Dumb question about a Goal Zero Lithium 500X and National Luna 50L Legacy Fridge/Freezer (1 Viewer)

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chriscosta416

chriscosta416

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Hi all,

I have been scratching my head at this trying to solve it.

My "solar" setup is currently a 100 watt solar panel, Goal Zero Lithium 500X powering a National Luna Legacy Fridge/Freezer.

Currently connected to the fridge via 12V cigarette lighter (goal zero) to DC input.

However when using the fridge/freezer combo (after both the goal zero (fully charged) and fridge (pre chilled days prior) in my vehicle it does not last a whole 24 hours. Parked/driving with clear skies and sun out

The output for my fridge (when the compressor kicks on, which is often is 113 watts)

Does any of this sound right? Am I doing something wrong?

I am a total noob when it comes to this stuff.

IMG_9525.JPG
 
chriscosta416 said:
Hi all,

I have been scratching my head at this trying to solve it.

My "solar" setup is currently a 100 watt solar panel, Goal Zero Lithium 500X powering a National Luna Legacy Fridge/Freezer.

Currently connected to the fridge via 12V cigarette lighter (goal zero) to DC input.

However when using the fridge/freezer combo (after both the goal zero (fully charged) and fridge (pre chilled days prior) in my vehicle it does not last a whole 24 hours. Parked/driving with clear skies and sun out

The output for my fridge (when the compressor kicks on, which is often is 113 watts)

Does any of this sound right? Am I doing something wrong?

I am a total noob when it comes to this stuff.

View attachment 3370070
Click to expand...
I have a Goal Zero 1500X.
A few questions: What is your Yeti's charging profile, how much time are you getting and how much power does your fridge take*?

Goal Zero lists the 500X as a 505 Wh battery. Let's assume that 's true for now.
If you had a charging profile of 20%-90%-100% which is what I use (Yeti cuts off at 20%, starts to charge at below 90%, continues to charge to 100%) then you start out with an available amount of energy of 505Wh-(.2*505) or 404Wh available.
So, while we know how much power is drawn when the compressor is running we also know it doesn't run all the time. Ouch!
So what we need is power usage over time. This will vary with ambient temperature, temps you set for your fringe/freezer compartments, and usage; i.e. how many times you open the lid. Triple ouch.

We're up to 4 ouches and we're not done yet. :bang:

*To get that you'll need a power meter like those from Powerwerx and a 24 hour test under realistic conditions. Get the 75A model if you decide to get one.

So here's how you can start to figure this out.
As an example, my Dometic CFX3 75L DZ pre chilled, takes 50 Wh/h at 75F ambient, fridge/frezer at 37/0F and only 1 quick open & close of the fridge lid in exactly 24 hours. OK, that's not how it will always be run but it's a BEST case scenario, a floor so to speak. It will only get worse sitting in a hot car and actually being used.

You don't state which model you have and Luna doesn't appear to publish their power estimates. So, to take a guess I'll assume your power usage is 70Wh/h. If you like that guess then 404Wh/(70Wh/h) is 5.8 hrs.
EDIT: you do state the model in your title. Sorry.

Charging by the car and solar offsets this and at full sun you might be at net zero.

Does this help?
 
Last edited:
Thats a large draw when running, it might spike to that on start but the continuous load should not be at 10 amps. FWIW that 100W solar in decent sun should keep that battery pack up to full and the battery pack should power fridge thru the night + phones, lights, etc... There is a diode in the cig lighter cord that can go bad causing fridge to draw high load but run fine, I had an engel that did this, cooled but had a high amp draw while running, removed diode and its still going.
 
peesalot said:
Thats a large draw when running, it might spike to that on start but the continuous load should not be at 10 amps. FWIW that 100W solar in decent sun should keep that battery pack up to full and the battery pack should power fridge thru the night + phones, lights, etc... There is a diode in the cig lighter cord that can go bad causing fridge to draw high load but run fine, I had an engel that did this, cooled but had a high amp draw while running, removed diode and its still going.
Click to expand...
Any idea why they would they put a diode there? Perhaps to prevent some current backflow when the compressor shuts off?

This stuff drove me nuts until I got a power meter and was able to see what was going on.
Also, what the Yeti reports on its screen is a bit off.
I am guessing that what's shown on the panel is measured at the battery. There's loss in the electronics so you don't quite get what's being displayed when it comes to power.
That's been my experience anyway and my guess as to the reason.
 
