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Steelie53

One battery or two

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We pick up our 1st 5’er at the end of September. It will have a residential refrigerator and 1000w pure sine inverter. The dealer will provide one battery. No generator or solar (yet). We typically stay in parks with full hookups with the occasional overnight with no electricity and like to drive no more than 300 miles in a day. With our scenario will one battery be sufficient or should I have two? Any suggestions on battery type and best wiring options (for two batteries) would be much appreciated.

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I would consider 4 batteries, a 2000w inverter and a good battery minder so you know the SOC.

We have a residential refrig and 4 batteries, round numbers 400A. Overnight, in cool weather, we use about 20-25%, that would be 100+ amps. We generally start with 90-95% SOC. One should try not to use more than 50% of their battery so even 2 batteries is dicey. In addition we have 4 solar panels for an additional 660w.

Our installer told us 3 panels is about the minimum for solar and a residential refrig. We did have 2 and that was not enough. We added the additional 2 as a complete separate system for several reasons. You should be able to get by with 3. 

Sometimes, if cloudy, we need to top off the batteries in the evening to get to the 90-95% level.

Edited by SWharton

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Residential fridge takes a lot of power.  One battery will not be nearly enough.  Two batteries might not be enough.  While driving, the cable between the truck and trailer will NOT charge your batteries enough to power the fridge all day.  So, you will be draining your batteries even if the truck engine is running.

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Our 2 6v batteries will last 16 hours powering nothing but the residential fridge.  As already mentioned, unless your tow vehicle has a 2 alternator option and a dedicated charge cable, you generally loose charge even when towing.

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Batteries can last 16 hours. Then dead batteries are hard to recharge. The TV alternator will not do that job. If the battery is not fully  recharged, they will not last very long before replacing. 

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I guess I am somewhat surprised that the mfg. only supplies one battery and a 1000w inverter with a residential refrig.

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Guys I have residential fridge and my orginal inverter died. We tow and no problems with fridge. My ice cream isn't even soft. Now we hook up at night in a park somewhere. As long as doors are closed, they will keep cool long time.

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2 hours ago, SWharton said:

I guess I am somewhat surprised that the mfg. only supplies one battery and a 1000w inverter with a residential refrig.

They cut corners to save money wherever possible, including the residential fridge.

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Most manufacturers do not supply the batteries.  These are installed by the dealers, and there should be no reason, for an extra charge, that they couldn't install as many batteries and whatever type you want.

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You will probably need more than two batteries.  I run two 6v GC batteries in series, and like that a lot.  I recently set that up for a friend with a larger trailer and kids, and he says the batteries "last forever" where before he'd get a day at most.  However we both have propane fridges.  Sam's and Costco sell the GC batteries for about $90 each, and you can get the extra cable needed for series wiring from any auto store.

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There is a lot of btu’s locked up in a gallon of propane. An electric fridge can use up to 1.5 kwatthours a day, maybe more. One battleborne lithium battery can output 1.2 kilowatts, equivalent to two 6 volt golf cart batteries essentially. Boondocks would mean a huge solar or extended genset run times.

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I read many assumptions in this thread.  #1- Size and capacity of batteries, #2- type of batteries(which will allow or not how much discharge they can handle), #3- what size and type of solar panels, #4- the other equipment relevant to the entire solar/charging system for the purpose stated by the OP, #5- RV manufacturers provide minimal equipment, rather providing pretty, shiny and many bells & whistles, rather than robust support systems.

Since I am learning about most of this, consider this to be an exercise in IF I have learned what is necessary to be able to properly design a system based on its intended purpose.

Any feedback?

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On 9/13/2019 at 9:49 PM, FBO Cookie Monster said:

There is a lot of btu’s locked up in a gallon of propane. An electric fridge can use up to 1.5 kwatthours a day, maybe more. One battleborne lithium battery can output 1.2 kilowatts, equivalent to two 6 volt golf cart batteries essentially. Boondocks would mean a huge solar or extended genset run times.

Battle Born batteries are 100A, it requires 200A to equal 1.2KW =  2 LifePO batteries completely discharged.

