No power from battery

[jbt816]

Got to the campsite yesterday and discovered the negative cable on rv battery had come loose at crimp. Repaired at campsite but I don't have power to rv unless hooked to my truck or to shore power.

Everything in the coach is working while connected to shore power.

I've checked the 2 inline fuses at the battery and those in the main panel along with the breakers.

It seems like it has to be a fuse issue but I’ve run out of places to look.

Battery is new. In-Command system says battery is at 13.8v

Thanks in advance for any help.

2019 Cougar 27SAB

[flybouy]

Dead battery? Do you have a VOM you can check the voltage on the battery?

[jbt816]

Sorry I meant to post the battery is new. The Lippert iN·command system says battery is at 13.8.

[sourdough]

Assumptions; Battery worked before. No power then found a loose connection on the negative battery cable and repaired. Still no power. Works OK from shore power or truck. New battery. Conclusion; check that connection again (or the other cable in case it has the same problem) - put that VOM to work.

[chuckster57]

In command will show 13.8V if your plugged in, that’s the voltage the converter is producing. I’m betting either your battery is dead or you have a loose connection.

[JRTJH]

Originally Posted by jbt816

Sorry I meant to post the battery is new. The Lippert iN·command system says battery is at 13.8.

When "hooked up to your truck" the IN-Command system is reading the truck charge voltage, not the trailer battery voltage. Typically, it's 13.6-13.8 VDC

When "hooked up to shore power" the IN-Command system is reading the output of the converter/charger. Typically is 13.6 VDC.

So, you can't check your trailer battery if the trailer is connected to the truck or to shore power. The only way to determine the trailer battery charge status is either to remove the trailer battery cables and let the battery sit for about 30 minutes, then use a voltmeter to check the battery voltage or you could just unplug the trailer from shore power and the truck, let it sit for about 30 minutes, then check the battery voltage reading on the IN-Command panel, which won't work if the battery is completely dead.

Essentially, the IN-Command system "reads and reports" the highest voltage sensed on the system, so even with a "dead trailer battery" if the truck or the converter are providing power, the IN-Command senses and reports that voltage, not the "dead battery status"....

Isolate the battery, it's the only way to properly check battery voltage.

NOTE: If the battery is "dead", after unplugging shore power and the truck power, you probably can't get the IN-Command system to boot up, so trying to read a dead battery voltage on the monitor panel will probably be impossible.... If you don't have a voltmeter, you might find it easier to just pull the battery, take it to an auto parts store and have them check the battery....

New, used, it doesn't matter, all batteries can be discharged. When that happens, "they're bad until recharged".. Often they are damaged and won't fully recharge, so a replacement is about the only alternative... If it's "still new" you might be able to get an exchange battery to replace it "free of charge" from the place where you bought it.

If it is "dead" your next troubleshooting steps will be finding out "why" it completely discharged. That could be the battery cutoff switch in the disconnected position, it could be a bad converter/charger or it could be blown "reverse polarity fuses" which is where I'd place my bet if, as you say, it's a brand new battery......

[GHen]

Good job JRTJH, I think you covered everything.

[jbt816]

Last night I started pulling fuses again and checking resistance with a volt meter. They were ok. After this little experiment, the system started working again. I don’t know. Gremlins?

[GHen]

Glad to hear. Keep tabs on that battery, remember to check if without shore power on, let it rest for 30 minutes then check voltage, should be around 12.7 for full charge.

[jbt816]

I did check the battery while checking the fuses. It was fine at 12.5. The issue started when the negative cable slipped out of the cheap crimp connector.

[flybouy]

12.5 volts is a 90% SOC (state of charge). If I'm reading the chronology correctly, you had an issue, found the ground cable disconnect, repaired the cable, then approximately 24 hrs later all is well. No gremlins just a dead battery that required overnight to charge. I would still pull it and have it load tested if you're going to depend on it exclusivly for power in the future.

[GHen]

If it’s been charging for a few hours and you let it rest and it shows 12.5, it’s ok but not great. As flyboy points out that’s 90%. Batteries will need to be replaced soon. A full charged battery should be around 12.7