Charging my new 2024 2720 Sport battery when stored

[Rebound123]

Just bought the 2024 2720 Sport!
We r very excited with our first camping trip being a success and it actually fitting in my garage when we got home.
The owner’s manual seemed vague on my question so I am going to ask you guys for help.
What is the best way to maintain the charge and life of my battery?
I currently have a wall plug and extension chord running to a heavy gauge connector that plugs into my Trailmanor’s main electrical chord.
There is also a factory installed battery on/off switch that is next to the battery which still allows me to utilize the electric lift for the hitch even when selected off but isolates power from the trailer.

Should this switch be turned on or off during storage and charging or should I disconnect the battery all together and just buy a trickle charger?

Thx in advance for any insights!

 

[Bill]

First, congratulations on your new camper! I've never seen one of the new Sport models, and am eager to do so.

I didn't realize that the factory is installing a battery switch now - that is new, and a good thing. You can turn off this switch anytime, and it will completely isolate the battery from any of the pesky parasitic loads that afflict most campers. (The parasitic loads will pull your battery down in a week or so.) We used to tell the owners to pull the main battery fuse, which accomplished the same thing but is annoying to do. Use the switch between trips - but don't forget to turn it back on before your next trip, or anytime you need to turn on lights, refrig, etc. Once this switch is off, the only thing that will discharge the battery is what is called the battery's self-discharge, which is very very slow.

I suppose you can use the old approach - leave the battery switch turned on and plug your TM's heavy black cord into a garage wall outlet - but now there is no reason to do this. And if you choose to do it, don't do it for more than a week or so at a time, since the TM's onboard charger may eventually overcharge the battery. Better and simpler to use the battery isolator switch.

Finally, a battery MAINTAINER is useful for long-term storage - months. Note that a battery maintainer is not the same as a trickle charger - avoid those.

Welcome to the TM Forum!

Bill

 

[Rebound123]

Awesome insight, thx!

I’ll post some pics after my next trip.
I’m excited about all of the options that come with the sports package
It wasn’t easy to come by. Only a few available in the country but I got lucky and found this one 3 1/2 hours away

 

[Kidkraz]

Not sure if this would be a good alternate, but maybe Bill or another electrical knowledgable person could clarify. Maybe get a solar powered battery trickle charger would help. I have a solar panel from the factory and it's kept my batteries up and serviceable. Just tossing out an option. Welcome to the forum.

 

[Rebound123]

Great idea!
The sport does come with a solar panel and it works great
We have it in the garage in between trips though

 

[Kidkraz]

Maybe hook a small secondary panel just outside where it could get decent sun.

 

[Rebound123]

Great idea, thx!

 

[Bill]

Maybe hook a small secondary panel just outside where it could get decent sun.

Great idea. It reminds me that I have a very small solar panel mounted on my pontoon boat, exposed to the sun as the boat swings on the mooring. Rated 5 watts, I think, and connected directly to the battery. Small panels exhibit self-limiting charging, so there is no need for a charge controller. When I tie up the boat, the panel keeps the battery at full charge (but not overcharged) until I use the boat again, which might be a few weeks later. I think I paid $10 for it at Amazon, and it has worked perfectly. Don't go more than 5 or 10 watts - this is a case where bigger is not better.

Bill

 

[Rebound123]

Great info, thanks

 

[Wavery]

I agree with Kidraz. I have a poll mounted 25W solar panel with a small solar controller on the outside of our carport. The wire end has clips on it to attach to the battery directly. A lot of RVs now come with an exterior outlet to plug in exterior solar panels.

Whatever method that you choose, be sure to check your battery's water level every 3 months or so. When filling, be sure to use distilled water only. Tap water will destroy your battery in short order.

I would strongly discourage leaving the camper plugged into your 120V home outlet while in storage. This is what happened to my brothers when he did that.

 

[Rebound123]

Yikes!
Thx for the information!

 

[rickst29]

If your battery pack(s) are a lead-acid variety (SLA, AGM, or GEL), then you should probably buy a high quality battery maintainer with both battery type selection and accurate temperature compensation (using a connected thermocouple temp sensor which can be placed on one of the battery packs, within the outer box.)

With the shut-off switch in use, you don't need high current. (The high current ones cost much more.) Solar controllers tend to have poor accuracy, using "canned" logic decisions which won't keep the battery cells at EXACTLY 99-100% state-of-charge under different temp conditions. Their temp sensors are generally used for protection only, not for carefully adjusting charge and float voltages.

Lead acid cells should be kept as near 100% as you can get, all the time, while not overcharging and causing issues with plate damage, incorrect acid concentration, or actual lost water by evaporating with hot plates. Before I switched to LFP cells, I used a high-quality swedish battery maintainer - but there are lots of good ones these days, generally china-made from USA designs. I'll guess that you shouldn't need to spend more than than $60, although prices may have changed since I last looked.

In long term storage, if the DC cords from the maintainer don't already have ferrites on the cables, you might want to clip on a pair -- to further reduce both AC and RF "noise" (ripple) coming in from the maintainer's power converter. They're cheap, here's an Amazon multi-pack: https://www.amazon.com/20pcs-Clip-Ferrite-Suppressor-Diameter/dp/B0CSXZWGD6

 

[rickst29]

For the case of LFP battery cells, you should modify your BMS maximum charging limit in long term storage - dropping to around 13.1 maximum total voltage (roughly 50% SOC, rather than floating higher). Your regular plug-in power converter will try to supply more, but the BMS will refuse to accept it until the battery cells have fallen lower. Be absolutely sure that the BMS does not allow charging below about 2 degrees C, or 35F.

