Odd Battery Behavior

Riffraff · 01-28-2019, 03:27 PM

I'd have searched for a solution to this... but not sure how you'd search for "weird battery occurrence that seems to make no sense" !?

5th wheel. In use Full time for past 5 years. 2 12v batteries in parrallel. Slightly over a year ago converter failed. At that time installed new converter and replaced batteries with 2 new AGM types. Also attached a Deltran wireless monitor - just because. No issues at all since that time.

Wintering at present. Full hookups at same campsite for past 2 months. Two weeks ago I get a notice on the wireless monitor of low battery state. Why - I've no idea. Been no change in use nor any indication of issues seen. The alert shows 38% charge on the batterys and voltage of 11.86 (essentially dead...).

I confirm that with multimeter. Check the distribution panel for reverse polarity fuses, just in case, but our panel has none.

Put on a trickle charger/maintainer. In a few hours the batteries are up up to 100% and 13.5v. Again, confirmed with multimeter. So I disconnect it and have been monitoring the batteries for the past 2 weeks. While the monitor has continued to show a full 100% charge, the voltage has very slowly been dropping back down over the 2 weeks. Confirmed every couple of days with the multimeter. They are presently showing 12.75v.

So - no idea what could have caused the initial drop. No idea why, with the exception of the slow voltage drop, they have since held at 100%. Yes, we are connected to campground power via 50amp cord and internally there have been no signs of 12 or 120v problems.

Possibly I'm missing something obvious but darn if I can explain this situation. I'd appreciate any thoughts, advice, things to look for or address... whatever.

Thanks in advance !

KeithInUpstateNY · 01-28-2019, 03:42 PM

I can't explain the sudden voltage drop, but AGM batteries require a different charging profile than standard lead acid batteries. You didn't say what model charge controller you installed. I ended up turning off the breaker for the. WFCO charge controller and using my Schmucher charger that has an AGM setting when I was boondocking last summer and running my generator to recharge the batteries. If the proper charging profile isn't used over time the capacity of the batteries can be diminished.

I haven't decided if I am going to upgrade my charge controller or take the AGM batteries to the cabin and go back to lead acid batteries in the camper.

Bostongone · 01-28-2019, 03:46 PM

First item is that you have reverse polarity fuses, just haven’t found them yet. Second quick check you could you could do prior to looking for the fuses is to lift the positive lead from the converter at the battery and with the converter on you should measure around 13.5 volts which would indicate that your converter is working. If no voltage time to look for those fuses although if you have been working fine there is no good reason they would open?

**sourdough** · 01-28-2019, 04:03 PM

Quote:

Originally Posted by compeakw

I can't explain the sudden voltage drop, but AGM batteries require a different charging profile than standard lead acid batteries. You didn't say what model charge controller you installed. I ended up turning off the breaker for the. WFCO charge controller and using my Schmucher charger that has an AGM setting when I was boondocking last summer and running my generator to recharge the batteries. If the proper charging profile isn't used over time the capacity of the batteries can be diminished.

I haven't decided if I am going to upgrade my charge controller or take the AGM batteries to the cabin and go back to lead acid batteries in the camper.

This is what I'm thinking ^^^^^. If you just took out the regular batteries and put in AGMs I believe it will cause you the types of issues you are dealing with. When replacing mine I had thought about AGM because it is such a pain to constantly check the water in mine but everything I read indicated I would have to go to a different charging system so just installed a watering system for my lead acids.

KeithInUpstateNY · 01-28-2019, 05:05 PM

I chased a phantom draw for a couple of weeks (there wasn't one) before I figured out the charge controller was the likely culprit.

I picked up my Schumacher charger the next time I was home and noticed an improvement almost immediately. I got even better performance once I invested in an Optima charger designed specifically for AGM batteries. I didn't do an actual load test and obviously day to day use varies when you are boondocking, but I was getting precharging voltages of 12.2 with the WFCO charger controller. With the Schumacher I was at about 12.4 and the Optima I was often only down to 12.5.

Riffraff · 01-28-2019, 07:18 PM

The replies are greatly appreciated.

My charger/maintainer is a NOCO Genius G7200 Smart Battery Charger, chosen specifically because it has an AGM charge setting. Which is what I used to bring the batteries back up to normal.

There appear to be a couple things mentioned I'd like a clarification on if possible...

First - would be the "different charging profile / model charge controller" references. Is there some aspect of the distribution panel and/or the converter that I'm not aware of and should look into to provide whats needed to feed those AGM batteries? As mentioned, everything has functioned fine for over a year but that doesn't mean I've covered all the bases...

Second - would be the "reverse polarity fuses, just haven’t found them yet" aspect. My GUESS is that since there are none in my panel, that perhaps there is some "other type" that might be in use somewhere downstream of the converter? If that's a possibility what might they look like?

