Battery Charging while Stored

[GLovedahl]

I've looked through the discussions posted on here, but I'm still uncertain about keeping batteries charged on our Airstream while it's in winter storage. I live in North Texas, and the temps get down below freezing from time to time. The Flying Cloud is stored at a storage facility. I went over today and plugged the trailer into shore power, thinking that that would also charge up the batteries. It's been about a month since the trailer was towed, and then only briefly. Will plugging the trailer into the facility power from time to time charge the batteries? How long should I leave it plugged in? How often should I plug it in? The trailer is new, so the batteries should be in great shape....used only once so far. Sorry for such a newbie question....the world of RVing is totally new to me.

[A W Warn]

You could use a timer where the converter plugs to the outlet, if you can stay hooked up to shore power full time. 15 to 30 minutes a day on the timer should keep the battery in good shape, if the only load is the propane detector. That's what I do when I leave mine in storage for 6 months. I found one for ~$10.

[lewster]

Originally Posted by GLovedahl

I've looked through the discussions posted on here, but I'm still uncertain about keeping batteries charged on our Airstream while it's in winter storage. I live in North Texas, and the temps get down below freezing from time to time. The Flying Cloud is stored at a storage facility. I went over today and plugged the trailer into shore power, thinking that that would also charge up the batteries. It's been about a month since the trailer was towed, and then only briefly. Will plugging the trailer into the facility power from time to time charge the batteries? How long should I leave it plugged in? How often should I plug it in? The trailer is new, so the batteries should be in great shape....used only once so far. Sorry for such a newbie question....the world of RVing is totally new to me.

Be EXTREMELY careful when using the original converter in your Airstream! It's continual 13.6VDC output will do several nasty things to batteries:

ALL LLA (liquid lead acid) batteries, whether they are flooded cells, AGM or gel (if you can even find them any more) require a bulk and absorption charge of anywhere from 14.2 VDC to 14.6 VDC (your voltage may vary, depending on the specific specifications from the battery manufacturer)

BULK is a beginning charge where the voltage and amperage both increase to the set maximums of either the charger or the programmed charge parameters (like 14.2 VDC for voltage and say 55 amps, which would be a charger max.)
ABSORPTION starts when the max. voltage has been reached. In this stage, the voltage remains constant and as the battery begins to fill, the amperage tapers until about 95% charge has been reached.
FLOAT then begins, and the voltage drops to the set point for this phase (13.2 in this example) and remains there and the charging amperage also drops significantly, as no more 'push' is required to add voltage back into the batteries. Again, this exact number will vary depending on the equipment set points or the programmed charging profile chosen.

Your stock Parallax single stage converter will never allow the battery to reach it's required level of voltage (14.2VDC in the example) to allow for complete charging and will also never allow the voltage to float at the lower voltage (13.2VDC) and reduced amperage.

This will kill ANY battery in short order! The constant voltage output of 13.6VDC is fine when plugged in to shore power to provide sufficient DC voltage to operate all of your interior appliances. It is control voltage for your refrigerator control board, the furnace igniter board, the A/C thermostat and upper control relay board....BUT IT SUCKS FOR BATTERY CHARGING!!!!

I would immediately replace your Parallax converter with a 'smart' 3-stage charger from Progressive Dynamics (or similar products) and you can then leave your trailer plugged in all the time without worry, and your batteries will be full and happy when you return to the trailer.

End of story..................

[handn]

Lewster is the guru. Even though there is a lot of technical jargon he is correct in his premise. Replace your single stage Paralax battery frier. It is not that expensive. Mine cost $250 at bestconverter.com. If you are handy and limber you can do the job yourself.
Meanwhile do as Mr. Warn suggests. Plug your new trailer into shore power for only a short time or don't plug it in at all. With minimal load your battery will last until spring.

[graysailor]

If you have a SmartCharger then just leave it plugged in. If you are outdoors and have solar panels then that would work also. If you do not have a smart charger then you run the risk of over charging the batteries by leaving it plugged in.

[acstokes]

Will plugging the trailer into the facility power from time to time charge the batteries? How long should I leave it plugged in? How often should I plug it in? The trailer is new, so the batteries should be in great shape....used only once so far.

I agree with all that's been said. If you had a 3 stage converter, you could just leave your trailer plugged in all winter and the batteries would be maintained at 13.2 volts...good for the batteries and trouble-free for you. The other item you're missing is a battery monitor. Currently, you're having to guess whether your batteries are fully charged or not and how long to charge them before they're fully charged. A very good one is the Trimetric TM2030-RV. There are others, but this is probably the most popular one.