 

[Rebound123]

Great info
The trailer did come with a deep cell led acid battery
Your info was really helpful

 

[Rebound123]

We primarily plan on camping at locations with power but would love to park remotely too.
Would it be beneficial to purchase a second battery and possibly a portable solar panel to directly charge it so we could switch it out as necessary?
We previously had a pop up but never boon-docked with it

 

[rickst29]

Thanks for your kudos.
Your best choices for 'adding electrical power' will vary, according to these 3 issues:

#1, how many hours or days you need to last with no plugins;
#2, how much power you might consume during each of those days; and
#3, (with regard to solar only) how much sun you will get while camping.

You probably want to start by estimating #2 first: "how much power will I want to use" during the not-plugged in hours or days. If not using "big electrical" things like the air conditioner, the fridge ON ELECTRIC, or electric cooking appliances, you might get by with about 150 watts consumed per day. That includes evening lights, flushing the toilet, running the water pump, operating a few 12v powered detectors (including the CO/gas detector), running the overhead fan while cooking, and driving the 12v-powered igniters for gas appliances.

But on cold mornings or nights, running the heater needs a lot of additional 12v electricity. The heater runs on propane, but the fan uses a lot of 12v power.

If you want to use 120-VAC appliances (microwave, household-style coffee maker, etc.) you will need an inverter -- and probably a big one, in the case or those particular cooking appliances. A great option for coffee without an inverter is boiling water on the gas stovetop, then pouring the water over a melita-style paper filter into a carafe. Another option is using a permanent Mr.Coffee-style flat filter full of ghrounds right in the pan on the stove, just swish it around for a couple minutes while keeping the water hot. The disadvantage if the permanent Mr coffee filter is cleaning the grounds out after, the disadvantage of the disposable Melita is sthe need to slowly drip the hot water from above. (You could use a paper Mr. coffee inside of the permanent filter, but the coffee tends to be weak from the double filters.)

You need only a small inverter to charge disposable batteries and cellphones from 120V chargers, although there are lots of good (and cheap) "5 Volt USB" chargers which run directly from 12 volts DC.

 

[rickst29]

Then move to calculate total power per day (or night), in comparson to your USABLE battery size. A few specialized lead acid batteries can be run down to only 20% remaining, but those batteries are made for golf carts and indoor forklifts. They're very expensive, hard to find, and they are now being replaced by LFP batteries built for exactly that usage. (In the case of golf carts, either 36 or 48 volts).

The deep cycle lead acid batteries your dealer probably installed shouldn't be used past about 50% remaining. If the battery size is rated "100 Amp-Hours", and you have two of them, you can't use 200 amp hours of power! You will kill the batteries on the very first trip. From 100% full, you can use about 1/2 of the rated capacity - that's a total of 100 amp-hours from two batteries, maybe not quite enough for "piggy" power users to last a full day. (By the way, 100 amp-hours at average voltage 12.4 volts is 1240 watt hours (1.24 kilowatt hours).

LFP batteries are about 85% usable, rather than 50% usable, and they weight barely 1/2 as much as a lead acid battery of the same nominal size. (That is a ratio of 70% more usable power from the same "size" battery.) They can last 10-12 years if maintained carefully, but they need higher charging voltages and pretty careful management. They are roughly 3x more expensive, but the 4x lifespan advantage, higher usable proportion, and lower weight often make them a better choice -- in the long term. I own 840 rated amp-hours of LFP batteries, that's over 9000 watt-hours of usable power. (I can run the air conditioner in the Nevada desert, with no plug-ins.) But my batteries cost A LOT of money.

 

[rickst29]

Portable solar panels can be moved through the day, to face into the sun better. But the "suitcase models" tend to have relatively low power ratings (100-400 watts), They are a bit costly, and hardly any can be adjusted to provide higher voltage for LFP batteries. In some locations, bad people might try to steal them, and you have to lug them around a lot (from RV or tow vehicle storage to the campsite driveway..

I think a better option would be to add solar on your roof. Your new model has side rails on the front shell, I don't know if those are intended for supporting "additional luggage" or other things. They could support a very large rail-mounted solar panels, or you could add smaller ones right on the roof.

Because the roof is flat, and does not face into the sun directly (except maybe at "Solar Noon" in June, at lower latitudes than my home in Reno), you loose some efficiency. But they cost less, you don't have to lug them around, and you can add a lot more power. (I have 800 rated watts on my SMALLER 2619). The rear shell of your new 2720 can also probably add another panel.

On an average summer day, with good sun for a total of about 6 hours, a 100 watt panel will generate about 450 watt-hours. The daylight lasts longer, but you get much less than 100 watts during most of the day.

 

[rickst29]

As an alternative to solar, you could also buy a small generator instead. They still work when its cloudy or raining, although they make a bit of noise. Some models can be run from propane, and using that fuel source (instead of gas) eliminates the issues of carb cleaning and draining gas at the end of the seasons before it goes "stale". I think that the rest of the engine, and the engine oil, also stays a bit cleaner when using propane. But the power goes down, and there are issues at higher altitudes.

 

[Rebound123]

You guys are a wealth of information!
My 2720 sport does come with a factory installed solar panel.
I'll try out using the solar panel without plugging it in at a camp site and see how much power I use and gauge my next step off of that
Thx for everyone's input and help! It is much appreciated