A problem and an attempted solutiion: 12v fridge and solar charger...

[Martinjmpr]

I'm not sure if I should post this in the "fridge" section or the "power" section, although it's really more of a power issue....
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I've been using a 12v fridge for almost 3 years now. Current fridge is a Truckfridge TF-41/Indel-B Travelbox TB-41 (they're the same thing.)
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Fridge works great - as long as we're traveling every day. However, every time we've gone camping where there was at
least 1 full day of no driving, I've woken up in the morning to find the fridge showing the dreaded "E1" error code and in most cases, the truck battery was too flat to start the truck.
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The first time this happened, I chalked it up to the fact that my 4runner still had the factory-original 2007 battery. So as soon as I got the truck started, I went to an auto parts store and asked for the biggest, most powerful battery they had that would fit the truck.
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Next I tried variations of the "low voltage cutoff" switch. My fridge has 3 settings, high, medium and low voltage cutoff. This worked under some circumstances - but it was only half a solution because when the voltage cutoff kicks in, of course, it cuts power to the fridge. So I might still be able to start the truck but my food is warm.
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The good news is that this problem has never left me stranded because in addition to getting a new battery, I also got a portable jump starter that I keep in the truck and I make sure it is charged up before every trip. It's also nice to know that if we're traveling with our trailer, that has a 12v battery we could use in an emergency, too.
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Most of our camping trips this year we've had electrical hookups most nights, so I've avoided the problem for the most part by bringing a long extension cord and just plugging the fridge into the 120vAC power source. But of course, that's not really a viable solution for "boondocking."
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Since I'd rather start small and see if that works rather than throw a bunch of money out there, I figured I'd get one of those cheap "battery maintainer" solar chargers. The one I found on Amazon was this one:
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http://www.amazon.com/gp/product/B00QRHDIPY?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
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I chose this one because of its low price and positive reviews on Amazon.
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My hope is that by having this hooked up to the battery on a sunny day, it will at least prevent the battery from discharging so quickly and keep both the fridge running and the battery from discharging to the point where the truck won't start. It will get its first test towards the end of the month - we have a 4 day camping trip by a lake and there are no hookups and no facilities, which basically means that once we get there, we're not likely to need to go anywhere (we'll have everything we need and we'll be right next to the lake where we'll be kayaking and fishing, so unlike other camping trips where we have to drive to the lake, we won't at this one.)
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I'll post the results of my experience after we get back! If this doesn't work, I may have to move to a bigger/more expensive solar array. The good news is that there seem to be some real advances in solar power out there and all the competition is driving prices down.

 

[jscusmcvet]

Definitely interested in this. Keep us updated.

 

[poriggity]

I bought a similar setup at Harbor Freight for my truck. I have run my fridge for over a week without starting the truck while the solar charger was hooked up to my main battery, and my ARB fridge was plugged into my constant hot 12V in the truck. I'm not sure that the solar charger is really doing anything, because I never measured current on the batteries, but I didn't get stranded....

 

[AndrewP]

Not to bust your bubble, but 5 watts won't even be noticeable in your scenario. Your fridge when running draws somewhere around 3 amps. If you assume it runs 10 hours per day, that's 30 amp hours needed from your battery every 24 hours.

A 5 watt panel at best is going to make .25 amp in good sun, so say .25 x 6 hours you're putting 1.5 amp hours back into the system. So you're off by at least a factor of 20.

There is nothing magic about solar, you just need to size your supply to the load.

I'd also get one of those inexpensive power meters so you can measure your power use. Like this:
http://www.amazon.com/GT-Power-Anal...pebp=1436885800802&perid=0YP69EVTZ1K4G3SWF1NK

Anyway, for $18 it's hard to go wrong and super handy for measuring cumulative power use-place in series with your fridge power supply, and you'll know exactly what your 24 hour use is in watts or amp hours (it records both), then you can more accurately pick a right sized solar panel.


You need a 60-100 watt panel to keep your battery charged and to keep up with your fridge during the day.

