Trying to Understand battery issues

[Sweets87]

Hi
-2018 Classic 30'; 200W factory-installed solar
-Boondocking in Florida and left trailer for 3 days to visit friends. 100% charged. No lights were left on - only refrigerator running on LP. Good sunlight for 2.5 days - some shade from nearby trees but mostly uncovered.
-When we returned batteries were at 45% charged. Connected 2000w generator and monitor showed batteries at 70% charged. Ran generator for approx 2hrs and batteries reached 80%. When disconnected the generator, the batteries showed 50% charged. Went to bed and woke up to 20% charged - only Alde system was on. Connected the generator and now showing 80% charged.

Questions: It seems the batteries are draining too fast for the amount of use they're getting. And re-charging at a slow rate. Accurate? If so, solution?
Why does the monitor show batteries at 80+% when connected to the generator and much less when disconnected from the generator?
Thanks.

[Al and Missy]

You didn't say where you were getting the percent of charge. If it is voltage based, it is only correct when the batteries are neither being charged or discharged.

The batteries have internal resistance. When the generator or solar is charging the batteries it has to put out a higher voltage than the battery total cell voltage in order to force current through the internal resistance. On a voltage-based monitor this will indicate an incorrectly high state of charge. When the batteries are discharging the voltage at the terminals is less than the cell voltage due to drop in the resistance. This will indicate an incorrectly low state of charge.

The best way to measure state of charge is with an energy sensing system like those made by Victron and others. You put in the capacity of your batteries and the monitor keeps track of current in and current out to continuously monitor the state of charge. With voltage alone you must charge the batteries, stop charging them and "let them rest" for an hour or so and them measure voltage. During that time there should be only minor, or preferably no, current being drawn.

Is your inverter on? It draws a significant current when on, even if not in use. There are many phantom draws possible depending on equipment, propane detector, subwoofer, and if you have a central control system, that also draws current to mention a few. Don't forget to check storage compartment lights. I'm not up on the newer trailers, so some of this may not apply and other things may. I like my simple system with a mechanical battery disconnect.

The best way to troubleshoot this is to get an ammeter and measure the current being drawn from your batteries. Then pull fuses until you find what draws how much. Once you know the total draw, you can figure out how long the batteries should last.

A 200 watt panel is probably only good for about 50 amp hours on a good day, that means an average current draw of only 2 amps. That is not very much.

Also, 50% state of charge is the lowest you should let your batteries be discharged to. Any more than that is damaging the batteries such that their storage capacity is reduced.

Al

[OTRA15]

Welcome to the forum!

No experience with solar, so some general comments . . .

Good advice from Al.

Here is a good Battery School resource for reading up on RV battery care:

http://www.batteriesnorthwest.com/ba...hool.cfm?TID=0
State of charge etc. -- http://www.batteriesnorthwest.com/ba...cfm?TID=5#ANC5

When you leave the trailer, you must minimize all "phantom loads" like the inverter, audio/visual equipment, and so forth. The propane detector draws a small amount, but even with the fridge running on propane, that would not account for your battery drop IMO.

The new search function above in the blue box works great if you are using the desktop version of this site. [The App search function is not so hot apparently IMO.]

"battery phantom loads" -- https://www.google.com/search?q=batt...=airforums.com

Have you contacted your dealer about this? They may have not cared for the batteries well before your purchase. "Lot rot" is a common occurrence unfortunately: https://www.google.com/search?q=lot+rot&sitesearch=airforums.com

I would recommend that you take the batteries into a battery dealer, and have them tested. Are they AGM or lead flooded-cell? If defective they should be replaced under warranty IMO. If only one is defective, insist that both be replaced at the same time with identical batteries.

Good luck,

Peter

PS -- It is possible that your battery charger/converter is not operating correctly, so hopefully someone can chime in with advice on testing for this, or go to a local Airstream dealer in Florida. When did you get the AS, and have you ever let the batteries go below 12.2 volts? If so you might have damaged them.

[gypsydad]

Not up to speed on the Alde system draw, but I know my furnace will eat up the batteries, especially if running off/on over more than 24 hours. Once your 12v wetcell batteries are bad, they never recover fully. I would not go 3 days without power without disconnecting the batteries totally from the AS with a mechanical disconnect switch. If I needed power for heat while gone, I would check into an RV park with power...solar could work I suppose, but think you have battery issues.

Likely from what you have said, if they are 12V batteries from Interstate, (??) you have bad batteries. Happens to many of us even with new trailers. It has happened to me personally on my new 2014 25' FC and my 2017 28'FC models; also a close friend with his 2017. I would get my batteries tested first to see if they have a bad cell. Interstate is pretty good about doing this and also typically will replace them if bad. There are several threads on this. Once you eliminate that problem and know your "new replacment batteries" are good, you can troubleshoot the converter, but my money is on the batteries. Few choices to replace them with..ask Interstate about a trade in value for either an AGM, a pair of 6V Golfcart batteries, or perhaps move up to Li if you want the best. I moved to 6V Golfcart batteries and replaced my converter also with a multistage. Your 2018 model has a 3 stage converter now, so don't suspect that is the issue. Could be wrong but start with batteries.

