2023 Micro Minnie 2100BH fridge won’t run solely off 12v

[Atreides]

We are new to RV’s, new to this forum, and purchased a 2023 Micro Minnie 2100BH in February. The dealer said that the Dometic fridge would run solely off of 120v -OR- 12v -OR- Propane. Of course I went through all the wiring diagrams, volt meter, hours of internet searching etc… before actually reading the owners manual. The owners manual confirms that the fridge will only run off of 120v & 12v, -or- Propane & 12v. It will not run solely off of 12v.

This also makes sense looking at the fridge amperage ratings of [email protected] and [email protected]. Dometic model: DM2872RB4

Just wanted to post this in case other owners were confused like we were.

Now I guess we need to look into an inverter to be able to run the fridge, but at least we got that figured out.

I also just realized I should have posted this in Heating Cooling Appliances sub-forum, but I can’t figure out how to delete and re-post… sorry

[creativepart]

What to understand about this, is that heating elements that make heat via electrical resistance - and that's space heaters, coffee makers, hair dryers, etc - use a large amount of power. A very large amount.

The way your fridge works, since you have a dual fuel RV gas absorption fridge, is by heating ammonia to the boiling point which causes it to gas and rise. When the gas cools and turns back into a liquid it creates cooling.

When you are on Propane the flame created by burning LP gas does the heating of the ammonia. It uses a small amount of 12vdc to operate the control board, lights, and display.

When you are on 120v shore power or generator an electric heating element - a resistance heating element - heats up the ammonia for the cooling process. Again, the 12v just runs the same things as above.

IF you could run your RV fridge off of 12v power from your battery it would use so much power, so quickly that it could easily run your battery dead in a few hours.

So, RV fridge manufacturers are doing you a favor. Preventing you from being your own worse enemy.

PS. Since this is very common - even though it's news to you - no *NOTICE is needed in your thread title. So, I"m removing it.

[Morich]

Maybe there is something I don't see here but most find running on 12Volt and propane as working really well.
While traveling, the batteries will not run down as they will be connected to the engine alternator which is really way big to do all the things we need when traveling.
The controls are 12Volt which you will have lots of time and then the choice for the heat it needs is either from propane or 110AC and either work really well for us.

Is there some other point that I'm missing? I don't see an inverter working very well as it takes lots of 12VDC for the inverter to make 110 AC to run the frig. Much less complex to simply run the frig on propane?

[creativepart]

Originally Posted by Atreides

Now I guess we need to look into an inverter to be able to run the fridge, but at least we got that figured out.

WHOA there Atreides... not so fast.

No, you do not want an inverter to be able to power your RV Fridge from the 12v battery.

While using 12vdc is one of the worst ways to power your fridge... the absolute worst way is to use an inverter, to invert 12vdc to 120vac to do this job. Inverting DC to AC isn't "free power" - all inverters use more energy than they produce. So, you'd just be increasing the inefficiency of running your fridge and using up your battery's power all that much faster.

When not on Shore Power or generator run your fridge on LP Gas and call it good.

If you had wanted a 12v powered fridge you should have shopped around more for a Micro Minnie with a 12v powered COMPRESSOR refrigerator. In fact, most of the Micro Minnies we see from owners here all have 12v compressor fridges.

And we do see those that get the compressor fridge and wish for nothing more than a Micro Minnie with a dual fuel gas absorption fridge, but they couldn't find one when shopping.

[Atreides]

Thanks for the replies and education. Bummed that the dealer didn’t let us know this before, as they said specifically that we could run the fridge off battery and not propane.

It just seems really sketchy to run propane for the fridge while driving, and especially while filling up at a gas station. Curious to hear from others on this point.

So when people drive and/or dry camp they just use propane for the fridge?

[creativepart]

There are a subset of RVers that are super concerned and I'm sure well meaning people that refuse to run Propane while driving. I know you may run into those folks here or at other RV forums.

However, it is a vast majority of RV owners that run their propane fridges on propane while driving, filling the tow vehicle with fuel and even through tunnels that warn of propane appliances before entering.

You get to decide which of those you are.

You can install an inverter to run your fridge while driving - however it is likely that your fridge will use more power than your tow vehicle can apply to your batteries. If so you can arrive at your campsite with lower battery power available then when you left in the morning.

I've seen posts by those that refuse to use propane while driving pack their fridge with ice packs to keep things cold while driving.

You get to decide what you want to do on this. But now you know the reasoning behind the inability to run off of the battery. There are old RV fridges that did have AC/DC/LP settings. But that's got to be 15 or so years ago since those were available.

Without much looking you could probably find someone with the same TT that desperately wants your style of fridge instead of their 12v compressor fridge. Perhaps you could trade and meet up and swap refrigerators.

If you are a diehard boondocker you want the fridge you have. If you stay at CG with shore power you want the compressor fridge. The compressor fridges are much better fridges and even have more room. But for Off Grid campers nothing beats running their fridge off of easy to replace LP Gas.