You'll spend about $300 - $400 to upgrade to a converter and battery monitor system that will maintain your batteries at optimal float voltage. However, if you plan to keep your trailer for several years or more, an upgrade will eventually pay for itself in longer battery life and provide you peace-of-mind as well.

[ROBERT CROSS]

Many folks have dealt with the problem. In our case it was the first "up-grade" we did.

Our Classic came from the dealer with fried batteries. Interstate replaced them under their warranty.
6mos later they were fried dry again from 24/7&14 daze on the P-lax burner.

Installed a new converter and 2 Lifelines, 7 Seasons and we're still happy.

Seriously consider the change, it's a very worthwhile improvement, that will probably save you money in the long run.

Bob

[Rjpuckett]

I have read many threads here about replacing the Paralax converter and most referenced extending the life of our batteries. I believe there is a much more important reason to do so. That reason is the safety of your family and trailer. The open design of the converter itself is a tragedy waiting to happen. In our 16' 2008 International it is located under the bed up against the wall for the wet bath. It sits an inch or two from the floor protected by only the open vented front plate.

I can tell you that when water is spilled onto the floor in that area there is a Lightning type arc that lights up the interior before the breakers kick off.


I replaced it with the fully enclosed Boondocker converter that is not hard wired to the electrical panel.

[Wingeezer]

I just pull our coach batteries out when we take our trailer to the storage yard. They are AGM batteries and have a very low self-discharge rate, but when i have them at home in the garage, I put a "Battery tender" on them for a day or so every month or two.

Brian.

[tjdonahoe]

We have cold here in Mt., I disconnect the positive cables, then battery tender once a month and they do fine,never had any problem.

[Rocinante]

Just a quick note: I love my Battery Tenderizer Plus. It's very useful for maintaining charged batteries but less useful for charging them up unless I am willing to be patient. So, I use the BT+ on my electric start generator at home. I use another for my TV in the driveway because it's not my daily driver and that ensures this battery also stays happy for when I need it.

On my trailer I swapped out the converter for a PD4655 because that lets me charge the TT batteries quickly when needed and also maintains them nicely when stored with the trailer plugged in. See, the Plax 7355 not only boils batteries given the chance; it's also a pretty slow charger. I won't tolerate either of those characteristics.

That said, there are plenty of ways to solve this problem, and a BT+ on the trailer batteries is a legitimate solution for winter maintenance.

[JRF0st3r]

Our '67 Safari, undergoing rescue now, has a NOCO Genius G3530 charger for a battery or battery bank not yet selected. (Batteries will most likely be AGM, definitely not wet cell.) Our trailer will be parked under our "guest cottage" shelter all year with shore power unless it is on the road. I assume this charger could be left connected full time. So why do I also need a smart converter? What benefit would the right type of modern converter provide that would not be given by this charger + batteries? Does it depend on DC power load or type of load?
Thanks for any advice you might offer.
Jim

[flyfisher]

Originally Posted by tjdonahoe

We have cold here in Mt., I disconnect the positive cables, then battery tender once a month and they do fine,never had any problem.

I keep my truck and trailer stored all winter in MT. I keep my truck batteries on a Deltran Battery Tender, installed in the truck all winter and have never had a problem, and have done this for the past several years. I past years, I took my trailer batteries home where I periodically hooked them up to a battery tender, but this year I just took them out of my trailer, and left them in my unheated storage unit hooked up to a Deltran Battey Tender. I expect they will be fine when I put them back in the trailer in the spring.

[Rocinante]

Please bear in mind that I'm not an expert on classic Airstreams - it's possible someone else will be able to provide a much better answer.

First, a general comment that may or may not apply to a 1967 Safari, depending what you have in there: converters normally do a few things in a trailer: (1) Convert AC to DC power and pass that through to the DC circuits on the trailer (e.g. lights, fridge, fantastic fan, furnace fan) and (2) charge the trailer batteries when the battery kill switch is in the "USE" position. Some might argue they also distribute AC power to any AC circuits on the trailer (e.g. air conditioner, microwave, power outlets), but that happens in a separate fuse box that also feeds AC power to the converter...for conversion to DC. Dumb converters apply a constant amperage and voltage to your batteries, no matter what, as long as that switch is in the "USE" position.

