Battery cap popped off

[sjandkf]

Just checked my 5th wheel and saw the cap, on one side of the battery, had popped off. It is not plugged into the house, but the battery was still connected. I removed the negative cable and the battery post was very hot.
Never had that happen before. Any suggestions, comments or experiences with this issue.

Thanks

[16WhiteColly]

Can you tell if the sides of the case are pooched out? If so, internal short, do not charge.

[sjandkf]

No. Checked all sides and there is no bulging on any side.

[Jagiven]

Welcome aboard!

Good chance the battery it toast. When my batteries die, they tend to get warm and stink of sulfur (I keep my TT plugged into shore power) as they boil off the fluid. You can bring it into an automotive shop and they can test it.

Popping off the top sounds like a build up of hydrogen gas occurred, and the top popped to release the pressure. In your case it sounds like the battery failed. If you were connected to shore power it might indicate a bad inverter, over charging the battery.

How old is the battery? How much fluid is in the cells (all 6 cells)? Is the top of the plates dry? Have you ever added any additional fluid to the cells? If so, what did you add?

How long has the 5ver been sitting at the house and not connected to shore power? Was the battery disconnect flipped? Do you have any auto levelers? J-Command? or remotes that drive the slides/awning? Those items bypass the disconnect switch, and continue to drain down the battery even with the disconnect flipped.

In the past has the battery been depleted to completely dead?

[sjandkf]

Rig was not connected to any power source.
Battery is 18 mos old. Have not added any fluid to the batteries.
Has been sitting for about two weeks but did not have the disconnect switch flipped.
I will usually disconnect the negative terminal when we park it at home, but did not do that this time.
Have never had the battery go completely dead.
Sounds like getting a new battery would probably be the best way to go.

[16WhiteColly]

Sounds like a new battery is in order, since the disconnect was not flipped. Don’t want to have headaches in the future. Batteries are too cheap for that.

[sjandkf]

Thank you to all who responded. Appreciate all the feedback and recommendations.
Looks like a new battery is coming.

[Old Paratrooper]

Strange situation..... The cap blowing off would usually indicate the battery was over charging, boiling away the fluid and creating gas pressure that forced the cap off. You said it wasn’t connected to shore power? Did you look at the battery after returning from your last trip? Maybe the cap came off then while charging was going on. Is there solar or another system feeding a charge?

Also, those gases you are smelling are flammable. A spark near the battery can cause the battery to explode (ask me how I know). ALWAYS be careful when making connections to a battery since that connection alone can cause the explosion. SAFETY GLASSES!

[Jagiven]

Originally Posted by Old Paratrooper

Strange situation..... The cap blowing off would usually indicate the battery was over charging, boiling away the fluid and creating gas pressure that forced the cap off. You said it wasn’t connected to shore power? Did you look at the battery after returning from your last trip? Maybe the cap came off then while charging was going on. Is there solar or another system feeding a charge?

I was thinking the same thing.

OP, these wet cells do require some maintenance. Periodically you should pop the caps, check the fluid levels. The plates always need to wet, ONLY use DISITILLED WATER. Fill the cell to just below the bottom of the plastic ring below the cap.

My guess, the cells went dry. As the parasite power draw pulled down the last of the power, as the cells started shorting out they heated up. You just happened upon it as it was going terminal.

It is very important to have the battery fully disconnected when not in use or have a battery charger on it. There are a number of parasite power draws on the battery. These parasite power draws can deplete a battery within a few weeks.

Pending on your rig, the following items can be parasites Radio, CO/gas detector, auto leveling controller, J-Command controller (BMPro), all just sipping a little power.

From what I can tell, most 5vers have a disconnect switch, but a number of systems bypass the disconnect. Well worth getting a cheap multimeter with a clamp amp meter and confirming the battery is completely disconnected. Disconnecting the negative battery terminal works to, just have to have a tool and takes more effort than flipping a switch.

Just note the E-Brake system should never be disconnected. You need to make sure it is working whenever you are pulling. Even if you forgot to flip the disconnect switch before leaving home.

Example of a multimeter with an amp clamp
https://www.amazon.com/Klein-Tools-C...ustrial&sr=1-8

[jetlag]

Originally Posted by Jagiven

I was thinking the same thing.

OP, these wet cells do require some maintenance. Periodically you should pop the caps, check the fluid levels. The plates always need to wet, ONLY use DISITILLED WATER. Fill the cell to just below the bottom of the plastic ring below the cap.

My guess, the cells went dry. As the parasite power draw pulled down the last of the power, as the cells started shorting out they heated up. You just happened upon it as it was going terminal.

It is very important to have the battery fully disconnected when not in use or have a battery charger on it. There are a number of parasite power draws on the battery. These parasite power draws can deplete a battery within a few weeks.

Pending on your rig, the following items can be parasites Radio, CO/gas detector, auto leveling controller, J-Command controller (BMPro), all just sipping a little power.

From what I can tell, most 5vers have a disconnect switch, but a number of systems bypass the disconnect. Well worth getting a cheap multimeter with a clamp amp meter and confirming the battery is completely disconnected. Disconnecting the negative battery terminal works to, just have to have a tool and takes more effort than flipping a switch.

Just note the E-Brake system should never be disconnected. You need to make sure it is working whenever you are pulling. Even if you forgot to flip the disconnect switch before leaving home.

Example of a multimeter with an amp clamp
https://www.amazon.com/Klein-Tools-C...ustrial&sr=1-8

Wow, excellent explanation, thank you

[2021JayFlight28BHS]

Can always add your own disconnect closer to battery to make sure you don’t have parasitic draws, and then rewire the brake to bypass the new disconnect. That’s what I did at least.

[Springhook]

Are the battery caps screw on type? Seems it would take lots of pressure to pop off a screwed on cap. Possibly the cap was not screwed on tight to begin with. Just sayin...

[sjandkf]

Was not connected to any power. I always check that front compartment when I get home cause I keep my tools in that area also. When I smelled the gas, I let it air out for a bit before I disconnected the terminal. Nothing else was being charged.

[sjandkf]

No, they were the three caps all together. Never seen that before.

[16WhiteColly]

On most batteries, them caps fit pretty tight, it took some pressure to get it to pop off. I believe, I would replace that battery and not take any chances.

[SmokerBill]

Any kids in the neighborhood that might have been able to access the battery while you weren't looking???