2016 F-233RBS power system upgrade

[AnimalHungry]

After having our F-233RBS for a couple of month I've found that the power system is woefully incapable of keeping up with our usage. We exclusively boondock and have found that after one night of running minimal lights (all LEDs), a bit of water pump, the fridge and the furnace the CO detector starts chirping indicating the battery is low. Then it will take 8 hours plus of running the generator to get the battery back up to 2/3-full charge. Then on the second night the battery will die around 5am.

I think there are a few things going on here. First, I need to add battery capacity so I'm going to get two 6v deep cycle golf cart batteries. Then I'll replace the converter/charger with a three-stage unit which should charge up the batteries much faster from generator power. I'll also add 200W of solar to the roof to try and keep up the batteries charge. Then I'll wire it all up through a transfer switch. If I have any funds/inclination left after doing that then I may add an inverter.

Does anyone know if this is the best thing to do for my situation? And any recommendations for specific components? For example, I hear good things about the Renogy solar kits, but I'd probably want to buy a separate (better) MPPT controller that I could add extra panels to down the line.

All suggestions greatly appreciated!

Cheers
Simon

 

[beddy]

Simon,

Here's a link to our post on our setup. http://www.funfinderclub.com/forums/f11/solar-battery-charging-2890-2.html#post15651

We experienced exactly the same lack of endurance you are having now.

Good Luck

Mac & D

 

[LJAZ]

I would check your battery first - sounds like it may be time to replace it. I recently boondocked for 4 days using a single battery with no issues. Although I didn't use the heater which can tend to be a bit of a power hog from what I've heard.

 

[runner421]

I'm sure there are several options to add electrical capacity. I opted to go with 4 deep cycle 12-volt RV batteries. I added a solar charger and flat/flexible panels. Went with an outback charger/inverter. This gives me limited AC to use my Kuerig in the mornings, charge my devices during the day, run fans and lights. I've boondocked in the sun for more than a week without running a generator. I've been in the shade and it's about 3 days before I need to run a generator to bring the batteries back up.

 

[michellep]

I've been gone just over 3 weeks, mostly boondocking. With my 2 x 100W flex panels, I have not had to use the Honda eu1000i even once (to charge the battery...but yes, to use it as the World's Most Expensive Hair Dryer).

With the Dometic climate control system disconnected, a new Group 31 deep cycle/marine battery, 2 solar panels, LEDs in all interior lights, and NOT using the furnace or water pump (gallon bottles of water and Coleman propane heater), I basically have a hard-sided tent with a fridge and a comfortable bed, and could stay out for a very long time.

What drives me to a hook-up campground is that I need me some television watching...

 

[John_C]

What drives me to a hook-up campground is that I need me some television watching...

Hey Michellep,
I don't know if there is a Menards near you, but Menards is having their annual sale on the little Proscan 19" flat screen TV w/built-in DVD player. Oh I almost forgot to add that they can be connected to either 120vac OR 12vdc ...

I have purchased a few over the last several years and they have worked well so far... Two in the trailer, one in the spare BR, and I just bought one 2-weeks ago for the office... I have two group 31 batts in the trailer and the TV (I only wired one for 12vdc ) doesn't draw much current... We have dry camped for several days at a time and the Boss runs the TV up to maybe several hours a day...

They are not priced too bad at $79 (after a $20 Rebate)... Of course, that's a Menards rebate, meaning you get a rebate that can only be spent at Menards... AND, the TV is a store only item... You would need to find a store near you:
https://www.menards.com/main/electr...44428127187-c-6299.htm?tid=774810298988342542

BTW... The same TV DVD combo sells at Amazon for around $150...

Just thinking...

 

[John_C]

Oh, BTW, Menards usually have two sales a year on this little guy... One about now (Back to school) and another one before X-mas...

 

[michellep]

Sadly, I don't even have a Menard's where I live. I have nothing where I live. Well, Lowe's and Walmart. They are my world.

But, your post made me poke around the back of my tv and Directv DVR.

Someone correct me if I've done the math wrong:

TV: 120V, 0.45A, 54W

DVR: 100-240V (I used 120), 0.58A, 70W

So, plugging into an inverter connected directly to my battery, I would be using a little over an amp to run the tv and DVR (plus an unknown-to-me draw from the inverter)??

