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nickdarr's avatar
nickdarr
Explorer
Jul 01, 2017

Can two 6V and one 12V be charged by rv system?

I searched and could not find answer that did not involve using large solar setups. Since obtaining new neck hardware, I have a CPAP. We have used our two 6v batteries and camped, but not since my new CPAP friend travels with us. We are getting a separate 12 volt for the CPAP. Can I place this inline (parallel) with the two 6v and charge through the TT wiring system? Or, am I better served to run a separate charger for that battery? We have a small solar panel and hope to add more as cash allows. We run the generator to fully charge each day.
  • time2roll's avatar
    time2roll
    Nomad
    Jul 01, 2017
    While in use or charging they can be together or separated as you like.
    I would only separate during storage with no float charge.
  • ktmrfs's avatar
    ktmrfs
    Explorer II
    Jul 01, 2017
    ktmrfs wrote:
    2oldman wrote:
    A 12 in parallel with 2 6s should work.


    not really. for charging you will likely be ok, but not for discharge. the issue is that unless the 12V is the same AH as the 6V the 12V will discharge faster than the 6V bank and the 6V bank will end up charging the 12V and you'll end up with well under the assumed AH

    better thing would be to use a battery selector switch to select one or the other.

    now I expect Mex to chime in and give more details and/or shoot my analysis down.

    And unless the CPAPs are also running with the humidifier on, a pair of GC batteries will go many weeks even running two CPAP's. Data on three different CPAP machines, a resmed, a resperonics and one other from another member indicates an average current draw of an amp or less.

    My resmed will run 4 1/2 nights off a 250WH (that's around 20AH) lithium battery pack.

    and residual draw in my trailer over night from propane detectorm fridge electronics etc. is about equal to the CPAP.

    Now turn on the tube heater and heated humidity and it will run the draw up to about 3A average or 25AH, even that will go many nights on a pair of GC batteries.
  • ktmrfs's avatar
    ktmrfs
    Explorer II
    Jul 01, 2017
    2oldman wrote:
    A 12 in parallel with 2 6s should work.


    not really. the issue is that unless the 12V is the same AH as the 6V the 12V will discharge faster than the 6V bank and the 6V bank will end up charging the 12V and you'll end up with well under the assumed AH

    better thing would be to use a battery selector switch to select one or the other.

    now I expect Mex to chime in and give more details and/or shoot my analysis down.

    And unless the CPAPs are also running with the humidifier on, a pair of GC batteries will go many weeks even running two CPAP's. Data on three different CPAP machines, a resmed, a resperonics and one other from another member indicates an average current draw of an amp or less.

    My resmed will run 4 1/2 nights off a 250WH (that's around 20AH) lithium battery pack.

    and residual draw in my trailer over night from propane detectorm fridge electronics etc. is about equal to the CPAP.

    Now turn on the tube heater and heated humidity and it will run the draw up to about 3A average or 25AH, even that will go many nights on a pair of GC batteries.
  • azrving's avatar
    azrving
    Explorer
    Jul 01, 2017
    Charge both at the same time. If you are going with more or different panels look at places like solar blvd. I noticed a sale right now for 180 watt panel for $150. What type of solar controller do you have? It's best to try and size your system to what you ultimately need rather than replace components and wire as it grows.
  • 2oldman's avatar
    2oldman
    Explorer II
    Jul 01, 2017
    That panel isn't going to do much. 2 amps, maybe, tops.
  • RJsfishin's avatar
    RJsfishin
    Explorer
    Jul 01, 2017
    Its like 2old said !

    What makes you think it would ruin anything. Whatever batts you use, 6 or 12v, in the end your charging system sees it as one big 12v battery. Just make sure your arrangement stays 12 volt
  • nickdarr's avatar
    nickdarr
    Explorer
    Jul 01, 2017
    Small, 36 watt, trickle charge panel with 20amp control. Does trickle, top off. Question is, can I parallel the 12 to two 6 and not damage the six or the onboard shore converter/charge controller?

    Thanks 2oldman.
    That is what I hoped.
  • Lwiddis's avatar
    Lwiddis
    Explorer II
    Jul 01, 2017
    How small a solar panel? Standard is one solar watt per battery AH. Then you adjust for location, type of controller, expected daily use etc. Idaho is a state where more solar watts may be needed in the fall and winter months.

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