What Is The Best Generator To Run Dorm Fridge & AC?

[John61CT]

There is nothing new there other than very pricey LFP batts, and certainly nothing that will magically enable producing the kind of AH per day that constant aircon requires without running a genny all or most of the time.

Even with an alternator setup that puts out many hundreds of amps, you'd need to be driving at least a few hours several times a day to keep up with running aircon. And the LFP bank would cost at least a few grand, likely $5+K

If you think you understand what he's talking about well enough to prove the above statements wrong, start a new thread and I'd be happy to help you learn more, maybe I'd learn something too.

 

[RVTravel]

lol...James of Fit RV is not a boondocker. He lives in a house, from what I gather, and travels in his RV, driving everyday for most of his charging needs. He has a 400+ amp hour lithium battery with 300 watts solar. It is interesting that he spends that kind of cash on the RV, battery, and 3000 watt pure sine wave inverter but won't buy an MPPT controller. It's a good site to learn stuff. Lots of people on this CRVLiving site are alternator charging.

The fit rv is "doers" of a New type rv electrical system. Except you don't need a $150K rv like they started with. It can be done with a 2012 to 2016 Nissan NV high roof (or anything really.)

The problems it overcomes are:
1. Solar charging capacity and time (alone by itself, esp. for running an ac),
2. No work-you-to-death generator gas runs, and loud smelly diesel chargers (no generator at all!),
3. Don't generally need shore power,
4. No break your back 500 lbs. of lead acid batteries sloshing around with their high levels of expert maintenance and low levels of reliability.

Even if you have the answers in front of you, as you well know, it's still not easy absorbing all the interrelated technologies. But I think it's easier than what you learned with lead acid batteries being a 'black art' of unknown and expertise factors. On the other hand, not many people know anything about Li-ion and 2nd alternator 'system' (no-maintenance) charging, so you have to depend on a few (real busy) vendors. Ymmv.

 

[Weight]

Lead acid batteries are very reliable. Adding water as needed is not expert level maintenance. Charging parameters are well known and easily programed into any lead acid charging system. Li-ion batteries do require expert operation.
Wouldn't be great if we all could mount a dedicated heavy duty alternator to our vehicle engine and with just a small amount of extra fuel, charge while driving. To make up for only 300 watts of solar used for air conditioning, it must be a humongous alternator. Guess we would not stay in one place but just keep moving. White Line Fever.

 

[John61CT]

So if 400AH, say 340AH usable, at 13V, that is 4,400 wH.

How many hours can you run a normal 5000 BTU aircon off that much energy?

To paraphrase Roy Scheider in Jaws, "You're gonna need a bigger bank"

 

[HerzeleidMeister]

LOL @John61CT Yeah that is true. I'm trying to do this on a shoestring budget. Don't have millions to spend or the ability to have a pricey rig or setup.

 

[jimindenver]

So if 400AH, say 340AH usable, at 13V, that is 4,400 wH.

How many hours can you run a normal 5000 BTU aircon off that much energy?

This is how I am trying to change how people say it. It seems just as a new person gets a grasp on one set of terminology that we have to toss a new set in just to keep them confused. So lets simplify it.

My A/C requires 35 amps to run. Each of my 250 watt panels produce 15 amps mounted flat mid summer. Three panels equals 45 amps, hence enough to run the A/C off of the solar and still cover the loss to the inverter.

My 675 Ah bank of AGM Lifelines have 337 usable amp hours. It takes 35 amps to run my A/C when the compressor is running. 8 hours is 280 amp hours not considering starting surge if cycling of the compressor. There are losses to the inverter but which inverter you have is a variable. Still over 50 Ah should cover most.

Simple

 

[duncanshannon]

This is how I am trying to change how people say it. It seems just as a new person gets a grasp on one set of terminology that we have to toss a new set in just to keep them confused. So lets simplify it.

My A/C requires 35 amps to run. Each of my 250 watt panels produce 15 amps mounted flat mid summer. Three panels equals 45 amps, hence enough to run the A/C off of the solar and still cover the loss to the inverter.

