Need the solar/power pros to weigh in

TantoTrailers

Active member
I have been getting a bit geeky on solar with my camper as I have just about run out of other things modify or to add to it for the time being. I built my rear galley around 2 20qt Orca Coolers on a tray that slides out so I can access them for food and drinks. I found a cool 12V fridge which through some research and various posts on here, reviews on amazon, etc, I have determined would be a worthwhile investment should my power supplies hold up to the task. I am posting this thread to see if my current battery + my new solar system will work to power the things I run + the fridge without damaging my battery...essentially want to know if I can generate enough solar to not need shore power, ever?

Here is what I have now:
100Ah Renogy AMG battery
MaxxFan 5100 (running at 3rd lowest setting pretty much the whole time at camp)
2 USB outlets with LEDs behind them illuminating the ports (never actually use these to charge things but the LED behind the outlets stays on)
Voltage display next to the USB outlets, small little basic display similar to an old digital clock or calculator
2 Small LED lights - these are on for 15 minutes per day at the most on any given day
1 40" LED light bar in rear galley - this is on for 20 minutes per day at the most on any given day

Above is everything that currently runs off of the 100Ah system now

I have a 120W Folding Solar Panel + 20A Renogy MPPT Charge Controller that I will be using to charge the battery, it is mobile so I can move it into the sun but chances are it will sit on top of my camper as I am gone from camp 90% of the time during the daylight hours, so it won't be getting direct sunlight the entire time.

This is the little fridge I am looking to buy if I don't have to make too many upgrades to my power system: https://www.amazon.com/dp/B07HSQQ6FJ/?coliid=I1N8JQHDBYVRWP&colid=1GX525C7GL5BQ&psc=1&ref_=lv_ov_lig_dp_it

Details from manufacturer:
1568137377622.png


Let me know what other details I can provide to help make this decision! Thanks in advance!!
 

Photobug

Active member
While no solar expert: I'll take a crack at it.

You have not given enough info to solve this riddle. If someone wants to they could look up each of your items and try to calculate your daily amp needs based on your estimated numbers. It would be better if you did some more research into your amp needs and charging capability by buying a battery monitor to check your power draw each day as well as your solar producing capacity. There are battery monitors around $20 on amazon.

Another question is the fridge you chose it looks cheap so I would guess it is less efficient than known fridges at 3 times the price. With only a few people having purchased it, it's real numbers and capacity are likely not known and most cheap chinese manufacturers lie about their numbers, I would not trust their published numbers.

If you decide to add a fridge, and your current solar needs can't keep up, you can up your solar panel count.
 

jonyjoe101

Adventurer
If you set the fridge to 40 degrees and have good sunlight you can do it. I use to run a larger edgestar fp430 fridge 24/7 off of a 120 watt panel and 75ah agm. The only thing I see that might complicate things is the maxxfan since you run it all the time, it might prevent the battery from getting fully charge everyday. From most reviews I seen on 12 volt compressor fridges and my own tests I done,they use about 26ah total in a 24 hour period when set to 40 degrees. For the price the apicool seems ok and I watch reviews on them on youtube, I like the weight its only 33 pounds, the old edgestar I had weighed almost 60 pounds, it wasn't easy to move around.

120 watt panel with either pwm or mppt will only get you about 6 amps of charge power when the sun is overhead. You subtract whatever the maxxfan consumes and the remainder will go to charge the battery.

The small usb leds indicater lights power use is insignificant, I leave them on all the time even when I use lead acid.

I would recommend you get a coulombmeter, I use the tk15 (cost about 25 dollars) it counts amps going in/out of battery, that way you know if you are fully charging your battery everyday. You program your battery amp hour (100ah) then if you use 30ah today, you know tomorrow you need to at least put 30 amps back into it. No guessing if your fully charging your battery, very important with lead acid.
tk15 couloumb.jpg
 

hour

Observer
From some amazon review or Q/A for your fan model: "The fan will pull from 0.2 to 4.7 amps @12v, depending on the setting from 1 to 10. The middle setting pulls 1.1 amps, which is 13.2 watts per hour."

So idunno, maybe estimate that you have a constant draw of 0.8a with the fan running nonstop and the little LEDs for your USB ports and voltage display always illuminated.

That fridge says 45w but ambient temperature will impact how often it runs.

Your little LED lights and light bar for the durations you stated could probably be balanced out by grabbing two beers out of the fridge at once, once or twice per day (making it run one less time). Peanuts.

I'd be surprised if you had any issues running that setup with your 100ah battery and 100w solar for a few days but you might reach a point where you can't put in enough during the day to prevent a significant discharge of your battery. No problem with your ground deploy panels in conjunction with the 100w. The 100w alone might put in 30ah a day.

