• saharts
    0
    I only have the space for two batteries, in your opinion should I use two 12v in parallel or two 6v in series? I have 200w of solar and we enjoy boondocking.
  • RVsolar
    167
    Well it comes down to how much power do you use or need ?
    I would go with two 6 but if you can afford it then I believe
    Lithium Is the way to go.
    I have both 2deep 6 volts @ 1250 amps and 2 Chevy volt Lithium @ 400amps
    With 2880 watts of solar I need the power.
  • Greg F
    154
    Assuming FLA or AGM:

    General consensus is that (2) 6v golf cart type batteries will be a more durable longer lasting battery bank than (2) 12v batteries. If you go the 12v route make sure they are true deep cycle batteries. Most 12v batteries are "deep cycle marine". If the case of the battery lists CCA (cold cranking amps) it is a starter battery and not optimal for slow, deep discharging in an RV. 6v batteries are also larger than 12v typically so make sure that you have the space for them before you buy.
  • Steve S
    31
    Hi, I use lithium batteries, but keep in mind that, below a specific temp, the BMS is designed to prevent charging. However they will discharge and will be usable. i.e. if doing a lot of skiing and staying overnight, I would go with AGMs instead.

    I run into cold, below freezing, overnight temps, while snow birding; the days are warm enough to fully recharge my lithiums.

    A 100W solar panel is permanently mounted on my RV roof and also use a 100W suitcase panel that I can shift with the sun. Due to the low angle of the sun, during the winter months, my roof top panel was basically useless - the suitcase panel was sufficient to charge my batteries. Now that it is approaching summer, I only need to use the roof top panel.
  • Logan X
    69
    I use 2 6v golf cart batteries in series and I’m happy with that set up. It gives me 240 amp hours. 4359n7rieea9548m.jpeg
  • saharts
    0
    Logan, what brand of battery is that? And the battery box would be nice to have, any info on that would be great also?
  • Frank
    10
    Hi Logan, I was wandering as well what kind of battery box that is, looks pretty nice with those cable cut outs.
  • saharts
    0
    Frank, I found it on Amazon. (NOCO HM426 Dual 6-Volt Battery Box). https://www.amazon.com/dp/B003VAUG5A/ref=cm_sw_r_oth_api_i_lMQaDbNK8F6Q9
  • Frank
    10
    Thanks for that info.
  • Logan X
    69
    The above link is the correct link for the box I have. It’s from Noco. It looks like Amazon has a good price, I think I paid closer to $100.

    I’m happy with the box, but just for information, it doesn’t fit in the battery box mount on the tongue of the trailer. I screwed a piece of pressure treated lumber to the battery mount and then screwed the battery box to the pressure treated wood. I’m happy with that set up.

    The small box next to it is a weatherproof box made for outdoor lights or something like that to be plugged in to an extension cord. I use it for my battery monitor shunt. I also considered using a weatherproof combiner box for the shunt.

    Here is a link to the small box:

    https://www.amazon.com/BLACK-285-DRI-BOX-WEATHERPROOF-CONNECTION/dp/B00274SLK8
  • Logan X
    69
    the batteries are from US battery. I am happy with them but I don’t know that they are the cheapest or the best. I bought them off of the recommendation of my local battery shop.

    https://www.usbattery.com/
  • Frank
    10
    Thanks Logan
  • Jerry D
    3
    I found that 6V were really expensive in Canada.
  • RVsolar
    167
    sometimes you can find them at Costco or Walmart .
    If you have a local solar store check there.
  • George
    2
    I would look for two twelve volts stationary service batteries. One company I’ve used in standing applications is made by Marathon. They are fully sealed battery with bolts for terminals. They are a new technology called Starved Electrolyte Batteries. They are designed for applications that and location that require little of no batteries. I’ll post a link for them .
    https://marathonbatteries.ca/
    Also yo an explaination of starved electrolyte batteries
    https://hieline.com/faq-items/difference-gel-cell-starved-electrolyte-batteries/

    They are direct replacements for gell cells or lead acid batteries.
  • Rjack10
    6
    Here is interesting information on cost comparison of different types of batteries. They compare cost per amp hour for the life of the battery.

    http://www.thervgeeks.com/wp-content/uploads/2019/01/RVgeeks-Battery-Comparison-Xscapers-Annual-Bash-2019.pdf
  • Fumes21
    1
    Are two 6 volt golf cart batteries ok? Also can you charge the two 6 volt batteries with a the 12 volt RV charger? Thanks in advance.
  • Eddie Aileen
    81
    Howdy!
    Two 6-volt GC-2 batteries in series will give you a 12 volt battery bank with around 225-AH's.
    This could work for a weekend 12-volt supply, depending on the amount of Amp Hours you will need.
    Adding in an inverter or larger 12-volt loads will need a bigger battery bank.
    Happy Trails!!!
  • Logan X
    69
    yes, the factory on board charger should charge 2 6v batteries in series with no issues.
  • Rush and Lola
    104
    I use 8-6 volt trojans T-105's. 4 are T-105 RE's and two are just the old T-105's.zl46b0nntknigxi2.jpg
  • Fumes21
    1
    I was planning to put in a 1000 watt inverter, but still run off 2 batteries.
  • RVsolar
    167
    sound like you may have kids or need to charge a laptop 1000w will do that
    Make sure that it is a pure sine wave most TV and laptops well most eclectic items need pure sine .
    If it is something else like microwave or any thing bigger 1000w will not work most things are about 1100w to 1800w .
    https://m.youtube.com/watch?v=wa7L96ENJ_M
  • Keith
    24
    Not trying to steal the thread, but if you use two 6 volt batteries in series (12v), wouldn't the amp hour rating for 12 volt be equal to the amp hour rating of one of the batteries?
    i.e. two 6 volt batteries with 225 AH rating in series, would be equal to a 225 AH 12 volt battery?
    Or am I missing the mark?
  • Greg F
    154
    In series the voltage is additive and the amperage stays the same. ie: (2) 6 volt 200AH batteries in series would be 12v @ 200Ah.

    In parallel batteries voltage remains the same and amp hours are additive.

    (2) 12 volt 100AH batteries in parallel would be 12v @ 200Ah.

    So yes, the amp hour rating of a single 6v battery would be the same as 2 12v batteries but at only half the voltage. You need (2) 6v batteries in series to make a useful 200 Ah for a 12v system.


    volts x amps = watts.
  • Logan X
    69
    the logic is correct but in reality it’s not that simple. Using the 225ah example, it’s easy to find a 225 ah 6v battery and they are small, light, and cheap enough to work with. A 225 ah 12v battery, if you could find one, would be more expensive, bigger, and heavier.

    Another reason why the 6v batteries are popular is they have a greater capacity to be more deeply discharged and then recover. I believe this is due to the size and thickness of thier lead plates.

    All of the above is just what I have found while researching this and hearing from other people, I am not an expert.

    If you can find a 12v battery set up that gives you more amp hours for less money then that’s great. In my opinion, the 6v batteries give you more bang for your buck.
  • Rush and Lola
    104
    I recently found Crown batteries 6volt at 220 ah's priced $113.80 plus tax and exchange. That's hard to beat.
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