More power problems

[bkenobi]

I thought I had my power problems sorted out on my NL 10-2 but I just found out that's not the case. We haven't used it in a few weeks (4-5 if memory serves). When we got back, I unloaded the camper and plugged it into ground power. I pulled the batteries and took them to Interstate to make sure they were good. Initially they said 1 had a dead cell but later called back to let me know they were good.

Tonight we drove 2.5 hours with nothing turned on (yes, I checked the fridge). Prior to leaving, the batteries reported 12.5v or so. We stopped for the night and they are at 10.4v. I am completely lost on how they could be draining when they should be charging at 2A.

[bkenobi]

Interstate confirmed a bad cell on one battery and warranty replaced it. I'm crossing my fingers that all electrical issues are behind me!

[Sam_Spade]

bkenobi wrote:
The outboard cell dropped to 3.0v under load and returned to 12.12v. I'd say there's an issue with the outboard battery!

NO, really ?? :B

Sorry couldn't resist.
Good job with the testing.
Now it's off to the battery store.

And good luck getting them to "upgrade" with a warranty replacement, even if you pay extra.

If they are receptive to that, you might want to discuss two 6 volts if there is room. That often gives you more total capacity. And AGMs should give you longer life.

[bkenobi]

I think I've already said that's the plan. Interstate isn't open on Sundays and I was following other users suggestions on what to check first. Fwiw, I've already had the batteries in for testing at interstate twice and the dealership checked them once. Since they were brand new when I bought the camper, warranty would be appropriate. However, I want to be sure that pushing for the replacement is not a waste of time. I tried to get them replaced last time I dropped them for testing but interstate changed their mind at the last minute.

I appreciate all the suggestions even if it's perceived that I'm ignoring them.

[996Pilot]

There's a WHOLE bunch of suggestions here HINTING that you probably have a dead/shorted cell. I'm dying to see if you check for that or just keep doing what you're doing. :S

[bkenobi]

I've recorded voltage on both batteries for the last 2 days without anything connected (1 side of battery disconnected on each). I could post a table, but basically the inboard battery dropped from 12.65v to 12.54v and the outboard dropped from 12.65v to 12.40v. I wasn't convinced this proved anything conclusive, so I dug out my load tester. The inboard battery dropped to 11.5v under heavy load and recovered after removed. The outboard cell dropped to 3.0v under load and returned to 12.12v. I'd say there's an issue with the outboard battery!

[bkenobi]

I contacted Interstate today. They said they can warranty the batteries for me if one tests bad. If they decide they're bad, I may see if I can upgrade while I'm at it since these are the smallest available.

[996Pilot]

Have you used a hydrometer on the batteries to test each cell? Easy test to see if one cell is completely out of the ballpark. I've also used a meter to test individual cells by attaching a piece of copper wire to one meter lead and dipping the wire into each cell while the other meter lead is attached to a battery post. The reading should be 2.0 - 2.1 volts on the cell closest to the post the meter is attached to and another 2.0 - 2.1 for each of the next cells e.g., 2.1, 4.2, 6.3, 8.4, 10.5, 12.6. If you get to one (say 4.2 on the second cell) and the next one doesn't add up (say 4.6 0r 4.8V) then you've isolated the bad cell.

You really need to check the health of each cell of each battery. Sounds like an intermittent bad cell on one battery. It will show up with an individual cell test - quickly.

One bad/shorted cell on one battery will drag the other battery down - either to its level or close.

Get out there and test cells - then get back on here with your results.

[time2roll]

bkenobi wrote:
* the batteries were charged until this morning (4 days) when I disconnected from ground power and drove to the insurance adjuster. The batteries should have been maintained during transit at 2A. The combined batteries were providing 11.8-12.0v after 2 hours unplugged.

Good chance one of the batteries has a shorted cell or has failed.
Should hold 12.6 fairly easy when charged and disconnected.

13.8 is a slow trickle charge and still 4 days should have them very close to full. If you have a portable battery charger maybe use it on one battery at a time.

Probably looking at 2 new batteries.

