Powering a Mini Freezer 24/7

[Reef95]

Hi!

I'm in the process of buying items to fit into my conversion van and I have questions about running a mini freezer 24/7. I did read the sticky for this section and it seems like 200 watts of solar would suffice, but I've also read other articles that say I'll need more power to run it indefinitely. I just want to make sure I have the right amount of solar for my van before hitting the road and running into a problem with it.

(i'm on the verge of purchasing 400 watts of solar panels since the price difference between 200w and 400w isn't bad)


I don't need such a large freezer but this 20-quart one is the smallest I could find! If you know of a smaller freezer please let me know! I have a few smaller items which have to be stored below 0° F.

Outside of running this mini freezer I'll also be using solar to charge my phone, laptop, and two to four 6.5" car coaxial speakers.. and on occasion (once a week?) I'll be charging a Jackery Power Station 240wh.

Thanks!

 

[Gypsy Freedom]

beyond the general 200 watt recommendation, you would need to take into account of where you will be running this. what ambient temps will you be dealing with, ie. a hot van parking the desert sun or 60 degree coastal days. where will you be in the winter? stormy northern areas with clouds and low sun angle and real short days will need a lot more solar. will you be putting frozen items in and just need to keep them frozen? or starting with room temp items and tring to freeze them.

 

[Reef95]

Those are some good points! I'm located in the midwest in Byron, MN. I won't be connecting the freezer until the beginning of 2020, I'd just like to make sure I have the watts to be able to cover it when I do connect it. The winters are partially cloudy on a normal day, with the occasional one week of complete sunshine every month. The solar panels will be installed and in use by the end of October.

I'd like to start from room temperature when freezing the food.

 

[B and C]

You can never have too much solar. With enough solar you will get some charging even on heavily overcast days. I have 200 watts permanently mounted and another 200 watts as portable. Each pair is wired in series and the two sets are then run in parallel. I can get a tiny bit of charging even during rain if not coming down in buckets. I generally recommend as much solar as you can afford/fit. You won't regret having too much solar, only too little.

 

[Elbear1]

You can have 2kw and still not fill your battery every day like it demands for its health. It takes time at a slow rate of charge to get that last 10%. Often much more than 6-8hrs.

Its very real issue and theres 2 ways around it: lithium (doesnt need totally filled and is way easier to fill) or a generator/alternator to bulk charge before 9am. And they have to be wired very well or have a converter to push significant amperage.

200w is your minimum. Thats 5 amps to charge and 5 amps to run appliances. If I had the money I would do at least 200w on roof and 200w loose to sit in sun so you can have some shade. Then either get a generator or a lithium battery. And either way setup your alternator with the proper solenoid and minimum 4awg wire to house battery.

If money is an issue 200w on roof, appropriate size rv converter used as a charger and an open frame 2000w generator. A quieter inverter generator if you can afford a few hundred more.

You can never have enough charging backup. Plus having all that lets you limp to town if your alternator goes out.

 

[Spaceman Spiff]

 . . . It takes time at a slow rate of charge to get that last 10%. Often much more than 6-8hrs.

Its very real issue and theres 2 ways around it: lithium (doesnt need totally filled and is way easier to fill) or a generator/alternator to bulk charge before 9am . . .

???

I have 200W solar and 208AH of FLA.  I run a 2 cu. ft. refrigerator (not a freezer), LED lights, Maxxfan, Booster, and charge a MacBook and some USB electronics.  I am usually back to 100% by 1 P.M. in the afternoon, (batteries accepting less than 1 amp), Trimetric reported.  Batteries are 5 years old, with measured capacity of 208AH and the S.G is ~1.275.

I do have a Sportsman 1000W inverter/generator and a Powermax 35A battery charger for those long Minnesota cloudy days and when I am camped under heavy forest canopy (like Northern Minnesota).  Run for ~1 hour in the morning and the solar will finish the absorption the rest of the day, even in shade.

With lithium, in Minnesota, you will have to keep the batteries warm 4 months a year.

 

[Elbear1]

Its just a fact of FLA batteries. As they fill their resistance goes up as resistance goes up time overcomes current. Its why you have multistage charging. Real world use is cloudy afternoons, canyons, partial shading leading to several days of undercharging which adds up to requiring extending charge times beyond sun available.

