Battery life without running generator, and how much time do extra batteries add?

[content]

We were hoping to buy a Force 34KD or 37BH (with loveseat, not entertainment center option) with 2-way refrigerator to use this summer.

We dry camp about 75% of the time, and would prefer the extra battery life you get by running the refrigerator and heat with propane. We also park overnight at family's house sometimes, and don't want to fire up the generator in a residential neighborhood if the batteries are low.

Unfortunately, there is little to nothing available with a 2-way refrigerator, so we are considering buying a Force, or DX3 with cabover bunk, with residential refrigerator, or possibly a DX3 with cabover bunk with all electric.

Can you please tell me approximately how much time you can expect to run on batteries without firing up the generator: 1) on a propane coach with residential refrigerator; or 2) on an all electric coach? Assume light TV use, light cooking, light lights, and moderate temperatures so moderate heating needs.

Since there is so much OCCC on these rigs, could you add 2 or 4 or 6 additional batteries, and will that significantly affect how long you can power things before needing to fire up the generator?

Thank you.

[FFred]

Adding more batts , or spending big bucks on Lithium batts that can be more deeply discharges only solves the problem a bit.And require longer charge tines.

Any way you could install a proper RV 2 way fridge?

Batts are harmed by a "too deep" discharge , so I suggest a SOC meter as first purchase.

SOC = State of Charge.These will need a shunt installed (no big deal, comes with most SOC meters).

An RV unit will run about $150 , the marine versions are over $200.

But compare that with replacing the house batt bank often .
TriMetric Battery Monitor - - Bogart Engineering

www.bogartengineering.com/products/trimetrics.html
○Measures battery % full, based on amp hour measurements for accurate information on state of charge (SOC). This method is more accurate than monitors ...


You need to understand the electric you now use to be able to extend boondock time.

[FOURWHL]

Stock my 37RB is good for about 24 hours give or or take (no scientific Ah calculations there, just past experience)

My recommendation, and what I'm in the process of doing, is to look at a properly sized solar system if you dont want to run the gen.

Battery upgrades, especially lithium, are nice and will stretch it out but they all need to be charged. Solar coupled with batteries would allow you to be self sufficient as long as the sun is out

[tomkatb]

Got to learn the math.

P=I*V.

Unfortunately the big problem is batteries. Batteries do not hold a lot of juice. You have to learn to manage your power. More batteries the longer you can go. Remember the 50% discharge rule for wet batteries.

Rv’s with all electric appliances are not designed to boondock without the generator being used often.

Inverters are 80-90% efficient, another issue.

For example running a microwave or convection oven can wipe out a 100 amp battery in 25 minutes. A cpap machine will wipe one out in a night. A residental fridge could do it in 4-6 hours (worst cases, south Texas in the summer). A furnace would wipe one out in a night.

Our fiver has four six volt batteries. With that and an rv fridge best case we can go 3 days without ac power, generator. Does not include the furnace.

So the answer to your question depends.

If you have 8 solar panels and $6,000 worth of batteries then, you can change the numbers, if the sun shines a lot.

[Flybob]

You state "running the refrigerator and heat with propane."


Running a fridge on propane can significantly extend battery life, but the furnace uses both propane ( heat) and 12VDC ( fan) to operate and the fan consumes a considerable amount of power so there are not choices here. Based on your comments you are going to need some method of charging the batteries almost daily. Also keep in mind that high capacity deep cycle batteries do not charge quickly.

[FOURWHL]

Just to keep the conversation on track here the OP is looking at models that come stock with 440 Ah of AGM batteries. Not a nominal amount, but as I stated the residential fridge will draw them down.

[content]

Thank you for the replies and insight above.

I probably should have stated the question this way:

Without running the generator, roughly how much more operating time can you get with a 2-way refrigerator compared to: 1) residential refrigerator and propane system; or 2) all electric?

If the answer is 2-3 hours, I don't know that there is a big advantage to the 2-way refrigerator.

If the answer is more like 24-48 hours, it seems like the 2-way refrigerator would be a high priority for us.

[Magnatudes]

Originally Posted by content

Thank you for the replies and insight above.

I probably should have stated the question this way:

Without running the generator, roughly how much more operating time can you get with a 2-way refrigerator compared to: 1) residential refrigerator; or 2) all electric?

If the answer is 2-3 hours, I don't know that there is a big advantage to the 2-way refrigerator.

If the answer is more like 24-48 hours, it seems like the 2-way refrigerator would be a high priority for us.

My two cents, the frig will run for months on propane. Lots of factors, tank size, ambient temp, cooling fans behind frig, frig contents, ...

