems' strong, when you start subjecting it to deeper cycles, especially since it is a starting battery, and 6 years old, it will probably fail in short order when cycled.

Since a jumperpack itself cannot start a v8, you might wind up shooting yourself in the foot.

If your truck's battery were a new dual purpose battery such as the DHP I'd say just bring the fully charged jumperpack as backup.

But since your battery is 6 years old, it is ticking, and just looking for an excuse to quit. That excuse might be named ARB.

Also realize that recharging anything through a ciggy plug will take forever. Do not think your 130 amp alternator will ever produce that to recharge a battery. The battery could not accept it. The wiring could not transfer it, and the alternator can only meet it's rating for a very short duration, at very high rpm, and before it heats up.

I'd say replace your current battery with the biggest DHP you can shoehorn in there, and later when you add another isolated DHP, they will get along nicely when being charged by the alternator.

You should always think of the jumper pack as a last resort, and always keep it as fully charged as possible. It's battery will probably be drained to zero overnight by the fridge anyway, and die a premature death.

Also you will get better performance if you wire in a ciggy plug receptacle over 10 awg wire directly to the battery. The OEM wiring is usually pretty thin, through multiple connectors, causing voltage drop.

 

[goodtimes]

When ever we take my Marisa's Jeep Patriot (instead of my truck), we run the fridge off of the jump-start pack. We charge the pack via the cig. lighter (the lighter plug is only hot when the key is on, so we leave it plugged in the whole time).

It helps to keep the fridge full (liquid is better than dry foods) and cold, limit the number of times you open the lid &/or add anything to the fridge.

 

[BajaXplorer]

I used my ARB in my Tacoma for several years before I added a second battery. I just turned the fridge off when I went to bed and turned it back on in the morning when I started out again. The temp would only rise about six degrees (32 to 38) on most occasions. Less in cooler climes. Also had the insulated cover on it, but towels would work as well, or better.
BX

 

[trump]

I used my ARB in my Tacoma for several years before I added a second battery. I just turned the fridge off when I went to bed and turned it back on in the morning when I started out again. The temp would only rise about six degrees (32 to 38) on most occasions. Less in cooler climes. Also had the insulated cover on it, but towels would work as well, or better.
BX

This is what I have been doing as well without any problems.

Also to back up what was said above. I was using the fridge in the Xterra and forgot to turn it off before going out on the lake in northern AZ. Came back in 4 hrs later and the battery was completely flat... not enough juice to even remote unlock the doors. I had one of those jump packs in the vehicle and it saved the day, but that 4 year old battery was officially toast. Had to change it out the next day.

 

[Roaming Robertsons]

Thanks for all the advice. I stuffed a Die Hard Platinum Marine Group 31 battery under the hood in place of the stocker. I'll test it with the fridge load overnight in a week or so. If it still starts the truck, it should last me a few months until I get a second one.

 

[trek 4wd safaris]

you know engel make a solution for this....

http://www.engelaustralia.com.au/cg...bm12&item_string=&category=Fridge Accessories

turns the fridge off automatically when the battery starts getting too low, waeco do one as well thats simpler and cheaper about $40

basically its a voltage sensitive relay but only for 15 amps unlike the dual battery kits which will do over a hundred

 

[Roaming Robertsons]

you know engel make a solution for this....

http://www.engelaustralia.com.au/cg...bm12&item_string=&category=Fridge Accessories

turns the fridge off automatically when the battery starts getting too low, waeco do one as well thats simpler and cheaper about $40

basically its a voltage sensitive relay but only for 15 amps unlike the dual battery kits which will do over a hundred

Thanks. I just found out the ARB 50 on the way to my house has one built in. Very comforting. I'll test it out to see how the truck does at the three levels, 14.8. 14.4, and 10.1.

 

[Dave Bennett]

I used my ARB in my Tacoma for several years before I added a second battery. I just turned the fridge off when I went to bed and turned it back on in the morning when I started out again. The temp would only rise about six degrees (32 to 38) on most occasions. Less in cooler climes. Also had the insulated cover on it, but towels would work as well, or better.
BX

x2

 

[gjackson]

Thanks. I just found out the ARB 50 on the way to my house has one built in. Very comforting. I'll test it out to see how the truck does at the three levels, 14.8. 14.4, and 10.1.