Put a 50% battery on say a 20A garage charger. It takes 15, 20, sometimes 30 hours for it to call it done.

 

[MrNoodly]

Freezers and refrigerators don't run 24/7. They run to achieve your set temperature, then they cycle on and off as necessary to maintain that temperature.

Also, you can add insulation around the unit (leaving the vents uncovered) to reduce how often it cycles on and off.

That said, I'm running a Dometic CF-25 and charging my electronics with 270W of solar and 208Ah of battery.

 

[Gypsy Freedom]

You can have 2kw and still not fill your battery every day like it demands for its health. It takes time at a slow rate of charge to get that last 10%. Often much more than 6-8hrs.

i HAVE 2005 watts on my short bus. even here in the pacific north west in the worst of the winter. short days, low sun and days on end of solid clouds and rain. i got into float almost every day. this is running a 2.5 cu ft FREEZER, lights laptop and cell phone. but during normal sunny times of the year, it takes way, way less to keep up with a moderate sized fridge.

   in my other rig, a minivan, i have a 3.2 cu ft fridge/freezer (big separate door for freezer about a cu ft of freezer) it just so happens i have been doing a little testing on battery consumption and what it takes to recharge the battery. the last 2 days, yesterday and the day before middle of july on the coast (i can smell the ocean and see it, if i stand on top of my rig) of oregon.
  
   along with the refer, i use more than a few hours of laptop and charge cellphone and lights every day.  but for the test i turned on the laptop and left it on all day connected to an external wifi and only put it to sleep for about 6 -8 hour each night when i slept. this is way more than i would ever use as i put the laptop to sleep anytime i walk away and i dont live behind the screen. but i wanted to see how things looked with a worst case.

   so for those 2 days my consumption of watt hours from the battery were measured by a shunt based meter and totaled 1520 watt hours for a 48 hour period. from 9pm 2 days ago to 9pm last night i chose 9 pm as that is when the solar charger stops charging and goes into sleep mode. so 760 watt hours per day, my usual is around 400-500 watt hours split pretty even between fridge and laptop as the big draws. yes, several hours on my laptop uses around the same amount as a full day for my 3.2 cubic foot minifridge.

   now we all know, or should. you have to put more into a battery than you took out to get back to full charge. that is the conversion lose and/or the low efficiency of charging. the efficiency is pretty good up to around 80% recharged capacity, but then the efficiency drops off considerably as you get closer to full charge. for this reason i deplete my battery deeply each day, well below 50%. but i make sure i get back to a full charge each day.
   in the picture below, taken just a few min ago around 930am you can see that in the 2 days of testing it took 820 watt hours each day to not only recharge the batteries but to run everything through the day as well. my math (760 watt hours used divided by 820 watt hours to recharge)puts the charge efficiency around 92% for cheap flooded lead acid. (this is skewed some what as some of the power was going direct to run devices through the day and that power is closer to 100% efficient. but this is a consistent style of test i can do and compare different setups) the bar graph shows in white the bulk phase, light gray is the absorb phase, and the dark gray is the float phase.
   you can see both days i spent considerable time in float. you can see the max PV wattage output was 200-250 watts(435 watt panel flat mounted with ratchet straps over it) and the peak voltage that is held for absorb is 14.8 and that i draw the battery down to about 11.5v each night (intentionally well below 50%)
   you can also see the solar is putting out about 200 watts at the moment when i snapped the pic and the batteries were climbing in bulk at 13.6v



this is the current data from my system and usage. i made no mention of inverter efficiency as i was measuring at the battery and thus that is taken into account already. but i have a 375 watt victron puresine, very efficient little unit. based on this, i am confident with a smaller fridge and less abusing the laptop you can totally care for you batteries with 200 watts of solar in a decent solar climate. you dont need 2000 watts a generator or lithium batteries. (they sure are nice to have, still waiting on santa for the lithium)

the picture is from the victron app, and there is even more info to be gleaned from that pic and more yet from other aspects of the app.

 

[Elbear1]

Going into float is also a major problem with some controllers. They stay in absorb based only on a preset time i.e. 120 min, 180 min, etc and automatically go to float.

I know all renogy and renogy clones (aco power, eco worthy, etc) are programmed this way. You can get around it by setting float voltage to 14.4v or there about and trick it into a cv/vc mode.

IDK about victrons but going into float is def not a good way to judge SOC if it is the case.