[gbaldwin]

75% boondock = fridge that will run on propane IMO. Using Gas power wherever possible is much more desired; conserve battery.

I think a generator is also pretty essential when BDing. I dont use super batteries but find I need to charge daily, even though I do use gas whenever possible.

[content]

And to frame the question one more way...

The 2-way refrigerator is a $3,000 (retail) option. If you get an all-electric unit (i.e. no 2-way refrigerator), could you get the same amount of operating time (without running the generator) as the 2-way refrigerator/propane unit if you spend that $3,000 on aftermarket power system upgrades/more battery storage?

Appreciate your patience. Power systems are not my area of knowledge (yet!)

[dbledan]

Originally Posted by content

And to frame the question one more way...

The 2-way refrigerator is a $3,000 (retail) option. If you get an all-electric unit (i.e. no 2-way refrigerator), could you get the same amount of operating time (without running the generator) as the 2-way refrigerator/propane unit if you spend that $3,000 on aftermarket power system upgrades/more battery storage?

Appreciate your patience. Power systems are not my area of knowledge (yet!)

Yea I think you nailed it right there.

I suspect the install for the solar meter, charge controller and additional battery bank would be more costly than the fridge change out unless you planned to do the work yourself on one vs the other. It does not really extend your boondocking timeline because you have to run the fridge.

Panels are about a dollar a watt at best prices and you would need several to get what you want and run the fridge plus maybe more battery (though 440Ah is nothing to laugh at) and the controller. Then there is the whole mounting concern. Parts for the solar kit would be about $1500 depending on your wattage needs. Now you have to park in the sun which here means you need AC so back to generator or plug. More batteries depends heavily on what you have already and your usage.

If the fridge is not in the slide it should not be too hard to change out later. Vents and a gas line would be the biggest issue and you would need to build or buy a cabinet to set it on.

Wouldn't you get some money back from the residential fridge or inverter (assume they downgrade or remove without the fridge) when you removed that option or are you paying more for it as well?

I have not priced it out specifically for this but I have investigated solar. For the way we camp it is too expensive to justify. DW likes her AC so I need a plug or a generator.

For the family stays you could plug the fridge into the house or garage instead of running the generator if you stick with residential the fridge but not when boondocking.

Good luck!

[TitanMike]

Originally Posted by FOURWHL

Just to keep the conversation on track here the OP is looking at models that come stock with 440 Ah of AGM batteries. Not a nominal amount, but as I stated the residential fridge will draw them down.

Replace that 440 Ah battery bank with four LiFePo batteries and the available power will double as you don't need to worry about the 50% discharge rule. Usable power would go from around 220 ah to 400 amp hours.

Charge time will be quicker too with a converter upgrade for Lithium battery charge. No more 3-4 stage charging. Lithium's charge at a wide open rate until fully charged then they stop charging. Lead acid's charge more slowly as the charge rate naturally tapers as SOC increases.

If really impatient you can wire two Lithium chargers in parallel and charge at a much higher rate although overall battery life can be compromised somewhat.

Then there is weight. Just guessing but that 440 AH battery bank probably weighs close to 300#. Four Battleborn LiFePo batteries will weigh about 120#. Over half the weight and twice the available energy.

Compare an upgrade to Lithium versus cost of a diferent refrigerator.

Yes, initial cost will be significant but compare life cycle cost. Lead Acid batteries will give 500-800 cycles average with lots of maintenance (adding water, controlling corrosion, etc). LiFePo batteries will yield 3,000 - 5000 cycles. If you run down and recharge every day on both types of batteries the lead acid will last 1 to 2 years. LiFePo will last 8 to 13+. And that's if you use all available power and recharge every day. If you only recharge every few days, the LiFePo will last twice as long before needing a recharge so their life can extend to well over 15 years, perhaps over 20.

There's an old saying: "It's not how MUCH you pay, it's how OFTEN you have to pay it".


Lastly, if one has a 440 AH battery bank comprised of FLA batteries, they can get effectively the same usable power with two or three Lithium batteries which would reduce cost, and an even greater weight reduction.

[NMWildcat]

If you will be primarily boondocking (no hookups), then get the two way fridge. You will also need a generator, solar setup, or both, for charging batteries. At 75% dry camping, I think this is your only option. When not running the heater, we can go several days on two series 27 marine batteries w/o charging, if we pay attention.
If you will be primarily at full hook ups, then the residential fridge will be fine. My dad could only go less than a day with four batteries and his residential fridge. He got rid of that RV and went back to a two way fridge. When his residential fridge needed replacing, they had to take out a slide.......