So probably 20 amps every 24 hours running the lights +, (the leds & the fan constantly). Maybe 25 amps every 24 hours running the fridge. 30ah in off the 100w panel. You could spend $40-60 (normal vs bluetooth enabled) for a 65 amp Victron BatteryProtect if you wanted to be sure you never put a hurting on your battery.. probably worth the extra $20 to get the BT one for complete control. Just don't lose the contents of your fridge - it'd be nice if the batteryprotect kept a record of when it had cut off for risk assessment eating something.

FWIW my 62 quart Whynter fridge pulls over 70w despite the literature claiming 4.5a max @ 12v (while also saying 65 watt on the site, and also 5a in another place... beats me).
The consumption chart states 28amps @ 90*F with fridge set to 39*F every 24 hours. My average discharge according to my Victron BMV was 29ah (a little less actually since that's averaging my handful of complete discharges during testing phase) this summer with the temps inside the enclosed truck bed where it lives over 100* every day. 200w of solar on my roof started putting out less than the 70some watts the fridge draws by about 530pm when the sun would start to go behind my house and shade my truck, but even still would contribute since the fridge isn't a constant draw. It was still 80* most nights at 2am. Solar would more than cover even a constantly running fridge by 730am with the slope of my driveway and clear clear Colorado skies. So far this month every morning I check the Victron and it says last discharge ~22ah. Still hot as hell most days but getting in to the 60's at night. Both of my compartments have been set to 36*F.
 
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shade

Well-known member
ExPo thread on Alpicool fridges

Ditto on the comments about logging consumption, when possible. Kind of hard to do until you have the fridge on hand. :)

I highly suggest that you give the fridge the best connection to the battery that you can to minimize voltage drop. Same goes for the solar panel - charge controller - battery path.

This wire would work well for both.
 

TantoTrailers

Active member
While no solar expert: I'll take a crack at it.

You have not given enough info to solve this riddle. If someone wants to they could look up each of your items and try to calculate your daily amp needs based on your estimated numbers. It would be better if you did some more research into your amp needs and charging capability by buying a battery monitor to check your power draw each day as well as your solar producing capacity. There are battery monitors around $20 on amazon.

Another question is the fridge you chose it looks cheap so I would guess it is less efficient than known fridges at 3 times the price. With only a few people having purchased it, it's real numbers and capacity are likely not known and most cheap chinese manufacturers lie about their numbers, I would not trust their published numbers.

If you decide to add a fridge, and your current solar needs can't keep up, you can up your solar panel count.
Just before my bump I purchased a watt meter to hook up to my system to get an exact consumption reading of everything I stated so that I could give better info for the math. I appreciate the replies!

I will also be measuring the output of my 120W panel. The nice part is its very small when stowed away so I can get 2 of these and have them both fit in my tongue box. 240W would be nice! I will report back after the weekend once I have the watt meter and I can run my rig off grid in the garage to see how much it really pulls.

My battery will literally be next to my fridge as the tray that the coolers sits on is next to the battery/electrical area. All of my runs are quite short in and around my battery. I plan on putting the charge controller box about 3-5' from my battery (it will be in a self contained box not attached to anything). The panel will have some cable length but I may make a few lengths keeping a short one for when I just lay it on my camper roof and a longer one for when I am moving it to chase the sun.

Thanks again everyone and I apologize for the minimal input I gave to get this started!

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Photobug

Active member
Just before my bump I purchased a watt meter to hook up to my system to get an exact consumption reading of everything I stated so that I could give better info for the math. I appreciate the replies!
One thing to keep in mind. It sounds like you are like me, miserly in energy use. I have yet to use the capacity of my battery and solar setup. At first I was surprised at how little I was getting from my 50w panel. Turns out I was not getting much because I did not need much. My panel was only topping off and floating, it has never needed to really charge the battery.

You might need to run an inverter or add more dc items to bring down your battery so the solar has to work harder to charge it back up. That way you can see the true potential of your current solar panel.
 

dreadlocks

Well-known member
Sweet spot is 200W per 100AH of Lead Battery, you can try with less but good chance you wont be terribly happy with the results.. if you go more you hedge a bit against poor lighting conditions/fractional outputs.. nobody ever regretted putting too much solar up, but many have found that trying to scrape by with minimal solar on the road, with ever changing locations, latitudes, and environments to be mostly inadequate. Keep in mind most conventional wisdom you find on the internet regarding Solar setups, is intended for fixed locations with adequate and predictable sun exposure.. once you start dragging panels all over the world, you have to start designing for the worst solar conditions if you are looking for true grid independence.