I have no idea and not sure all manuf. do it. I had a 23 year old engel that worked but killed battery in 1 night, couldnt figure it, ran a test to verify run time & interval time and it cooled ok. Ran fine on 110 & 12v, put in truck and whamo, dead batt. Frustrated I got a new engel and sold that one for 200 bucks, the guy I sold it to then told me about removing the thingy in the cig. lighter plug, did that and we tested fridge draw and it was within specs, put thingy(may not be a diode) back in and tested, current draw was almost 6 amps higher with thingy inline vs. removing thingy. So I learned a lesson selling what I thought was junk for 200 bucks and then getting shown the cause & simple fix. So if you see old engels for sale(rarely) they may be an easy fix.
 
To original poster, FWIW the draw on the NL products is typically similar or better than comparable units so its not a simple fact that the NL draws more power, the NL's have so far been competative in specs with other major brands.
 
OP, 113W seems inordinately high for a typical travel fridge, but maybe this is some specialty affair? For context, my big kitchen fridge uses less than that when running.
 
Is there anything in the fridge or is it completely empty?
 
Interesting about that diode affair mentioned above. What is it supposed to be for?

It's odd that this battery system up there would have a cig lighter and a barrel plug but no Anderson PPs outlets. (And, yes, I do not like cig lighter plugs...) Nice USB assortment, though.
 
if it is above specs, you could maybe check to see if the airflow in and out of the unit appears reasonable as in is there some blockage, or are the condenser fins clogged up possibly?
 
e9999, I was thinking of the graph you did of power draw thru a time period or more importantly from off to on to illustrate the draw during start vs while running after started. And IIRC the 113 is more than twice what a crappy fridge (12V) draws at the start up spike ? If its a 10 amp fuse then its feasable it could be going direct to short with 113 ? am I crazy or could it be happening ? if all wires were sized right I suppose a 10 amp circuit could continually pass just less than 10 amps.
Anyway, if it is doing that something is still worong
 
well, if the 113W is only very briefly during the startup, and now -going back to OP- I see that the OP stated something possibly suggesting that, that could be normal if the continuous draw is around 50W. It would be a bit surprising to me that the meter would have captured that spike and it being long enough for a pic, but possible.

OP what does the output show a bit after startup when things have stabilized?

(But dang, all this speculation, is there no number on power draw anywhere in Luna's literature? Or can you call tech support?)
 
Here's a comparison for our Dometic CFX3 75L DZ (albeit under ideal conditions running in our dining room, 74F ambient, 1/2 full, 0F/37F):

Capture.JPG


A, W, V are steady state values, the power meter is capable of showing peaks which suspect occurred when the unit was switched on.
I have seen W lower in the range of 30-35W at the same voltage under the same conditions. Maybe the compressor is only cooling one zone then?

Voltage displayed on the Goal Zero will decline but output will be a constant 13.5 +/- 0.1V
Note that the Watts displayed on the Goal Zero doesn't quite add up: 11.6V*3.3A=38.3.W. The Goal Zero doesn't display all values simultaneously and I tried to cycle through them as fast as I could to come closer to an instantaneous reading.

I'm sure the Luna products are competitive power-wise.
 
IMHO, it is wise to take readings from all these inexpensive meters (including the built-in ones) with some appropriate caution. I have several of these power meters and I have calibrated some with lab-quality instruments cuz I was curious. Turned out they were generally fine with voltage, OK (not great) on the upper ends of the current ranges and bad at the lower ends (all subjective assessments for my specific needs, of course). I would not trust the stated peak values at all for startup peaks, though, they just happen too fast, but the peak values may be OK for slower (multi+ seconds) variations. For context, I have a very good Fluke multimeter with a max/min feature and even that one does not catch a startup peak very accurately. (But they do have devices specifically for that.)
 
Caution indeed!

So I'm the man with 2 watches that doesn't know what time it is.
I wish I could tell the OP whether or not the 113W he was seeing is real.

I ran a 12 hour test to see total energy usage which I have done before.
The point is not to report the Dometic's power usage but to illustrate how different the Yeti displays are from how much power you're really getting. That's assuming my watt meter is correct and my particular Yeti 1500X isn't somehow defective! :bang:

In exactly 12 hr the results are:

Watt hrs as shown by the meter/Yeti: 290/346
Average Watt hrs per the meter/Yeti: 24/29.

So while it makes sense that the Yeti would display more energy used as it has to power DC-DC electronics etc... that's quite a significant difference.

Conclusions:
  1. The values displayed on Yeti units don't begin to tell the whole story - at least mine doesn't. It says more energy was used than we got. A lot more.
  2. Use the power rating listed on the unit you're running at your peril as it won't really tell you how long your battery will last.
  3. Get a good power meter.
    1. Maybe 2 just for good measure. Just kidding. :)

My how things have changed. I remember sitting in the car with my dad about to leave for a weekend camping trip and my mother bursting out of the house with the marshmallows and marshmallow forks that we forgot to pack. Today I'd bet it might be a power meter instead.
 
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