Battery to run a fridge

[wasanah2]

I saw Bob's video with the man with the Kia Sedona and he was running his fridge on a second battery that was charged while he was driving, and when he stops, he's got a full battery to run his fridge on.  That is an awesome idea as I don't have the money for the solar yet. 

So what I was wondering, if I got a set up like that guy with the battery isolator and such, how long would the charge last to run the fridge?  I know it depends on the type of fridge you get and all, but for a small efficient one, would it keep things cold for more than a day?  And then how long would you need to run the engine to charge up the battery again. 

I'm thinking this set up might be good for long trips, but what if you want to stay put and don't want to go into town all week?  If so, would I be running the engine for hours at a time to get enough juice to power the fridge?

Thanks in advance,
Wasahah

 

[highdesertranger]

" If so, would I be running the engine for hours at a time to get enough juice to power the fridge?"

yes.

first, the battery needs to be charged everyday.
second, it takes hours to charge a battery of an alternator.
highdesertranger

 

[jonsun]

100w solar panel and all the stuff for it under $200

 

[John61CT]

Ideally both.

Dino juice sources are great for getting a lot of AH into a depleted batt during the early part of the charge cycle, say up to 80-85% full. To minimize runtime, choose high acceptance like quality AGM from Odyssey, Northstar or Lifeline.

But for that expensive battery to last, you need to charge to 100%, the "long tail" at Absorb voltage for another 3-5 hours, where the batt is accepting low amps only, solar is perfect for that.

 

[wasanah2]

100w solar panel and all the stuff for it under $200

Bardo, would 100w be enough for a really efficient small fridge?  I was thinking you'd need 200w or more.

 

[wasanah2]

" If so, would I be running the engine for hours at a time to get enough juice to power the fridge?"

yes.

first,  the battery needs to be charged everyday.
second,  it takes hours to charge a battery of an alternator.
highdesertranger

OK so this isn't the right move for me.  I could easily burn a tank of gas in a week just sitting in paradise.  If I were driving to a job site and the car sitting all day or if I were going overland on a long trip, that would be a viable solution.  Thanks, that's one thing the video didn't cover!  An important thing!!

 

[John61CT]

> would 100w be enough for a really efficient small fridge?

Depends on latitude / mounting angle, climate and weather (temperature, overcast vs clear), so many variables.

Also really no other loads?

For my situation, 200w is minimum in summer, 300w in winter.

Some say they get by with 100w, but then many (most) don't get good lifetime because they fail to get back to 100% every cycle, perhaps don't even realize​ it.

 

[wasanah2]

Ideally both.

Dino juice sources are great for getting a lot of AH into a depleted batt during the early part of the charge cycle,  say up to 80-85% full. To minimize runtime,  choose high acceptance like quality AGM from Odyssey, Northstar or Lifeline.

But for that expensive battery to last, you need to charge to 100%, the "long tail" at Absorb voltage for another 3-5 hours, where the batt is accepting low amps only, solar is perfect for that.

Hmmm, both?  What is Dino juice?  What is AH?  Sorry I don't know the lingo!

I'm east of the Rocky Mtns and not likely going to be in the bright desert sun every day.   Are you saying I can use the isolator set up I saw on the video to charge when I drive and then use solar panels if there's enough sun?  Then if not enough sun, I run the engine enough to generate enough electric?

 

[John61CT]

Dino juice = fossil fuel charge sources, as in Alternators and Generators.

 

[John61CT]

Amp Hours, basic measure of energy, e.g. battery capacity and device usage over time.

One amp over an hour is 1 AH.

A fridge might use 30-50 AH per 24 hours.

So IMO you would want to add 120-150 AH to your bank capacity.

 

[John61CT]

An isolator doesn't charge anything.

It is one option to keep your Starter batt from going flat, needed only if you use the Alt for charging House, or the Starter for things other than just cranking the engine

A combiner (VSR / ACR) would be better.

 

[John61CT]

A portable generator would be IMO better than running your engine just to charge a battery.

You need to do a lot of driving every day for the Alt to be a major contributor to keeping the House batt full.

If you have a LOT of solar, that can be your only power source, but most vehicles don't have much space up top.

Best is a combination, dino juice in the early morning, solar to get to 100%.

 

[wasanah2]

A portable generator would be IMO better than running your engine just to charge a battery.

You need to do a lot of driving every day for the Alt to be a major contributor to keeping the House batt full.

