Chassis Battery Charging from House Battery

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  • ZoNiE
    Solar Fanatic
    • Jul 2014
    • 129

    #1

    Chassis Battery Charging from House Battery

    Hi Folks, I have a 1996 Safari Motorhome which seems to drain it's chassis batteries over three weeks while sitting in the storage lot. I need to find the drain, but in the interim, I was thinking, I have 1,120W of Panels and a Midnight Classic charge controller keeping the four GC2 house batteries up while it sits in a storage lot 100 miles away. I can monitor it with my wifi hotspot from home. There is an old Siemens 75W panel and a PWM charge controller installed by the factory, but I think it's pretty much at the end of life, and it is obviously not keeping up with the drain (I think I found and eliminated one). I am over producing when the coach sits, so I started thinking about putting some sort of crossover to charge the chassis batteries off of the house batteries when the sun is up, and tying this after the shunt so the Classic can keep track of the usage. A simple timer and relay would work, but something more sexy like a 12V powered trickle charger would be simpler. Any ideas?
    House-Sun Earth Hot Water.
    RV-390W Kyocera, Kid.
  • Sunking
    Solar Fanatic
    • Feb 2010
    • 23301

    #2
    You really do not need anything special to do what you want. A 75 watt panel is more than enough to keep both House and SLI battery topped off at the same time. Just wire them all in parallel.
    MSEE, PE

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    • bcroe
      Solar Fanatic
      • Jan 2012
      • 5209

      #3
      I would use a couple big diodes to the 2 batteries, since these systems are supposed to be
      isolated. Otherwise starter current etc could try to flow across your connections. Bruce Roe

      Comment

      • PNW_Steve
        Solar Fanatic
        • Aug 2014
        • 433

        #4
        Another option may be a 12v to 12v charger :https://www.amazon.com/Tecmate-OptiM.../dp/B011J76CFE

        Comment

        • littleharbor
          Solar Fanatic
          • Jan 2016
          • 1998

          #5
          If you have a hard wired smoke or carbon monoxide detector, pull the fuse for it/them and leave the power center access open to remind you to replace them when the RV is in use. Whatever else you can do to keep your batteries from cycling daily will help keep your batteries from losing electrolyte when not in use. Be sure to check electrolyte monthly.
          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

          Comment

          • ZoNiE
            Solar Fanatic
            • Jul 2014
            • 129

            #6
            Thanks guys. Yeah, that Amazon thing looks like what I need, but seemed kinda cheesy.

            I'd like to keep the systems separate but may connect them via some diodes and maybe a relay to pull in when the voltage drops too low. Not sure what I want to do yet.

            The issue is not anything on the house draining the batteries. I have 400AH and 1,120W on that and it keeps things nice and charged.

            The chassis batteries were draining down for some odd reason, however I think I found the culprit. The coach has a switch to keep the motorized step out when opening and closing the door. This is on the chassis battery. I found that an aftermarket lighted handle was tied to this and was never on, but I noticed the bottom of it was warm. I remove it and found a rather large current limiting resistor was hot and the LED was burned out. I will be up there in two weeks and will know if that was it.
            House-Sun Earth Hot Water.
            RV-390W Kyocera, Kid.

            Comment

            • SunEagle
              Super Moderator
              • Oct 2012
              • 15161

              #7
              Originally posted by ZoNiE
              Thanks guys. Yeah, that Amazon thing looks like what I need, but seemed kinda cheesy.

              I'd like to keep the systems separate but may connect them via some diodes and maybe a relay to pull in when the voltage drops too low. Not sure what I want to do yet.

              The issue is not anything on the house draining the batteries. I have 400AH and 1,120W on that and it keeps things nice and charged.

              The chassis batteries were draining down for some odd reason, however I think I found the culprit. The coach has a switch to keep the motorized step out when opening and closing the door. This is on the chassis battery. I found that an aftermarket lighted handle was tied to this and was never on, but I noticed the bottom of it was warm. I remove it and found a rather large current limiting resistor was hot and the LED was burned out. I will be up there in two weeks and will know if that was it.
              There is a switch in my RV that will allow me to disconnect the coach batteries from all loads when my RV is stored for a long time without having any charging source.

              Comment

              • PNW_Steve
                Solar Fanatic
                • Aug 2014
                • 433

                #8
                Originally posted by SunEagle

                There is a switch in my RV that will allow me to disconnect the coach batteries from all loads when my RV is stored for a long time without having any charging source.
                I have the same thing on mine. If I leave it turned on when parked my batteries will drain the batteries in 4-5 weeks.

                Comment

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