Forum Discussion

steveh2112's avatar
steveh2112
Explorer
Sep 21, 2013

battery charging basics

i'm planning a 6 month trip in a minivan staying mostly in nat parks, probably with no hookups since i think hookup sites cost a lot more

i need a bit of power for my electronics mostly and maybe a small 48W travel fridge. i hope to be parked up about 6 days out of 7.

i figure a 100W solar panel would keep a battery charged so long as there is sun and i'm not in a shady spot. but assume many days of no sun or lots of shade, what are the other options if i don't want to get a generator.

i guess charge from the van's alternator but how fast could i charge a battery if the van is idling and would i use a deep cycle/marine battery or a normal starter battery if i want fast charge?

my trip is only 6 months then i get rid if everything and fly home so i don't need stuff to last so long. i understand that the main difference is, starter batteries will die quicker than deep cycle if fully discharged often, but in my case that may not be a big problem so long as it lasts 6 months.


thx steve

37 Replies

Show More
  • time2roll's avatar
    time2roll
    Nomad
    Sep 21, 2013
    I would go larger than 100w and keep it portable for such a trip.

    If you will be in So CA (Norco) here is a 140w panel, $140.


    http://www.solarblvd.com/Solar-Panels-&-Systems-12-Volt-Solar-Panels/c1_269/p2668/Solar-Cynergy-140-Watt-12-Volt-Solar-Panel/product_info.html

    Morningstar 10a controller $45

    Get 100' of MC4 cable and cut in half. MC4 connectors to the panel and the cut ends to the controller. This will allow you to position the panel into the sun.

    Just some random thoughts, best of luck.
  • Ron3rd's avatar
    Ron3rd
    Explorer III
    Sep 21, 2013
    Forget the starter batteries; there's a reason the marine/deep cycle cost more. The starter batteries will discharge quickly in your intended use. The plates are thinner intentionally to allow a large rush of instant power to start a vehicle. Deep cycle batteries have thicker plates for long sustained draw.
  • steveh2112's avatar
    steveh2112
    Explorer
    Sep 21, 2013
    so i've been looking at batteries

    is seems starter batteries cost about $2/AH
    http://www.walmart.com/ip/Schumacher-Electric-SB121000-Schumacher-Electric-12V-100AH-Battery/25955634

    and marine about $5/AH
    http://www.walmart.com/ip/EverStart-Maxx-Group-Size-29-Marine-Battery/20531539
    this one is size 29 which as far as i can tell is about 20AH

    so starter batteries look like most bang for the buck, especially if you can get wallmart to replace it free
  • steveh2112's avatar
    steveh2112
    Explorer
    Sep 21, 2013
    westend wrote:
    Is this 48w travel fridge a 120v dorm type fridge?
    I have one in my TT and it draws about 80w at a 1:5 duty cycle at about 80f ambient. Also, the locked rotor draw at startup is significant. It was necessary for me to go to a 1000w inverter to handle the startup draw. I haven't done any exact daily amp hour measurements but I have my solar system at 235w module with 320 AH of capacity.
    A possible better solution, if you wish to travel without a generator would be to find a cheap camp site that offers electrical and pull your power off the pedestal.
    IMO, a single battery and 100w of solar is not going to cut it.

    If you discharge one of those marine/starter batteries continually until it is discharged (probable in your use), it won;t last a month. If you want to have electric devices running every day, you'll need to have more battery capacity and if you want to charge those batteries with no generator, you'll need more solar output.


    really, not last a month! car batteries usually come with a 1 or 2 year warranty, what would happen if i take it back to sears or wallmart every month?

    how successful is your solar setup, do you get enough sun to provide 235W for 8 hours a day?

    i'll be going from CA to NY from March to September so i should hit most of the sunny months but i'm guessing most camp sites are pretty shaded by trees
  • westend's avatar
    westend
    Explorer
    Sep 21, 2013
    Is this 48w travel fridge a 120v dorm type fridge?
    I have one in my TT and it draws about 80w at a 1:5 duty cycle at about 80f ambient. Also, the locked rotor draw at startup is significant. It was necessary for me to go to a 1000w inverter to handle the startup draw. I haven't done any exact daily amp hour measurements but I have my solar system at 235w module with 320 AH of capacity.
    A possible better solution, if you wish to travel without a generator would be to find a cheap camp site that offers electrical and pull your power off the pedestal.
    IMO, a single battery and 100w of solar is not going to cut it.

    If you discharge one of those marine/starter batteries continually until it is discharged (probable in your use), it won;t last a month. If you want to have electric devices running every day, you'll need to have more battery capacity and if you want to charge those batteries with no generator, you'll need more solar output.

About Technical Issues

Having RV issues? Connect with others who have been in your shoes.24,284 PostsLatest Activity: Jul 20, 2025