Free 7 Day Trial RV GPS App RV Trip Planner Campground Reviews RV Maintenance Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
Old 05-15-2021, 06:58 AM   #1
Member
 
Join Date: Jun 2019
Posts: 41
Overwhelmed by Battery Monitoring

Hello everyone, I've found myself the owner of a Salem Cruise Lite with the exact Floorplan we wanted. After getting home, it turns out it has a 12v refrigerator, no propane. We camp without power much of the summer, this is going to be an issue.

To figure out how to overcome this, I think I'm going to need to start by finding out how much power the camper actually uses on 12v. Time for a battery monitor. And there are a ton of them!

I'm looking for recommendations on something simple, on the less expensive end that will just tell me enough information about how much I'm using so I can figure out charging/batteries from there. Bluetooth only would be nice, I don't really want to run wires and cut holes if I don't have to.
NotLost is offline   Reply With Quote
Old 05-15-2021, 12:57 PM   #2
Pseudonym
 
BrandonSmith's Avatar
 
Join Date: Mar 2021
Posts: 119
FWIW, my 12V pulls 1.5A constantly and 2.0A when compressor kicks on.

If you don't have a second battery, you will need one. Do the math for amp-hours and you'll find that a battery does not last very long. 10 hours @ 1.5 amps is 150 amp-hours needed to run the fridge alone, not including the times the compressor kicks on.
__________________
2021 Shasta 18FQ
2017 Ram 1500 Lone Star Crew Cab 5.7L HEMI
Attachment 251949
BrandonSmith is offline   Reply With Quote
Old 05-15-2021, 01:26 PM   #3
Senior Member
 
Join Date: Nov 2017
Location: Dayton Ohio
Posts: 2,068
I own the old BM2 from Amazon. $40 5 minute installation.

It is a bluetooth voltmeter. It also records history and has alarms.

The information you said you wanted is a amp meter type. About $100 or more from Vitron.

However the information you need, not want, is on the charts listing amperage for devices and to learn how to minimize their use. The continuous monitoring is for folks that will be major users of power. Major systems. You are $10,000 away from that. Much to learn.

Typically you will use 50 amp per day for lights and stereo. Adding an electric refrigerator will add 50-150 amps per day depending on the weather.

My cpap uses about 40 amps per day.

If you use the refrigerator and the furnace be prepared to be awaken by the DW the first night at 3am with 100 available amps.

We have 430 amps of power. 200 available. Come hell or high water we can go a night without the generator. Two nights if we are careful. No electric fridge.

Today Costco is selling a set of lithium batteries for $1400. 180+ amps available.
tomkatb is offline   Reply With Quote
Old 05-15-2021, 01:30 PM   #4
Retired Panpsychist
 
Theo's Avatar
 
Join Date: Jul 2016
Location: Western Massachusetts
Posts: 712
My vote is for either of two Victron battery monitors:
  • SmartShunt - a 500A "smart" shunt that has no display. The battery monitor info is sent via Bluetooth to your mobile device and the free Victron Connect app. These run ~ $130 USD.
  • BMV-712 - a 500A "dumb" shunt with a "smart" display. The display also sends the battery monitor info via Bluetooth to your mobile device. These run ~ $206 USD.
I have a BMV-712, but I always check my battery data with the Victron mobile app. Were I to do it again, I'd go for the ($75 less expensive) SmartShunt.

Victron's products are durable, reliable and accurate. Their battery monitors offer a full range of parameters that one can adjust to dial-in their accuracy and to allow them to adapt to different battery chemistries. I have no experience with other premium manufacturers' products like the Bogart Engineering TriMetric.

My recommendation would be to forego the less expensive products as they may not give you all the features Victron offers. Since we do a lot of dry camping, the important data for me are: temperature-compensated state of charge, charging rate (in Ah), predicted amount of days/time before the battery hits the discharge floor (50% of LA battery capacity) and real-time Ah draw. Note that the last bit of data is important in inventorying the current draw of each 12V appliances/accessories.

HERE is a pretty good write-up for battery monitor introductory information.

HTH
__________________
Theo & Carol

2007 GoldenDoodle ("Cooper")
2020 Rockwood Roo 23IKSS
2015 F-150 4WD XLT SCab, 5.0L, 3.73, 36gal, HD Towing Pkg (53A), 1,980lb Payload
Theo is offline   Reply With Quote
Old 05-15-2021, 02:56 PM   #5
Member
 
Join Date: Jun 2019
Posts: 41
Thanks, I was initially looking at the smartshunt but the reviews weren't great. Mostly about the app itself. Which can be user/phone dependant.

