Battery Trickler/Charger Question

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Oct 9, 2018
Hello everyone,

I own a 2018 Keystone Summerland 3030BH travel trailer.  We've just bought it in a private deal, so although it's practically new we didn't get it through a dealer so I don't have them as a resource.

My question is in regards to the camper's 12V battery, which I've disconnected and brought into the basement for the winter.  I purchased a battery charger/maintainer to keep the battery topped off over the winter.  The battery itself is an Interstate Deep Cycle RV/Marine battery, and since the camper is a 2018 that was bought new in May of this year, I assume it's a relatively new battery also.

The problem is that the charger/maintainer I have hooked up to the battery is always in "full charge" mode - indicating that the battery is at less than 80% charge and the charger is trying to bring it up to 80-100% to get into the "float"/maintaining level of charging.  This is the second charger/maintainer I've purchased because I thought the first one was faulty, but this second one has the same problem so I'm starting to suspect the battery itself is the issue.

I've made sure that the battery is fully charged by plugging our camper into a shore line at my house to charge it up for 1-2 days, then disconnecting the shore line and checking the battery charge level through the camper's monitoring system.  That system indicated the battery was fully charged, at which point I brought it straight in to the basement and hooked up the charger/maintainer, only to get the indication that it's less than 80% and in need of "full charge" mode.  I know this charger/maintainer isn't made to charge this type of battery, only to maintain and keep it topped off.  Could the problem be with the battery itself?  According to the camper's monitoring system, the battery has seemed to drop from fully charged to 2/3 charge within 1-2 days of being unplugged, which seems like a pretty significant drop in less than 2 days especially when it's just sitting there and not being used to power anything on the camper.  At that rate the battery would probably fall from fully charged to dead within a week even when not being used which doesn't seem right.  Any thoughts?
First, the systems built into the trailer are basic and can't be depended on for good information.  Your maintainer needs to be connected for some period of time to get down to trickle mode, I don't know if you left it on long enough.  The battery may be almost new but folks have a way of destroying them quickly by completely discharging them, for maximum life they need to be kept fully charged as best you can.  Marine batteries are not really deep cycle, that is just a sticker to market them to an unsuspecting customer, if you need to replace you should try to find a true deep cycle battery.  Now what I would do is charge the battery to full as best you can tell, then take it to a battery store that can load test it for free.  Advance Autoparts and AutoZone are two sources.
Great information, thanks for the quick reply. I?ll leave it connected to the charger/maintainer for a bit then to make sure. I was just afraid I could overcharge it if the battery was already fully charged and the charger didn?t switch over, but I suppose I should give it a chance to do its thing. I?ll keep that in mind if and when I replace it too. Thanks!
If that auxiliary charger is truly a maintainer type, it will be unable to over charge. It should have a max output of around 13.6-13.7v and maybe 2-3  amps. If it can do more than either of those, then an overcharge is possible. Check the voltage with a voltmeter at the battery terminals, with the maintainer running and not running. 

If the battery is not a sealed type (maintenance free), open the cells and check the electrolyte level. Low electrolyte in even one cell can cause the battery to always appear low.  Add distilled (mineral-free) water if needed.

Let us know what you learn.

A battery can take a licking on the dealer lot of by being excessively discharged a few times. That type of battery doesn't have a long useful life under the best of circumstances, and a bit of abuse can reduce its capability severely.
I have checked the water and those levels are fine. If I?m plugged in to a shore line about how long should it take to fully charge the battery? My plan would be to leave her plugged in for that period of time, so I know it SHOULD be fully charged, then hook up the maintainer to see what she has to say.
If you can measure the charging current. voltage and tell us what size battery you have.

I know when my converter failed the batteries got a bit run down. the charger I put on was a 20 amp job and it ran at full output for most of 24 hours.. Measured.  Eventually it did slow down but it was between 23 and 24 hours before it said "FULL".

By the way it was a Deltran Battery Tender/Charger/Booster it can jump start at 70 amps though I've not yet figured out how to do that. Chats via Wi-FI with my phone or the internet so I can log into it from anywere.. only I've not yet figured out how to do that either. I do connect to it via Wi-FI. 
Measure the voltage of the battery.  Even though it is called a 12 V battery, if it reads 12.0V, it is significantly discharged.  Fully charged is 12.6V.  If a charger is connected, the charger output should push the voltage to 13.6V.

Before you replace the battery, please come back for advice on getting the RIGHT battery.
Can you select the type of battery on your charger? If so make sure it is set on the Deep Cycle setting
Hello everyone,

I can't select the type of battery so there is no deep cycle option.

I bought a multimeter that should be arriving today to troubleshoot this, and because I want one for other projects.  So I should be able to report back with some more information on the voltage the battery is kicking off, with and without the maintainer/charger connected.  I've had the camper plugged in to 120V at my house for almost two days now, so I would assume this battery should be fully charged at this point unless it's dead.  I'd also like to keep it unplugged for a couple days and check to see how much the voltage drops.  If it seems to be losing too much charge too quickly then I'd prefer to get a new battery in the Spring, probably based on recommendations from you fine folks, so that our 12V power will be a bit more reliable when we need it.

More to come ... thanks again!
So I've done a bit more fact finding here ...

I kept my camper plugged into a 120V line from my house for two days - plenty of time to fully charge the battery.  Yesterday afternoon I disconnected and brought the battery straight inside for testing the voltage.  Testing it within 15 minutes of disconnecting the battery showed voltage of approximately 12.5 - a bit short of the 12.6 that one might expect on a full charge.  I brought the batter downstairs and connected the charger/maintainer - which still indicated that it was in "charge" mode rather than the "float" mode it kicks into once adequately charged.

With the charger/maintainer connected and in charge mode the total voltage came out to 12.9-ish, which was still lower than I anticipated.  I left the charger on and checked again this morning, still 12.8-9ish.

I've since disconnected the charger and let the battery just sit as-is.  Within 2 hours the voltage reading was down to 12.4.  I just went home for lunch and the battery is already down to 12.2.  That's within 6 hours of fully disconnecting the battery.

To me that seems like the battery crapped out right?  On what should've been a full charge the battery was kicking out at 12.5, and that's down to 12.2 within hours.  I'm new to monitoring 12V batteries and I'm learning my way through this, thanks to you fine folks and the internet, but my novice opinion is this battery is no good.  I bought the camper used from the prior owner who bought it new in May, but they only used it 3 times and it had probably sat unused for at least 2-3 months before I got it.  Plus I'm not sure this generic Interstate "Deep Cycle/Marine" battery is really quality to begin with.
Yeah, this battery needs to be replaced, in the future try to never let it drop below 11.9 - 12.0 V (50% charge level) for maximum battery life, chances are the previous owners ran it down all the way multiple times which is a quick way to kill a battery.

At 50% depth of discharge you may get 500+ recharge cycles out of a battery, at 90% you may get 100 if you are lucky  (depending on battery quality, but you can see the trend), on the other end if you use the battery minimally at at only 20% depth of discharge you may get 3,500 charge cycles.
Isaac is right.

Have it tested just to prove you are right.  I suggest a TRUE deep cycle replacement.  I believe Trojan makes one.  The typical RV/Marine is not a true deep cycle. 

Others can give specific model advise.

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