(I'd think, given that some sort of charge -has- reached the batteries since the incident since they are still in a full charge state, that it would almost have to be some kind of auto reset... but what do I know?)

Again, my thanks and look forward to what info might be offered.

Bostongone · 01-29-2019, 07:32 AM

The fact that your batteries continue to drop from the 13.5 to 12.75 tells me that your converter is not in the picture for some reason. You have charged the batteries with your separate charger/maintainer and then with shore power on the trailer the battery voltage drops. I’m thinking that with the shore power connected the converter is supplying all of your 12 volt needs and the battery is not being drawn down or is not even needed. I again suggest lifting the positive feed from the converter from the batteries and measuring the converter output. Then we might have an established fact?

ChuckS · 01-29-2019, 08:21 AM

If this is what you are using it’s no where near enough amperage capacity.

https://web.bootman.nl/manuals/28-g7200_manual.pdf

traceintime · 01-29-2019, 09:13 AM

Just a thought but being winter and how we tend to use more lights, furnace on more and other 12V loads is it possible that you are using slightly more dc amps than your new converter can put out. Consequently your battery is being drawn down just a little bit each day to keep up with the extra load and eventually running down. If you installed a shunt on your battery bank you could set it up to monitor the amps in or the amps out and see what happens, google shunts and battery monitoring if you're not familiar with them. Can't comment on the AGM issue but I would definitely look into that a little more as it is a valid point.

Good luck
Steve

Riffraff · 01-29-2019, 04:35 PM

Bostongone - I would love to remove the positive feed from the converter from the batteries and measure the converter output... if I could find it. Which seems kind of ridiculous but darn if I can. Despite contortions and tracing lines in and out of the battery compartment I can't spot it. In my case primary battery negative runs to frame while positive runs to a 2 post (what I assume is a) circuit breaker. What comes off THAT is a cable to the hydraulic pump, and a second short cable to the 2nd circuit breaker in the line of 3 of them.

I did open up the storage area to get to the converter again, and I do measure 13.7v coming -into- it. Any recommendations welcomed to find that output cable!

And, I suspect at this point you may be correct that the converter is not feeding the batteries. They just are not being drawn on given the shore power. Somewhat belatedly I considered the possibility that for an unknown reason the reverse polarity fuses (which I found actually on the converter itself) blew. I intend to pick up some 40amp tomorrow and swap them out. Can't hurt...

ChuckS - the g7200 is not in use normally. I simply used it to bring the batteries up to full, then removed it.

Again, do appreciate all taking time to try to assist!

Bostongone · 01-29-2019, 06:10 PM

Something is missing here. You should have a pretty heavy gauge wire coming off of the batteries to the thermal breakers for the hydraulics and whatever else the other breaker feeds but the heavy gauge wire should continue uninterrupted to the converter output. The 13.7 volts you see is coming out of the converter. It may be that when you installed the AGM batteries that somehow a cable was missed. Hard to understand but a connection is missing?

Bostongone · 01-29-2019, 06:12 PM

Also should be able to do a quick continuity check of the 40 amp reverse polarity fuses with the multimeter. That could still explain the missing voltage.

Riffraff · 01-30-2019, 05:17 PM

So... I guess I still have a mystery on my hands, but - seem to have the problem resolved (hopefully). After obtaining some 40 amp fuses I tackled the converter.
(which in my case is a royal pain. I'd tidied the area as much as possible when I installed the new one last year but it still has water lines and innumerable electrical lines running over and around it. Asinine install at factory).

Pulled the reverse polarity fuses. They were fine visually. However, ONE was bad per a multimeter check. The other was ok. Regardless, I changed both of them out. Lo and behold, the batteries are getting current. and back up to 13.5v.

Apparently I misread the situation. I believed that the batteries were still getting current after the "drop" episode. Perhaps they were not, and the voltage drop over a couple weeks was just an ongoing discharge.

That does not explain what the heck happened originally - just a badly constructed fuse, maybe. On the other hand it functioned just fine for over a year. And the 2nd fuse still being good... geez!

I will of course keep an eye on things for another week or two to be sure... and hopefully will not need to come back asking for input on this one.

Having said that, I'd definitely appreciate some further education on a couple aspects of the situation..............

Bostongone - "but the heavy gauge wire should continue uninterrupted to the converter output" it doesn't. Be happy to post a couple pic's of the setup if you think it might generate pointing to where it IS. I'd love to know. My thanks.

I'm still a little concerned regarding the references to "charging profile / charge controller". I'm not dealing with a solar setup, just standard installation. But if there is an aspect I should be considering relative to my distribution panel and/or converter and those AGM batteries, I would love to get some clarification.

Thanks to all !

