Nova Kool R3800 AC/DC Refrigerator

[GallenH]

I want to say thanks for all of the commenters on this thread and a parallel one on battery monitors. I've learned a lot that I wasn't aware of. Being the owner of a more vintage RV (1997 PW) I also find it interesting that back then a simple idiot light bank to monitor battery was stock. I suppose changes in the complexity of electrical systems and demands on them have changed significantly to warrant more complex monitoring considerations. Obviously batteries were charged by simpler single stage chargers and no one really cared. When the batteries no longer held a charge, you bought new ones. Even my old RV had a 12v CRT TV/DVD combo...and non-LED lighting....and a single 80AH battery. And somehow it all worked....I think. I removed the TV and converted to LED right when I got it 3+years ago. But existed on the 80AH ok. Simpler times?

Right now I'm running a test on my old Dometric 2310 3-way getting ready to leave in a few days. Starting temp in RV and fridge = 100F. Ah Phoenix.
Starting time 7:00pm. Will check both in the morning and record. Then later in the heat of the day. We'll see where it sits at the 24 hour mark.

[booster]

Originally Posted by GallenH

I want to say thanks for all of the commenters on this thread and a parallel one on battery monitors. I've learned a lot that I wasn't aware of. Being the owner of a more vintage RV (1997 PW) I also find it interesting that back then a simple idiot light bank to monitor battery was stock. I suppose changes in the complexity of electrical systems and demands on them have changed significantly to warrant more complex monitoring considerations. Obviously batteries were charged by simpler single stage chargers and no one really cared. When the batteries no longer held a charge, you bought new ones. Even my old RV had a 12v CRT TV/DVD combo...and non-LED lighting....and a single 80AH battery. And somehow it all worked....I think. I removed the TV and converted to LED right when I got it 3+years ago. But existed on the 80AH ok. Simpler times?

Right now I'm running a test on my old Dometric 2310 3-way getting ready to leave in a few days. Starting temp in RV and fridge = 100F. Ah Phoenix.
Starting time 7:00pm. Will check both in the morning and record. Then later in the heat of the day. We'll see where it sits at the 24 hour mark.

Yep, the old systems were typical of the low tech battery care then. Single stage "boiler" chargers with wet cells that were quite small and often lasted only a couple of years. Car starting battery were similar for a long time. Back then if you wanted to watch much TV or any other power use it was with a generator, or it really was not possible to do.


Especially with the very basic systems of those times, the monitor lights could be used successfully. The low use and small batteries made things like voltage drop from loads less in general, I think, knowing how much time you had for various tasks off battery is easier when there are few of them. The monitor lights then, as now, just come on at various voltages, so really are giving voltage snapshots rather than a movie. Loads put in error in voltage readings and are why voltage is getting harder to use for SOC guesses with the higher loads seen now compared to the old days. The monitor lights even come on at lower voltages now compared to then (thanks Marko for listing them again for us) to compensate for the bigger loads, it appears.


Now days, that single battery wouldn't last a lot of folks even one day, and generators are falling from favor, so it all has changed. Very few are willing to deal with the water and corrosion from wet cells, so costlier AGMs are used. Expensive batteries justify taking better care of them with fancier charging stuff, so it keeps stacking on.


Having a generator that you don't mind using regularly, and are allowed to use when you need it, really made it pretty easy for the simpler systems to be very practical and usable, along with low cost wet cell batteries that were basically considered consumables.


And, of course, the old systems relied on the propane frigs, as there really is no other choice on a single wet cell. The propane units worked OK if used carefully, and still do, plus they use tiny power now, and no power back then.

[RossWilliams]

Simpler times?

Simpler batteries in part. With flooded lead acid batteries you could check state of charge with a hygrometer and top off the battery if the charge lowered the electrolyte. A single stage charger wasn't ideal, but in practical terms it didn't make that much difference when your primary use, as you note, was electric lights.

All flooded lead acid batteries were (and are) pretty generic in operation. AGM, gel and lithium batteries all have different management issues, even within batteries of the same type in the case of lithiums. For those who want to optimize their batteries, the possibilities for tinkering are almost endless.

The demands we place on those batteries are also much larger. You had a single 80ah battery, our used Roadtrek has an 800ah battery bank. Your battery was primarily for lights, ours run a convection microwave, an induction stovetop, an instant hot water heater, water pump, fan, fan for the furnace ... not to mention recharging various electronic devices. Then there is the TV and AC that some people use a lot. You can't wait for the lights to dim to recharge, which I suspect was the real "battery monitor" many people used. Using those heavy draw items means the batteries discharge much more quickly and unevenly than a 60w light. It also reduces the batteries' capacity and shortens their life beyond the relative amount of power they draw. Mitigating those effects can get complicated in a hurry.

