Super-simple 12v power source for fridge?
- Thread starter Martinjmpr
- Start date
dwh
Tail-End Charlie
Yea fine. Even draining the battery 100% - IF it's a deep cycle - should get you 300-500 full/dead/full cycles. That's plenty for what you're doing. I'd recommend a Battery MINDEr (not "tender") desulfator for when home charging.
https://www.batteryminders.com/12v-onboard-desulfator
Size the fuse to protect the wire. #14 wire, 15a fuse. #12, 20a. Of course you can always use a fuse rated less than the wire, so a 15a fuse will probably be all you need.
Haven't looked at that conversion formula, but RC is usually measured with a 25a load, while AH is whatever load will drain the battery in 20 hours (if meauring @20hr rate)...or 10 hours if they are measuring @10hr rate. So say a 100ah battery, a 5a load will drain it in 20hrs. The important factor is Peukert, so a 25a load (RC) will result in less overall battery capacity than a 5a (AH) load. Thus, a straight conversion formula might be a handy rule of thumb, but might deviate quite a bit depending on battery size.
Note that while all batteries can be measured in terms of cranking amps, cold cranking amps, reserve capacity and amp*hours...which numbers the manufacturer chooses to publish is often a pretty clear indication of the battery's purpose. If it's a cranking battery, they'll list the CA, CCA, and RC, but not the AH. For a deep cycle, they'll list the AH but not the others.
Buy a deep cycle for what you are doing.
https://www.batteryminders.com/12v-onboard-desulfator
Size the fuse to protect the wire. #14 wire, 15a fuse. #12, 20a. Of course you can always use a fuse rated less than the wire, so a 15a fuse will probably be all you need.
Haven't looked at that conversion formula, but RC is usually measured with a 25a load, while AH is whatever load will drain the battery in 20 hours (if meauring @20hr rate)...or 10 hours if they are measuring @10hr rate. So say a 100ah battery, a 5a load will drain it in 20hrs. The important factor is Peukert, so a 25a load (RC) will result in less overall battery capacity than a 5a (AH) load. Thus, a straight conversion formula might be a handy rule of thumb, but might deviate quite a bit depending on battery size.
Note that while all batteries can be measured in terms of cranking amps, cold cranking amps, reserve capacity and amp*hours...which numbers the manufacturer chooses to publish is often a pretty clear indication of the battery's purpose. If it's a cranking battery, they'll list the CA, CCA, and RC, but not the AH. For a deep cycle, they'll list the AH but not the others.
Buy a deep cycle for what you are doing.
FJR Colorado
Explorer
My thoughts...
Yes, Martin, I think this will work.
Use a deep cycle battery. I would suggest the Renogy Gel 100AH battery. I am having gobs of success with mine, albeit connected to solar. Heavy sucker though at 63 pounds...
You should set the fridge to "Medium" or even "High" as far as the low voltage cut-off. This can save from sucking the battery dry and causing permanent damage.
Yes, as many others have mentioned, a boost from the alternator and/or solar would potentially help a lot especially when it is very hot.
Schumacher has a cute little 15watt solar panel and charge controller. It all just plugs together. You could face it in the sun and connect clamps and it would actually help a lot. I use this as a back-up at my off-grid cabin. It keeps a dedicated 35AH MightyMax topped off and constantly ready for emergency use.
As an aside... For years, I powered the LED lights in my off-grid cabin by way of a cheap little Wagan jump starter that I'd charge at home and bring with me. Worked like a charm. I now have a primary and back-up installed solar system. It's nice not to lug a battery pack, but for lighting it really works no better. It was amazing that I could NOT drain that crappy little Wagan. I still have it and it still works. Sometimes simple ideas rule...
Yes, Martin, I think this will work.
Use a deep cycle battery. I would suggest the Renogy Gel 100AH battery. I am having gobs of success with mine, albeit connected to solar. Heavy sucker though at 63 pounds...
You should set the fridge to "Medium" or even "High" as far as the low voltage cut-off. This can save from sucking the battery dry and causing permanent damage.
Yes, as many others have mentioned, a boost from the alternator and/or solar would potentially help a lot especially when it is very hot.
Schumacher has a cute little 15watt solar panel and charge controller. It all just plugs together. You could face it in the sun and connect clamps and it would actually help a lot. I use this as a back-up at my off-grid cabin. It keeps a dedicated 35AH MightyMax topped off and constantly ready for emergency use.
As an aside... For years, I powered the LED lights in my off-grid cabin by way of a cheap little Wagan jump starter that I'd charge at home and bring with me. Worked like a charm. I now have a primary and back-up installed solar system. It's nice not to lug a battery pack, but for lighting it really works no better. It was amazing that I could NOT drain that crappy little Wagan. I still have it and it still works. Sometimes simple ideas rule...
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Martinjmpr
Wiffleball Batter
Interesting! Was it one of those little 35ah batteries they sell with the solar stuff at Harbor Freight? I was wondering about hooking a couple of those up in series for a battery box just to make it lighter and more compact.
Battery 12V 35Ah - Fresh & Real 35 Amp - Deep Cycle AGM/SLA Seal Lead Acid Designed for Generic Use - Genuine KEYKO KT-12350 - Nut & Bolt L2 Terminal https://www.amazon.com/dp/B01M0AXD00/ref=cm_sw_r_cp_apa_i_JUCCDb8T14XFX
BlueFire PWM 30A Digital Solar Charge Controller Regulator 12V 24V with USB/DC Charger Port https://www.amazon.com/dp/B00W5GF4DU/ref=cm_sw_r_cp_apa_i_FVCCDb4HE74X0
Stuffed it into an ammo box with 3x 12v cigarette plugs.
