Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
Old 05-21-2018, 04:53 PM   #1
Senior Member
 
Wprather's Avatar
 
Join Date: Apr 2018
Location: Granite Bay California
Posts: 111
Roughly how long do 2 12V batteries last?

Hi, I know this is a "it depends" question, but I'm looking for any kind of rough guess here. We are first time RV'ers, new 233S, lots to learn. We are going out for first trip this weekend. 3.5 days, 3 nights. No hookups. I saw a video showing that 2 12V batteries with a constant 5A drain (3 led lights, a small fan, and a small stereo) lasted 17 hours. I guess that seems short to me! We will of course try and not use lights, won't need the heater, but will use the water pump, refrigerator, some cooking (gas), some light usage at night but we will bring lanterns, etc. I guess I just have NO IDEA what to expect as far as how fast our 2 12V batteries will drain! Was sort of hoping that they would get you through a long weekend and get the slide back in! Any feedback is appreciated. Thanks!
Wprather is offline   Reply With Quote
Old 05-21-2018, 04:58 PM   #2
Site Team
 
bikendan's Avatar
 
Join Date: Jan 2007
Location: Goodyear, Arizona
Posts: 33,554
Guessing that they are dual purpose batteries(not true deep cycle batteries)and you don't use the furnace, 3-4 days if they are fully charged on arrival. That's what we would get.

But that was just the two of us and we are long time dry campers.
__________________
Dan-Retired California Firefighter/EMT
Shawn-Musician/Entrepreneur/Wine Expert
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity
bikendan is offline   Reply With Quote
Old 05-21-2018, 05:05 PM   #3
Senior Member
 
rsdata's Avatar
 
Join Date: Aug 2014
Location: Northern KY
Posts: 5,724
Quote:
lasted 17 hours. I guess that seems short to me!
You might be surprised that this quote is close to being correct.

You might make it 3-4 days with light (not constant ) usage...

You need to pack a cheap VOM to measure voltage and not drop those batteries to less than 12.1 to 12.2 VDC ( 12.7+ VDC is nominal @ full charge)... and then quickly (within 24-36 hours) charge them back up otherwise you will permanently compromise the batteries... that is you will never be able to get them back to 100% capacity again.

ASSUMING you are boondocking and not within a good earshot of your camping neighbors... I would get to a Harbor Freight and pick up one of their cheap $100-$120 generators (900 watts) and charge the batteries for 8 hours (about 1 tank of gas) at least once during your trip. Be sure to get a dogbone adaptor ( 30A to 15 Amp) for the TT hookup or get a separate charging appliance to hook to the batteries.
__________________
"nothing can now be believed which is seen in a newspaper. Truth itself becomes suspicious by being put into that polluted vehicle."
Thomas Jefferson to John Norvell pg. 2, June 11, 1807

2014 Shamrock 183
2014 RAM 1500 Bighorn Crew Cab, HEMI, 3.21 gears, 8 Spd, 4X4 TST TPMS
rsdata is offline   Reply With Quote
Old 05-21-2018, 05:08 PM   #4
Senior Member
 
Join Date: Feb 2017
Location: Spartanburg, SC
Posts: 504
The high tech guys will tell you that you should never run batteries down more than 50%. The low tech guys (like me) don't hesitate to run them flat, so I'd just isolate one battery and run whatever you want on the other. If that battery dies you'll know how long you 'should' go with two, and will also have a spare to bring that slide in when you break camp. I'm sure you'll also hear from the solar crowd - personally, I'm a generator kind of guy.
jeffnick is offline   Reply With Quote
Old 05-21-2018, 05:11 PM   #5
Retired Navy
 
Join Date: Mar 2018
Location: Afton, VA
Posts: 62
Quote:
Originally Posted by Wprather View Post
Was sort of hoping that they would get you through a long weekend and get the slide back in! Any feedback is appreciated. Thanks!
The instructions for my RV say to use the slide either under generator power, or under 30 amp plug in power. It indicates not under the house batteries only power. I would consider it under an emergency situation only, not a routine procedure.
__________________
2012 Lexington C Class
Toad: 2009 Honda Fit
Bob_K is offline   Reply With Quote
Old 05-21-2018, 05:15 PM   #6
Scoundrel
 
HangDiver's Avatar
 
Join Date: Feb 2017
Location: Montrose, Colorado
Posts: 2,786
If you check to see how many amps each of your batteries are you can use the chart in the link below to guestimate your amp hour usage. Like some of the others stated above I never run my 2 12v batteries down below 50%.

