Deep cycle battery in an RV

Discussion in 'The Garage' started by JAB, Oct 2, 2013.

  1. JAB

    JAB Unsprung Weight

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    Just had to replace the "house" battery in the RV. This battery only lasted 2 or so years. I thought it would last longer since it is always being trickle charged by a solar panel. Is there a charge/discharge routine that helps a deep cycle battery last? What kills this kind of battery?
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  2. moymurfs

    moymurfs Play stupid games, win stupid prizes!

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    Did your solar system have a "maintainer"? Meaning, it senses the battery is fully charged and discontiues the charge until it drops to a certain level then starts charging again. A trickle chage can still overcharge a battery if left on, thus shortening its life. 2 years out of a battery of that type seems screwy. If you can, I would take the battery out in the off season and at least bring it in the garage on a Battery Tender.
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  3. JAB

    JAB Unsprung Weight

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    The charger will stop or taper the charge at a certain level. The battery never needed water or seemed to be "cooked" in any way. The panel always
    showed 12.5-13.5 volts. The "starting" battery (not a deep cycle) never gets any love and is about 4 years old and doing fine.
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  4. Tweaker

    Tweaker ...

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    Interesting the panel has a charge controller. What exactly do you have?
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  5. hugemoth

    hugemoth Long timer

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    12.5 - 13.5 volts isn't really enough. Really should be brought up to 15 or 16 volts once in a while. The fact that it never needed water indicates an undercharge. BTW a pair of 6V golf car batteries wired in series is a better way to go if you have room. Those are true deep cycle batteries that hold up much better.
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  6. sailah

    sailah Lampin' it

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    ^ and cheaper
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  7. Beezer

    Beezer Long timer

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    many lead acid deep cycle and marine batteries use a lower specific gravity electrolyte. so.... they also may not ever come up to 12.5 volts simply because that chemistry. best thing to do is get in touch with the manufacturer & see what constitutes a full charge, and what method and rate of charge the recommend.

    when the plates sulphate is what usually kills them. sulphation is a normal part of the discharge process & is reversed when charged.... but it doesn't necessarily all convert back, and eventually the battery loses capacity. things that make it worse are discharging & staying discharged, loss of electrolyte, exposing the plates to oxygen... doesn't sound like that's what you have.

    also, as the battery ages, the sulphate flakes off and collects in the bottom. there is a space provided, but it can eventually build to the point where the residue shorts the plates

    another thing is a breakdown of the cell barriers. that can be caused by over heating (rapid/high charge rate) or simply taking a bad bounce.
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  8. JAB

    JAB Unsprung Weight

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    The charge controller is a Go-Power. It has a float voltage of 13.7 volts and when the battery is charged it will taper the amps to 0. Every 28 days it does a equalization charge of 14.8 volts. There is a boost feature for a discharged battery. There are times when the RV isn't used so there is no discharge to speak of. I wonder if I need to turn something on once a week or month and discharge the battery some.
    I would love to have 2 big 6V batteries and another solar panel but don't have a great place to mount the batteries without some surgery. With the existing system and an inverter I hardly have to start the generator.
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  9. MJS

    MJS Long timer

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    How far do you run the battery down when using the inverter? To deep a discharge hurts battery life. I went from max 2 years of life with the housse batteries in my boat to an easy 5 years once I wired in a smart charger (Heart Interface) with occasional equalization charges. I did have to watch the water level though.
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  10. chokozip

    chokozip Been here awhile

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    What brand of battery?
    Flooded lead acid,AGM or gel?

    Trojans are over priced for the performance I have gotten out of them.
    Stay away from the Interstates they are junk.
    I will use Deka or Crowns with outstanding performance.
    US battery has done well but the Deka has been tops out of the three.

    Alot of the new chargers have a pluse mode that keeps the sulfation down.
    Confirm your controller is doing what its suposed to.I see alot of chargers crap out and just charge or over charge a battery untill its dead.

    Sean
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  11. ttpete

    ttpete Rectum Non Bustibus

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    You might want to replace that solar unit with a Solargizer. These have been adopted by the US armed forces to keep batteries properly charged in reserve vehicles that sit for months in motor pools in between usages. Think of it as a sun powered Battery Tender. AGM batteries are available in the large sizes, and typically last longer than the flooded electrolyte type.
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  12. Tweaker

    Tweaker ...