For most people with lead acid batteries of appropriate size, the "idiot lights" are probably sufficient. Properly interpreted they will tell you when you need to recharge. They will also tell you when you are reaching a level of discharge that may damage the battery. I have a solar panel and an underhood generator that charge the batteries. So in practical terms, that is enough for me. My cheap voltage meter gets used to satisfy my curiosity about how close I am to the next light.

[peteco]

Originally Posted by RossWilliams

For most people with lead acid batteries of appropriate size, the "idiot lights" are probably sufficient. Properly interpreted they will tell you when you need to recharge. They will also tell you when you are reaching a level of discharge that may damage the battery.

I don't think the idiot lights are sufficient. Most chargers do not fully charge lead acid (LA) batteries and because of this, over time, the batteries sulfate and lose capacity. In some cases the sulfation can swell the battery case enough to crack the case. I am in the process of installing a battery monitor (Trimetric) and upgrading my charging system to properly charge my two LA batteries.

Hopefully the price of lithium batteries will drop enough someday so I can add one or two in the future. I will most certainly install a quality monitoring system for those batteries as well.

[RossWilliams]

Most chargers do not fully charge lead acid (LA) batteries

If someone has a charger that doesn't fully charge their battery they need to replace the charger, as you are. They don't really need an expensive battery monitor to determine that. All they need is a voltage meter to check the battery voltage after it has been charged and rested.

Whether "most" chargers in newer rv's fail to fully charge the battery I have no way of knowing. But in my case it hardly matters. I have no intention of replacing the under hood generator and solar charger unless I absolutely have to.

[booster]

Originally Posted by RossWilliams

If someone has a charger that doesn't fully charge their battery they need to replace the charger, as you are. They don't really need an expensive battery monitor to determine that. All they need is a voltage meter to check the battery voltage after it has been charged and rested.

Whether "most" chargers in newer rv's fail to fully charge the battery I have no way of knowing. But in my case it hardly matters. I have no intention of replacing the under hood generator and solar charger unless I absolutely have to.

It is unequivocally untrue, IMO, that you can check for full charge with a voltmeter. Approximate, maybe, but not true full that is required to prolong battery life. Go to the battery manufacturers sites, and yes, you will see a reference to some voltage for a charged battery, usually 12.7/12.8v as a quick guide. It does not indicate that the battery was fully charged to nearly all of the manufacturers actual charging recommendations. They say to charge at absorption voltage until the amps get to a specific reading that is usually expressed in a %C in amps. For Lifeline it is .5%C others are different with some like TPPL as low a .1%C amps. Wet cells are usually in the 1 to 3%C, our Trojan GC2 batteries were about .8% when new, so 1% was good.



I have tested our Lifelines from 12.8v rested just to see if they are full to charge specs and they took about close to 50ah to get to the .5%C charging cutoff, so even at at 50% charge efficiency they were at least 25ah short of full. I then let them rest for 3 days and they were at 13.1v and that is not abnormal at all if you talk to Lifeline about the difference from 12.8v, which they know is not full on a good condition battery, but might be typical for an older or short charged one and is why they list the 12.8v instead of higher. It is the minimum voltage that they think a non failing battery should be able to get to, not necesssarily what a good condition battery will get when fully charged. IMO, it isn't a great way to list it, but I understand why the do it that way. Unfortunately, it can cause people to think they are taking good care of their new batteries, when in reality they are short charging them.



Anyone who wonders about if amperage is the best, albeit not easy because the chargers are not capable of doing it for the most part, way to assure full charge, without overcharging, should look at all the information and testing done and documented on this forum and go to the manufacturers sites, or call them and ask about it.


Chronic undercharging of RV batteries is systemic it appears, with nearly all systems undercharging and some overcharging. Hitting the full but not over point requires very good charging equipment or manual monitoring and controlling during charging. And you can't do that monitoring with a voltmeter.


This topic has been discussed here extensively, so there is lots of information available to read.


Peteco just went through this whole thing on his van and charger an is upgrading to a monitor and better charger, it appears, based on what he found out. IMO, he is typical of what many of the rest of us have found out.


As Ross mentioned, he has no intention of replacing any parts anyway, so not knowing he is getting fully charge is of no consequence to him, as long as he is willing to accept the possibility of shorter battery life, IMO. Lots of folks have made that same decision, especially the ones that have fewer and lower cost batteries which are less expensive to replace a few times than upgrade the systems, and nobody can argue that is a bad decision as long as they understand what is going on.


We have close to $1300 worth of batteries, so I want to take good care of them and have as much reserve power as possible by getting them full when charged. That was our choice to do.