 

[Elbear1]

I have the fridge/freezer, 250w of solar, and 235AH. To charge at C5 including converter inefficiency it takes 900-1100w continuous wattage real world measured. A 2kw generator only outputs around 1300-1600w continuous. Then factoring in altitude losses a 2kw unit is running 75%-90% capacity.

There is no way you can make it on 200w alone in the real world. The first time theres 2 days of clouds its over and freezer will have to be shut off for at least 24hrs.

200w is a 10A charger in reality.

 

[Gypsy Freedom]

i hate to be like this, but before you condemn a product you should know a little about them.

the victron controllers have a dynamic algorithm that changes the absorb time based on many variables

i also dont just rely on the victron. i look at tailing amps. do you know what that is? i also have other battery monitoring systems. when looking at the whole picture, i can not only see if i am fully charged, i can also get a good idea of the health of the battery. i also monitor how much is being used and how quickly that depletes the battery. to really understand a system you need more than one snapshot. but one snap shot with all that data is pretty clear that you can do the job.

while their might be a million ways to do it badly and destroy your batteries that does not mean it cant be done and done well

you need to study up on actual applications and understand how things work and why. do some tests your self and study the data. rather than just regurgitating what you saw on some video. dont just jump on the hype. dont dismiss the possibility it can be done, just because you have not or can not figure it out

previously you recommended using an RV converter as a charger, that is about the poorest method possible to charge deep cycle batteries.

you talk about a small garage charger taking forever to charge. of course they do, we are not talking about garage chargers here. they work on a totally different principle and are horrible for charging deep cycle batteries

who ever said you NEED to charge at C5 rate?

a generator does not charge your batteries. you could have a 10KW generator and if your battery charger is only 20 amps, that is all you get

what does altitude have to do, i think i said i was within sight of the ocean?

 

[Gypsy Freedom]

i dont mean to be rude, but it is clear you dont fully understand. if you would like some help getting your system to work better i would be glad to help you out. start a new thread and post as much info on your set up. the exact model of fridge, the exact model os your solar and how you have them wired. the exact charge controller and the exact battery and how they are all wired together do you have a generator if so what exact one and what charger are you using, the exact model

any pictures would help

also any data like amp hours or watt hours consumed or data logs from the charge controller like i posted would also help

also post the general area you are, nearest major city and the elevation

with 250 watts of solar, you should have no trouble this time of year gathering 1200 watt hours of solar under decent solar conditions. that is way more than enough to maintain batteries and run a modest sized fridge

 

[Elbear1]

Again, doesnt matter how much you can produce. Youre controller regulates current. You have a 7-9hr window of current production where acceptance is dictated by physics and chemistry.

 

[Gypsy Freedom]

if you want to stick your head in the sand, go ahead. i offered to help

you could do much better than you currently are.

there are tons of system currently operating very successfully contrary to your claims

when you are ready to let go of your preconceived ideas and learn how to do it and do it well. i will be glad to help.

 

[Elbear1]

previously you recommended using an RV converter as a charger, that is about the poorest method possible to charge deep cycle batteries.

Lol...I'd love to hear more. We not talking a magnatek. Most after market converters are 3 or 4 stage.

IDK why youre so worked up and insulting me. I hope this forum doesnt condone such hostility.

you talk about a small garage charger taking forever to charge. of course they do, we are not talking about garage chargers here. they work on a totally different principle and are horrible for charging deep cycle batteries

No, garage chargers are CV/VC or they are 3 stage. They are the exact same as absorption charge on all charge controllers. Its actually a much better charger than controller that just has a preset absorb time. You'll note they will take a very long time to get from 80-100%.

Plain and simple FLA has resistance and simply will not accept the current as it closes in on 100%. It needs time. Period.

 

[highdesertranger]

ok lets cool off a bit and stop the back and forth bickering. highdesertranger

 

[Elbear1]

please dont lump me into that. I wasnt belittling anyone.

 

[highdesertranger]

it's only a 13 word post, did I mention belittling? highdesertranger

 

[highdesertranger]

Jeez the deleting posts has stared. just drop it people.

any post that doesn't pertain to the original poster question will be deleted and the poster will get warning points.

this is the biggest reason people get in trouble on the forum because they can't, JUST DROP IT, understand DROP IT.

highdesertranger