Advice on solar fridge system for everyday use.

[J.Spicoli]

Hey guys, been lurking around a while taking it all in and got some questions about a setup I'm thinking about.

I'm going to be spending a lot of time in the back of a full size truck with 6.5' bed for work and camping and I'm planning a whole setup in the back with bed and storage underneath and I need a sustainable solar powered fridge system. I'd like this to be able to run off the battery and solar only. ***I am however thinking about adding the second battery to the engine compartment to be able to be charged via alternator and getting an isolator so that it doesn't drain the primary starting battery, but that's another issue for another time. I'd like to charge cell phone and laptop through an inverter as well and aside from that power consumption will be minimal.

I've been reading up and looking and so far I'm thinking:

30-45 qt. Norcold or Dometic
12v battery in the 120-150 Ahr range
100w Renogy solar kit with MPPT controller

Looking for input all around. I'm a bit of a boyscout so I'd rather spend a bit more now to know I have what I need than to guess and hope. I live in a fairly mild climate where the temperature outside stays between 50-90 most of the time.

1. Which of these fridges is most efficient? Or is there another manufacturer I should consider?

2. Suggestions on batteries, 12v or 6v might be better?. (I've thought about two 6v in series but space is at a premium and, I may be wrong here but I'm thinking 120-150 Ahr from a 12v should be doable and provide the capacity I need just not sure the charging method is good for the 12v).

3. Solar power, should I consider more, 200w maybe?

4. What else am I missing? Battery cables and gauge?


Thanks

 

[Ducky's Dad]

Some of the answers depend on the vehicle and its charging system and available space.

I looked at a bunch of fridges and settled on an Indel B 50. Price is right and it works like a charm. Used it as a freezer on a couple of Arizona trips at the beginning of the month and it got down to -21C with daytime ambients around 110F, froze the stuff in the freezer section but just left the drinks in the fridge section real cold.

Batteries are a crapshoot, but bigger is always better. If you have space, a bank of Trojan 6V might be the best solution. My house batteries are a pair of Optima G34 Blue dual purpose and they ran the Indel B just fine. I don't have solar yet but will probably add some. Others will comment, but 100W seems to be the bare minimum, 200 way better. Battery cables fall into the bigger/better category, and will depend on alternator output, run length, loads, etc. You should probably consider 1/0 cable as the minimum, but 2/0 is better and still workable. 3/0 is gross overkill, so that's what I used. Best bet is probably to find some welding cable on CraigsList and make whatever cables you need. Make sure you get 100% copper stranded cables. Look for the super-flexible cable because it is a lot easier to run. You may not need an inverter for charging phones and laptops, depending on the laptop. I added some Blue Sea/Marinco 12V power outlets with removable USB inserts and we charge a variety of phones and iPads with no problems. My isolator is a switched solenoid from Painless Performance, augmented by a Blue Sea Systems rotary switch to control the house batteries. The solenoid is switched from the dashboard and the Blue Sea switch is next to the fridge, and all three batteries have National Luna battery monitors on them. I'm not a fan of automatic charging/switching systems.

 

[AndrewP]

If this is going to happen this winter, with it's frequent cloudy days and rain, you might be asking too much from a solar only set up.

I would instead prioritize making sure it will also charge when your truck is running. Because the truth is, your truck will make much more power than any practical solar. Even a 20 minute drive to work will do any bulk charging your batteries will need, and the solar can sit there all day and keep them topped off, and running your fridge, while also doing the important higher voltage absorption stage of charging.

It is highly unlikely you will need wire larger than 2 gauge, but if your run is very long go for it. In your solar circuit, 10 ga wiring for what you describe will be plenty. I do not agree with the wiring advice of using used welding cable. Since this will be truck mounted, frequently wet and hot/cold you would do better with "boat cable" or marine wire where the insulation is rated for oil, grease, 105C and the wire strands are tinned.

Regarding batteries, since you are making a new set up, I'd use cheaper batteries the first time. Normal flooded 12 volt lead acid deep cycle batteries will work just fine-the brand is up to you. Just don't use a "starting" battery. If there is room, keep it under the hood and make sure it has a stout hold down/battery box. Make sure all your wiring is appropriately fused at the battery.