[AirMiles]

Sweets, from my experience running a generator for only a couple of hours on a 45% state of charge battery would only add about 10% to a battery if its being charged at 13.8V, which is what the stock converter in my 2017 FC25 did. I replaced the stock converter with a PD4655 so when I "bulk" charge with my generator, it charges at 14.4V. Even at 14.4V, I need to run my generator about five hours each day to bring my battery to 80-to-90% charged. It then drops into "absorption" mode and I turn the generator off. So your generator and converter seem to be performing as designed. The design of the Airstream stock generator is to output continuous 13.8V so the converter can stay connected to shore power without overcharging the battery. Therefore, the battery never gets completely charged and it takes days, not hours, to get the battery to 80-to-90% charged.

Now let's move on to the solar. In Fall/Winter, the days are short, the sun is at a poor angle with significant shading, and cloudy skies are prevalent. These are not good conditions for maintaining a battery bank with solar. Even with my 400W, it was barely enough to keep my batteries charged while boondocking in November. I found 200W was adequate in the summer with long days and plentiful sunshine, but not in the winter months.

So lets add the solar and the generator charging together. It sounds to me that you are just taking more juice out of your batteries than the solar and a couple hours of generator charging at 13.8V is putting into your batteries. My solution was to install 400W of solar and a new converter that was capable of putting out a 14.4V. If you want to keep your stock converter and not add watts to your solar system, you may need to run the generator all day in the winter months to have enough battery to run your heat, refrigerator, and lights all night.

You did get very good advice above. Have your batteries tested to make sure they are not damaged. Get an Amp Meter to check your Amp draw. And figure out a plan to replace the Amps you are taking out of your batteries each day.

And yes, I too murdered my first set of batteries in under 11 months in my new Airstream by not realizing that I was taking more juice out of my batteries than my generator was putting in. Then I added the 400W of solar, the PD4655 converter, and a pair of 230AH 6V golf cart batteries which have been happily providing all the boondocking power I've needed ever since.

[Sweets87]

Thanks everyone for the tips/advice. Much appreciated.

[OTRA15]

Please let us know what you end up doing, and whether the batteries are bad, replaced under warranty, etc. etc..

Good luck,

Peter

[gypsydad]

Yes, agree with Peter...we are always curious about the problem and the outcome... Good luck!

[jnm30327]

Some additional thoughts:

1. There really is no substitute for a Victron style monitor. With it you can see parasitic draws and overall usage.

2. The original equipment Interstates do not have enough capacity with furnace running to last more than 24 hours. I ended up buying 2 Lifeline AGMs with 100 Amp-hr capacity. They have to be turned sideways but will fit in the battery compartment you have.

3. You can buy 500 Watt-hr lithium batteries with charger and inverter built in for about $500. They weigh only 12 lbs. I have two. They can be fully discharged without damage and can act pretty close to an additional two batteries of the Interstate size which suffer damage after a 50% draw down. I have a 7 AMP smart charger that I connect to the lithium batteries to keep the trailer batteries charged. These lithium batteries can be recharged from any 110 V outlet. When dry camping, there are usually 110 V outlets in the restrooms which I use to recharge them - daily in some cases. A way to fake hookups. :-) I have a front bed trailer so was able to run a 12 V line from the trailer batteries (through a Victron monitor) to the compartment under the bed where I put the lithium batteries and charger. That way the lithium batteries stay warm in cold weather which keep them near full capacity. You could also connect these lithiums directly to the trailer electrical system with a dogbone converter to the 110 V output of the lithiums. but they draw down pretty quickly that way. I prefer going through a charger.

I rarely need to use a gas generator although I have one as a backup. I nearly always dry camp in the "no generator" areas of campgrounds in winter.

This is what I bought, but there are others.

https://smile.amazon.com/Powerpro-Po...hium+generator

[jnm30327]

Incidentally, a great way to make your batteries last when dry camping or boondocking in winter is to turn off the heat at night and sleep in sleeping bags. If it is so cold, you are worried about freezing pipes, then just turn the thermostat way down. When you get up in the morning, the trailer will still heat up pretty fast.

[ROBERT CROSS]

10/4 on a quality monitor...the Victron,(with remote dongle), was also our choice.👍
Nice not having to go into the trailer during the 'polar vortex'. ❄️

Bob
🇺🇸

[Kyoshi]

Have you tried checking for a bad battery cell. Get a specific gravity battery tester and pop the caps on the batteries. If a bad cell in one or both batteries, then you need new ones.

I had this problem of batteries not holding a charge for more than a few hours ,and that was the problem.

[uncle_bob]

Hi

If you left the trailer and the "normal" stuff was running ( in cooler weather on a 30' Classic) 3 days to half power on the batteries is doing very well. In normal use ( = you in the trailer doing stuff) the batteries are good for maybe 24 hours. Even with the sun out, you don't get a lot of solar this time of year. Solar isn't going to stretch those numbers a whole lot.