Most of the newer fridges come with that functionality. Works very well, in all the ones I've tested.

cheers

 

[UK4X4]

I do the turning off at night as well running it a about 0oC during the day
next morning things are still frozen.

There is a 3 plug extension at walmart for 9 usd which just happens to have an auto shutoff as well.

its a silver one, and written in small letters, it works just fine as a backup

 

[dwh]

Thanks. I just found out the ARB 50 on the way to my house has one built in. Very comforting. I'll test it out to see how the truck does at the three levels, 14.8. 14.4, and 10.1.

A "12v" battery is considered completely dead at 10.5v.

If the low-voltage disconnect is variable, set it to whichever voltage will still start your truck. That's likely to be more than 11.5v and possibly as much as 13v.

14.4v is the voltage of of a fully charged battery before it has had a chance to rest and stabilize. After resting it should drop to usually around 13.5v - 13.8v. If you set your low-voltage disconnect at 14.4v (or higher) then it basically won't ever run from the battery because the battery will only be at that voltage while being charged, and will rapidly fall below 14.4v when the charging stops.

 

[Jay H]

I just ran an advanced search and found this thread, saved me the trouble of making a new thread.

I am in need of advice on this very topic and have found what I have already discovered to be a helpful starting point.

I have a waeco CDF-35 fridge I am running in a 2004 Rav4. There is course no off the shelf kit for me to add a second battery under the hood, and I probably couldn't afford it any way. I hope to add one eventually as the space does exist but It will take some time to fabricate a tray. I am currently on the road so i don't have time or space. I was hoping to run the fridge off of my one and only starting battery, a group 24r kirkland brand (manufactured by johnson controls I think) that's less than 2 months old.

This is not working. I got the danfoss data sheet online and found out I could swap a resistor to bump up the cut off voltage to 11.3 the max value listed. This resulted in my fridge turning off at the cut off voltage,some time in the 15 hours my car sat over nite. That part worked. I checked the open circuit voltage and it was 11.88 which could easily be 11.3 under load. Than I tried to start the car, this where it all went wrong. It turned over slowly less than once and then all I got was the dreaded click click.

I am now wondering if I can use a different resistor to bump up the cut off voltage to 11.7 as some waeco models with the same controller have this option even though the Dan foss data sheet shows a 82k ohm resistor for 11.3 as the biggest value on the chart. Of course I am starting to think it does not matter and 12.00 - 12.15v should be the lowest I go.

Another problem I can't find a cut off any where that is set that high. I know I should ideally not go below 1/2 a charge to make the battery last.

Hmm I already have a very nice 9.95- 15v dc input smart battery charger. Maybe I need to buys cheap sealed battery. I know very little about these.

Any one have any good suggestions, besides setting up a typical dual battery with an expensive controller and a tray I have to fabricate. Perhaps some one can recommend a good deal on a sealed, safe to use inside the car, battery. Or a cut off I can set high enough to protect the battery over many cycles.
As I already spent 335 on the fridge I would like to stay cheap for now. I wish I could just buy an identical battery to the starter and keep it in the car but I know I should probably be looking at AGM or SLA.

I will be going to the parts store to get my battery and alternator checked soon.

 

[JPK]

I run a small Engel in my Jeep, with a low voltage cut off switch equipped 12v "extension" cord. The set up won't work with a starting battery but works quite well with a deep cycle marine battery. I don't know what the cut off voltage is but there is enough in the deep cycle to start a 5.7 Hemi without issues.

The deep cycle I have is a Group 31 Optima, but if I had to do it again I believe I would go with the Sears Platinum Group 31 if it would fit.

To save some $'s, going with a Costco brand deep cycle would work. Great warranty, lots of places to swap for a new one if req'd and there are good reports on the batteries.

The 16l fridge will run about 2 1/2 days in the summer without starting the Jeep before the low voltage cut off switch kills power to it. Much longer in the winter, but it all depands on weather. I believe the power draw is similar to Engel's 35 and 40l fridges.

JPK