All batteries dead after truck/camper sit for 7 weeks. Rookie here.

[melcooke]

RV/Camper Electrical Systems Rookie here. I don't know where to start troubleshooting so I'll list the circumstances.

When we returned from a 7 week time away from home (truck was parked the entire time) and I went to start the truck the battery was totally dead.... nothing lit up in the truck, zilch.

I connected my portable charger and set it to 12 volts/2 amps. The gauge pegged to 8+ amps (max amperage on the charger). When I switched to 12 volts/8 amps, same result. I thought this odd but have not experienced a scenario like this before.

Out of curiosity I turned the truck key on.... zilch. I let the batter charge for about an hour.... zilch. The charger cycled about every minute of so between 0 amps and 8+ amps, I suspect a cooling circuit was engaging to prevent overheating.

I disconnected the positive battery cable and the charger went to 6 amps (where it was set) The battery was now taking a charge and there are lights on the dashboard, and a dead battery click when attempting to start.

I then reconnected the positive battery terminal and disconnected the positive line that runs from the truck battery positive terminal to the camper house battery in our All Terrain Osprey. Truck battery still charging.

At this point there was no power whatsoever in the camper.

I connected shore power to the camper and my Victron Connect monitor showed 13.27 volts, 100% charged, infinite time remain but 8.92 amps of current! Hmmmmmm. I'm assuming the current is shore power charging the house batteries (2 12 volts AGMs). This does not make sense to me but I'm a novice at RV power systems.

All of the 12 volts accessories work fine with shore power connected.

Out of curiosity again, after about 1/2 hour of being connected to shore power I disconnected shore power. The camper positive power lead from the truck batter is still disconnected.

The Victron Connect shows the house batteries to be at 11.5 volts, 100% charged, infinite time yet still showing 6.9 amps! This just doesn't make sense to me. Current to what? A short to ground somewhere?

Also, seems the battery cutoff in the camper should have stopped the truck battery from draining if the camper is the problem and should have prevented the camper batteries from draining if it is a truck problem.

 

[ckent323]

It seems you are saying your truck battery is completely discharged but your camper house batteries are charged.

What components (relay or isolator, fuses or breakers, wire size, etc) do you have between your truck battery and the camper?

e.g. DC-DC charger? or Blue Sea ACR? or Solenoid or something else?

Do you have solar on the camper?

Have you checked the connectors (and the wire) from the truck to the camper for damage and signs of shorting?

Seems like there is a short somewhere on the truck side that is not pulling the camper house batteries down. Which causes me to ask if you have an ACR in the path from the truck battery to the camper house battery bank.

 

[melcooke]

It actually appears to be an issue in the camper.

I disconnected shore power, the camper is still disconnected from the truck battery and the house voltage is steadily dropping from 11.5v (when it had been connected to shore power for about 20 minutes) to 6.5v currently. The amperage on the Victron is now only .42a which makes sense since the voltage is quite low.

My plan is to keep the camper disconnected, fully charge the truck battery and let things sit so I can observe what happens.

I'm now thinking there is something in the camper discharging the house batteries. Nothing in the camper is on with the exception of the hard wired fridge light. The fridge is set to off and the fridge light goes out when the door is closed.

The battery cutoff shows to be open, even though the power to it is disconnected.

 

[CPT Davenport]

What type of batteries are you using for the house? Most (non LiPo) batteries don't like sitting for long periods of time. A trickle charge (solar comes to mind) helps keep things topped off. Most systems have a parasitic load somewhere, somehow unless a disconnect is inline.

A standard truck battery can drain in 7 weeks especially if it is old and worn out.

What was the SOC of the house bank when you parked the rig?

 

[melcooke]

AGM batteries in house. I can't really tell you what the SOC was when it was last parked but I can reasonably say they were fully charged.

I've got the truck nicely charged now. It is a 5 year battery that is about 4 years old. Something to think about I guess. The AGMs are 3ish years old now. Yet more to think about.

I'm going to keep the shore power on for a couple of days then reconnect the camper to the truck and see what happens. Thanks

 

[CPT Davenport]

May be worth load testing the batteries just to eliminate that as an issue. If any of them have ever dropped to 50% they have been compromised. I have AGM batteries in my off grid cabin that are 12 years old and still getting it done with vigor. They have never been discharged below 50%. I adversely have a friend who burns through his batteries every two years due to not keeping them topped off.

 

[ckent323]

I have two 220Ah 6v AGM Lifeline batteries in our camper. They are 6 years old and working like new. The camper has a 360W solar panel with Victron Solar charger and Victron BVM-712 battery monitor. We never run the batteries below 50% full charge. Also they always get fully recharged everyday from ground power or solar power (in inclement weather I can connect the camper batteries to the truck but it is normally disconnected)..

On the other hand the 1100Ah 12v FLA battery in my truck has a constant drain I have not been able to locate and it will go flat in a few weeks. I have a positive terminal disconnect so the battery is not getting pulled down when not in use.

The truck battery and camper are generally not connected because with the large solar panel it is rarely needed.

 

[goinoregon]

I have two 220Ah 6v AGM Lifeline batteries in our camper. They are 6 years old and working like new. The camper has a 360W solar panel with Victron Solar charger and Victron BVM-712 battery monitor. We never run the batteries below 50% full charge. Also they always get fully recharged everyday from ground power or solar power (in inclement weather I can connect the camper batteries to the truck but it is normally disconnected)..

On the other hand the 1100Ah 12v FLA battery in my truck has a constant drain I have not been able to locate and it will go flat in a few weeks. I have a positive terminal disconnect so the battery is not getting pulled down when not in use.

The truck battery and camper are generally not connected because with the large solar panel it is rarely needed.

so, is there anything to watch out for, when u use the positive terminal disconnect on your truck? i guess u could not use a key fob to open the doors ?

 

[Vic Harder]

From your descriptions above, it seems that both your house and truck batteries were totally discharged. Never mind the 100% SOC on the Victron app. If you have a parasitic load or a load that does not go through the shunt, that SOC# can be misleading. On the Victron app, there is an option so SYNCHRONIZE to 100% (if and when you are sure the batteries are full, you can press that button), and above that an option to set the SOC to a value you guess at. Try setting that to a very low value... say 5%, and then keep charging your systems. The % should climb.

What leads me to the conclusion that your batteries are not at 100%? Well, nothing works, for one. Two, 6.9A charging means that one of your charging systems thinks it can take more juice.

Also on the Victron App, the 13.27 you saw, that is the result of actually charging. As soon as you stopped charging, that dropped back down (close) to the actual resting voltage of the DEAD batteries.

AGMs and FLA batteries do not like being fully discharged, it shortens their lives considerably; however, it is not terminal UNLESS they freeze. The acid these batteries keeps them from freezing. When totally charged they can withstand -40* temps. When discharged, the liquid inside them is no longer acidic, it is mostly just plain water, and it can freeze and ruin the battery.

I'm chasing a slow drain in my rig as well, probably the alarm system in the truck and/or the propane detector and my Cell/Starlink routers. Good luck tracking yours down!

 

[crashmaster]

Maybe a bad cell in one of the house AGM’s? I would test those individually. I had one house 6V AGM go bad that was pulling down the others but in my case the Blue Sea Battery Link separator worked at 12,7V to protect the truck batteries. My guess is your truck battery won’t last 7 weeks sitting without a charge regardless of the battery separator.