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    I am confounded on why you even need a controller. If the panel is sized properly, there won't be any overcharging. I've had a ~16v 10w panel on a gate battery for years. VW used to send their cars out with small 5w panels. Your company GoPower sells three of them at the appropriate voltage. Why are you introducing this gadgetry into what is a simple process? Battery Management Systems are probably the leading cause of premature battery failure. I don't believe lack of equalization is reason with the apparent light? use that you describe.
    Or you have a draw that you don't know about. My RV batteries are lucky to see any attention for months and still last their 5 years but after switching out a pile of deep cycle lead acids for LiFePo4, I will never ever go back.
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  13. MookieBlaylock

    MookieBlaylock Long timer

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    that's definitely one thing that kills them. Going under 12 volts/50% charge is bad for rv bats
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  14. JAB

    JAB Unsprung Weight

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    Bingo. This could be part of my problem. I have pushed the inverter use a couple of times. If I remember correctly, the volts were high 11's and capacity was around 70%. As far as the controller is concerned, I think it needs to be there as the solar panel is rated at 135 watts rather than a 1.5 watt maintainer. When we dry camp, the system does a good job keeping the battery topped up. Our uses are pretty low for the inverter. Usually a pot of coffee or a hair dryer. Can't run the microwave on it, if we need that, we can use the gen, but the gen is noisy and a very poor battery charger. If I could make one quick/easy change it would be to add another battery to the system, followed by another panel.
    Might be nice to try a better grade of battery too. Currently using a Napa (Interstate?) battery, the largest that will fit in the current space.
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  15. RVDan

    RVDan Long timer

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    It could have been a random crappy battery. Ive had plenty of batteries go bad inside of two years while others from the same batch lasted many years.

    The Walmart energizer batteries in my camper are over ten years old and still going strong.

    Generally I only sell Interstate unless the customer request something else, they are made by Johnson controls, Johnson Controls knows how to build a battery.
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  16. Langanobob

    Langanobob Been here awhile

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    It takes awhile to read through all of this guy's articles, but he seems like he knows something:

    http://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/
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  17. JAB

    JAB Unsprung Weight

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    That's quite the find. It is a long read but seems like good background info
    with links to other stuff that I have not had time to get to. If I were to believe HandyBob, seems I could be undercharging from either a voltage drop
    or a pre-set level on my controller. Will keep reading and see what I can come up with.
    #17
  18. Cpt. Ron

    Cpt. Ron Advrider #128

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    I'll second (or is it third?) Bob's blog. Lot's of great info.

    As for your issue, how far from the battery is your solar charge controller? Is your battery a true deep cycle battery, or one of those RV/Marine batteries that is supposed to be deep cycle as well as a starting battery? When I was shopping for mine, I had to go to a battery specialty shop to get a true deep cycle battery (I opted for a single 12V one for now, though may switch to a pair of 6V batteries at the next battery change-out). What gauge of wire runs from the panels down to the controller and from the charger to the battery? Have you actually measured the voltage AT the battery during the various cycles of the charge controller? Have you measured the amps in the system?
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  19. JAB

    JAB Unsprung Weight

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    I have a gen-u-ine NAPA deep cycle battery. (says deep cycle on the sticker) I can not state the size of the wire for a fact at the moment other than to say it is what came with my system. A guess would be 10ga. It's not zip cord or welding cable. The wire down from the panel to the controller is about a 12 foot run and from the controller to the battery is another 16-ish feet.
    At the moment, I only have my trusty VOM, so I can measure volts at the battery and compare that value to the control panel read-out. Might be able to borrow a amp-clamp and give that a go, but this is getting to the outer edge of my current 'lectrical knowledge.
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  20. JeffinTD

    JeffinTD Long timer

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    Handy Bob is great. I learned a lot from him when designing my solar system.

    Anyway if when charging at full power you are getting more than about .3 volt loss in your cables, I'd upgrade those. If they used the little automotive circuit breakers, you could be loosing that much right there.

    Deep discharge, going long periods of time without being fully charged, and being run low on water will shorten the life of lead acid batteries.

    I've also seen corrosion at the terminals or in the battery end of the cables be mistaken for a dead or failing battery...
    #20