[Old Navy]

Originally Posted by Atreides

So when people drive and/or dry camp they just use propane for the fridge?

Most leave it on, but some people turn off the propane when driving, and there are a few places where it is mandatory, like tunnels and ferries. As mentioned earlier, running an adsorption fridge on AC is inefficient. Adding an inverter into the mix makes it even less efficient. You likely have a 325W heating element, plus some additional draw for DC circuits and fans (directly from the battery). By the time you add the inverter, you are probably drawing 30ish amps DC when the fridge is cooling. Even when the fridge is not cooling, it draws a small amount of power, plus the inverter's standby draw. Of course, while you are driving, you get some charging from your tow vehicle, and maybe from your rooftop solar if you have it. So maybe you are fine there. But for dry camping, you'll want to use propane.

[Atreides]

@Creativepart @Oldnavy thanks to you both for the info, its appreciated and super helpful.

Sounds like I can just rely on my dual 20lb propane for the fridge. I’ll search on this forum to see if there is any info on propane usage rate to see if I need to upgrade to larger propane tanks. We’ll be at dry camp sites for a week at a time with limited ability to refill propane. Or maybe I just rent some cows and feed them refried beans… err wait, thats methane…

[creativepart]

Some folks change out the 2-20lb tanks for 2-30lb tanks. But you will be surprised how little LP the fridge uses. And, you can always remove one tank and go in the tow vehicle to get a single bottle refilled.

It's the furnace that will be going through LOTs of propane.

[Raxel7851]

We always leave our fridge running on propane while we drive. When we fuel up, we always shut the fridge off. As far as tunnels go, there’s usually a warning sign before you enter that warns you. At the Chesapeake Bay Bridge and Tunnels you let them know at the toll booth. Now at the Hampton Roads Tunnels you must stop at a guard shack. The guard will watch you turn it off, take down your vehicle info, and let you go thru. He said he if he sees an RV go past without stopping, he’ll notify the State Police and if they catch up with you, there’s a fine.

On another note like others have stated I was surprised at how little propane the fridge uses.

[Atreides]

@Creativepart @Raxel7851 thanks for the info based on experience. I was just reading other forum posts about propane and it looks like we’ll be fine using propane for the fridge.

As a new trailer owner, I see so much content for boondocking/dry camping hyping the need for more solar and lithium batteries. If I can run fridge, furnace, water heater off propane, are people just getting solar and batteries to run the AC while off grid? I’m kind of confused…

[Old Navy]

Originally Posted by creativepart

It's the furnace that will be going through LOTs of propane.

And battery too. The furnace draws 7.6 amps. The OP hasn't mentioned battery type yet, but I found the cheap marine battery dealers usually install wholly unsuitable for dry camping.

[Atreides]

Originally Posted by Old Navy

And battery too. The furnace draws 7.6 amps. The OP hasn't mentioned battery type yet, but I found the cheap marine battery dealers usually install wholly unsuitable for dry camping.

I have two 6v deep cycle 225ah Interstate batteries in serial. But my understanding is only half of that capacity is usable given the battery type. The RV dealer upgraded them at purchase of the trailer to get us by until we figure out what we need for solar/batteries/electronics for dry camping. The trailer came with one 200w solar panel, and a 30amp PWM charge controller.

But as of right now I’m confused as to what we will need from an electrical standpoint as it seems like we can get by with propane for most everything except for AC…

[Raxel7851]

Originally Posted by Atreides

@Creativepart @Raxel7851 thanks for the info based on experience. I was just reading other forum posts about propane and it looks like we’ll be fine using propane for the fridge.

As a new trailer owner, I see so much content for boondocking/dry camping hyping the need for more solar and lithium batteries. If I can run fridge, furnace, water heater off propane, are people just getting solar and batteries to run the AC while off grid? I’m kind of confused…

We’re by no means expert RV’ers and we’ve gotten so much help on this forum. So far this year we’ve been camping 22 days total. We only put the propane water heater on when we shower and also do the dishes. And we travel with the propane on for the fridge. I topped the tank before we started our travels this year. We’re on the road now in upstate NY and heading towards the Mt. Washington area tomorrow. So at a campground we stayed 3 days ago I decided to fill up the propane tank. The guy thought I had wasted his time because it only took a gallon!!! So that’s 20 days of the hot water heater and probably 8 days of driving with the propane running the fridge.

[Morich]

I have no specs on how long the propane lasts but that is becasue we have never found it a concern. We used to do Workamper and the propane use in warm weather was just not enough to make us consider how long it lasted??
The furnace is a big user and if you were to go into running the oven for a long time like a roast, it likely would go quicker!
For the water heater, we are conservative enough, that we don't turn it on until we are about ready to use it. The six gallon tank heat quick enough that it just takes a second cup of coffee for it to get ready.
We've been doing different RV for a very long time since about 1967? and the longer we do it, the less we stress over getting it all done right! We used to do th eboondock things but we gradually got less and less interested in spending THAT much time out there. We now are more inclined to go where the comforts are handy and if we need to, we'll drive out to the woods!
I'm more interested in finding a good waiter at IHOP than watching yet another moose breed!