My 675 Ah bank of AGM Lifelines have 337 usable amp hours. It takes 35 amps to run my A/C when the compressor is running. 8 hours is 280 amp hours not considering starting surge if cycling of the compressor. There are losses to the inverter but which inverter you have is a variable. Still over 50 Ah should cover most.

Simple

That's helpful!!

Gets a newbie all excited that AC on solar IS POSSIBLE until he realizes that, as you say, you have 750 watts worth of panels, which is probably 3.5x the usual setup most people have on their trailer here. Right?

Helpful to way to describe/think about it though!


Sent from my iPhone using Tapatalk

 

[frater secessus]

IMO John's version was the simpler one.  

The only "new" term in his post was Wh (watt-hours), which is becoming much more common in marketing smaller banks.  And can be derived from Ohm's law, probably the most critical concept for solar beginners to learn.  Personally I still think in Ah but I admit Wh may be a more useful standard because it sidesteps 12v versus 24v or other bank voltages.

Of course, we all think our own flavor of explaining things is the best or we wouldn't be doing it that way.    I like both of your approaches.

 

[jimindenver]

new Champion 1700/2000 inverter generator is $495, refurbished is $375

https://supergenproducts.com/catalog/p-100047/73536r-17002000w-refurbished-inverter

 

[jimindenver]

I just gave a talk to hundreds. They are not there for a science lesson, they want to here what to buy and do so that everything is okay. Even trying to explain the basic concepts of use, storage and production was too much for some. Bob's chart of this many watts of solar if you want to run (fill in the blank) is far more useful than any formula fill with terms they do not understand.

Our banks are listed in Amp hours. Our controllers show how many amps are being produced. Our devices show how many amps are needed to run them. Amps stored, amps produced and amps used. One standard and no formulas.

 

[breeze]

RVTravel wrote:

[font=Verdana, Arial, sans-serif]lol...James of Fit RV is not a boondocker. He lives in a house, from what I gather, and travels in his RV, driving everyday for most of his charging needs. He has a 400+ amp hour lithium battery with 300 watts solar. It is interesting that he spends that kind of cash on the RV, battery, and 3000 watt pure sine wave inverter but won't buy an MPPT controller. It's a good site to learn stuff. Lots of people on this CRVLiving site are alternator charging.[/font]

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James is a brilliant dual degreed engineer: like Bob, both are brilliant people as well. I have no criterion for their resume's to learn from them. Most people who own RV's have houses as well: I don't care. I have never seen ANYTHING about alternator driven li-ion systems on this site until lately. I am no where near as smart as James or Bob, but I am also a dual degreed engineer and know when systems will or cannot work under normal lifetime conditions.

I owe a lot to Bob and James for their investments in time, sweat, and money; and then their kind willingness to share their knowledge is priceless. For the electronic systems portion, I'll tend to go with the rocket engineer since his logic is sound in all areas. If you decide to invest in a system, run a web site, and commit to teaching others, I may look at yours as well. But for now, I assume the dual degree rocket engineer has a much stronger electronics resume than you do: and I'm not going to limit myself to learn exclusively from boondockers only. 

 

[jimindenver]

Gets a newbie all excited that AC on solar IS POSSIBLE until he realizes that, as you say, you have 750 watts worth of panels, which is probably 3.5x the usual setup most people have on their trailer here. Right?

Sent from my iPhone using Tapatalk

You are right, I do not have the magical hat that makes it possible with what most people install hoping to keep a fridge running, a cell phone and laptop charged. The first thing asked in setting up a system is what do you want to do with it, you can not do what I do with 200-300 watts. You can not have a four bedrooms and two baths in a van either right? One choice limits or controls another.

Then again many vans and cargo trailers can handle two of the larger panels, it is possible without a 25 ft travel trailer.

 

[Weight]

Any problem can be solved by throwing enough money at it. I do not have enough to waste on un-proven or mega-expencive batteries and alternators. So thank you. MLN

 

[John61CT]

Keeping to the FitRV setup

400AH of LFP, $2,500-3K investment

Call it 340AH usable.