RV Converters and Amp Draw - RV Information (RV Maintenance)
__________________
2024 Geo Pro 15TB, 400W Solar, 2 Golf Cart batteries
2015 F-150 5.0L V8 XLT Crew Cab, 4x4, Tow Package, 36 gal tank, 3.55 locker, 1891 payload, Integrated Brake Controller, Roadmaster Active Suspension

Wooden Spoon Survivor
HangDiver is online now   Reply With Quote
Old 05-21-2018, 05:23 PM   #7
Senior Member
 
Join Date: Apr 2016
Location: Port Charlotte Fl/Hinsdale Ma
Posts: 4,823
Run the refrigerator on GAS. Charge the batteries up and practice in the driveway. That will give you a good guess as to how long things will go.

If you doo buy a generator, read up on them in the search box. If you gonna boondock often I'd buy a Honda/Yamaha/Champion 2000 inverter/generator.

If one doesn't do it for you, you can buy a 2nd and run them in parallel. 4000 Watts. 1- 2000 will run your AC but not leave you for much else.
cavie is offline   Reply With Quote
Old 05-21-2018, 06:19 PM   #8
Senior Member
 
Join Date: Feb 2018
Location: TEXAS
Posts: 9,097
No idea how long your batteries will last.

We're former tent campers, so we bring solar/battery powered lights, fans,radio, and a solar charger and charged battery pack for the phones.

Critical is keeping that battery up for the electric ignition for the refrigerator on propane and the water pump. I'd leave the lights off inside at night unless absolutely necessary. Your lanterns should do the job.
__________________
2015 Dynamax REV 24TB class C
Reverse_snowbird is online now   Reply With Quote
Old 05-21-2018, 06:28 PM   #9
Junior Member
 
Join Date: Jun 2016
Posts: 9
In a pinch you can also plug into your tow vehicle and run it for a time. Works for retracting slide and/or awning.
henrypretz is offline   Reply With Quote
Old 05-21-2018, 06:53 PM   #10
Senior Member
 
Join Date: Nov 2017
Location: Dayton Ohio
Posts: 3,566
The math is easy.
Find the available amps on a battery. Likely a dealer installed battery is 85. Divided by two is about 43 available. 8 hours at 5 amps. 16 hours for two. No day two and three.

If you run them down more it damages them. I. E. They hold less. Should last 6-8 years or 18 months. Your choice.

Get a table with usage by item. Easy.

My solution is 4 six volts. 520 amps. 260 usable. Makes 3 days easy. We have 85 a day.
tomkatb is offline   Reply With Quote
Old 05-21-2018, 06:56 PM   #11
Senior Member
 
Wprather's Avatar
 
Join Date: Apr 2018
Location: Granite Bay California
Posts: 111
Quote:
Originally Posted by rsdata View Post
You might be surprised that this quote is close to being correct.

You might make it 3-4 days with light (not constant ) usage...

You need to pack a cheap VOM to measure voltage and not drop those batteries to less than 12.1 to 12.2 VDC ( 12.7+ VDC is nominal @ full charge)... and then quickly (within 24-36 hours) charge them back up otherwise you will permanently compromise the batteries... that is you will never be able to get them back to 100% capacity again.

ASSUMING you are boondocking and not within a good earshot of your camping neighbors... I would get to a Harbor Freight and pick up one of their cheap $100-$120 generators (900 watts) and charge the batteries for 8 hours (about 1 tank of gas) at least once during your trip. Be sure to get a dogbone adaptor ( 30A to 15 Amp) for the TT hookup or get a separate charging appliance to hook to the batteries.
rsdata, thanks! question, would one of those cheap volt meters that you can plug into a cigarette lighter plug (there is one of those, not cigarette lighter but 12V plug, in the coach) that shows the voltage from the battery be sufficient for quickly checking the voltage output coming from the batteries? Seems like a quick and easy thing to buy/do if that will work? Thanks again!
Wprather is offline   Reply With Quote
Old 05-21-2018, 07:07 PM   #12
Senior Member
 
rsdata's Avatar
 
Join Date: Aug 2014
Location: Northern KY
Posts: 5,724
Quote:
question, would one of those cheap volt meters that you can plug into a cigarette lighter plug
personally I would get a less then $10 digital voltmeter from any hardware store or Harbor Freight. Take the reading off the battery terminals, not the cig lighter... possibly a little more accurate and MORE portable then your suggestion.

you will use the voltmeter for many things as the years go by... just keep it in the camper...