Eventually I'll want more data, I'm trying to find out how much battery I'll need so I can balance capacity with solar, and if I go lithium. But I don't want to spend a ton now when a lithium setup might have the monitoring built in.

Basically I park my camper for weeks at a time at a family camp. Last year, LP refrigerator would be left on all week with 2 standard deep cycle batteries and ~100W solar, just cheap stuff. Run generator overnight Friday and Saturday, leave Sunday. Major power draw on this new camper will be keeping this new 12v refrigerator running.

At a minimum will be needing it to be able to cool down and run all day and recharge off generator at night. Measuring the actual usage will steer me to how much panel and battery I need.
NotLost is offline   Reply With Quote
Old 05-15-2021, 03:08 PM   #6
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 11,930
Quote:
Originally Posted by NotLost View Post
Thanks, I was initially looking at the smartshunt but the reviews weren't great. Mostly about the app itself. Which can be user/phone dependant.

Eventually I'll want more data, I'm trying to find out how much battery I'll need so I can balance capacity with solar, and if I go lithium. But I don't want to spend a ton now when a lithium setup might have the monitoring built in.

Basically I park my camper for weeks at a time at a family camp. Last year, LP refrigerator would be left on all week with 2 standard deep cycle batteries and ~100W solar, just cheap stuff. Run generator overnight Friday and Saturday, leave Sunday. Major power draw on this new camper will be keeping this new 12v refrigerator running.

At a minimum will be needing it to be able to cool down and run all day and recharge off generator at night. Measuring the actual usage will steer me to how much panel and battery I need.
Based on what you said I'd recommend the BMV712 Victron monitor. It has a monitor "meter" that can be mounted on an interior panel so it isn't App dependent or it can just be placed in a zip-loc bag then put out of the way near the batteries. Then just use the app. The "meter" is the bluetooth device so it does have to be hooked up.

Advantage of the BMV-712 versus "Smart Shunt" model is it works without the app and also has a relay built in that can be programmed for any purpose you want based on battery state of charge, temperature, voltage, etc. I use the relay in mine to turn on or off the Converter when my Battleborn batteries reach a given state of charge I select. If you absolutely have to be warned when batteries are low, when inside or out of RV, this relay can be used to trigger a louder alarm. Just one example.

The biggest advantage to using the Victron versus some of the less expensive monitors is that it is more precise in measuring the state of charge than a meter that just measures "amps out/amps in". Using the Peukert factor, which you set for the type of battery chemistry you have, it takes into consideration the inherent inefficiencies of high current discharge, charging, and temperature to mention a few. For lead acid batteries this is critical if you really want to know the SOC and less so for Lithium.

The less expensive monitors are probably OK for those who only use their batteries during an overnight stop while traveling and spend the rest of their camping time hooked up in RV parks.
__________________
"A wise man can change his mind. A fool never will."

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is offline   Reply With Quote
Old 05-16-2021, 12:52 PM   #7
Senior Member
 
DustyRoads's Avatar
 
Join Date: Mar 2014
Location: NY Capital District
Posts: 393
I have the BMV-712 and love it. Keeps me posted on my phone via Bluetooth and display monitor I installed inside the trailer. I don't really look at the one inside the trailer. I like the app so much better.
I would highly recommend.
__________________
2017 Forest River Surveyor 251rks
2016 Chevy 2500HD

DustyRoads is offline   Reply With Quote
Old 05-16-2021, 01:25 PM   #8
Senior Member
 
Join Date: Jan 2018
Location: Raleigh, NC
Posts: 4,343
You do the math

Quote:
Originally Posted by BrandonSmith View Post
FWIW, my 12V pulls 1.5A constantly and 2.0A when compressor kicks on.

If you don't have a second battery, you will need one. Do the math for amp-hours and you'll find that a battery does not last very long. 10 hours @ 1.5 amps is 150 amp-hours needed to run the fridge alone, not including the times the compressor kicks on.
Brandon, your math is weak. 10 hours at 1.5 amps is 15 amp-hours, not 150.

