How long does a Group 27 Battery last (1999 Coleman Utah)

Discussion in 'Boondocking' started by steppinthrax, Aug 16, 2017.

  1. steppinthrax

    steppinthrax Member

    Aug 7, 2013
    I'm thinking of doing some camping in sept. My camper has a water pump, LED lights inside, gas furnace, fridge, etc...

    The only thing I envision using the most and the most critical would be the water pump kicking on every once and awhile. Afterwards the LED lights inside the camper (about 6).

    I guess my question is a fully charged group 27 marine (750 MCA) battery. How long theoretically would it last in this situation.

    Also, if I hooked my vehicle to the 7 way and ran it for 30 mins or so, would it fully charge the battery?

    Or, if I how about solar panels (although I've read that they take forever to charge a battery)....
  2. rabird

    rabird Howdy!

    Mar 3, 2006
    I suggest you think in amp-hrs (ah). A group 27 is about 90-100 ah and generally for long battery life ya don't discharge below 50%, so let's say ya got 40 ah avialbe.
    Furnace is ~4A so you can run it 10 hrs and then you ar at 50%, this could be days.
    all 6 LEDs I'll guess 1-2A or 40-20 hrs.
    water pump doesn;t run much but might be 5A, 5ah/day or less.

    A weekend or longer is doable with one g27.

    You 7way will provede some charge but not much, jumper cable with the vehicle exhausl pointed away from the PU gives a little charge but takes time.

    Solar is great if there is sun and makes a great battery maintainer while not camping.

    caring for a batt is important for long life,
    with proper care, many years of service.
    bob barnes likes this.
  3. kitphantom

    kitphantom Well-Known Member

    Dec 26, 2009
    Albuquerque, NM
    You really need to assess the power drains for the items in your camper. We found that the original water pump in our TT was a power hog. We installed a new one but have yet to put it to a dry camping test (that's next week). The furnace fan motor can be a pretty big draw too. The refrigerator in ours doesn't use a lot of power, it's just for the brains and ignition (same with the water heater). Part of the equation is the health of your battery and the outside temperature (batteries have less capacity in the cold).
    Solar is great, but it depends on the size (watts) of your solar panel, tree coverage, angle of the sun, cloud cover, etc. We have 160 watts of solar, in most of the places we camp, the batteries are topped off by early afternoon, if not sooner. In SE Ohio last fall, we had to move the panel to chase the sun on a couple of days, since rainy weather and sun angle (+trees, etc) meant we didn't have full charge until very late afternoon.
  4. jmkay1

    jmkay1 2004 Fleetwood/Coleman Utah

    Oct 10, 2013
    Northern Virginia
    Not trying to hijack this thread but I kind of have the same question; except I don't plan on using the furnace. Do you think the battery could last longer than a weekend if I took it easy on the water pump, say once a day. Assuming temps will still remain in the positives.
  5. Aneemal33

    Aneemal33 Active Member

    Aug 25, 2016
    I plan on doing some "boondock" camping in early October here in Minnesota, so I am assuming I will need some heavy furnace use at least in the evening and morning. I have one group 24 battery and have decided to buy a small generator to run a battery charger to recharge the battery each day. It should only take a couple hours on the generator with the 12v items off to recharge. That way I only need my battery to last one day at a time.
  6. JPBar

    JPBar Well-Known Member

    Sep 22, 2016
    The fan on the furnace will eat up the charge on the battery pretty quick.
    bob barnes likes this.
  7. rabird

    rabird Howdy!

    Mar 3, 2006
    depending on how fast you can recharge!
    Data from someone charging 2 x golf car batteries from 50% with a charge that had 14.4v set pt, I 'unitized' (per 100ah) it so the Y axis reads % of capacity, so 25 would be 25% of 80ah (G24) or 20A charge rate for a G24, x axis is minutes. Note constant for 1hr (until battery gets to 14.4v) then constant 14.4v while current tapers. ~2.5hrs to 90% from 50%.

  8. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

    Jul 18, 2013
    Thornville, OH
    With a group 27 battery you should think in the rating of Reserve capacity. I would use the 5 amp drain rate scale. Its depends, how many days, how cold, and how you use your battery. When we camped with a group 2 battery (sons camper) in the GSMNP it dropped several nights to high 20's and we had the stat set to 65 only heating and only when we were in bed. Furnace was running about 50% of the time. we I got 2 nights. With our group 31 we have about 45 more RC amps and can go 3.5 nights.

    Not sure about recharging with the 7 pin TV connector, it may not charge that fast. Voltage drop, wire length and wire gauge issues?? I would use a good set of auto jumper cables. But no you will not fully charge the battery in 30 minutes. Maybe 85%. Auto chargers are not designed to full recharge a battery fast, but to bring the battery up to a good starting voltage fast and then slowly continue charging and maybe fully recharge the battery after many hours of driving.
  9. PointyCamper

    PointyCamper Active Member

    Nov 25, 2015
    This is similar to our December camping trip and we do use our furnace(but Aliner easy to heat) but dont charge each day
  10. theseus

    theseus Centerville, OH

    Feb 6, 2007
    Centerville, OH
    The 7-blade plug on your camper is not a reliable way to recharge. The voltage put out by most factory installed 7-blade sockets on tow vehicles provides what could best be described as a trickle charge. It is designed to keep your battery full as you drive down the road, possibly running your refrigerator. It isn't moving enough amps to recharge the battery quickly if it is depleted.
  11. Aneemal33

    Aneemal33 Active Member

    Aug 25, 2016
    Agreed, but we sleep with very warm comforters and like it cold while sleeping. The furnace is for bedtime prep and mornings before we get into the warmer clothes. Overnight we turn it down to roughly 56 degrees if the forecast is for a really cold sub 50 degree night. (Perfect sleeping weather [:D]) We use rechargeable battery operated lights when boondocking - not the lights in the pup and of course run the fridge off propane. We bring fully charged back up battery packs for the phones, lights etc. I can charge an iphone7 10 times before recharging the battery packs.

    Basically, all I need the group 24 to do is run the furnace and water pump. When it comes time to put it away, I can fire up the generator and plug in the camper to run the power roof winch if the battery is too tired.

    That's my plan at least :)
  12. bob barnes

    bob barnes Well-Known Member

    Mar 26, 2017
    Since we boondock we cut everything to a minimum I don't use the furnace but a wave 3 for heat no battery draw from the furnace then. we use very little lights, no tv we use our portable radio 9v cheap. we went out for a month one time came back hooked the charger up it took only a short time and it was back to full charge.

    Here is what I would do run all this at your backyard for a weekend!
  13. tenttrailer

    tenttrailer Art & Joyce - Columbus, O

    Jul 18, 2013
    Thornville, OH
    I would expect about 7 to 9 days. I'm assuming you will run the fridge on propane. Water pump uses about 4 amps for every hour its on. I would expect you run the water pump between 7 to 15 mins a day call it 1 amp. I normally pull the fuse out for the propane detector during the day and put it back in at night. That little decor pull a lot of amps each day.

    Now if you run the furance I would say 2.5 nights.

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