Forum Discussion

SJ-Chris's avatar
SJ-Chris
Explorer II
Nov 15, 2020

Boondocking --- Average AH consumption/day?

I'm going to be adding solar to my 2015 Class C Majestic 28a. I currently have 2 lead acid batteries that state they have 122AH capacity each (from Walmart). I'm trying to figure out if I should add 100w or 200w. My assumption is that 100w of solar will on average add about 30AH/day back into the batteries.

If you have a battery monitor and happen to know on average how many AH/day you use when boondocking I'd love to hear. Let's assume you are NOT using your furnace at night (summer camping) and that you aren't plugged in or solar charging. Yes, I know that everyone's use will be different and that's what I'm curious to see. If you could, please share what your rig is, what your battery bank capacity is, and approximately how many AH/day you go through. Perhaps tell us what sort of things you are running in your RV, and whether you try to be energy frugal or if you consume with reckless abandon (lol!).

Will be interesting to see various people's input! In the end, I'll probably just add 200w as a likely overkill for most typical usage.

Enjoy!
Chris
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Nov 15, 2020
    Your average won’t be 30 amp hours per day for each 100 watt panel. When in bulk charging you might see 5 in bright light and cool temperatures for a while but as you enter the absorption phase the accepted power goes way down. Solar panels are cheap and rigid panels last a long time. Minimum is one solar watt per battery amp hour. Not the time to go cheap...and barely adequate. Use big wire...bigger wire.

    I have two Trojan T125s and 245 amp hours when they are full. I use 75 to 100 amps per day mostly depending if I can get local TV news and if I run the Fantasic fans.
  • madjack60's avatar
    madjack60
    Explorer
    Nov 15, 2020
    My 87 bounder had 300watts solar and 400ah battery. It did ok. Just got a 2001 31ft Itasca class C and put 680watts solar and 380ah of battery it does excellent
  • SJ-Chris's avatar
    SJ-Chris
    Explorer II
    Nov 15, 2020
    madjack60 wrote:
    My 87 bounder had 300watts solar and 400ah battery. It did ok. Just got a 2001 31ft Itasca class C and put 680watts solar and 380ah of battery it does excellent


    Good stuff! 680watts of solar sounds like a nice little power station!
    Do you have a battery monitor and do you have any idea on average how many AH/day you are USING?

    Using a rule of thumb of 30AH per 100w of solar, it appears your system is capable of putting ~200AH/day back into the batteries. Are you using that much? I was under the assumption that an "average" camper might be using 30-50AH/day (not counting any furnace usage).

    Happy camping!
    -Chris
  • Chum_lee's avatar
    Chum_lee
    Explorer
    Nov 16, 2020
    SJ-Chris wrote:
    I'm going to be adding solar to my 2015 Class C Majestic 28a. I currently have 2 lead acid batteries that state they have 122AH capacity each (from Walmart). I'm trying to figure out if I should add 100w or 200w. My assumption is that 100w of solar will on average add about 30AH/day back into the batteries.

    Enjoy!
    Chris


    One thing you need to be very clear on is if solar people are using an inverter or not. Using an inverter to power things like a 2/3 way gas/electric refrigerator (on electricity 12V or 120V)) or a microwave oven, coffee maker, etc. makes a HUGE difference on your electric consumption. In general, put the most solar panels on your roof that you can afford and have space for. For your application, 3-140 watt panels, if they fit, is a good place to start. IMO, you'll be glad you did.

    Chum lee
  • SJ-Chris's avatar
    SJ-Chris
    Explorer II
    Nov 16, 2020
    Chum lee wrote:
    SJ-Chris wrote:
    I'm going to be adding solar to my 2015 Class C Majestic 28a. I currently have 2 lead acid batteries that state they have 122AH capacity each (from Walmart). I'm trying to figure out if I should add 100w or 200w. My assumption is that 100w of solar will on average add about 30AH/day back into the batteries.

    Enjoy!
    Chris


    One thing you need to be very clear on is if solar people are using an inverter or not. Using an inverter to power things like a 2/3 way gas/electric refrigerator (on electricity 12V or 120V)) or a microwave oven, coffee maker, etc. makes a HUGE difference on your electric consumption. In general, put the most solar panels on your roof that you can afford and have space for. For your application, 3-140 watt panels, if they fit, is a good place to start. IMO, you'll be glad you did.

    Chum lee


    Good point! For my purposes, I will be installing a small ~500-800w inverter primarily to be used for say a laptop or the TV/DVD player. It will not be for the microwave, AC, fridge, or coffee pot.
  • Boon_Docker's avatar
    Boon_Docker
    Explorer III
    Nov 16, 2020
    I have a 230 AH battery bank and 200 watts of solar.
    Never watch TV or listen to the entertainment center. Use an inverter sparingly to charge camera batteries and cell phone. Have LED lighting, absorption fridge on propane, use water pump throughout the day and the exhaust fan sparingly.
    On an average 24 hour day we use about 50 AH (a little over 25% of the battery bank). Batteries are back to 100% charge by early afternoon each day (as long as there is sunshine).
  • Chum_lee's avatar
    Chum_lee
    Explorer
    Nov 16, 2020
    SJ-Chris wrote:
    Chum lee wrote:
    SJ-Chris wrote:
    I'm going to be adding solar to my 2015 Class C Majestic 28a. I currently have 2 lead acid batteries that state they have 122AH capacity each (from Walmart). I'm trying to figure out if I should add 100w or 200w. My assumption is that 100w of solar will on average add about 30AH/day back into the batteries.

    Enjoy!
    Chris


    One thing you need to be very clear on is if solar people are using an inverter or not. Using an inverter to power things like a 2/3 way gas/electric refrigerator (on electricity 12V or 120V)) or a microwave oven, coffee maker, etc. makes a HUGE difference on your electric consumption. In general, put the most solar panels on your roof that you can afford and have space for. For your application, 3-140 watt panels, if they fit, is a good place to start. IMO, you'll be glad you did.

    Chum lee


    Good point! For my purposes, I will be installing a small ~500-800w inverter primarily to be used for say a laptop or the TV/DVD player. It will not be for the microwave, AC, fridge, or coffee pot.


    Cool. Based on what you say, you should be fine with 200 watts (2 x 100 watt) of panels. If you're like me (and I hope you aren't) eventually you'll be sitting there (after paying to fill your propane tank multiple times) thinking "Why am I paying all this money for propane when I could run my refrigerator off the sun."

    Chum lee
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Nov 16, 2020
    The solar is not going to do what you think. So start w/ 200 watts and go from there. You don't need more batteries
  • time2roll's avatar
    time2roll
    Nomad
    Nov 16, 2020
    100 watts is for storage. 200 watts would be the minimum I recommend for the effort to provide 12v power while in use.
  • SJ-Chris's avatar
    SJ-Chris
    Explorer II
    Nov 16, 2020
    time2roll wrote:
    100 watts is for storage. 200 watts would be the minimum I recommend for the effort to provide 12v power while in use.


    I was just coming to the same conclusion... I'll be adding it myself (I'm pretty handy). I just reached the conclusion that if I'm spending the time to do it, I might as well make it 200 while I'm at it. Adding the 2nd panel is probably one of the easiest steps in the entire process and only an extra ~$100.

    The controller I bought can handle 300watts, so if I ever decide I need a bit more I could always just add a 3rd panel.

    Would still love to hear more people's experience with their Average AH consumption/day and what sort of items they are using/etc.

    -Chris

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