So Ive been pretty proud of my recent solar upgrade to the camper, but haven't really had a good workout with it. Fun just knowing everyday the batteries are being topped off and floating due to solar power. So it was quite a shock today when I stepped into the camper to do dome things to prepare for this weekends upcoming trip only to find I had no power and my digital gauge was dark. OMG. So I went to my truck to get tools and a DVM to check the level of charge directly off the bats, only to find the truck was also dead. I had inadvertently left the camper connected to the truck after towing it this past weekend to a local park to dump. My thought is that somehow the truck drained my batteries, even though they were being charged all day by my 320 watts of solar. How is that possible.When I finally got my DVM on the batteries (2 6 volts in series) they were reading 7.75 volts. Have I killed them? Now I've got my camper plugged into 110 shore power and the converter is charging them and they were reading 8.8 as I came in to type this post. I jumped the truck and got it started, but is THAT battery now fried as well? Any ideas why leaving the camper connected to the truck would kill all the batteries? Any thoughts on what I should do next. I appreciate any input.

Leaving the camper hooked to the truck should have kept it charged with that much solar. Are you sure your solar system has output? I'd look for a blown fuse, bad connection, fried charge controller, or something like that. With a Chevy the truck plug is always live so the parasitic loads in the RV drained it too.

You must have left something on in the camper. Where you parked where you solar panels where partially shaded. That can kill the output.

Even thought I have a TC and my battery isolator works fine, I still unplug my truck from the camper when it sits and length of time. Better safe than sorry.Your batteries may come back and they may not. Flooded cell batteries don't like being discharged past 50% of their capacity and heavy discharge usually (but not always) results in decreased capacity and plate sulfation. All depends on how old the batteries are and how many times you discharged them below 50% capacity.I run a SeeLevel battery monitor on mine so I can tell at a glance the state of charge as well as the battery temperature, which is an important consideration because when you have a heavy charge rate or discharge rate, the batteries heat up from the chemical reaction. I like to keep them as cool as possible by limiting the charge and discharge rates.

I assume you will find the solar stopped charging due to some fault or you left something on to drain the batteries.Often you will get one pass and the battery(s) will recover. Next time you might have to grab your wallet so find what happened.

Camper AND truck batteries dead | Good Sam Community

23 Replies

GaryS1953
Explorer II
Sep 06, 2017
MrWizard wrote:
I assume you have unplugged the truck
So the converter and solar only have to charge the camper batteries

Something drained them, lights, fans, trailer brakes ? ..is the pin pulled out, it has happen to more than one person on here
MrWizard was right. It's never happened to me before, and when he mentioned it I didn't even realize what he was talking about, but somehow the Break Away switch pin got pulled, causing the electric trailer brakes to be on drawing all the power out of the batteries on the camper and the truck. Never happened in the 10 years I've owned the camper and I have no idea how it happened. Anyway, now that the problem is solved the batteries have charged up just fine, charging to 14.4 volts during the day and then dropping to 13.3 to float, and finally to 12.9 after dark. This weekend with heavy furnace use and a couple hours of TV each night, we woke in the morning with battery gauge reading 12.5. Not sure how much this episode shortened their lives, but for now it seems like the batteries are going to live:)

Thanks to everyone for all their thoughts on the problem, and special thanks to you MrWizard for hitting the nail on the head.
MrWizard
Moderator
Aug 30, 2017
I assume you have unplugged the truck
So the converter and solar only have to charge the camper batteries

Something drained them, lights, fans, trailer brakes ? ..is the pin pulled out, it has happen to more than one person on here
time2roll
Nomad
Aug 30, 2017
I highly recommend a BIRD relay.

No more hassle to worry about unplugging and reconnecting. No more both batteries dead. Solar can maintain both sets.

Trouble at home is inconvenient, trouble on the road is far more hassle.
j-d
Explorer II
Aug 30, 2017
Most motor homes have an Isolation Relay between Chassis and Coach Batteries. This allows the Chassis (truck in your case) to charge Coach (your trailer) but keeps the Coach/Trailer from drawing from the Chassis/Truck. Your Solar would NOT charge the Truck with this setup.

I suppose you could install a BIRD. Electronic device that lets Either end (Truck or Trailer) to charge the other IF the charging voltage is adequate. Given you don't normally leave your trailer connected, the extra cost doesn't seem justified.