Here is a link I posted before but it is an analogous experience to yours:
http://forum.ih8mud.com/threads/rubicon-solar-power-experience.867614/

 

[228B]

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The very first thing I'd be concerned with is the battery you're using in this scenario. Your fridge draws less than half of what one pair of 55W headlights will draw (3 amps as opposed to 8 amps). Like verkstad just mentioned, repeated deep discharge of a starting battery will place it's future reliability in question.
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Your battery is truly the heart of any 12V system. Learn what it needs, then treat it as best you possibly can. And like Andrew said, "there's nothing magic about solar"... a good rule of thumb as the minimum solar input necessary for any given battery size is: 100 watts solar for every 100 Amp-hour battery capacity.
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Remember too that especially with 12V systems, wire size is VERY important. Too small wiring will choke the battery then it will never become fully charged... which is kind of what's happened to your starting battery. Once your battery is healthy (either properly recharged if not too damaged or better yet replaced), a good, simple solar charging setup can do the job you're looking to do!
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Here is some of the absolute best, most-experienced boondockin' solar info you'll ever see ---> https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/

 

[calicamper]

Not to bust your bubble, but 5 watts won't even be noticeable in your scenario. Your fridge when running draws somewhere around 3 amps. If you assume it runs 10 hours per day, that's 30 amp hours needed from your battery every 24 hours.

A 5 watt panel at best is going to make .25 amp in good sun, so say .25 x 6 hours you're putting 3 amp hours back into the system. So you're off by at least a factor of 10.

There is nothing magic about solar, you just need to size your supply to the load.

I'd also get one of those inexpensive power meters so you can measure your power use. Like this:
http://www.amazon.com/GT-Power-Anal...pebp=1436885800802&perid=0YP69EVTZ1K4G3SWF1NK

Anyway, for $18 it's hard to go wrong and super handy for measuring cumulative power use-place in series with your fridge power supply, and you'll know exactly what your 24 hour use is in watts or amp hours (it records both), then you can more accurately pick a right sized solar panel.


You need a 60-100 watt panel to keep your battery charged and to keep up with your fridge during the day.

Here is a link I posted before but it is an analogous experience to yours:
http://forum.ih8mud.com/threads/rubicon-solar-power-experience.867614/

^ what he said roughly figure 1 amp of generated power from every 10 watts of solar panel. I have two 10watt panels they generate about a solid 1amp per hour charge in marginal conditions and around 1.2 amps an hour under ideal conditions. In your case you need about 7-8amps generation capability to both power the fridge during the day light hours but also charge your battery to replace the amp hours you burned over night. Meaning you need at least bare minimum 80watt panel and I would advise just hooking it up to a secondary battery to keep your truck battery isolated from your camping power needs. Anything over 18watts should use a solar controller I use a cheap parking light lamp solar controller has a max of 20amps in or out manages the battery condition and charging cost me like $37 on Amazon works great. If your savy you can even just wire your load side from the load side of the controller which will prevent you from running the battery past 11.4 volts by cutting off the power feed (prevents battery damage)etc. You could install one of these on a marine style battery box with a deep cycle battery add a plug for the fridge and solar panel and you would be all set. The off grid parking light solar controller type units are designed to be mounted in the box with the battery given they also manage power based on battery box temp if the box gets too hot the controller will shut down both charging or power out to avoid over heating the battery. Nice feature. I would also fuse the panel input, battery and any load items you connect up. Which case I bought a simple 6 fuse fuse box very small and little ground bar to place the ground connections on which in my case all fit in a small ammo box with a small 18ah battery. You need a good size battery if your burning 3+amps an hour during non solar hours.

 

[AndrewP]

^ what he said roughly figure 1 amp of generated power from every 10 watts of solar panel. I have two 10watt panels they generate about a solid 1amp per hour charge in marginal conditions and around 1.2 amps an hour under ideal conditions.

No don't figure this. Your own numbers show the truth. About 20 watts of solar for each amp in a small 12volt system. That's why Martin is so far off in his generation vs need. The panel he wants is only 5 watts. It *might* be enough to maintain a fully charged battery with no loads on it, but 5 watts is almost nothing.

I do agree that 80 watts would be the minimum panel, and 100-120 watts would be much better.

It is possible to run with just one battery, but you'll want to use an "RV" or "Marine" type battery that is rated for both starting duty and some degree of deep cycle. I'n an ideal world, you'll run your house loads off a second battery isolated from your main engine starting battery.