And you also missed a step. It's called "duty cycle." Assume, for example, that at 70 degrees F, without opening the refrigerator very frequently, that the compressor and fan only run about 1/3 of the time.

So it would really only be 15 * 1/3 = 5 amp hours. That's 20 hours on a battery that has 100 usable amp-hours.

Maybe today, I'll play the role of arithmetic teacher and you can be the student.
__________________
Larry

Sticks and Bricks: Raleigh, NC
2008 Cherokee 38P: at Ivor, VA permanently
Larry-NC is offline   Reply With Quote
Old 05-16-2021, 02:56 PM   #9
Senior Member
 
Adrian Gordon's Avatar
 
Join Date: Mar 2018
Posts: 389
Quote:
Originally Posted by Larry-NC View Post
Brandon, your math is weak. 10 hours at 1.5 amps is 15 amp-hours, not 150.

And you also missed a step. It's called "duty cycle." Assume, for example, that at 70 degrees F, without opening the refrigerator very frequently, that the compressor and fan only run about 1/3 of the time.

So it would really only be 15 * 1/3 = 5 amp hours. That's 20 hours on a battery that has 100 usable amp-hours.

Maybe today, I'll play the role of arithmetic teacher and you can be the student.
I don't think the two of you together could add a column of two single digit numbers. :-)
You are correct that his math was wrong and that 10 hours at 1.5 amps is 15 amp hours. I will assume that you are also correct when you say the refridgerator only runs about 1/3 of the time and thus it uses only about 5 amp hours every 10 hours of clock time, or about 0.5 amp hours per hour of clock time. In that case, it's 200 hours on a battery that has 100 usable amp hours. I can't vouch for the accuracy of the input numbers, but I'm pretty sure on the math.
Adrian Gordon is offline   Reply With Quote
Old 05-16-2021, 03:44 PM   #10
Senior Member
 
Join Date: Jan 2018
Location: Raleigh, NC
Posts: 4,343
Oops!

Quote:
Originally Posted by Adrian Gordon View Post
I don't think the two of you together could add a column of two single digit numbers. :-)
You are correct that his math was wrong and that 10 hours at 1.5 amps is 15 amp hours. I will assume that you are also correct when you say the refridgerator only runs about 1/3 of the time and thus it uses only about 5 amp hours every 10 hours of clock time, or about 0.5 amp hours per hour of clock time. In that case, it's 200 hours on a battery that has 100 usable amp hours. I can't vouch for the accuracy of the input numbers, but I'm pretty sure on the math.
Thanks for catching that, Adrian. A little foggy today.
__________________
Larry

Sticks and Bricks: Raleigh, NC
2008 Cherokee 38P: at Ivor, VA permanently
Larry-NC is offline   Reply With Quote
Old 05-16-2021, 04:22 PM   #11
Senior Member
 
Join Date: Mar 2018
Posts: 186
Quote:
Originally Posted by Theo View Post
My vote is for either of two Victron battery monitors:
  • SmartShunt - a 500A "smart" shunt that has no display. The battery monitor info is sent via Bluetooth to your mobile device and the free Victron Connect app. These run ~ $130 USD.
  • BMV-712 - a 500A "dumb" shunt with a "smart" display. The display also sends the battery monitor info via Bluetooth to your mobile device. These run ~ $206 USD.
I have a BMV-712, but I always check my battery data with the Victron mobile app. Were I to do it again, I'd go for the ($75 less expensive) SmartShunt.

Victron's products are durable, reliable and accurate. Their battery monitors offer a full range of parameters that one can adjust to dial-in their accuracy and to allow them to adapt to different battery chemistries. I have no experience with other premium manufacturers' products like the Bogart Engineering TriMetric.

My recommendation would be to forego the less expensive products as they may not give you all the features Victron offers. Since we do a lot of dry camping, the important data for me are: temperature-compensated state of charge, charging rate (in Ah), predicted amount of days/time before the battery hits the discharge floor (50% of LA battery capacity) and real-time Ah draw. Note that the last bit of data is important in inventorying the current draw of each 12V appliances/accessories.

HERE is a pretty good write-up for battery monitor introductory information.

