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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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