[HMS_Beagle]

I would attack this with a clamp on DC ammeter. You need one that will measure DC current down to 20 ma or so - these are now available for less than $50. With this you can clamp it onto wires starting at the battery and working back towards the panel to see what (if anything) is drawing sufficient current to drag the batteries down. This is much easier and more informative than measuring voltages, which are a result, rather than the cause.

[Sam_Spade]

bkenobi wrote:
The batteries should have been maintained during transit at 2A.

From what source ?

IF the system really is designed to charge in transit, there usually is a solenoid that closes to charge the house batteries from the chassis alternator......but that would not be limited to 2 Amps.

Both of the used RVs I've bought recently had that solenoid bad. The last one called it a "battery isolator".

More tests are needed, including testing that "charging in transit" source that you think should be present.

P.S. The breaker tripping would tend to indicate that the converter/charger is drawing a REALLY high initial current, maybe indicating that the batteries are indeed weak.

[bkenobi]

time2roll wrote:
You have a lot of stuff going on. My solution with electrical issues is to divide and conquer.

You have at least three components in play. Two batteries and a converter that all provide 12 volt nominal power.

First disconnect one terminal at each battery and plug in the main cord. The converter should provide about 13.6 volts very steady. All systems should work.

Assuming that works connect the two batteries and let them charge 72 hours. Check twice a day for excessive heat or gassing that would indicate a shorted cell. Voltage should be same as the converter at about 13.6 volts right on the battery terminals. If batteries are low on charge the voltage should steadily climb to 13.6 volts over 2 to 6 hours.

Assuming that all seems good disconnect the batteries again and monitor the battery voltage disconnected for several days. Battery voltage should drop from 13.6 volts to 12.65 in about a day and then hold for at least three more days.

Post the results and we can go from there.

I have not posted results yet as I was delayed by an incident. Someone ran into the back of the camper and left without leaving a note (hit and run). I've been learning about insurance this week. 😞 I think the camper will be ok, but it really messed up the left rear compartment the jack is attached to.

I'm assuming it can be fixed, so the results so far:
* the converter provides a steady 13.8v. All systems functional.
* the batteries were charged until this morning (4 days) when I disconnected from ground power and drove to the insurance adjuster. The batteries should have been maintained during transit at 2A. The combined batteries were providing 11.8-12.0v after 2 hours unplugged.

I will charge the batteries again and perform the proper tests.

One other thing that I've noticed that's probably unrelated and maybe a non-issue. Most of the time when I plug in to the house, I pop the house breaker. I'm connecting the camper to a 25' 10ga extension cord (fed under garage door), then to an outlet inside the garage, which runs to the main panel with a GFCI breaker. I can reset the breaker and if it stays set, it will never pop again while it's connected.

[Sam_Spade]

bkenobi wrote:
I have no problem buying a pair of batteries, a generator, some level of solar, etc. I have a problem buying something without knowing it will help or understanding the problem I'm trying to solve.

Good for you.

Assuming that the batteries are 12 V each and are wired in parallel.....The kind of problem you are seeing is EXACTLY why the consensus recommendation is to NOT do 2 twelves in parallel because if one goes bad it drags BOTH down and complicates the testing.

You need to catch it when it is down around 10.5 and then disconnect enough cables that you can measure each battery individually with the converter OFF.

Hopefully that will let you identify which one is really going bad.

If that doesn't work, you can run the system for a while on only ONE battery to see which one is bad.

BUT.....if both have really gone down to 10.5 or below several times and stayed like that very long, then even the "good" one probably has been weakened too.

[bkenobi]

I have no problem buying a pair of batteries, a generator, some level of solar, etc. I have a problem buying something without knowing it will help or understanding the problem I'm trying to solve. It doesn't matter what the problem with the battery is (if it's bad), I'll replace it. But, if I have a bad converter, replacing new (March 2017) batteries doesn't make sense unless it's really cheap. $300 for a pair of batteries would be a nice fix but not cheap if I'm just throwing out new batteries.

[Photomike]

If you want to learn about batteries and connections, a good read.

12V side of Life