I don't like automatic voltage cut offs especially if you rely on it to save you. Much better to have an isolated fully charged starting battery.

 

[228B]

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Indeed. Figure roughly about 5 amps per 100W panel. I'm seeing over 6 amps now, per panel (in peak sun), but that's with two 100W panels connected in series, producing an average 35 volts at this MPPT controller which then sends over 12 amps to this battery when the charge profile is in it's "bulk" phase...

 

[FJR Colorado]

You really need to get yourself a 100W Renogy solar panel (with controller) and a deep cycle battery.

This set-up works absolutely great for running a fridge.

See my build thread on the 2006 Tundra.

In sunny Colorado, I can run the fridge 24/7/365 and still have power left over for charging cameras, phones, laptops and such plus the occasional light.

 

[calicamper]

You really need to get yourself a 100W Renogy solar panel (with controller) and a deep cycle battery.

This set-up works absolutely great for running a fridge.

See my build thread on the 2006 Tundra.

In sunny Colorado, I can run the fridge 24/7/365 and still have power left over for charging cameras, phones, laptops and such plus the occasional light.

Yup, given his 3amp per hour load from the fridge this would be a pretty ideal set up. Going smaller 80w would require micro managing the power and keeping close tabs on the solar output during the day.

I don't use a fridge (yet) if we are lucky we find a block of ice. So our power needs are far far far far lower and are easily met by the two 10watt panels and 18ah baby battery set up.

 

[CaliMobber]

while everyone is mostly right and are throwing out random sizes of panels, Ill just tel you what is working on mine.

I have a 80w alko solar panel from amazon and a morningstar controller with 2 yellow optimas. I have my edgestar fridge set at 40deg F and the solar keeps my battery maintain indefinitely. while i not currently in a hot location and days only get to about 70-80 on warmer days my fridge does say on always . I do go over 5 days without driving and my batteries are always topped up and happy.

But i always say bigger is def better when it comes to solar and I recommend getting the largest panel your roof can support, so you wont have anything to worry about power wise

 

[LandCruiserPhil]

I have a client that has been running a stand alone set up (not tied to the vehicle at all). Uses a 100w panel and a 55ah battery to power his NL fridge and charging small electronics. Lives out of his vehicle, spends his winters in Aspen and summers in Santa Barbara never an issue in over 2 years.

 

[Martinjmpr]

You really need to get yourself a 100W Renogy solar panel (with controller) and a deep cycle battery.

This set-up works absolutely great for running a fridge.

See my build thread on the 2006 Tundra.

In sunny Colorado, I can run the fridge 24/7/365 and still have power left over for charging cameras, phones, laptops and such plus the occasional light.

So would you be talking about something like this?
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http://www.amazon.com/Renogy-100W-M...d=1437069218&sr=8-2&keywords=100w+solar+panel
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What else would I need to run this setup?

 

[Bbasso]

http://www.amazon.com/RENOGY-Monocr...pebp=1437069763022&perid=129K2RT8QBDGXC6FESKY
and
http://www.amazon.com/Sunforce-6003...pebp=1437069784103&perid=1F2YN7J5NAPFEWJ09KAM
along with 10GA wiring, MC4 Cable extension to go from panel to controller. Just be sure to get copper strand cables/wires.

makes up the bulk of my system, I choose the 30 amp controller so I could add more panels without too much worry.
I'm pretty sure this is the most popular affordable option. An MPPT controller would be better but at higher cost.

 

[Martinjmpr]

http://www.amazon.com/RENOGY-Monocr...pebp=1437069763022&perid=129K2RT8QBDGXC6FESKY
and
http://www.amazon.com/Sunforce-6003...pebp=1437069784103&perid=1F2YN7J5NAPFEWJ09KAM
along with 10GA wiring, MC4 Cable extension to go from panel to controller. Just be sure to get copper strand cables/wires.

makes up the bulk of my system, I choose the 30 amp controller so I could add more panels without too much worry.
I'm pretty sure this is the most popular affordable option. An MPPT controller would be better but at higher cost.

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So how does this "tie in" to the vehicle's power system? Alligator clips on the battery or is there something more high tech?