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Apollo11 09-20-2020 04:43 PM

House Battery Issue?
 
1 Attachment(s)
Since I got my rv back from the mechanic Ive been having house battery issues. When I dropped it off I had the batteries switched off so somewhere along the line they were turned on and drained. Well now im recharging them and I noticed something yesterday while cleaning the terminals- the metal bracket/ handles that are holding the house batteries down are corroding, to the point of rotting away. Does that mean I have positive to ground somewhere or will just grounding to the frame do that on its own without positive juice? Pictures included.

twinboat 09-20-2020 05:39 PM

No, thats from the acid fumes, created by charging the batteries, settling on the steel.

It corrodes them over time if you don't rinse them off often. It didn't happen fast.

Next battery change you may need to replace them. Look for plastic type.

Apollo11 09-20-2020 05:46 PM

That new battery change may happen soon, I think my batteries are bad after sitting at the mechanics for a couple months... apparently they drained and sat dead for some time. Thanks for the reply.

AnotherMike 09-20-2020 09:07 PM

One trick... a mechanics trick from the 1930s... my dad learned it from a motor pool mechanic in WW2.

Smear petroleum jelly on the metal that you don't want acid fumes to rot away.
It also prevents the creeping green glop on the battery posts and battery cable connectors.

Yes, it's messy, but it is cheap and it works.

Mike

HarryStone 09-21-2020 12:09 AM

Rustoleum paint

Apollo11 09-23-2020 05:14 PM

Topped off my battery cells, cleaned the terminals and the problem went away (the bad battery problem, not the decaying metal handle problem, I'll fix that with petroleum jelly or paint) . I like cheap fixes.

Apollo11 09-24-2020 01:50 PM

I have a question for you experienced people... when running the generator and air conditioning, maybe a light or two but that's it, is it normal for the blade fuses in the "house" fuse box to get warm? I'm talking in the mid 90 degree area. Ive always been told that warm wires mean loose wires but it seems like some warming might be normal?

twinboat 09-24-2020 02:10 PM

It could be heat radiating from the circuit breakers, but with a few lights on, heat on the 12 volt fuses seems odd.

Apollo11 09-25-2020 02:18 PM

Quote:

Originally Posted by twinboat (Post 5453733)
It could be heat radiating from the circuit breakers, but with a few lights on, heat on the 12 volt fuses seems odd.

A few lights and the air conditioner (if that makes a difference).

It seems like a general warming of ther board instead of individual fuses I think. Kinda hard to tell exactly.

HarryStone 09-27-2020 05:16 PM

Get a handheld temp sensor. You can find out exactly where the heat is coming from.

Apollo11 10-19-2020 10:15 PM

Quote:

Originally Posted by Apollo11 (Post 5453721)
I have a question for you experienced people... when running the generator and air conditioning, maybe a light or two but that's it, is it normal for the blade fuses in the "house" fuse box to get warm? I'm talking in the mid 90 degree area. Ive always been told that warm wires mean loose wires but it seems like some warming might be normal?

I need to update this, the air conditioner doesn't play any roll in this, idk what I was thinking.

But just by turning on 3 or 4 overhead lights inside, after a little while I hear the fuse box fan kick on, so i checked again and the blade fuses are really hot... hot enough to make me instinctually pull my hand back. But none have blown.

Does anyone know off hand if theirs does this, iow, normal, or is this abnormal?

I'll do another temp reading tomorrow and see exactly how hot they're actually getting.

HarryStone 10-19-2020 10:59 PM

How easy or hard are the fuses to remove? It could be there is a bit of corrosion on the blade, or the spring grip has weakened a bit, allowing a bit of resistance, which causes heat.

twinboat 10-19-2020 11:44 PM

The converter/charger is built into the bottom of the fuse/breaker box.

The harder that works, the more heat it makes. As it gets hot, the cooling fan runs to cool it.

If its running real hot, you may have a battery problem.
How long do your lights run without shore power ? If they do out in a few hours, the battery is bad.

Another test, is to see if things cool down, when you switch the battery disconnect switch off, while on shore power. That takes the battery out of the circuit but leaves the converter/charger powering the lights. If it runs cool like that, its another sign of a bad battery.

Apollo11 10-20-2020 08:59 AM

I'll see how hard they are to remove today.

I took both batteries to auto zone and had them test them. Their tester said they're both good batteries. Idk how reliable those are, could the guy have tested it wrong, therefore ending up with a false reading?

Unfortunately I can't disconnect battery on shore power unless i physically disconnect. The switch turns on automatically when plugged in.

