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Camper batteries drop when truck is running


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#1 FoxenTec

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Posted 04 February 2019 - 04:03 AM

I recently noticed the following.  Ram Truck and 2018 Grandby camper sits in fog, gray skies and rain for a number of days.  The solar panels (2 x 100 watt) don't quite keep the two AGM batteries floated in this weather.

 

I take the truck out for a long drive, expecting the FWC installed wiring to my truck battery/alternator and separator to bring up the batteries but when I return home they are lower then when I left.

 

Once the engine of the truck is shut off, I observe my Overland Solar MPPT display unit.  I see they are in BULK and as I watch the voltage display, I see the display then slowly climb from say 13.2 volts to the normal 13.8 float.   

 

I noticed this has happened on 4 hour drives also.  When we arrive at the campground, the AGM batteries have gone from 13.8 volts in float when we left to 12.9 volts and BULK when we arrive.  Once the camper sits for a while in partial sun, the batteries start coming back up.  All this info occurs when the battery disconnect is active meaning nothing should be drawing power from the AGM batteries.

 

My question is whether or not something is drawing power away from the AGM batteries when my truck is running instead of the opposite, actually charging the batteries.  Not sure yet how to diagnosis but will start looking into.  The first 6 months of ownership this did not happen but the last 4 months it has.

 

Thank you,


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#2 Vic Harder

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Posted 04 February 2019 - 05:49 AM

Jon,  Do you have a volt/ohm meter?  Check the truck and camper battery voltages before starting the truck.  Start the truck and let the isolator connect and measure both again.  Drive for a bit, repeat the measurement, then shut down the truck and measure again.

 

I'm thinking the truck batteries must have a lower "resting" rate than the camper, maybe because a cell has gone bad sometime in the last few months.  The truck's batteries will then drag down the camper batteries.  


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#3 DYNOBOB

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Posted 05 February 2019 - 04:37 PM

Not sure if this is your problem but If the house batteries drop below a certain voltage the FWC isolator will not connect to the trucks charging system when you start the truck.  This has caught a few folk out.  You have to bring them up with solar or shore power to get them to reconnect.  I wired a manual 60a switch around the isolator so I can get them charging if they're not connecting automatically. 

 

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Edited by DYNOBOB, 05 February 2019 - 04:38 PM.

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#4 FoxenTec

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Posted 06 February 2019 - 04:07 AM

Thank you Vic and Bob for your help.  I do have a VOM and will follow what you said to do.  Always appreciate the great input!


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#5 Pax2525

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Posted 10 February 2019 - 12:58 AM

May be a silly question but want to ask regardless...

Do you have the master kill switch pulled out during these drives and such or is it pushed in?
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#6 FoxenTec

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Posted 22 February 2019 - 01:46 AM

Sorry for not getting back to the forum on this.  Regarding the master kill switch.  Answer is twofold. 

 

When going camping, it is pushed in because our ARB fridge is then running off the batteries.

 

When we just take it out for an hours drive, (aka not camping) then it is always pulled out.  

 

When it sits in my driveway during the day, it is also pulled out.

 

Once this rain stops, I will get in there with my VOM and check what Vic mentioned.

 

Thank you!


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#7 veryactivelife

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Posted 22 February 2019 - 12:06 PM

When charging from either the truck or solar the switch position does not matter. To change from shore power it must be out. To utilize the 12 volt camper system, as in running the fridge, it needs to be out not in. Unless your ARB is wired straight to the batteries.

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