DaveInDenver
Middle Income Semi-Redneck
What I've found is a ~50 A-hr stationary gets me a couple of days on my Engel MT45 using a 50 watt panel and an MPPT controller with typical Colorado summer weather, e.g. hot, low humidity and good sun interrupted by afternoon (losing good solar but reducing fridge load) clouds and storms. Running the panel just about balances the fridge hovering around 12.9 V or so. So I get a very slightly charging current but mostly it's about not discharging very much most of the day. I can stretch to a third day if I'm careful about opening and turn the fridge down at night. If I turn it completely off at night, which I do sometimes if it gets cool enough and you know here that is possible, I could probably start pushing it to 4 or 5 days. But that would take a lot of effort and plenty of good sun. With 100 watts of solar I think I would get significant charging during the day so a week on 35 A-hr *might* start to be possible but I have my doubts and it would have to be a week without too much overcast. Bear in mind that is only running a fridge that consumes about 2.2 A running and it might be as much as 50% duty cycle at the peak of the day.
Martinjmpr
Wiffleball Batter
Our travel trailer (2018 R-Pod 179) is currently set up like this. 2 x Duracell 6v 230ah FLA batteries in a NoCo dual battery box sitting on the tongue. It is connected to the "solar on the side" plug (just a reversed SAE connector) and I have an SAE harness with the plug hanging out of the box as well. When we boondock I just plug the solar panel into the harness and it typically keeps the batteries at 90 - 100% (according to the controller) most of the time.
My cost was a bit higher though. I wasn't a Costco member at the time so I got the batteries from Batteries +. IIRC they were ~$165 each so $330 for the pair. Not cheap but definitely more usable capacity than the 12v that was on there before.
Martinjmpr
Wiffleball Batter
Having thought this through, I may or may not go through with this. There is a zero-cost alternative: Leave the TruckFridge at home (since we have a 3 way fridge in the R-Pod that will run fine on propane.) When we go to our next two camping trips after that we'll have shore power so bringing the truckfridge just means bringing an extension cord so I can plug it into the 15a (house current) plug on the power post.
That way I'll have all Winter to come up with a better long term solution (power box with DC-DC charger most likely.)
That way I'll have all Winter to come up with a better long term solution (power box with DC-DC charger most likely.)
DorB
Adventurer
You need to run over a short check list to determine if the100ah battery is sufficient god you.
As I measured it, a good fridge set to “32f at about 70f ambient temp, shaded and well ventilated, draws an average 1.5 ah in 24h (low night consumption and normal day consumption).
As 35~ah/24h in total.
Now,
If you re-stock it with new “hot” products that need to be cooled, the consumption will go up.
If you open it many times, it will go up..
If you set the fridge to 39f(safe temp for chilled food), it will be slightly less ah consumption.
As I measured it, a good fridge set to “32f at about 70f ambient temp, shaded and well ventilated, draws an average 1.5 ah in 24h (low night consumption and normal day consumption).
As 35~ah/24h in total.
Now,
If you re-stock it with new “hot” products that need to be cooled, the consumption will go up.
If you open it many times, it will go up..
If you set the fridge to 39f(safe temp for chilled food), it will be slightly less ah consumption.
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Do you have a towing package and a 7 pin trailer connector? Ford ignorant. My 2014 Silverado has a hot all the time pin on the truck/trailer plug. I connected a two wire 14 gauge extension cord to a 7 pin trailer end and connect that to the Edgestar 12V fridge in the bed by simply passing the wire through a gap in the tail gate. Draws 3-4 amps when occasionally running.
I've also sat the fridge on the ground in the shade and ran the cord from the truck to the fridge. Longest time using without the truck being cranked was about 72 hours. The truck battery drained to about 12.2vdc.
I've also sat the fridge on the ground in the shade and ran the cord from the truck to the fridge. Longest time using without the truck being cranked was about 72 hours. The truck battery drained to about 12.2vdc.
Edit: I forgot. Four small powerpole connectors on the fridge end to allow feeding solar to the truck battery. Haven't used solar so far for that purpose. Also, neighbors cranking that whisper-quiet V8 generator at any time of day has never disturbed me like even a quiet inverter generator. Doesn't take long to keep the battery out of trouble.
dreadlocks
Well-known member
DC Fridges are very subjective in consumption, one should always test for worst case scenario and use that as a baseline.. everyone's usage and backing systems are so different what one person gets another may never accomplish.. be weary of people who are giving you feedback on runtime that clearly have no monitoring, yeah it may be possible to get 4 days, but in all likelihood at the cost of a new battery every season if they are just letting it drain batteries way past their comfort... all seems fine and dandy until in the middle of a trip the battery meets the grim reaper and all your food starts to become questionable or you chew a few hundred dollars out of your trip budget youd of rather spent on other things than a battery.. this happened to me more than once when I first started bringing a fridge along.
In my case it seems my beer is the largest consumer of energy, if I pre-chilled all my beer for a weekend outing, I'd have no room for any food and longer trips would require multiple fridges.. tossing a warm six pack in every day per person really takes some effort to chill and I like my beer frosty cold, so it also means running my fridge at 0C.. I aint giving up my beer for another day or two of fridge use thats for sure.
In my case it seems my beer is the largest consumer of energy, if I pre-chilled all my beer for a weekend outing, I'd have no room for any food and longer trips would require multiple fridges.. tossing a warm six pack in every day per person really takes some effort to chill and I like my beer frosty cold, so it also means running my fridge at 0C.. I aint giving up my beer for another day or two of fridge use thats for sure.
DaveInDenver
Middle Income Semi-Redneck
My aux Odyssey died mid-trip, at the Dollhouse in the Maze back in April actually. It was a matter of keeping things together with bailing wire and duct tape for a couple of days on one battery. It's a pain but it's why one builds redundancy in the system. What's the saying, two is one, one is none.