I agree that data is key to success, with each new location you need to be able to observe performance and see if its adequate or not.. I'd suggest a Victron SmartSolar simply for the app and built in historical data, and a SOC battery monitor is also key.. Stuff like fans can run entirely off solar if you overbuild the solar enough so that it can still charge and operate your day time needs.. otherwise they could suck nearly all the charging current and your batteries will never charge at a rate faster than your consumption.
 

TantoTrailers

Active member
In the closeup pic of my wiring there is a NOCO Genius G3500 Smart Battery Charger mounted sort of out of view in the top left corner. You can sort of see that. This is my shore power charging when I am in the garage or at a site where I can hook up (have yet to camp at one of those with my rig). Where would a SOC battery monitor sit in my setup? Also, would the fan run off the battery when not running off the Solar in your suggestion dreadlocks? Sorry I am very new to all of this =) Thanks guys!! I do like the sound of 200W of solar with my 2x120W idea. I already have one, easy enough to get a second...
 

dreadlocks

Well-known member
My SOC Monitor (Victron BMV-712) has a shunt that sits between the battery ground and everything else.. all grounds are hooked to a bus bar, thats hooked to shunt, and shunt is hooked to battery.. there is no path to the battery ground that does not pass through the shunt.. thus its able to tell me how much energy is being taken out of the battery, and how much is being put back in.. and can calculate me a pretty accurate state of charge.

If you run a fan during the day with solar hooked up, its going to siphon power off the solar panels.. If you have enough excess solar input going unused, and you run the fan in these conditions.. its basically running directly off the sun w/just the battery as a buffer for like a random cloud or something.. and your battery is still getting adequate charge current, win.. win.. like thanos and the infinity stones, your gonna use the sun against its self.. however if you just have enough solar to charge the battery at a decent rate, than any daytime loads you add will siphon power away from that charge and can easily extend the time required to get the battery back up to full beyond how many hours of direct sunlight you have at your disposal.

The battery monitor will give you enough information you'll know when you can do such things w/the fan.. basically if you see the solar is charging battery at like 8A, and you turn on your fan and its still charging at 8A.. then you deduce your able to run your fan off the unused solar capacity and use that excess energy to your advantage.
 

TantoTrailers

Active member
My SOC Monitor (Victron BMV-712) has a shunt that sits between the battery ground and everything else.. all grounds are hooked to a bus bar, thats hooked to shunt, and shunt is hooked to battery.. there is no path to the battery ground that does not pass through the shunt.. thus its able to tell me how much energy is being taken out of the battery, and how much is being put back in.. and can calculate me a pretty accurate state of charge.

If you run a fan during the day with solar hooked up, its going to siphon power off the solar panels.. If you have enough excess solar input going unused, and you run the fan in these conditions.. its basically running directly off the sun w/just the battery as a buffer for like a random cloud or something.. and your battery is still getting adequate charge current, win.. win.. like thanos and the infinity stones, your gonna use the sun against its self.. however if you just have enough solar to charge the battery at a decent rate, than any daytime loads you add will siphon power away from that charge and can easily extend the time required to get the battery back up to full beyond how many hours of direct sunlight you have at your disposal.

The battery monitor will give you enough information you'll know when you can do such things w/the fan.. basically if you see the solar is charging battery at like 8A, and you turn on your fan and its still charging at 8A.. then you deduce your able to run your fan off the unused solar capacity and use that excess energy to your advantage.
Would I be able to get the same SOC information from my MPPT controller?
 

dreadlocks

Well-known member
if your loads are low enough you can run everything through the controller, perhaps.. I think some of the smaller smart solar chargers by victron has a load output..
 

TantoTrailers

Active member
I purchased the Renogy Rover PG 20Amp controller and got the Bluetooth module for it. I thought my question through and it didn’t actually make sense since I’m not looking to have load on the controller. Controller will be strictly for charging the battery and the battery has a direct feed to my fuse panel where everything terminates. The SOC would need to go between my battery and fuse panel but that’s a $200 item I was not planning on buying. We’ll see how my eBay sales go haha, cleared out some stuff. I’ll post pics of my controller box I put together when I get some time to process them. Can’t wait to get to testing this stuff. What is a cheap way of testing a watt meter to see if it’s on point?
 

Alloy

Active member
The SOC would need to go between my battery and fuse panel
Quote from Dreadlocks - Post #11
"My SOC Monitor (Victron BMV-712) has a shunt that sits between the battery ground and everything else.. all grounds are hooked to a bus bar, thats hooked to shunt, and shunt is hooked to battery.. there is no path to the battery ground that does not pass through the shunt.."

QUOTE="TantoTrailers, post: 2677259, member: 205878"]
Would I be able to get the same SOC information from my MPPT controller?
[/QUOTE]

Only if it has a shunt as Dreadlocks mentioned will track SOC.
 
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