Bostongone · 01-31-2019, 07:50 AM

Riffraf, glad that things are back to normal and the converter seems to be connected to the battteries! You said “Odd” in your title and it certainly turned out to be. A 40 amp fuse opening due to an internal mechanical issue is something that doesn’t happen very often!
As far as finding how the battery is actually connected to the battery you mentioned that the current cable coming from the batteries positive goes to a series of two terminal thermal circuit breakers and nowhere else. If that is the case one of these breakers must be installed to prevent a catastrophic short to ground of the cable going to the charger. You could try lifting the wire from the secondary post of each of them with the converter off and then turn the converter on and see if you get the 13.5 volts on one of the lifted leads?

As to the AGM issue your NOCO Genius charger does have a AGM charging option but you did not state what type of converter you replaced your faulty one with. Compeakw said he installed a Optima converter which does handle AGM batteries. I am not sure how that is done but I have to assume that when setting up the Optima converter that some switches or jumpers may need to be set? Compeakw, could you comment on this?

Most things I have read (recently) on AGM batteries seems to agree that while they are superior in some regards they do have a different charging profile from wet cells and would benefit from a converter tailored to their chemistries/construction.
Again, glad your Converter is talking to your batteries again!

KeithInUpstateNY · 01-31-2019, 10:32 AM

Quote:

Originally Posted by Bostongone

As to the AGM issue your NOCO Genius charger does have a AGM charging option but you did not state what type of converter you replaced your faulty one with. Compeakw said he installed a Optima converter which does handle AGM batteries. I am not sure how that is done but I have to assume that when setting up the Optima converter that some switches or jumpers may need to be set? Compeakw, could you comment on this?

The Optima charger is not a charger/converter, it is just a charger like the Schumacher more people are familiar with, but designed specifically for AGM batteries, though it does have settings for standard lead acid batteries. It is manufactured by Optima, who make AGM batteries, exclusively I believe, and is available on Amazon. I used it the same way I used the Schumacher charger. I turned off the charger/converter at the breaker and connected the Optima charger to the batteries on the tongue while the generator was running. The charging profile seemed to work slightly better than the Schumacher AGM profile. Of course it was also more than twice as expensive as the Schumacher charger.

UPDATE: I have taken my AGM batteries to my cabin where I have a small solar system with the appropriate Renogy charge controller and will go back to standard lead acid batteries on my camper so I don't have to replace the charger/controller. Initially I will use the 12V batteries wired in parallel that the AGM batteries replaced. They have been at the cabin and are still fine, even though they are past their 2 year warranty period. When it is time to replace them I will make a decision between new 12V batteries wired in parallel or 6V batteries wired in series.

This is pretty long so I will try to address the charging profile question of the OP in another post.

Edit: I should have said do not have to replace the charger controller immediately. Replacing it is on the "to-do" project list as even lead acid batteries will benefit from a better multi-stage charger and it should also reduce the charge time, allowing fewer hours on the generator every day when I'm boondocking.

MrEnto · 02-03-2019, 09:28 AM

Bad grounds can create strange anomalies?

BadmanRick · 02-03-2019, 09:55 AM

FYI I have a AC/DC Converter WFCO 8900- 55 Amp/ 5 amp charge w/float
Input: 120 Vac
Output: Absorption 13.6 Vdc range (includes charging and load); Bulk 14.4 Vdc range; Float 13.2 Vdc range.
Mod WF8955PEC
Which came standard on my 2011 Bullet Premier 19FBPR. In 2013 I installed an Optima 31m AGM Battery. Have not had any problem since install. Still using same mastery after 5 years. The converter automatically adjusts for AGM batteries.

SR71 Jet Mech · 02-03-2019, 05:05 PM

As an auto technician over many years I have seen a few times that ATO fuses will crack internally as would the older AGC fuses. With the bouncing of an RV or just possibly a defective fuse could explain the failure. Most of these you can’t see with out a meter.
In the same career field I had a great understanding of 12v and 24v dc power distribution systems (I thought). Once I started researching and building my solar setup for my RV, I found out how little I knew about battery charging and maintaining especially of AGM and deep cycle batteries. My first upgrade was to the converter charger that came with the RV to a 4 stage charger. Those however do not have a programmable charging curve. As stated above 14.4 bulk, 13.6 absorption, and 13.2 float. Mine also will equalize every 30 days. I then added an inverter charger that is totally programmable. Both of my solar chargers are as well programmable. There are different charging voltage rates and times for FLA, AGM and gel batteries I have 4 6v batteries and all 3 of the “good” chargers have profiles of 14.8 bulk, 14.0v absorption, and float at 13.2. They also all 3 have an equalization I can set on or off and set the frequency it equalizes.
If you plug in all the time all this info doesn’t mean much, but if you boondock it’s pretty important.

Jusy my $.02

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