Relay and BIRD allow "Start Assist" where you activate a connection with Coach/Trailer battery as a "Jump Start" for the Chassis/Truck. I DO NOT recommend doing that. You'd be trying to crank a V8 though small wiring, trailer plug, etc. Keep that feature for MoHo's where the connections are made with Battery Cable.
SidecarFlip
Explorer III
Aug 30, 2017
MEXICOWANDERER wrote:
I'll stick with the battery issue...

Those batteries need to be recharged "hard" in order for them to have any chance at all to recover. A 40 amp electronic charger to full automatic charge then press the equalize button half a dozen times may do it. The electrolyte in all cells has to bubble vigorously for a couple of hours. Take the voltage level to 16.0 But disconnect the battery before you do this. A high quality hydrometer would tell you immediately where you were at in this process.

The old man is right on, hard charging (not wimpy charging) to get the electrolyte gassing off inside the batteries (make double sure your venting is adequate and no open flames around them either) because they are 'gassing off' very flamable gas....

You need a charger capable of around 30 amps or better. NAPA should have what you require or Tractor Supply or even the automotive department at Wally World.
SidecarFlip
Explorer III
Aug 30, 2017
fitznj wrote:
I had the same thing happen to me - came back to the camper in the evening
and the batteries were < 10V even though the solar was hooked up and it was a sunny day. Never found the problem and it has not happened since.

I used a neighbor's generator to charge the camper batteries and they seemed okay for the rest of the trip BUT they did not seem to have the same capacity. I swapped them out 3 months later.

BTW - can a solar system work in "reverse" and drain the batteries?BTW - can a solar system work in "reverse" and drain the batteries?

Yes and no. Most solar arrays have what's called 'blocking diodes' that only current to pass one way, the right way but not all. One has to check the specifications to see if they ate installed...

I use a pair of battery terminal disconnects on my truck batteries when it sits over the winter so the parasitic loss from on board electronics don't kill the batteries.
brulaz
Explorer
Aug 30, 2017
KD4UPL wrote:
Leaving the camper hooked to the truck should have kept it charged with that much solar. Are you sure your solar system has output? I'd look for a blown fuse, bad connection, fried charge controller, or something like that. With a Chevy the truck plug is always live so the parasitic loads in the RV drained it too.

Agree, that much solar really should have maintained all the batteries. Somethings wrong.

My RAM's plug is always live too. So I was thinking to leave the truck plugged in deliberately so my trailer's solar can maintain both the truck and trailer batteries during long-term storage.

The truck has so many parasitic loads itself that, according to the manual, more than 3 weeks storage is bad for the batteries. Found out about that the hard way last winter when I killed both of the truck's batts with 7 weeks storage.

BTW - can a solar system work in "reverse" and drain the batteries?

The panels are supposed to have diodes to stop that. And I would think the controller itself should prevent that as well.
fitznj
Explorer
Aug 30, 2017
I had the same thing happen to me - came back to the camper in the evening
and the batteries were < 10V even though the solar was hooked up and it was a sunny day. Never found the problem and it has not happened since.

I used a neighbor's generator to charge the camper batteries and they seemed okay for the rest of the trip BUT they did not seem to have the same capacity. I swapped them out 3 months later.

BTW - can a solar system work in "reverse" and drain the batteries?
GaryS1953
Explorer II
Aug 30, 2017
MEXICOWANDERER wrote:
I'll stick with the battery issue...

Those batteries need to be recharged "hard" in order for them to have any chance at all to recover. A 40 amp electronic charger to full automatic charge then press the equalize button half a dozen times may do it. The electrolyte in all cells has to bubble vigorously for a couple of hours. Take the voltage level to 16.0 But disconnect the battery before you do this. A high quality hydrometer would tell you immediately where you were at in this process.
Can you recommend such a charger? I've only got a small trickle charger so I'm charging it with the converter currently. I just checked this morning and the batteries were only up to 10 volts.
MEXICOWANDERER
Explorer
Aug 30, 2017
I'll stick with the battery issue...

Those batteries need to be recharged "hard" in order for them to have any chance at all to recover. A 40 amp electronic charger to full automatic charge then press the equalize button half a dozen times may do it. The electrolyte in all cells has to bubble vigorously for a couple of hours. Take the voltage level to 16.0 But disconnect the battery before you do this. A high quality hydrometer would tell you immediately where you were at in this process.