 

[AnimalHungry]

Thanks everyone for all the replies! The battery is only two months old and is in good health, but it's a group 24 and just takes a beating each time we go camping. We have to run the heater all night since we have a 2 month old who needs to stay warm - I'm pretty sure that without that I wouldn't be looking to upgrade so quickly.

Cheers
Simon

 

[brackenlip]

Sadly, I don't even have a Menard's where I live. I have nothing where I live. Well, Lowe's and Walmart. They are my world.

But, your post made me poke around the back of my tv and Directv DVR.

Someone correct me if I've done the math wrong:

TV: 120V, 0.45A, 54W

DVR: 100-240V (I used 120), 0.58A, 70W

So, plugging into an inverter connected directly to my battery, I would be using a little over an amp to run the tv and DVR (plus an unknown-to-me draw from the inverter)??

Nope, sorry, your math is wrong ! You have to go back to school on Ohm's law. Your current ( amps ) draw at 12V is going to be much more than that.

 

[michellep]

Even though I'm using an inverter?

 

[brackenlip]

Even though I'm using an inverter?

....as Ronald McDonald says, "there's no free lunch".

Just because you are using the inverter does not mean that you magically created free "extra energy".

Bottom line is if you are going to use the TV, the DVR and/or the sat dish, you are probably going to end up using the Honda genny.... oh, I mean the world's most expensive hair dryer.
Which is still cheaper than going to a commercial CG ;-)

EDIT: ps, in truth, when you are using the inverter, you're actually using a slight bit more power out of the battery, overall, due to ( as you alluded to earlier ) the fact the inverter is not 100% efficient. In other words, as you step up the 12V to 120V ( and create a pure sine wave, AC waveform ), a little bit of that energy is lost as heat. Which is why the inverter has cooling fins on it.

 

[michellep]

Disregarding the power used by the inverter:

Will a 120V television at 0.45A running for 1 hour at 120V at home consume the same amount of energy, or more, or less, as the same television going from 12V BATTERY > INVERTER > TELEVISION for 1 hour?

And is it impossible to remove the inverter from the equation?

 

[brackenlip]

Disregarding the power used by the inverter:

Will a 120V television at 0.45A running for 1 hour at 120V at home consume the same amount of energy, or more, or less, as the same television going from 12V BATTERY > INVERTER > TELEVISION for 1 hour?

And is it impossible to remove the inverter from the equation?

Yes, it uses the same amount of energy, or close enough that we will say "the same". It appears what you are failing to do is you're not understanding how the energy use is calculated.

And yes, it's impossible to remove the inverter from the calculations. Or at least if you want meaningful numbers when all done, for sure you need to consider the inverter as part of the system.

There is some efficiency gain by utilizing higher voltages, but for this discussion, the difference in efficiency between 12VDC and 120VAC is not enough to be of concern. We would have to get rather deep into the technical side of it, and into theory to be really accurate.

But...like....holy smoke Batman.....we're getting way off tangent, and truthfully way beyond my knowledge of it ! I've sat in on conversations between EE's ( my former supervisor has a masters in EE ), and I'll tell 'ya, it get's really deep and techy real quick, and my eyes glazed over......)

gee.....how did we get side tracked so tech wise right here on good old simple funfinder forum !! ??

The honest truth is regarding RV'ing and trying to set up a true solar/wind boondocking rig, you have to fairly seriously over engineer the whole system. There are too many variables that you cannot predict, such as the availability of sun ( or wind ) to generate power, etc.
With your genny, it's all pretty much straight forward.....you know what it's rated output is, and as long as you have a gas can full of good old unleaded, you can provide the electrical power.

 

[michellep]

Further "poking around" has led me to this:

I have a friend who was my morse code teacher over 20 years ago.
He got his ham license maybe 40+ years ago.
His answer to my question was:

Since the TV is running off the inverter at 120VAC the current draw is still .45A. It's the same as if it was plugged into a normal house 120VAC outlet.

Then, I found this, which was helpful to my understanding:

Formulas and Examples for 12 & 24 Volt DC Systems

This “Rule of Thumb” is intended as a general guide for estimating the DC amps required to operate a DC to AC inverter. Since the calculations yield approximate values, an appropriate safety factor should be considered when designing and specifying system components, such as wire size and length.

12 Volt DC Systems

Formula: 12 volt inverters require approximately one (1) amp of DC input for each 10 watts of AC output.