[tinglett]

Originally Posted by Atreides

But as of right now I’m confused as to what we will need from an electrical standpoint as it seems like we can get by with propane for most everything except for AC…

You will be amazed how much battery you use even without using any 120v appliances. Very quickly you will find you need something better for measuring your battery usage. There are very good battery monitors like the higher end Victron BMC (seriously consider the Smart Shunt if you are comfortable using a phone app), or a cheap but viable monitor like the Bayite DC (https://www.amazon.com/gp/product/B013PKYILS). If you boondock or dry camp, a monitor is essential so you know how you personally use the battery. Everyone is different.

The AC, microwave, coffee makers, and hair dryers can work after an extraordinary number of upgrades are made (and thousands of dollar spent). To begin, don't consider going there, or if these are essential to you then you should get a generator for when they are used. There are many threads discussing all this stuff out there.

But for now it seems you have an absorption fridge which can run on propane+12v, which means you have that part of boondocking nailed already. Personally, I never travel with propane on, but then again we never take long trips so it hasn't been necessary either.

[creativepart]

Originally Posted by Atreides

I see so much content for boondocking/dry camping hyping the need for more solar and lithium batteries. I’m kind of confused…

The need for more solar and more batteries, perhaps LFP batteries, is for people that want to off-grid camp for 5 or 6 days at a time without ever needing to run a generator to recharge batteries.

Many of these people don't have the dual fuel refrigerator you have. RV dual fuel fridges used to be the norm but have fallen WAY out of favor in the market place. The truth is a compressor fridge cools, better, faster and offers more interior storage room. So, people like them.

A residential compressor fridge runs on 110v power and you must have an inverter to dry camp with one of those style fridges. This uses a lot of power - but provides a fantastic fridge in your RV. So, bigger batteries and solar is needed to create the 110v power to run this big residential fridge.

If you have a 12v compressor fridge - which is becoming the more standard fridge these days - you don't need an inverter, but you still need lots of battery power to run the fridge for days. If you don't want to use a generator to keep those batteries charged up, then you need a solar power system and larger batteries for multiple days of boondocking.

You "got lucky" IF you plan on doing a lot of dry-camping. Not everybody does a lot of off-grid camping, so it doesn't suit everyone.

As to running A/C while boondocking for a number of hours that's really not possible without a massive amount of battery storage and then a large solar array to recharge that big battery bank.

It's not really confusing. You'll learn there are all kinds of RVs and all kinds of campers so, everyone's needs are different. As you read all these posts and reviews keep in mind their needs and your needs may be completely different.

[Atreides]

@raxel7851 this is great info, and is helpful for us to know how to prep for our upcoming dry camping trips

@morich sounds like you have a lot of experience camping and it makes sense that your interests would change over time.

@tinglett that is great info, and makes sense that each campers electrical needs are tied to the devices they want to run. Really we only need to run the fridge, led lights, and charge our ipads, and of those the fridge will be the biggest draw. If we’re ever camping off grid and feel we will need AC we’ll rent an inverter generator to see how it does before buying one.

I’ll definitely look into that Victron power usage meter as I was just looking at their solar charge controllers and from what I’ve read they are a very reputable brand.

@creativepart great info as well, and your content about appliance type vs electrical draw makes sense. I got a chuckle out of you saying “its not really confusing” because you have 7,000 posts on this forum. After that many posts and that much experience, I’m sure it wouldn’t be confusing to me either

I appreciate your perspective on letting personal preference for the experience dictate the system we need. We’re on our 6th trip and we’re learning that Winnebago setup the Micro Minnie well for what we are doing, which is awesome. With no experience with travel trailers, but a lot with dry tent camping, we put our faith in the Winnebago brand upon purchase, and it looks like it paid off.

We’ll be dry camping a lot in the next month so we’ll find out pretty quick if our current setup can keep up with our lifestyle. If not, it’s all good because there will be a whole bunch of new gear that I will “need” to buy

[Wakullabob]

When I buy an RV I put the refrig on " auto " and never ever change it . AUTO is smarter than most of us . A 20 lb tank will last us 24 to 30 days . Many are afraid to have propane on while driving , not many . Most just let the refrig do what it was designed to do . Propane refrigs have been around for over 100 years !

[Old Navy]

Originally Posted by Atreides

I have two 6v deep cycle 225ah Interstate batteries in serial. But my understanding is only half of that capacity is usable given the battery type.

The 50% rule is just a compromise between battery life (how many charge/discharge cycles the battery lasts for) and usable capacity. Most manufacturers recommend not discharging below 20% to avoid damage. Regularly discharging below 50% will reduce battery life, but for some of us who camp maybe 25 or 30 days a year, a 200 cycle life rather than a 400 cycle life doesn't mean much. Also, if you plan on converting to LiFePO4 within a couple years, there's not much sense in babying the GC2's.