AGM Battery Charging when camper is stored

jbajor

Greetings!  What is the general consensus on keeping battery charged when not using camper?  I have been keeping my camper on 20 amp hook up in my driveway when not in use to keep the refrigerator running as well as other electrical incidentals.  Battery is also left ‘on’ so it is seeing charge from victron.  I was just out dry camping and found that battery was not holding charge (2 years old).  Did I cook it by leaving it on all the time?  Should I start turning it off and put it on a trickle charger? What are others experiences and solutions?  Cheers!

jbajor

An additional comment…. I checked the victron and it is set for ‘gel victron deep discharge’ for battery type.  The only available choice for Agm is ‘spiral’.  Is my setting completely wrong?

pthomas745

Victron is in a class by itself with strange terminology. I know there are "spiral" designed lead acid batteries, and AGM designs that advertise themselves as "Gel" types.  Bottom line: they are AGM batteries. 

What you are seeing on the Victron app, if you are plugged in to shore power, is the charging coming from the trailer's converter.  The converter is simply a battery charger, also, so a separate charger is not needed.

What exactly are you seeing when you use your Victron to read the battery status?  Is the trailer battery switch "on" when you take these readings?  If the battery switch is on, and anything is running in the trailer, that voltage readout for your battery is "false".  It will always read low if the battery is "in use". 

What does your Victron app show you for solar charging during your trip?  Look over the history page....and if you can, show us some screen shots of the data.

jbajor

I will send some screen shots… it has always worked well until last night when battery voltage rapidly decrease in the evening (no solar) to the point where my refrigerator stopped running…. Charging now on solar…. I do not expect it to hold tonight. When I store trailer,  over is on so no solar charging, only constant power from victron. My fear is that it has been overcharging for long periods of time (when stored) and hence damaged battery.  I can always stop plugging in trailer (empty the refrigerator) or turn off battery and/or use an Agm trickle charger

pthomas745

Many owners leave their trailers plugged in all the time.  Converters can fail, of course, but that is pretty rare.  So, lets see how your solar reacts as the day goes on.

jbajor

What sort of charge rate does the victron provide to the battery when plugged in and there is no solar?

pthomas745

Your "Victron" is not a charger, unless you are talking about charging the battery with solar. The WFCO converter does the charging for a battery when plugged in, and, as you say, the cover is on.  When a battery reaches a charged state....all chargers will either stop charging or send only a very low amount of charge to the battery to keep it in that  charged state, or "float charge".  If the battery switch is on, and you are running the fridge, the charger will react to the amount of power the fridge is actually using.  So, the charger might only start up when it senses the small voltage drop from the fridge use.  Since the fridge might use only 2 amps over an hour in your trailer, the charger does not have much to do. 

If you watch your Victron app while the trailer is plugged in and the fridge running, you can see all these interactions: when the fridge kicks in, you will see the "negative" current coming out of the battery on the status page.  When the converter sees the drop (this will not happen immediately) it will turn charging back on.  You will be able to see the small amount of current flowing back into the battery as a positive number on the battery "current" readout.

jbajor

Thank you for the great data….  Bottom line is I don’t need to worry about leaving trailer plugged in with batter switch on…. It will keep it safely topped off…

jbajor

Update….  Fully charged battery on solar. Went from bulk to absorption to float…..  as sun is setting, battery voltage is quickly dropping with only significant load being refrigerator.  Just ordered new battery 

Sharon_is_SAM

@jbajor - voltage is a poor marker when the battery has a load (your frig).  A shunt will consider the multiple factors that determine the health of your battery.  

jbajor

I turned the fridge off in the middle of the night as the compressor kept turning off due to low voltage….  10.11 volts this morning, no load….  Checked the terminal connections on battery and they are tight.

jbajor

Sharon_is_SAM said:

@jbajor - voltage is a poor marker when the battery has a load (your frig).  A shunt will consider the multiple factors that determine the health of your battery.  

Sharon, with all of the shunts available, do you have a recommendation as to brand/model?  I will certainly add one to my battery

Horigan

Victron Smartshunt.  They have a bluetooth only version and one with a display.

AnOldUR

Sharon_is_SAM

@jbajor. Victron Smart Shunt makes a lot of sense to be able to use 1 app for battery and solar monitoring.  https://www.victronenergy.com/battery-monitors/smart-battery-shunt

jbajor

Thank You!  I will purchase one and install...  I guess my initial question is really around the WFCO power center....  In theory, it goes into 'float' mode when battery is charged...  Is the voltage (I believe 13.2v in float) low enough to leave on the battery (AGM) for an extended period of time so as to not overcharge (damage) the battery or should I 'turn off the battery' when leaving trailer plugged in while stored?  I am still perplexed why my AGM battery has failed (will not hold charge) after only 2 years of use.  Most outings have been with hookups, perhaps only a dozen nights dry camping....  Cheers!  Jordan

Sharon_is_SAM

The WFCO is a 3 stage charger and prevents overcharging.  You did not say what brand battery - maybe you got a lower quality one as these are provided by the dealer.  Also, if it has a limited number of amps, during boondocking, you could have easily depleted it and shortened its life span.  Best practice for storing an AGM is to fully charge, then turn off the battery switch.  The AGM will hold a charge for months.  Just check it from time to time and recharge as necessary.  We have had an AGM battery for 7 years, storing for 6 months straight and it is just now showing its age.  We always use a portable charger before storage as AGMs prefer a higher voltage that the converter does not supply.  

jbajor

That makes total sense...  I installed battery-Renogy 100Ah.  

jbajor

A further thought...  The WFCO will not drop to 13.2 volt (float) but stays at 13.6 volt (absorption) as it see the load from the refrigerator?  Once I empty it (the fridge) out I will test it again...  

Sharon_is_SAM

Are you seeing 13.6 when plugged into shorepower?  If so, that is the voltage supplied via the converter and does not reflect your true battery voltage.

jbajor

yes, it is on shore power...  that is what the WFCO is providing...  per the WFCO specs, it should drop to 13.2 volts for absorption which I am not seeing...  I was wondering it the load from the refrigerator is preventing it from stepping down to 13.2v float...

jbajor

update:

New Battery is working fine!  
2 Questions remain...  

1) I am still perplexed as to how I killed my old battery-2 years old and I was careful about not over discharging-Only left it on shore power when stored

2) WFCO never drops down to 13.2v float voltage--remains at 13.6v absorption after 14.4v bulk charge.

Thank you all for your wise and wonderful inputs!
Cheers!

Jordan

Grumpy_G

jbajor said:

1) I am still perplexed as to how I killed my old battery-2 years old and I was careful about not over discharging-Only left it on shore power when stored

I have not found any corroborating evidence either way but it appears having a lead acid battery on a (non-trickle/maintainer) charger for extended time can damage it. A friend of mine stores his trailer outside with plenty of sun on the solar panels and the batteries were toast within two years as well. 

When I still had lead acid batteries I did charge them for a day or two and then disconnect shore power and the battery for a couple of weeks. 

Cherokee

I prolong the life of my 6v AGM batteries keeping them on a continuous trickle charge when the Trailer is Idle - this was recommended by the battery specialist where I purchased my batteries