Edited by Ray,IN

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26 minutes ago, Ray,IN said:

Battle Born batteries are 100A, it requires 200A to equal 1.2KW =  2 LifePO batteries completely discharged.

Two 200 Amp-hour 6 volt batteries can deliver 100 Amp-hours at a 50% discharge level.

Since LiFePO batteries can be almost completely discharged it only takes one 100 amp-hour 12 volt battery to do the same.

12 volts x 100 Amp-hours = 1.2kWh.

Edited by Lou Schneider

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38 minutes ago, Lou Schneider said:

Two 200 Amp-hour 6 volt batteries can deliver 100 Amp-hours at a 50% discharge level.

Since LiFePO batteries can be almost completely discharged it only takes one 100 amp-hour 12 volt battery to do the same.

12 volts x 100 Amp-hours = 1.2kWh.

Good catch, thanks for correcting me. I used 6V in my calculation.

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For geeks, the cool way to go is a tesla battery module.

https://www.ebay.com/i/142839800943?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=142839800943&targetid=475515373381&device=c&mktype=pla&googleloc=1022808&poi=&campaignid=6469981122&mkgroupid=79220336802&rlsatarget=pla-475515373381&abcId=1141176&merchantid=138362550&gclid=CjwKCAjw5fzrBRASEiwAD2OSV7ALU0PQrlMjKfCBxTn7UuLSzMEbvYSJ7igz2XlchqgzBuv189GLChoCud0QAvD_BwE

 

Equivalent to more than 4 battleborns, or 8 200 amp golf cart batteries. Only weighs 60 pounds or so. Not for everybody, they require additional electronics to make usable,  but you certainly will not need to run the generator everyday. But huge power in a small form factor. Tom here does an excellent intro to it.

 

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Can you "camp" in your driveway after picking up the camper.  Turn on the fridge and let it get to selected temperature. Fill fridge with some gallon sized water bottles you've chilled in your home fridge. add a thermometer to the fridge.  Disconnect from shore power and turn off the inverter.  Check fridge temp periodically and you will be able to guess how long the fridge will stay at a safe temp with no power supplied. It may surprise you. I would still like to see a minimum of 2 "deep cycle" marine batteries.

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With a residential fridge I believe you should have 2 batteries if you only go campground to campground, always plugging in.  That will give you at least 12hrs without bringing your batteries below 12v which will start to harm them. 

If you want to be able to do a Walmart stopover, you need 4.  That’s minimum I would recommend for anyone with a residential fridge.

FYI - I have the equivalent of 6 (3 4D AGMs) along with an additional 2800W inverter, allows me to run everything by AC for a couple days.  Nice to have that margin if you have the room, weight capacity, and $. 

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from what you say,   you need at a min,   4 deep cycl 6 volt batt. or if you got the cash install at least 4 better 6 of the new style batts they are 12 volt units but can handle a deeper bleed off then any lead acid batt can.

also install as much solar as your roof can hold (you will never get the full charge rating from them).

get a honda eu3000, mount it hard to your rv. and install a remote start to it.

but do all this the right way,  and it will be worry free, 

and your beer will be the coldest in town.

 

but then i boondock.  hooked up in a park, can forget the solar and gen. but be ready for a black out in your rv.

Edited by packnrat

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On 9/14/2019 at 10:51 AM, rpsinc said:

I read many assumptions in this thread.  #1- Size and capacity of batteries, #2- type of batteries(which will allow or not how much discharge they can handle), #3- what size and type of solar panels, #4- the other equipment relevant to the entire solar/charging system for the purpose stated by the OP, #5- RV manufacturers provide minimal equipment, rather providing pretty, shiny and many bells & whistles, rather than robust support systems.

Since I am learning about most of this, consider this to be an exercise in IF I have learned what is necessary to be able to properly design a system based on its intended purpose.

Any feedback?

Ya - use big wires and fuse everything.

Let’s see..anything else... nope... that’s it from my extensive “knowledge base”

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6 hours ago, GlennWest said:

I must be doing it wrong. Have no inverter and a residential fridge. No problems. 

Depends on how you use your rig. Many of us want to boondock and not run a generator. 

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