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Topic: Unusual Battery Monitor Readings (Read 309 times) previous topic - next topic - Topic derived from Re: Battery advice?
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Unusual Battery Monitor Readings
Looking for suggestions to troubleshoot these unusual battery monitor readings while RV is sitting at home outside with nothing on other than solar charging system doing its thing.

The unusual Volt/Amp readings have been like this:
* before_equalize_day.jpg:  +13.5V/-17.3A (-17 with nothing on - WTH?)
* before_equalize_night.jpb: 12.8V/+4.8A (+4 with no incoming charge - WTH?)

Is it really a symptom of one or more "baked" batteries per AM Solar or something else?

A couple of months ago I noticed my battery monitor day/night readings were the opposite of normal.  I usually check it while picking up after the poopers during the day and again at night while letting them out to doo it all over again.

Typical Volt/Amp readings have been like so:
* after_equalize_day.jpg:  +13.5V/+.5A
* after_equalize_night.jpg: 12.8V/-.4A night.

I've had the rig since Apr 2016.  The PO had AM Solar install the following around Oct 2013.
* Blue Sky SB3024iL controller with IPN ProRemote display/monitor
* 5 100A AGM Lifeline GPL-27T batteries
* 3 150W Panels
* Magnum MS2000 inverter with ME-RC remote display

Electrical related changes I did prior to the unusual readings:
* dropped the total amps in the Blue Sky controller config from 500A to 400A based on info I read here and elsewhere just for grins.
* reconfigured RV side plug to match toad side harness plug .
* connected existing toad charge line PO had installed to chassis battery with 15A circuit breaker.

When the unusual readings started I pulled all the DC fuses on the panel plus the one on the propane detector but it made no difference in the unusual day/night readings.  Also disconnected toad charge line to get back to square one.

I emailed this info to AM Solar late on a Friday afternoon a few weeks ago seeking DIY troubleshooting tips and got a call back from Roger within 15min.  That was a pleasant surprise.

Roger thought the batteries were probably "baked" since they are nearing EOL at around 5yrs. He explained the battery monitor readings are unreliable if batteries bad.

He recommended this to squeeze a bit more life out of them until they can be replaced.
* reset total amps back to 500A.  AM Solar (Roger) doesn't recommend adjusting the total AMPs over time - I assume since the IPN ProRemote monitor ?is? smart enough to auto adjust charge efficiency but he didn't qualify and I didn't think to ask when on the phone.
* Plug in RV to shore power and do an equalization using the inverter to bring the batteries to full charge.
* After equalization reboot solar controller by disconnecting from PV array and batteries and then reconnecting.  This is so controller can relearn how to charge batteries to 100% after equalizing them to full charge.

After equalizing the batteries the readings returned to normal per the after_equalize pics and have remained so for the most part.  I have seen the day time readings with a small negative (-) amp draw on occasion but have not seen the positive (+) night readings yet.

Steve's recommendation on another "battery replacement" post motivated me to do the "at rest" voltage test to see if one or more batteries may be an issue.

Quote from: Steve  - 
Disconnect all charging sources for 24 hrs (shorepower, solar) and check voltage. If less than 12V, you may already have bad cells. If 12.5V or higher, they are still good, if reduced in capacity from age.

The results are in volts_at_rest.jpg.

The numbers look OK to my untrained eye though battery 2 seems to be in slightly better shape than the other 4.  Any advice is appreciated.

According to Lifeline docs they depreciate about 2% a month and mine are in the 3% to 6% range according to my calc - so is that in the ball park for nearly 5yr old batteries  or even related to the unusual readings?

My plan now is to hook them back up and draw them down during the night to see if they charge up to 100% during the day and/or if one or more dips significantly more than the others.

Any other suggestions?

I prefer to wait until next winter/spring to replace the batteries if these can get us thru the summer/fall.  We probably won't use the RV more than 10 to 20 boondocking nights between now and next spring so hardly seems worth expense to get 5 new batteries now if these can last thru the summer/fall.

Plus I'd like to know the cause of the unusual battery monitor readings if/when they return.  Equalizing does seem to have made a difference for now.  Though they always read at100% by nightfall before equalizing.

Truth is we really don't "need" 500amps worth of batteries for our usual 2 to 3 night trip but that's what the rig is equipped with so would like to keep it that way.

Rich M.
2006 MB
Re: Unusual Battery Monitor Readings
Reply #1 –
Well, I don't get what AMSolar did, but equalization should be done infrequently, if at all. I would start by disconnecting the 12V batteries from the coach and each other, and measuring the voltage of each at that time and several hours later. That will let you know what their condition is. Check with Lifeline for their recommended equalization schedule.  IF everything looks ok at that point, then perhaps there is a problem with the installation or the Blue Sky controller.

Steve
2004 FL
2013 Honda Fit
Re: Unusual Battery Monitor Readings
Reply #2 –
I disconnected the batteries based on recommendation you made in another post and I have been checking them daily the past six days:  4 are at 12.8+V and one is 12.9+ after six days.

Contacting Lifeline is a good tip.  Decided to check their web site out last night first and found the Lifeline Technical Manual  very helpful.

It has the info needed for testing their batteries.  AM Solar's recommendation to equalize does match up with info in the tech doc to me.    Other battery tidbits I thought interesting are - though not all related to my setup:
* routine conditioning/equalizing is OK if done using their guidelines.  The PO or AM Solar configured this solar controller for 4hrs every 30 days which is in range of Lifeline guidelines.
* it's OK for parallel strings to have different battery sizes as long as each string has the same size
* it's OK to replace one string of a multi-string parallel setup; so OK to have one old string and one new string
* 100% SOC is 12.78 for aged batteries.  4 of mine are 12.8+ and one is 12.9+ after 6 days so that seems to be a good sign.

Think I will try drawing them down to do the capacity tests but reading this leads me to believe the batteries are not "baked" or don't have any dead cells.

Still doesn't explain the unusual battery monitor readings so if they return will follow your advice to contact Blue Sky if can't resolve after doing a little more homework.

Thanks,

Rich M.

2006 MB
Re: Unusual Battery Monitor Readings
Reply #3 –
Hi Rich. Your batteries sound fine from here. I would suspect the connections going to your shunt. It is a small value resistor usually mounted in the ground lead closest to the main battery (in the original battery box?) The signal there is in the millivolt range and even just a little corrosion can cause 'flaky' readings at the display.   RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Unusual Battery Monitor Readings
Reply #4 –
Quote from: RonB  - 
I would suspect the connections going to your shunt.
I did try tightening the battery and monitor terminals on the shunt.  They did not budge.

It's under the fridge in upper right of latest pic.

It  looks clean but will take a closer look before hooking up the batteries again this weekend.
2006 MB