The NOCO website describes the Genius G3500 (not 3530) as being excellent for smart battery maintenance in an RV, but not so much for battery charging. Like a battery tender. This makes sense given it's a 3.5 amp unit. So, if you park that lovely 1967 Safari under cover with the battery switch in the "OFF" position and the G3500 connected to your batteries, the NOCO should maintain them happily. Your batteries would also be protected from any possible overcharging via the converter in your trailer.

That said, it's worth checking to see what kind of converter you have in there. Depending on what renovations / restorations have been done, it could be anything from an original Univolt, which I believe is not an intelligent charger, to a modern smart multi-stage converter that will treat them with kid gloves.

Originally Posted by JRF0st3r

Our '67 Safari, undergoing rescue now, has a NOCO Genius G3530 charger for a battery or battery bank not yet selected. (Batteries will most likely be AGM, definitely not wet cell.) Our trailer will be parked under our "guest cottage" shelter all year with shore power unless it is on the road. I assume this charger could be left connected full time. So why do I also need a smart converter? What benefit would the right type of modern converter provide that would not be given by this charger + batteries? Does it depend on DC power load or type of load?
Thanks for any advice you might offer.
Jim

[lewster]

'Some might argue they also distribute AC power to any AC circuits on the trailer (e.g. air conditioner, microwave, power outlets), but that happens in a separate fuse box that also feeds AC power to the converter...for conversion to DC.'

Sorry, but this statement is totally false and misleading. ANY power converter/charger found in modern RVs, as we are discussing in this thread, have 2 functions and 2 functions ONLY!
• provide DC power for the RVs many DC requirements, such as operating all of the control or PC boards located in the appliances and other 12VDC loads like lights, furnace, fans, etc.
• provide for '12VDC' battery charging, either as a constant voltage from a Parallax or other 'dumb' converter, or automatic 3-stage battery charging from a 'smart' converter like a Progressive Dynamics.

A converter/charger HAS NO RELATIONSHIP WITH THE 120VAC SIDE OF THE RV other than to be connected to a single circuit breaker that provides the converter with the 120VAC it needs to power DC loads and for battery charging.

A converter draws 120VAC from the 120VAC circuit breaker box while on grid/generator power and powers the 12VDC fuse panel and charges the battery.............THAT"S IT!

[Rocinante]

Lew, I'm pretty sure you and I just said the same thing (e.g. The converter does not distribute AC power, even if some may think it does.) Thanks for that vigorous reinforcement, though.

I've been paying attention, though I'll grant I should have substituted "two" for "a few."

[Boxite]

Originally Posted by GLovedahl

I've looked through the discussions posted on here, but I'm still uncertain about keeping batteries charged on our Airstream while it's in winter storage. I live in North Texas, and the temps get down below freezing from time to time. The Flying Cloud is stored at a storage facility. I went over today and plugged the trailer into shore power, thinking that that would also charge up the batteries. It's been about a month since the trailer was towed, and then only briefly. Will plugging the trailer into the facility power from time to time charge the batteries? How long should I leave it plugged in? How often should I plug it in? The trailer is new, so the batteries should be in great shape....used only once so far. Sorry for such a newbie question....the world of RVing is totally new to me.

Glovedahl... before you get steered the wrong way by those trying to be helpful here without knowing the equipment you have installed... YOU should determine WHAT converter is installed in your 2015 Airstream.
In years prior to 2005 Airstream commonly installed the problematical converters made by Parallax. Since that time, Airstream has been installing 3-stage converters. (In my 2008 model, it's a WFCO that is plugged in CONTINUOUSLY for 3 years now and keeps my ordinary flooded-cell battery properly serviced without a single problem.)
I suspect you'll find you have a more modern converter that includes a multi-stage charger that can be left plugged in to shore power continuously, and all you'll need to do is check your battery electrolyte regularly. Even if wrong, the most damage that will occur is a short-lived, low-cost battery. (Mine has need a bit of water in one or two cells ....only ONE TIME in the last 3 years. WalMart sells deep-cycle batteries for less than $90 that will last several years under warranty.)
Hope this helps.

[Mollysdad]

I've decided that I'll install a battery disconnect, and then keep a NoCo Genius charger plugged in while the trailer is stored.

[LABluebike]

Brian -
Thanks for sharing your battery-tender routine. I'm considering the same myself, as our 2021 trailer's AGM's don't seem to like being stored indoors at the RV yard for 3-4 weeks between dry camping trips.
Can you recommend hardware?