Mark_K5LXP 10-20-2020 12:37 PM

Petroleum jelly is OK but is a pretty light duty grease. I use high temperature wheel bearing grease on all terminations and it's less likely to wick/creep along surfaces and make a mess.


Corrosion of nearby surfaces can be caused by acid vapors but is more often caused by escaped electrolyte. If batteries are gassing/weeping electrolyte to any large degree it's implied they're being overcharged. My batteries are in their third season and there's nothing more than a light coating of dust on the tops and zero corrosion anywhere.


The test done at auto parts stores can tell you if a battery is "bad" but little in the way of how "good" it is. If you want to know how "good" a deep cycle battery is, a discharge capacity test will reveal it's actual vs spec'd amp hours.


Are the fuses getting hot from current running through them, or being warmed by being in proximity to heat from the converter? Seems odd that multiple fuses would be getting warm at once.



Mark B.
Albuquerque, NM

Apollo11 10-21-2020 09:01 AM

Quote:

Originally Posted by Mark_K5LXP (Post 5488289)
Petroleum jelly is OK but is a pretty light duty grease. I use high temperature wheel bearing grease on all terminations and it's less likely to wick/creep along surfaces and make a mess.


Corrosion of nearby surfaces can be caused by acid vapors but is more often caused by escaped electrolyte. If batteries are gassing/weeping electrolyte to any large degree it's implied they're being overcharged. My batteries are in their third season and there's nothing more than a light coating of dust on the tops and zero corrosion anywhere.


The test done at auto parts stores can tell you if a battery is "bad" but little in the way of how "good" it is. If you want to know how "good" a deep cycle battery is, a discharge capacity test will reveal it's actual vs spec'd amp hours.


Are the fuses getting hot from current running through them, or being warmed by being in proximity to heat from the converter? Seems odd that multiple fuses would be getting warm at once.



Mark B.
Albuquerque, NM

How would one go about doing a discharge capacity test?

I leave my shore power plugged in all the time, which means the batteries are on charge all the time. Do you think the RV is overcharging them? I figured it would have enough engineering to switch to trickle charge if needed.

HarryStone 10-21-2020 06:42 PM

Normally, if you overcharge wet batteries, it will become apparent with a loss of water in the cells or a bulging of the battery case.

Mark_K5LXP 10-22-2020 09:35 AM

Quote:

Originally Posted by Apollo11 (Post 5489260)
the batteries are on charge all the time. Do you think the RV is overcharging them?

What anyone would think is irrelevant because no one knows how your system was designed and what if anything has changed or failed since it was built. So it comes down to empirical measurement do discover what's going on, or prove everything is fine.

Quote:

I figured it would have enough engineering to switch to trickle charge if needed.
In an ideal world that's true. Let me know when you get there. :)

Most converters today are smart enough to do decent charge management. It's surprising though how long it took the RV industry to start incorporating those once they became available. The exent of their smarts though can only go so far. If your batteries are starting to give out for any one of a dozen reasons, some terminals or connections are compromised or some other component in the system is having an issue then the exact outcome can become arbitrary. So some manual testing and verification comes into play.

Most auto store "testers" put some kind of a load on the battery and monitor the voltage to see if it changes in some predicted way. For the most part it will tell you if the battery is charged and will detect significant issues like bad cells and interconnects, and performance degradation if it's severe enough. It's a quick go/no-go test. But these tests won't tell you anything about how many amp hours are in a storage battery. The only way to do that with any degree of certainty is to hook up a load and run it.

A capacity test can be pretty simple to do. Takes a load, a voltmeter and a clock. For a load I use an inexpensive AC inverter and some 120V incancesent light bulbs. Mix and match different bulb wattages to get the DC current you need. To keep things simple you use the 20 hour rate of the batteries. So for a 220Ah GC2 that would be an 11 amp load. You start with batteries at full charge and if your converter offers it, run an equalize cycle first. Connect the voltmeter, the load and start the clock. From there you're just counting time until the voltmeter reads 10.5V. A good battery will run the load at least 20 hours. If it runs it for 15 hours, your battery is about 75%. If it runs it 10 hours, 50%. That's it. Once you have your number you can decide if that's good enough for what loads and times you need to run. I then use the discharged batteries as an opportunity to see how long it takes for my converter to bring them back to full charge and if it correctly runs through its' cycles.

Many would say that's a lot of messing around. I view it as just another maintenance task I do like changing the oil or checking tire pressures. I'd rather know my batteries and converter are working right sitting in my driveway than discover they're not when I'm somewhere I can't do anything about it. I usually run a capacity test when I de-winterize so there are no surprises during upcoming season, then again when I winterize just to see where they're at after a season of use.

Mark B.
Albuquerque, NM


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