[GallenH]

I hope that it wasn't taken that I was implying that there wasn't a need for more accurate monitoring or charging. If I felt that way I wouldn't have added a battery monitor and upgraded to a multiple stage charger. I did upgrade my battery to a single 100AH. If I convert to a compressor fridge, I'll add more but right now I only run lights, pump, ceiling and heater fan. Everything else is propane except microwave and AC (which I've never used) and those I'll only use on shore power. Again, this is not a critique of anyone else's systems, practices, or lifestyles.

best.glenn

[booster]

Originally Posted by GallenH

I hope that it wasn't taken that I was implying that there wasn't a need for more accurate monitoring or charging. If I felt that way I wouldn't have added a battery monitor and upgraded to a multiple stage charger. I did upgrade my battery to a single 100AH. If I convert to a compressor fridge, I'll add more but right now I only run lights, pump, ceiling and heater fan. Everything else is propane except microwave and AC (which I've never used) and those I'll only use on shore power. Again, this is not a critique of anyone else's systems, practices, or lifestyles.

best.glenn

Not at all, but we have been repeatedly been being told by others that neither better monitoring or charging is needed and is even not as accurate as it should be. No issue with anything you have posted so don't hold back as all information is good information IMO.

[Ph0t0n]

Originally Posted by BillsPaseo

Not sure what model it is, but we have a NovaKool compressor fridge, factory installed in our Paseo. It has separate fridge/freezer, and is a pretty decent size for a class b fridge.

I'm guessing on a really hot day if you leave the van closed up, it will run pretty close to 100% duty cycle. But if you open windows and leave a roof fan running, more like 30-50%. We have 200W solar, and have found that in sunny weather, temps in the mid-70's to low-80's, the solar can keep up pretty well indefinitely. Rainy or cloudy days, and at bedtime you won't be sitting at a full charge, and after about 2 days you will need to either run the van or the generator to get back up to full charge.

Winter is a totally different story, even if it is sunny. The solar just can't keep up with the combination of running the heater fan and running the fridge. Even in bright sunny Death Valley in February, we end up running the van about 30 minutes per day to keep the batteries charged.

I much prefer running the van to running the generator - it charges quicker and is much, much, much quieter.

Thanks - that's great real-world info!

My class B has 480w of solar and 232 Ah with firefly oasis batteries. I'm considering swapping out this crappy Dometic 3-way and putting in a Nova Kool F3100 or similar compressor fridge. The stupid Dometic is always breaking, poorly designed, and never runs cold. Refilling propane is the main reason I keep having to return to civilization after 3-4 weeks. I'm a digital nomad and I boondock 99% of the time. Like you, I hate running the generator.

The only thing that is making me hesitant is the rainy day + low-sun-in-winter issue. There are times when I might go backpacking for 4 or 5 days or visit a friend for a week and the propane is great in those situations - I just fire it up and come back a week later and my food is nice and fresh.

Where's the propane + compressor combo fridge? lol!!

I suppose even the $180,000 Travato KL/GL with their fancy $20k lithium system has that same rain/winter problem though... so maybe I'm just being too fussy

[RossWilliams]

We have a small compressor fridge with freezer that draws 3 amps at 12 volts. Our 250 watt solar panels have had no problem keeping it running. But I haven't tried it in warm cloudy weather in the dead of winter. We did leave it for week at the grand canyon this march with no problems.

[BillsPaseo]

Originally Posted by Ph0t0n

Thanks - that's great real-world info!

My class B has 480w of solar and 232 Ah with firefly oasis batteries. I'm considering swapping out this crappy Dometic 3-way and putting in a Nova Kool F3100 or similar compressor fridge. The stupid Dometic is always breaking, poorly designed, and never runs cold. Refilling propane is the main reason I keep having to return to civilization after 3-4 weeks. I'm a digital nomad and I boondock 99% of the time. Like you, I hate running the generator.

The only thing that is making me hesitant is the rainy day + low-sun-in-winter issue. There are times when I might go backpacking for 4 or 5 days or visit a friend for a week and the propane is great in those situations - I just fire it up and come back a week later and my food is nice and fresh.

Where's the propane + compressor combo fridge? lol!!

I suppose even the $180,000 Travato KL/GL with their fancy $20k lithium system has that same rain/winter problem though... so maybe I'm just being too fussy

We've done two upgrades since I posted that, which have made a huge difference. First, upgrading from 200W to 380W of solar. Second, upgrading the Napa 105AH batteries to Lifeline 125AH batteries. Now we can easily go 7 days without running either the generator or the van in the summer, and 3 or 4 days in the winter.