2012 FC Charging Problems

[rgwatkin]

I have owned a 2012 FC for 27 months and encountered a situation last week on a boondocking trip where my battery indicator would read 100% during the sunny day then when the sun went down the battery indicator dropped to 70% immediately. This was also the case when I had a generator hooked up. I measured the voltage on both batteries disconnected and they measured slightly over 10V. I do not know the maker of the converter but "assume" the one I have is the 3 stage that people refer to as being preferable as the trailer is fairly new. The batteries I have are the Airstream stock Lifeline GPL-24T, not an inexpensive battery as new ones on the web cost $300. The posts on the batteries are the hybrid type that allow a screw terminator as well as a std. post which I would assume eliminates the Wal Mart category of batteries. Can anyone with experience shed some light on my problem?

[lewster]

First, I assume that you have the factory solar as Lifelines are NOT standard with no solar option from the factory.

Next, do NOT assume that you have a 3-stage converter in the trailer, as Airstream STILL uses the single stage battery burners in all of their trailers. So unless a PO upgraded it, you still have the bad one, which will effectively kill Lifelines in short order!!

Your batteries are heavily sulfated and not holding charge if they read at 10VDC after the solar charge controller is no longer providing power to the batteries. The 'full' reading you saw during the day was an indication of the voltage from the controller and NOT the batteries themselves, when a reading should be taken after they are at rest with no loads on them.

Sounds like you need at least a new set of batteries and a new converter.

[Al and Missy]

Lewster types faster than I do. Further, he is the expert.

I'll leave my post up anyway. I hope he doesn't make look bad.

Your battery indicator probably reads voltage; most do. It is not an accurate indicator of condition when the batteries are being charged. I presume you have a solar system installed, since the batteries appear to be charging during the day. I don't know what converter is used in a solar-equipped trailer, but it is my understanding that even the new trailers without solar have two stage chargers. Going on your voltage reading, the batteries are probably bad. Pull one and take it to an auto parts place and have it checked.

Here is the data sheet on your battery.
Lifeline Batteries - Marine & RV Deep Cycle Batteries

Note the float voltage rating. That is the third stage in a three stage charger. If your converter is putting out more than that it could damage the battery if left connected long term.

Just my opinion, but you probably don't need to spend $300 to get a good battery. Yours are sealed AGMs, and they have a lot of advantages, but if they are mounted outside, flooded batteries (conventional wet cell lead-acid) will probably do fine at a much lower price. You do need deep cycle RV or marine batteries, not a starting or combination battery. AGMs are, I believe, more tolerant of deep discharge, so if you do a lot of boondocking, they might be worth the extra cost.

Al

[bovk]

I just changed both batteries after 4 years of a lot of dry camping. I use the cheap (~$110) ones. The trick is to get a voltmeter and charge them when they get to 12.2 - 12.3 volts slightly loaded (switch on the lights or a fan), they are charged at over 12.5 - 12.6 volts

[lewster]

Originally Posted by bovk

I just changed both batteries after 4 years of a lot of dry camping. I use the cheap (~$110) ones. The trick is to get a voltmeter and charge them when they get to 12.2 - 12.3 volts slightly loaded (switch on the lights or a fan), they are charged at over 12.5 - 12.6 volts

First, liquid lead acid batteries of all types are not charge to 100% until they reach 12.8 VDC for a 12VDC battery. Next, why do 'slightly load' a battery for charging. Have never done, nor heard of this in 10 years of battery/solar/inverter/charging system installations. NONE of the equipment manufacturers ever mention a 'slight load' when charging.

Do you know something we don't?

[bovk]

Sorry, i was not clear. No need for a load when charging! To check the voltage of a battery it is good to put some load on them, even bad battery can show 13 volts when charged but it drops immediately when loaded. And yes, 12.8 instead of 12.6 volts is a better number for a charged battery. My main point was to charge only when needed, not all the time when stored. Fully charged lead acid batteries last even 20 years (security lights, alarms e.t.c.)

[dznf0g]

Maybe Lew can answer this one...I was reading some material the other day relative to depleting batteries to 50% level for longest life. (12.06V) They stated that the 50% level was checked only after resting the battery for at least 2 hours, with NO LOAD, and rechecking the Voltage. I experimented with this and the battery "regained" or recovered to a 12.2V level. I was able to get an additional 10Ah out of the charge before the battery rested at 12.05(ish) volts. (my Trimetric only goes out 1 decimal place and rounds, so when it flickers between 12.0 and 12.1V, it is presumably around 12.05V).

Is this correct? And I can run my batts to about 10Ah below 50%, consistently, without damaging their longevity?

[lewster]

Originally Posted by dznf0g

Maybe Lew can answer this one...I was reading some material the other day relative to depleting batteries to 50% level for longest life. (12.06V) They stated that the 50% level was checked only after resting the battery for at least 2 hours, with NO LOAD, and rechecking the Voltage. I experimented with this and the battery "regained" or recovered to a 12.2V level. I was able to get an additional 10Ah out of the charge before the battery rested at 12.05(ish) volts. (my Trimetric only goes out 1 decimal place and rounds, so when it flickers between 12.0 and 12.1V, it is presumably around 12.05V).

Is this correct? And I can run my batts to about 10Ah below 50%, consistently, without damaging their longevity?

In a word....YES! Here is a chart for Lifeline state of charge, and they specify 12.2 VDC as a 50% depth of discharge. You can see how the number of charge cycles decreases as you drop the voltage of the battery.

http://www.lifelinebatteries.com/manual.pdf . Go to page 30 and look at the bottom chart. This shows the open circuit voltage at 50% to be 12.2 VDC and 100% full at 12.8 VDC.

Page 38 shows the # of charge cycles to expect vs. the depth of discharge. Note that at 50% DoD, they estimate you will get 1000 charge cycles. This drops to 800 charge cycles at 60% DoD.

The less you actually use your batteries, the longer they last. And just to clarify: there is no problem leaving a Lifeline AGM battery on a 13.2-13.4 VDC temperature compensated float charge indefinitely. If you don't have temp/comp, then fully charge your battery and remove the negative terminal, isolating it from the trailer. Check the voltage every 30 days and re-charge as required to maintain 12.8-13.2 VDC (for Lifelines). This 100% state of charge will vary depending on the manufacturer of your batteries.