Forum Discussion

WesternHorizon's avatar
WesternHorizon
Explorer
Apr 11, 2018

Solar options, quick review requested

23' Class C, no solar, Lifeline 80 AH AGM battery 4 years old and still going good, UltraIII 6300 3-stage converter, and generator.

Typically 6 days a month boondocking, currently on first 68 day long trip, heading towards probably 6 months a year on the road / boondocking within 2 years.

Phoenix Costco today, heading for salad and... what is this?

Pallets of Interstate Golf Cart batteries, 6v, 210 AH... $94. Certainly not a product I have seen in Costco in 28 years.

Started doing some Googling.

This gentleman endorses 6 volt GC batteries as better than AGM for boondocking use: half cost, lighter, but AGM does hold charge longest.

https://trekwithus.com/rv-batteries-101-and-why-we-use-trojan-t-105-6v-golf-cart-batteries-in-our-rv/

And finally found THE calculator. This thing is AMAZING.

https://www.batterystuff.com/kb/tools/solar-calculator.html

Options I am weighing....

1. For my current 80AH battery, I get 480 WH, and some days I have to run the generator up to 4 hrs if I am working on the computer a lot. I would need two 100W panels to keep this setup charged! Somehow I thought I could get away with one.

2. If I doubled the battery size to 160AH, I get 680 WH, and would need three panels! Wow.

And, the 6 volt Golf Cart batteries all start around 210 AH so I can't really get to 160AH.

Closest in an AGM would be GPL-31XT 12 Volt, 125 Amp Hour Deep Cycle AGM, $347

3. If I bought two of these Costco batteries it would nearly triple capacity up to 210 AH, I get 1280 WH and need 5 panels!

Since I can buy 2 ea. 6V, 220 AH for $186 (plus $30 core fee), why not just buy these batteries, charge them with just 2 panels (which I already need) and frequent driving (I tend to move around a fair amount) and keep them charged way up all the time?

Obviously this is lots of reserve capacity that I might never use but wouldn’t the batteries be healthy because they stay well-charged?

Yes, it’s sort of a waste but the batteries are so discounted that it would seem to make economic sense.

Constructive feedback greatly appreciated. I need to buy them tomorrow if I am going to do it so quick responses appreciated.
Class C
  • OkieGene's avatar
    OkieGene
    Explorer
    Apr 11, 2018
    Not to derail the OP, but is anyone, who already has solar on the roof, having another panel that is not on the roof? I'm referring to a panel that can be put in rv basement storage, or somewhere in the rv, that can come out and plugged in to the battery bank, as needed, and positioned to start grabbing the sun rays in the morning and evening, when the roof panels just don't get enough overhead sun due to the angle? Seems to me to be a good idea to have a 150-300-ish watt panel for this purpose. Yes, it's some extra weight and space to deal with, and some expense too, but if you can swing it, why not? It would beat having to run the generator when you just don't have to. Just another option and choice. Thanks!
  • Ductape's avatar
    Ductape
    Explorer
    Apr 11, 2018
    Oversize batteries are no detriment at all, unless weight is a constraint. GC2 are always the best bang for your buck. Cycling them 70-90 will promote longer life than a smaller battery at 50-90.

    That said, I'll not trade my AGM for wet cells. I'm done cleaning corrosion and watering batteries, and the higher charge acceptance reduces run time on the genset.

    We use generator and solar, depending on circumstances.
  • azrving's avatar
    azrving
    Explorer
    Apr 11, 2018
    I know what you mean as I did the same thing early on. I bought a Progressive PD5650 14.4 which is still far better than 13.6 I put a boondocker 80 amp in my sons rig which I'm sure has hit 14.6 to 14.7 iirc.

    Thanks for the link, I bookmarked it for later. 14.4 is ok when you are running the genny earlier in the day and putting in the heavy amps. As the sun rises you can go over to solar for the lower amp higher voltage charging. People often run on genny early to cook and do the heavy lifting with the converter. It not one size fits all so there are various ways to accomplish it. I use my 3000 Honda a good deal and I have 1000 watts of solar and six 6 volts. It can sometimes be difficult to charge that many batteries even with 1000 watts so a generator is a great part of an energy management system. It's sometimes tough to get enough solar amps yet big amps are what generators and converters shine at.
  • WesternHorizon's avatar
    WesternHorizon
    Explorer
    Apr 11, 2018
    azrving wrote:
    6's are taller, will they fit? Rule of thumb 100 to 150 of panel to 100 ah of battery but you cant have too much. If I was building from scratch, even if you dont put all the panel up there now, size components for expansion. It's very common for people to want more.

    When running on generator you want a good converter that will do 14.8 volts. You also want a full feature solar controller with voltage adjustment, temperature compensation and equalize.


    Probably looking at a custom rack welded to the frame.

    Yes I would definitely leave space for more.

    Have been disappointed to find I only upgraded to a 3 stage converter. They claim 14.4, I guess it does that for a while.

    The low charging voltage is what made me start looking at solar again, after I came across this:

    "The biggest problem with this so called battery charger, is the charge voltage is preset to a safe zone voltage of 14.4v, and will only hold that voltage for a very short time at best. Then it will drop to a float charge (battery voltage maintainer) at 13.6v long long long before the battery is actually charged. If you have a flooded battery you add water to, they need to charge at 14.8v (check with your specific battery manufacture) in order to get fully charged, and usually that voltage will hold for 2-4 hours before it goes to a float charge of 13.6v. Even if you're plugged into shore power, or running the genset for 8-12 hours, or 6 months, you will NEVER EVER get your batteries 100% fully charged, and are slowly killing them. This is why Solar is far superior to your converter, and will actually charge your battery bank 100%."

    http://www.offthegridrvs.com/solar-school-s/136.htm

    Looking at the Victron BlueSolar models.

    Thanks.
  • azrving's avatar
    azrving
    Explorer
    Apr 11, 2018
    6's are taller, will they fit? Rule of thumb 100 to 150 of panel to 100 ah of battery but you cant have too much. If I was building from scratch, even if you dont put all the panel up there now, size components for expansion. It's very common for people to want more.

    When running on generator you want a good converter that will do 14.8 volts. You also want a full feature solar controller with voltage adjustment, temperature compensation and equalize.

About Motorhome Group

38,709 PostsLatest Activity: Mar 09, 2025