HTH
X2 on the BMV-712...everything you will ever need and the bluetooth app is great even providing firmware upgrades as available.
__________________
ArkRVHog
2018 Forester Model 2801 GTS
Little Rock, AR

Days Camped 2021 - 16/2020 - 29
2019 - 71/2018 - 49
ArkRVHog is offline   Reply With Quote
Old 05-16-2021, 05:11 PM   #12
Member
 
Join Date: Jun 2019
Posts: 41
Thanks everyone, I moved those 2 to the top of my list.
NotLost is offline   Reply With Quote
Old 05-16-2021, 09:06 PM   #13
Member
 
Join Date: Jun 2014
Posts: 35
I would just like to know when its time to charge my 2 6-volt batteries with my generator and also to know when they are fully charged so I can turn off the generator. If the BMV-712 is the best to use for that, I'll buy it but is there something else I should use instead?
jwalt313 is offline   Reply With Quote
Old 05-16-2021, 09:52 PM   #14
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 11,930
Quote:
Originally Posted by jwalt313 View Post
I would just like to know when its time to charge my 2 6-volt batteries with my generator and also to know when they are fully charged so I can turn off the generator. If the BMV-712 is the best to use for that, I'll buy it but is there something else I should use instead?
either of the victron units will be the most accurate especially with lead acid batteries. Also, I know the 712 will allow you to monitor the mid point voltage which will tell you if both the batteries in series are each fully charged and in good health. the shunt only model may too but I can only speak for the 712.
__________________
"A wise man can change his mind. A fool never will."

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is offline   Reply With Quote
Old 05-17-2021, 06:53 AM   #15
Senior Member
 
Join Date: Jun 2015
Location: Albuquerque
Posts: 775
To get the last 10% charge on the batteries takes some time because the charge rate drops as the battery gets full. That is where solar power shines, because it charges all day. I think I'd want to have enough solar to run the fridge during the day, plus charge the batteries. I'd also want to have enough battery to run the fridge for a couple of days without running the generator. I'd tear out the fridge and put in a propane fridge before I'd spend $1400 for lithium batteries.

Back to math. If BrandonSmith is correct about his amp draw, and all the other assumptions are correct, then the daily draw just for the fridge is (16 hrs x 1.5 amps ) + (8 hrs x 2 amps) which comes out to 40 amp hours.
__________________
2009 Roo 21ss + 2007 Superduty 6.0
mnoland30 is offline   Reply With Quote
Old 05-17-2021, 07:24 AM   #16
Junior Member
 
Join Date: Mar 2021
Posts: 6
Might look at the Powermon by Thornwave as well.
regal81455 is offline   Reply With Quote
Old 05-18-2021, 08:19 AM   #17
Senior Member
 
Dodge Guy's Avatar
 
Join Date: Oct 2006
Posts: 1,418
While you’re spending money, your going to need Solar. At least 400W.
__________________
2012 Georgetown XL 350TS, Hellwig front/rear sway bars, Sumo Springs, Blue OX True Center steering damper
2013 Ford Explorer LTD toad, Roadmaster Stowmaster 5000, VIP><Tow Brake

Better to have a bad day of camping than a good day at work!
Dodge Guy is offline   Reply With Quote
Old 05-31-2021, 06:13 PM   #18
Junior Member
 
Join Date: Feb 2017
Posts: 4
Quote:
Originally Posted by BrandonSmith View Post
FWIW, my 12V pulls 1.5A constantly and 2.0A when compressor kicks on.

If you don't have a second battery, you will need one. Do the math for amp-hours and you'll find that a battery does not last very long. 10 hours @ 1.5 amps is 150 amp-hours needed to run the fridge alone, not including the times the compressor kicks on.
It is 15 amp hours not 150.
Tampa Dave is offline   Reply With Quote
Old 05-31-2021, 08:49 PM   #19
Junior Member
 
Join Date: Jan 2011
Posts: 2
My dc fridge pulls 105 watts on defrost and 80 watts running. I always have 3 to 5 watt draw with everything off except the gas detector. I have 250 ah battery bank with 400 watts solar. Use Victron 100/30 charge controller and shunt. Works great.
Also added renogy 60 amp dc to dc charge controller. To supplement solar on a cloudy day. If you use a generator make sure your charging amps are sufficient to charge the battery in reasonable time.
sheading is offline   Reply With Quote
Old 05-31-2021, 08:51 PM   #20
Senior Member
 
Join Date: Feb 2020
Posts: 116
Looks like your generator is going to get a little extra run time.
garywilson is offline   Reply With Quote
Reply

Tags
battery

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 11:56 AM.