I do like voltage sensing relays in an application like this. In fact, they are ideal. The Blue Sea ACRs are excellent and widely available, (and simple to hook up) but there are other brands available too. Then you don't have to remember to turn things on and off.

 

[1leglance]

The flexible panels are more efficient in poor lighting and hot air temps than the glass panels.
On the laptop inverter look for a travel setup that only goes from 12v to 15-19v instead 120v, that will save your battery also. I love my I-GO but there are plenty of brands.
Remember that your goal is to NOT take a battery below 80% discharge if you want it to last.....Lithium Ion can handle lower but then you need to make sure your charge controller is meant for them (higher input charge).
Keep us posted on what you install and more importantly how it works so we can all learn from your efforts....not to mention post up reports/pics of your travels

 

[J.Spicoli]

I'm currently reading through dstock's 100+ ambient Temp - ARB 50qt - 100 watt solar panel - Not enough? thread and learning, I think, that how you charge the batteries and the temperature of the batteries is something to consider too. Is this correct and why AndrewP mentioned above to go with cheaper batteries for the first time? LOL, because I'll probably kill them learning how to care for batteries??

I also think I saw in dstock's thread mentioned above that someone said AGM batteries don't like heat and not to mount them under the hood in the engine bay?

Thanks for all the info so far, keep it coming. I'm looking into all suggestions as I still have a few months to research this before I get the truck and get this started. Ordering a 2016 F-150 : D

 

[J.Spicoli]

I do like voltage sensing relays in an application like this. In fact, they are ideal. The Blue Sea ACRs are excellent and widely available, (and simple to hook up) but there are other brands available too. Then you don't have to remember to turn things on and off.

Hadn't heard of voltage sensing relays so I looked into them and I'm wondering if the MPPT controller for the solar panel would be the same or kind of along the same lines?


Man, my head is spinning. Just when I thought I was starting to understand I came here and now I've got cable gauge, cable termination, voltage sensing relays, battery temperature, cooling fan systems, Watts Up monitors, cable run, battery discharge levels and on and on all running through my head.....

 

[4x4junkie]

I'm currently reading through dstock's 100+ ambient Temp - ARB 50qt - 100 watt solar panel - Not enough? thread and learning, I think, that how you charge the batteries and the temperature of the batteries is something to consider too. Is this correct and why AndrewP mentioned above to go with cheaper batteries for the first time? LOL, because I'll probably kill them learning how to care for batteries??

I guess that could be one reason... However I've used AGM twice and both times went back to standard FLA batts simply because the AGM offered little in the way of any improvement for my use. The FLA batts last just as long, run my loads just as well, and are about 1/3 the price (infact just last night I discovered one of my eleven-year-old Delco Voyagers had lost a cell and went kaput... 11 years, I'm not complaining ).
Will probably replace them with Kirkland/Interstate batteries from Costco, about $80 each for a 12V ~100Ah unit.
The only thing with some FLA batts is you might have to pull off the vent caps and put a little teflon thread-seal tape around each of the three plugs to seal them against seepage as the electrolyte sloshes within the battery (IMO a minor thing to save about 50-70% on the cost of batteries).

I'll ×2 the welding cable comment.
I ran a length of 2/0 welding cable when I relocated my batteries from under the hood to under the rear floor of my BII. Something I discovered was the insulation on it is not very abrasion or chafe-resistant. I noticed the cable starting to wear from vibration where it was resting against a frame crossmember. So I had to take additional measures to protect it anyplace it was resting against other components.

 

[AndrewP]

Same here. Flooded lead acid batteries are great, seem to last 5 years or so and much cheaper than AGM batteries that last 5 years or so. I like being able to open them and add water when needed-maybe every 6 months.

All the recent discussion about Odyssey batteries and complicated charging requirements only reminds me why I would never use one.

Regarding those Costco Marine batteries-that's a very decent battery for $80. You can count on 4-5 years of use, the group 27 is a 100 amp hour battery and fits the majority of vehicles members of expedition portal forum would have. I have 6 of those in use as we speak. They don't seem to mind a reasonable 50% deep cycle.