[rlh1957]

Originally Posted by content

We were hoping to buy a Force 34KD or 37BH (with loveseat, not entertainment center option) with 2-way refrigerator to use this summer.

Unfortunately, there is little to nothing available with a 2-way refrigerator, so we are considering buying a Force, or DX3 with cabover bunk, with residential refrigerator, or possibly a DX3 with cabover bunk with all electric.

Thank you.

Have had high wall popup, two bunk hybrid, travel trailer and all had 2 way or 3 way fridges in them. The LP mode on the fridge is very fuel efficient and works well. The DC on 3 way was nice on the popup, but when we realized the LP use was efficient we didn't mind the 2 way AC/LP fridge in our hybrid and trailer.
Usually only rigs with residential fridges are the only ones that only operate on AC... and Boondocking that is by way of an Inverter that changes DC from battery to AC for the fridge. Most have two batteries for this.

[jimmoore13]

"Hoping to Buy" gives you options.

Pre-Purchase options.
1. Get the dealer to swap in a 2 way fridge instead of the residential fridge. Don't buy a residential fridge to begin with.
2. Upgrade your battery bank. With a 2-way fridge, 4 x 6 volt golf cart batteries are typically enough. $500 for 4 batteries vs. $1000 for a single LiFePo4.
3. Add solar to the roof. Very basic rule of thumb, you need one x 100 watt panel for each battery. Negotiate with the dealer to install this for you as part of the deal. Windy Nation and Renology are good brands. "Factory" solar will set you back 3 times as much for very little if any advantage. You can do better and spend more, but if you use propane, this should keep you going.

Now some facts:
1. Calculate power use with this calculator. It's not rocket science, but if you add up your 12 volt loads and your 120 volt loads, and if you know the amp hour capacity of your battery bank, you can easily determine how long your batteries will last and estimate how much charge the solar array is providing during the day.
KEY POINT: ALL LOADS DRAWING FROM THE BATTERY BANK MUST BE CALCULATED AT 12 VOLTS. If you run a 1000 watt microwave (120 volts) off the inverter for 20 minutes, that's 83.3 amps for 1/3 of an hour or about 28 amp hours. Also, high amp draws deplete the batteries faster than the ratings suggest. Batteries are rated at about 20 amp draws. 83 amps hits them hard.

2. Inefficiencies in inverters, parasitic loads (eg the CO/Propane detector) and other loads like the water pump, spark for hot water heater, and so on all count. Get a rough idea how much they use. For example, a water pump draws 7 to 10 amps for a few seconds to a few minutes (shower). Over the course of a day, these add up. So does TV, and so on. Pay close attention to how much power the furnace uses when running, how much power the stereo system head unit draws when "off" and when running, the cumulative load of lighting, and so on.

3. And a harsh fact of life. Batteries, even Lithium, SUCK as power storage compared to propane. Going back to the "standard" 4 x 6 volt golf cart battery bank, it has a rated capacity up near 500 amp hours. USABLE capacity is roughly 50%. On a good day, you can suck 225 to 250 amp hours out of that battery bank without damaging it.
Let's say 250 AMP HOURS.
PROPANE has 91,600 BTU per gallon. A 20 pound tank hold about 4.5 gallons. That's 412,200 BTU. Convert BTU to kilowatt hours (1000/watts for an hour) = 120.8 KWH or 120,800 watts for an hour.
Back to the first calculator. Plug in 120,800 watts at 12 volts (for an hour) and you get 10,067 amps for an hour....10,067 AMP HOURS.

One tiny little 20 pound tank of propane has the energy equivalent of over 40 of your battery banks!

If you boondock, go with propane appliances wherever you can, and support your battery bank with solar. When you plan to run the micro or coffee maker, fire up the genny for a few minutes and run them on "shore power" supplied by the genny.

You'll be a happy (dry) camper IF you buy the right camper with the right equipment for boondocking!

[rlh1957]

And that my students is the old school math that your kids aren't being taught or having a chance to learn in todays public schools!
Thanks jimmoore13 for that refresher on basic math and power calculation.

[gbaldwin]

In ref to......And to frame the question one more way... Post 10....


Over my head ...sorry. Tooo many factors to consider ..... Dont know how far you might go with batteries. Never been there. But as iffy as they can be if not monitored perfectly, having the generator for recharge and using propane whenever possible contributes a whole lot to a many an RV'ers relax factor! just easy and no sweat. Never run out of power. Have fun!

[content]

Thank you for the information and guidance above!