I think that you are seeing answers that suggest the 17 hours is NOT out of the question...

Quote:
Find the available amps on a battery. Likely a dealer installed battery is 85. Divided by two is about 43 available. 8 hours at 5 amps. 16 hours for two. No day two and three.

If you run them down more it damages them. I. E. They hold less. Should last 6-8 years or 18 months. Your choice.
reducing your usage to the bare minimum is mandatory... and so is a solar charger or genny even for only a long weekend.
Attached Images
 
__________________
"nothing can now be believed which is seen in a newspaper. Truth itself becomes suspicious by being put into that polluted vehicle."
Thomas Jefferson to John Norvell pg. 2, June 11, 1807

2014 Shamrock 183
2014 RAM 1500 Bighorn Crew Cab, HEMI, 3.21 gears, 8 Spd, 4X4 TST TPMS
rsdata is offline   Reply With Quote
Old 05-21-2018, 07:11 PM   #13
Senior Member
 
Wprather's Avatar
 
Join Date: Apr 2018
Location: Granite Bay California
Posts: 111
Quote:
Originally Posted by Wprather View Post
rsdata, thanks! question, would one of those cheap volt meters that you can plug into a cigarette lighter plug (there is one of those, not cigarette lighter but 12V plug, in the coach) that shows the voltage from the battery be sufficient for quickly checking the voltage output coming from the batteries? Seems like a quick and easy thing to buy/do if that will work? Thanks again!
I think I found the answer to my question on Amazon. LOTS of people said that is exactly what they used these little devices for. BUT to keep in mind that any draw currently coming off the battery would effect the voltage showing on the meter.

I also have a cheap handheld volt meter that I can just connect directly to battery terminals (as later person suggested) and will bring that along too.

And have already started learning the amp draws from my equipment so I can do a better job of predicting for the future. (that's for that suggestion as well)

Thanks to everyone for your quick replies and help! This forum is fantastic!
Wprather is offline   Reply With Quote
Old 05-21-2018, 07:16 PM   #14
Senior Member
 
WolfWhistle's Avatar
 
Join Date: Apr 2012
Posts: 3,275
Two "typical" true deep cycle 12 volt batteries in parallel, are usually around 100 Ah each, giving you the same 12+ volts but doubled the Ah rating to 200Ah. You buy 200 but can only have 100, sorry that's the way it is. That's 50%, so 100Ah becomes what we say is usable Ah, all you should take. And its true a full 12v battery will read 12.7vdc (MOL) and dead'er than my head is 10vdc. Take them to 10vdc and expect to be buying new batteries. I suppose in an emergency I might take them to 11.5vdc.

A cheap dual purpose or marine battery will give you less Ah and less reserve.

LED lights use very little power, the TV not much either. You do need 12 volts to run fridge and WH, so if you kill the batteries, you won't have either even if you have plenty of LP gas. Keep that in mind.

The thing you saw on youtube, that steady 5A load that gave them 17 hours, if you truely have 100Ah of usable battery they should last 20 hours. But, there could have been other factors, such as the batteries were not really full at the start, or they had some age to them, or there were other loads not considered, like CO detector and some slide controllers, for example are parasites.

What I would not like about what you are embarking on, is you have no idea of the battery status (what has been used) as you go. As a dead minimum have a good digital VOM meter and read at the battery terminals to see how you are doing at intervals. That 12.0vdc under load would be a good place to stop running all things DC. Or seek away to charge.

Again, like was pointed out, I would take along a small generator and adapters necessary to plug you RVs power cable into. Run the generator when you can during midday for several hours each time. If you buy one new don't forget oil and gasoline. Take along something like a quarter or half sheet of plywood to shield you or you neighbor from the noise.

Charging off the tow vehicle plugged into the 7 pin using the converter is not a good way at all. If you only had the TV, turn the truck around and use jumper cables directly from TV battery to the camper battery (do them both at the same time is okay).