Example: How many DC amps will a Vanner 12 volt inverter require to operate three 500 watt quartz lights, or a 1500 watt electric heater?

Answer:
1) Total watts = 1500
2) 1500 watts/10 (from formula) = 150 amps

This is the DC current the inverter will use to operate the 1500 watt load. Note - if this 150 amps is drawn from the battery for one hour, 150 amp hours (AH) of battery power will be used. To support 150 amp hours of battery power, 300 amp hours of battery capacity is required.

SOURCE: http://www.vanner.com/brochures/Estimating-Power-Requirements-7-01.pdf

 

[brackenlip]

ok, so look at your example there in your last post:

"Formula: 12 volt inverters require approximately one (1) amp of DC input for each 10 watts of AC output."

....so, you said your TV set consumes 54 watts of 120 VAC power. Therefore in order to provide 54 watts of 120V out of the inverter, you are going to have to input approx 5.4 amps of 12VDC electrical potential from your battery.

....not the .45 ( less than half of one amp ) amp you were hoping for.

Since the voltage of the battery is lower ( 12V ) in order to "do the same amount of work" ( watts ), the amperage must increase. Raise the voltage, then the amperage drops, to do the same work.

It's true that at the inverter OUTPUT, the current ( A ) draw is .45 to run the TV. But in this case, what you are concerned with, is trying to figure how long your 12V battery is going to last. So it's the current draw on the battery that's killing you here.

Try it. Try running the TV and the DVR on the battery and inverter, and report back how long it takes to run the battery down.

 

[brackenlip]

Here's an analogy ( probably not a very good one ! ) that might make it easier to understand why the amps must increase, when the voltage decreases, in order to complete the end result being the same amount of work:

Visualize the voltage as the potential to do some work.
Consider the amp as an amount of work accomplished.

Think of a volt as your own personal little soldier there to do your bidding.

You have a pile of rocks there, that need to be moved from here, to over there. If you have 120 of these little workers, each one only has to do a small amount of work, just lifting one rock each. We'll call that work accomplished "amps" consumed.

Now then, 108 of your soldiers desert in the middle of the night. You now only have 12 hard working little guys left, but you still need to move the same pile of rocks back over to the space they started. So now each soldier ( volt ) has to do far more work ( amps ) on his own.
In the end, the same amount of total work was done, but each volt had to work harder, and we define that work completed as amps used.

So in our case here in our boondocked RV, we ran the battery down. Trying to run fairly high draw items ( like TV sets, DVR or sat dish receivers ) is going to require a steady flow of energy. This is why like class A motorhomes have a big battery bank, like maybe six or more deep cycle batteries. Or just run a genset. Or go to the KOA and plug into the pole !

ps, I have no doubt Blake knows the correct answer to your question. I suspect the issue is, you didn't ask the question in the correct way. Further, I think the correct question you are asking, is, "how many amps am I using out of my RV battery ?" Because THAT is what really concerns you, right ?

 

[brackenlip]

Easier still, if your clamp style multi meter is capable of reading small current draw, check it with that. See how many amps are pulling from the battery with your TV set turned on, and plugged into the inverter.

 

[John_C]

Ouch, you guys are making my brain hurt...

The little 19" Proscan I was talking about is actually a 12vdc TV with a 120vac to 12vdc wall converter (I just picked up a 12vdc cig lighter plug and plug it into a 12vdc wall outlet) at a max of 3.0 amp draw. I have two Grp 31, 950 Amp Hr Batteries, connected in parallel (When connecting in Parallel you are doubling/adding the capacity (amp hours) of the batteries while maintaining the voltage of one of the individual batteries), giving me somewhere close to 1900 Amp hours of use, IF only the TV was the draw. However, because we minimize electrical use when dry camping, we still can easily get 4 - 5 days, if the heater doesn't run very much, before I need to worry about getting my Genny on line...
We spent 3 days up near the boundary waters dry camping last year and didn't even realize we used electrical power ... Heat in the AM_the fan is elec, we cycled the water pump to flush the toilet, HW to wash dishes, people, and run water for whatever, we used the HW heater, but it is gas, ran lights, and the stove vent fan when cooking...

Anyway, the program says you would draw 4.97 amps, including inverter current... :idea:

Here is a quick printout from:
https://www.batterystuff.com/kb/tools/ac-to-dc-amperage-conversion-run-through-an-inverter.html