Battery/Power Question

[archham]

Checked on my 2020 Sandpiper - I figured the battery was down, even with the master switch off, and it was. Backed my truck up to it and connected the cable in the bed. I then turned the master switch on.

The marker lights were on, but even after running the truck for a while nothing else worked- no interior lights, jacks, etc. I didn’t connect to shore power but will when I go back in a couple days.

Does that sound like the battery went bad or something else? It was working perfectly when I parked it there about 45 days ago, so the only change is the battery probably running down.

[kenandterry]

I’m no trailer expert, but here’s my thought based on what I read…..

For whatever reason, I suspect your trailer battery is dead for all purposes.
However, you stated that after you hooked up the trailer to your truck, the clearance lights worked…..but nothing 12 volt “house-wise” in the trailer.

Is it possible that when hooked up to the truck, it only powers clearance lights (and probably running and brake lights) just like any trailer would get it’s power for exterior vehicle lights? That would work for a landscape or cargo trailer.

Dead house battery won’t do anything for you until you plug in shore power for the other things you mention, and then the converter will be powering inside stuff.

Sound reasonable?

[acadianbob]

It sounds like your battery might be unable to take a charge. That would mean in needs to be replaced. In know that my trailer still has a draw after the master switch is turned off. It sparks when I put the negative cable on the negative terminal. So, my battery would slowly be discharged. I finally put a cutoff switch on the battery. Now my batteries retain their charge much better; just the normal discharge of a stored battery.

[archham]

Thanks, I figured that is the most likely problem. I planned on taking it out and leaving on a maintainer for the winter in my garage but hadn’t done that yet. It is a Wal Mart Marine/RV battery

[kenandterry]

Originally Posted by archham

Thanks, I figured that is the most likely problem. I planned on taking it out and leaving on a maintainer for the winter in my garage but hadn’t done that yet. It is a Wal Mart Marine/RV battery

You can try…..but the battery may be “toast” depending on how depleted it was and for how long. It may NEVER come back.

Just sayin.

[CHICKDOE]

the master switch most probably does not turn off all the 12 volt loads in the trailer. things like co or propane monitors and even the radio may stay on. there may be other things. over 45 days these devices will drain the batteries. so most likely you batteries are quite depleted.

the trailer marker lights are powered by the tow vehicle and are not even connected to the trailer batteries. similar to the turn lights and brake lights.

the batteries were probably so low that they did not get much of a charge from the truck when you connected it. they will need a long time to get recharged, assuming they are not shot. do you have a battery charger that you can put on the batteries. or can you plug the trailer in to shore power and let the internal converter recharge the batteries. or can you take the batteries to an auto parts store and see if they can recharge them? try to get them fully recharged and then you will have to determine if they can still hold a charge or not.

i had a similar issue on our trailer. i installed a true cutoff switch on the batteries that truly disconnects the batteries from all drains. i ensure the batteries a re fully charged before i put the trailer in storage and disconnect them. since i did this no more discharge problems. many other have done this also.

[njfishing]

I assume when you said you plugged the trailer in you meant to the 7 pin connector on your truck. If so a few things. 7 pins on the trailer side are usually wired to allow the tow vehicle to charge the trailer but the tow vehicle needs to be wired correctly to do this. I know in the case of some f150s you need to install a fuse to allow that since the factory left that fuse empty. One way to see if you are getting a charge from the tow vehicle to the trailer battery is to use a multi meter and take a voltage reading at the battery terminal with the trailer disconnected and then plugged in..The other issue here even if everything is wired right, the voltage coming from your tow vehicle is no where near enough to charge a dead battery. You’ll either need to plug the trailer into shore power so the on board charger can charge it up or remove the battery and have it charged.

[ppine]

Lead acid batteries really do not like going much below 50% charge. Salesman will tell you that a battery will discharge 1% a day with no load on it. If you leave a battery for 45 days at idle, and it has a small pirate voltage load it is going to zero. Running the alternator on most trucks is not going to bring it back very easily. A four stage charger will do a much better job.

[W5CRE]

Originally Posted by ppine

Lead acid batteries really do not like going much below 50% charge. Salesman will tell you that a battery will discharge 1% a day with no load on it. If you leave a battery for 45 days at idle, and it has a small pirate voltage load it is going to zero. Running the alternator on most trucks is not going to bring it back very easily. A four stage charger will do a much better job.

So we are listening to salesmen now? Real experts.

A sealed lead acid battery generally discharges 3% every month. You can let it sit all winter fully charged and disconnected with no issue. If your battery can't handle that then you need a new battery as it's not likely to last one camping season.

[archham]

Thanks to all, I did use the 7 pin. All this is good info, will pull the battery in a couple days and go from there.

[ppine]

3% a month is wishful thinking.

[5picker]

Originally Posted by ppine

3% a month is wishful thinking.

Not in my climate.
Our winters here average from 28° to 0° (and below) and a fully charged and disconnected FLA battery will lose about 12% to 15% over about 5 months of sitting right in whatever unit it was disconnected from. R/Vs, tractors, dump trailers, etc. doesn't matter.

[yukongold]

When I was boating I had the two Trojan deep-cycles I had go dead on a week-end trip. Engines wouldn't even turn over. Took the dinghy back to the dock (two hours each way) and drove home to get my Honda eu2000 to recharge them.
Even using a 2000w generator it took over six hours before I had enough juice to start the engines. From start to finish - waking up to dead batteries and getting the engines to start - was a 12 hour ordeal.

I don't think 20-30-40 minutes of recharging a dead battery from an alternator is going to do anything. You need to hook up to shore power and let the charger do its work for 10-12 hours.

[tomkatb]

You are currently flying while blind.

Modern rv's use 20x the batteries of the 60's. You have that 60's battery likely.

Knowing the voltage at all times is important. A battery monitor is a good investment.

Your battery had a 1 year warranty which is about how long a battery will last if not treated well.

Tow vehicles deliver only a minimal charge via the 7 wire connector.

If you ran the battery to zero it might take a long time before the battery has any charge. full charge might be days of connection to the TV. Modifications to improve this are possible.

First thing is to plug the rv in. The built in converter will likely recharge the battery well in a day.

Using the voltmeter your have to check it after a while to see if it is charging. If you really discharged it 100% it may be DOA.

We live in Ohio. i do not trickle charge my battery bank. It will discharge about 30% in 5 months. If yours does faster, there is a wiring mistake somewhere. Removing a wire from the battery will stop that.