For J.Spicoli- Keep your dual battery and your solar thoughts separate. If you run a voltage sensing relay to control your dual batteries, (Called Automatic Charging Relay ie ACR by Blue Sea), It will work well in conjunction with a good solar system.

 

[J.Spicoli]

How will the FLA batteries handle being in the enclosed bed with shell that I'll be sleeping in? I've read the AGM do not vent and are ok to use in this type of environment as opposed to other types that may vent and are probably not a good idea for what I'm wanting to do. I don't want to wake up dead one morning because of the battery, lol.

Just want to say thanks to everybody for your help and insight thus far, much appreciated! Keep it coming

 

[jonyjoe101]

get a larger panel if you can. 100 watts will only get you about 5 amps. And mppt only works on 30 volt or higher panels. And if mppt did work on the 100 watt panel you would get at most 6 amps. 100 watt divided by 14.4 volts will
tell you what the maximum amps the panel is capable of producing with mppt when pointed at the sun. 14.4 volts is usually the minimum voltage a battery needs to get a proper charge.

120 watt panel will get you 6 amps, 240 watt panel with mppt will get you 12 amps. These are with the panel lying flat on the roof which is not the most optimum position but still adequate. I had both 120 watt and 240 watt panels with pwm and mppt, so my figures above is what I usually see the panels produce on a daily basis.

An edgestar fp430 12 volt fridge will use 25 amps total in a 24 hour period when set to 40 degrees.The edgestar uses the danfoss compressor as most 12 volt fridges use, so they all have similar power uses. If you set the fridge to freezing you need a much larger battery, maybe in the 200 ah range, and even the 240 watt panel might not be sufficient.

the bigger panel will charge your battery quicker the following day, it will make you 100 percent solar, where you dont have to run your engine or generator the following day to top off your battery.

Also research using a chest freezer with a fridge conversion thermostat. The thick insulation on the chest freezer make them very efficient on power. Some of the chest freezers are not much bigger than 12 volt fridges. 200 dollars versus 500 dollars for a fridge, If I had to get another fridge for my van I would definitely look at the chest freezers.

 

[Ducky's Dad]

I do not agree with the wiring advice of using used welding cable. Since this will be truck mounted, frequently wet and hot/cold you would do better with "boat cable" or marine wire where the insulation is rated for oil, grease, 105C and the wire strands are tinned.

I agree that tinned marine cable is preferable, but at what difference in cost? Around here, the tinned marine 3/0 is about $13/foot, tax included, plus whatever the shipping cost would be. I bought a large batch of 3/0 pure copper welding cable for a little over $1/foot on Craigslist, and since I needed a lot to do my truck, the savings were substantial. Re the qualities of the cable, there is cable and there is cable. My cable is PrestoFlex, manufactured by PrestoLite in the USA. Rated for 105C (also available with 120C rating), cover is EPDM with thickness of .105", so abrasion is not likely to be an issue, especially if cables are anchored properly. My old system was 1/0 cable and was encased in milsurp kevlar sheath (pic attached), and the new stuff is being wrapped in either split sheathing or tubular nylon as I get to it. The EPDM cover is rated for oil, grease, solvent, etc. exposure. All sheet metal penetrations are grommeted and sealed with RTV silicone. And, since the truck lives in the desert southwest, surface corrosion of the copper strands is not likely to ever be an issue. The possibilities of corrosion are mitigated by soldered and heat-shrinked terminations.

 

[AndrewP]

That military kevlar abrasion guard is nice. Got a source for that?

 

[Ducky's Dad]

That military kevlar abrasion guard is nice. Got a source for that?

Unfortunately, no. That batch was coiled up in the back of an old auto electric shop, so I grabbed it. Used it all and wish I had more.

 

[Ducky's Dad]

Here is something similar, but it is $2.30/ft in 1/2" diameter, 50ft spools. I'm going to look around again for the milsurp stuff.

http://www.cableorganizer.com/kevlar/

 

[rayra]

A pair of 0/2 cables will fit thru a 3/4" rubber heater hose, with a bit of work. Lash that down with zip ties and your chafing woes gone for many years. Usually <$1 a linear foot, any automotive store. And you don't really need it everywhere, depending on your run. You can just put it in a few places where you are crossing edges or where you necessarily have a loose section which might vibrate against something.