If you have a LOT of solar, that can be your only power source, but most vehicles don't have much space up top.

Best is a combination, dino juice in the early morning, solar to get to 100%.

OK, the reason I need so much power is the fridge.  I used ice in an ice chest on my trial run and in a few days (at most) I have to go back into town when I don't want to leave.   Even if I stepped up and bought a Yeti, I can't last a week without power.  So another option would be the fridge I'm looking at which is really the size of a small cooler, has 3 way capacity.  That means I can use it on 12 volt, house current or propane.  What if I used it on propane?  I don't see anyone doing that on the youtube videos.  Is there a reason?  It appears it goes through 1/2 lb propane a day.  A BBQ tank would last 20 days.  I could even get a smaller tank since I really want to last at least a week.  But since people don't seem to be using them, is there a problem with using a fridge on propane?

 

[jonsun]

100w is plenty with a generator. One hour in the morning and the panel youre good to go. Fridges 12v or 120v use about 40-60a a day in the summer and 15-20a in the winter. Right about the limit of a 100w panel.

After you get the other stuff for solar an additional100w panel is only another $100 more as well. So lets say $300 ish on 200w. Solar is very reasonable nowadays.

 

[Scout]

OK, the reason I need so much power is the fridge.  I used ice in an ice chest on my trial run and in a few days (at most) I have to go back into town when I don't want to leave.   Even if I stepped up and bought a Yeti, I can't last a week without power.  So another option would be the fridge I'm looking at which is really the size of a small cooler, has 3 way capacity.  That means I can use it on 12 volt, house current or propane.  What if I used it on propane?  I don't see anyone doing that on the youtube videos.  Is there a reason?  It appears it goes through 1/2 lb propane a day.  A BBQ tank would last 20 days.  I could even get a smaller tank since I really want to last at least a week.  But since people don't seem to be using them, is there a problem with using a fridge on propane?

It would cost more in the long run.After your intial investment in solar and the time to make back your investment the electricity is free.

 

[wasanah2]

100w is plenty with a generator. One hour in the morning and the panel youre good to go. Fridges 12v or 120v use about 40-60a a day in the summer and 15-20a in the winter. Right about the limit of a 100w panel.

After you get the other stuff for solar an additional100w panel is only another $100 more as well. So lets say $300 ish on 200w. Solar is very reasonable nowadays.

It'll be a hassle carrying all that around.  That's why I was thinking the propane setting on the fridge would be a better plan.  I'd probably get a suitcase kind so I can park in shade and gather sun in a clearing.  But the place I camped just recently had no direct sun.  It was in the forest and shaded well and cool.   If I were running a fridge/cooler on propane, it wouldn't matter where I camp.  Just want to know why people aren't already doing this.  Wondering if there is a reason.

 

[John61CT]

Yes propane fridge works great, but usually not much good on 12V, very inefficient, totally unsuitable for solar.

So get it and the contents cold on shore power, put on 12V for maintenance only while driving.
Then turn on the propane when you set up camp, make sure it's level, don't run propane while travelling.

But IMO if you take on the boondocking lifestyle you'll likely find you need solar power anyway, and the compressor fridge really is **so** much more efficient. . .

 

[wasanah2]

It would cost more in the long run.After your intial investment in solar and the time to make back your investment the electricity is free.

Well, I plan to get the 3 way fridge anyway.  If it runs on propane and no one sees a problem in it, I can save for the other power methods and get out faster.  I also would have to get the second battery set up (not sure what that costs) and the isolator and such.  I don't have any of that bought.  I found a pretty good deal on a 3 way, so I'm thinking of pulling the trigger on that and using propane for the fridge.  I simply don't want to move the vehicle till I run out of resources (water or food or whatever) or it's time to leave the National Forest due to rules.  I used to backpack and carried freeze dried food.  I still have a lot of it.  It's good for like 25 years (supposedly).  Anyway, with a small fridge for medication and cold tea (I'm hooked on tea) and my freeze dried food, I'd like it if I could be on my own for at least a week without having to move from my camp.  Two weeks would be even better.

 

[John61CT]

If your vehicle can carry a decent size undercarriage mounted propane, you'd be good to go for the fridge, a genny, heat / hot water and cooking for nice long stays.

 

[steamjam1]

I have a three way Norcold refrigerator. I never use it. Which is too bad because its brand new... I did once use it on all three settings... On 12V is killed my house battery pretty fast... I bought a 12V cooler and it goes all day.