When you are back, plug in to landline power and let the batteries full charge, don't let them sit around discharged... that's also a bad thing.
WW
__________________
Hyper Lite was sold

2017 F-250 4x4 6.2L Gas
I can't fix everything, but I can make it so nobody else can
WolfWhistle is offline   Reply With Quote
Old 05-21-2018, 07:31 PM   #15
Senior Member
 
Wprather's Avatar
 
Join Date: Apr 2018
Location: Granite Bay California
Posts: 111
Quote:
Originally Posted by rsdata View Post
personally I would get a less then $10 digital voltmeter from any hardware store or Harbor Freight. Take the reading off the battery terminals, not the cig lighter... possibly a little more accurate and MORE portable then your suggestion.

you will use the voltmeter for many things as the years go by... just keep it in the camper...

I think that you are seeing answers that suggest the 17 hours is NOT out of the question...



reducing your usage to the bare minimum is mandatory... and so is a solar charger or genny even for only a long weekend.
rsdata, Thanks for the pointer to the generator! I have been looking at generators. I definitely will be buying 1 (or 2) but wasn't quite ready to make a decision on that yet. Still trying to decide if I want 1 larger one that will run everything or 2 (leave 1 at home when don't need air conditioner, etc).
Wprather is offline   Reply With Quote
Old 05-22-2018, 08:45 AM   #16
Senior Member
 
Join Date: Oct 2014
Location: Raleigh NC
Posts: 289
Remember that solar is always an option as well. We almost always boondock without a generator and have not had an issue with batteries for over a week.
We have 200W solar and two 6 volt deep cycle batteries.

Quote:
Originally Posted by Bob_K View Post
The instructions for my RV say to use the slide either under generator power, or under 30 amp plug in power. It indicates not under the house batteries only power. I would consider it under an emergency situation only, not a routine procedure.
I have never heard that you should not use battery power to open and close slides. Does this depend on the slide manufacturer? We always use battery power for our slides and have never noticed an issue.
__________________
Old- 2002 21 Roo
New- 2015 Shamrock 23 IKSS
TV- 2010 Nissan Titan CC
wharfrat48 is offline   Reply With Quote
Old 05-22-2018, 10:29 AM   #17
Senior Member
 
Join Date: Aug 2016
Posts: 108
Quote:
Originally Posted by cavie View Post
Run the refrigerator on GAS. Charge the batteries up and practice in the driveway. That will give you a good guess as to how long things will go.
practicing in the driveway seems like the easiest way to find out how long your batteries will last under your usage pattern

I have 6 84ah true deep cycle batteries for 500ish useable AH It gets my family of 4 through a 3 day weekend no problem
BigLou80 is offline   Reply With Quote
Old 05-22-2018, 01:40 PM   #18
Senior Member
 
Join Date: Feb 2016
Posts: 308
Purchase and install (easy) a solar panel kit from Amazon.. and you won't have to worry about batteries going discharged for several days.. see:

https://www.amazon.com/dp/B00JML23X0...v_ov_lig_dp_it
__________________
Clint...
2015 F350 4x4 gasser.. 2017 Rockwood 2506S TT
Ardenvoir, Washington (near Wenatchee)
clintbonnie73 is offline   Reply With Quote
Old 05-22-2018, 01:50 PM   #19
Site Team
 
bikendan's Avatar
 
Join Date: Jan 2007
Location: Goodyear, Arizona
Posts: 33,554
We never had issues opening and closing our slideout with just our two 12v batteries.
They are made to be used without needing shore power. Otherwise they would be 120v AC.
__________________
Dan-Retired California Firefighter/EMT
Shawn-Musician/Entrepreneur/Wine Expert
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity
bikendan is offline   Reply With Quote
Old 05-22-2018, 01:58 PM   #20
Junior Member
 
Join Date: May 2018
Posts: 2
If you are looking at a generator mostly for recharging your batteries, you might like one that Home Depot has on sale. It's a Ryobi 700W propane generator. It has a true sine inverter and is supposedly very quiet. It's on sale now for $249.

I suspect you could hook it to your 30AMP input using a dogbone adapter and charge your batteries. An added bonus is that you can carry a extra 20# propane tank to power or connect it to the propane on your trailer.
markedman1132 is offline   Reply With Quote
Reply

Tags
batteries

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.



All times are GMT -5. The time now is 10:47 PM.