Small efficient aircon unit

My A/C requires 35 amps to run.

So call it 9 hours at a time

given other loads also running,

so high-amp recharging is required three times per 24 hours if you're running that much.

A powerful alt setup at 200+A could fully recharge in 2-3 hours of driving.

That's another grand, maybe two with labor, depending on vehicle mods required.

If not driving that much, then a 3k inverter genny, feeding a 120A LFP compatible charger, $2,500-3K for both.

Going to a larger battery bank would not reduce the total energy used per day, just allow you to cut down on the charging / cycling frequency to 2x per 24 hours instead of 3x, and extend the bank's lifetime before needing replacement.

Whether using the vehicle or the genny, running 9-10 hours a day is going to be a fair bit of fuel total per month.

Even with whatever solar fits on the roof, its total contribution to the 700-800AH every 24 hours is not going to be a very high proportion, and of course would be an additional up-front investment.

If I've gone wrong with any of the math here, I'd be happy to get corrected.

 

[jimindenver]

Fit's system FITS his needs, methods of camping and budget. My system fits mine. Are either of us wrong? Only if our needs are not being met. In the end they are just a variety of options that others can look at and possibly get some useful info out of. People thinking that this or that is the only answer for everyone is just a distraction.

Is charging a battery, any battery with a alternator via daily driving new? Not really considering every car has been doing it since forever. Is using the panels like a generator new? No, we have been suggesting that people charge their phone and laptop during the day when excess power is available for a long time now. We may take the concepts to different levels but they are not new.

John

You are correct. The more you wish to do, the more it will cost you. Sitting in a RV park plugged in gets pretty expensive too. The difference is it is expensive forever.

 

[John61CT]

You have said nothing I'm disagreeing with.

My intention has been to show the realistic details behind what the OP appears to need

and to show there isn't some magic bullet in RV Fit's setup.

With enough resources anything is possible.

Or by reducing the usage to within wgat is produced.

Neither approach seemed feasible for this scenario.

 

[frater secessus]

I just gave a talk to hundreds.

 
I remember;  I came to show support and was standing by the bulletin board.  Nice job, by the way.

Still, argument from authority is a logical fallacy;  it does not follow that because someone is an authority that they are correct in any given case.  I mean you know what you are talking about but the Kardashians talk to millions at at time and they are idiots.

They are not there for a science lesson

It is easy enough to remind folks of what they already know and how to apply it to the task at hand. 

And, yes, I've done this in front of hundreds of people in an audience, on the TV (once), radio (three times), in front of literal rocket scientists, and in front of adult education, private, and public school classrooms.  Still doesn't mean I'm right. 

Bob's chart of this many watts of solar if you want to run (fill in the blank) is far more useful than any formula fill with terms they do not understand.

Our banks are listed in Amp hours. Our controllers show how many amps are being produced. Our devices show how many amps are needed to run them. Amps stored, amps produced and amps used. One standard and no formulas.

WATTS?  Holy crap, new people will be confused by Bob's tossing the new terminology "watts" into his graphic!

Oh, wait.  They won't because:

1. the marketing is often in watts; and
2. Ohm's law is most commonly taught in 9th grade, and sometimes as early as 6th grade.

which is the same thing I said about the use of about watt-hours. I may be an optimist, but I think folks planning to boondock in the wilderness or pilot a multi-ton vehicle down the highway have at least the mental ability of a 12-15 year old child.

As for the examples:  small banks are often rated in Watt-hours and we are seeing plenty of this in recent threads.  My controller displays in Amps and Watts.  I just picked up and read the closest 3 electric-powered objects.  The first listed watts then amps.  The second listed only watts, and the third last only amps.  Consumers should know how to convert between those units the same way they use formulas to convert cooking recipe units, minutes-to-hours, calculate restaurant tips and MPG, etc. 

If we had to have one standard (which we don't) Watts would be simpler;  watts describe the same amount of power no matter if the system is 12vdc, 24dc, 120vac, or at different states of battery charge.