Some math:

Fridge pulls about 1.1A. Parasitics are about 1/4A. In three days, that's 100 AH all by its self. At 70% capacity (if it's cold out) that's about all you have if you get 10 AH a day from solar.

If the magic control system is turned on, that adds another amp to an amp and a half. You would now need to get 130 AH from solar simply to be at 50% charge. That would be doing well for solar this time of year.

Bob

[waninae39]

i agree with the victron post

get some of their systems and get a shunt to measure actual loads.

when the load is on, open the breakers one by one to see where the load is

[pteck]

A battery monitor is not the issue here. It's hardly a requirement and 99%+ of people out there with RV's get by without one. Including myself. It's like trying to measure every once of fluid in the water tanks. It's just not necessary.

Regardless of battery monitor, I'd agree that your current indications show that there's something going on and that the batteries are either being drawn down prematurely, or they are not holding charge appropriately.

It wouldn't be the first time a newer trailer was delivered with damaged batteries.

I'd check the batteries first. Check water levels and general condition of the battery. I strongly suspect batteries to be your issue.

Get a clamp meter so you can measure for parasitic draws. It's a great troubleshooting tool to have.

[68 Overlander]

The way I have approached this issue over the years is no different than if I had to leave my truck at the airport for a week or two, or even a couple months for that matter. If we can't visit friends or family for a few days without having to worry about otherwise healthy batteries, we have a problem.
Monitors are great and we move a bunch of them but understanding and pin-pointing your parasitic and known power consumption is the answer. Even a monitor uses power but not much. Self discharge is likely not your problem (unless your dealer ruined them prior to delivery) although 10-15% per month is often assumed. I feel your pain, this is not an uncommon question!
I've had 4 Airstreams and my favorite that I no longer own was a 76. I would leave it 3 or more months when deployed and come home to take the family camping with no shore power during storage. Only because I took the time to eliminate and draw and put it to bed fully charged. That was only one battery BTW back in the day. You'll get there, don't give up. I do think that fridge and inverter might be part of the equation too of you have one.

[lsbrodsky]

All of this is good advice, but because there are so many variables, it is hard to suggest just one thing. While I agree that a monitor is not required, you really need to know how much load is on those batteries in your current mode. I am also not familiar with the Alde system, but if it has pump running, I feel certain that the load exceeds your winter solar charging capability.
I also believe that what you are describing is very clearly batteries that are not holding a charge. While other have said that it is common for dealers to destroy these before delivery, that is not really true of the AGM's in a factory solar-equipped trailer, UNLESS the trailer was stored indoors with no sun. And that would be unusual. The factory solar is good at keeping a stored trailer charged up. However, if you ever drained your batteries down to below 50%, and it sounds like you have, then you are responsible for damaging their capacity. The only solution for that is new batteries and you should spend the money for AGM's, as a minimum. I thought that sometime in 2018 Airstream started installing the better charger, but if you have the older more common version, upgrade through Randy at BESTCONVERTER.
Larry

[wizardglass]

When I upgraded our old deep cycle to an AGM battery, and took half the summer of not getting a full charge with a little homework to realize or charger wasn't suited for AGM. Those batteries need about 14.4+ volts to charge properly. The small CTek charger/maintainer works great, also suited for long term float charging. If we're plugged in for an extended period of time I just disconnect the battery and run the Paradox 12v power supply.
Easiest way to narrow down a power draw is with an ammeter, then simply pull fuses or breakers one at a time.
By the way, a battery disconnect is a must for storage, although I realize in this case you were running a refrigerator.

[steverino]

Hi - I am a little late to this party but I thought that I would share some power consumption data that I just took on my 2018 Classic-

Use/store switch in “use”, everything off, pulls approximately 1.6A. This includes solar controller and inverter back-currents and Firefly. I did notice that periodically the ALDE circulation pump would kick on, despite water heat and radiant heat shut off on the Firefly. This pump would run for a few minutes, pulling an additional 0.7 A, then shut off. I didn’t hang around long enough to see the frequency. Nor did I contort myself under the kitchen sink to shut down the ALDE from its dedicated panel.

Turning on the refrigerator on propane mode would pull an additional 0.9A. So, just these basic loads (not including ALDE) consume about 60 AHr per day. 200 W solar will have a hard time keeping the batteries topped, especially in winter months.

[steverino]

Originally Posted by lsbrodsky

I thought that sometime in 2018 Airstream started installing the better charger, but if you have the older more common version, upgrade through Randy at BESTCONVERTER.

Larry

I have the “better charger” in my 2018 Classic - A WFCO WF-9855 - and I have NEVER seen it kick back into float mode, even after sitting quietly in my storage unit for days.

As part if it’s upcoming battery upgrade, it will be getting a quality converter. In the interim, I have it on a timer which applies power a couple days a week.