Impetus for our switch
I hate to admit it but our situation is a perfect example of why an upgrade to lithium makes sense.
As is unfortunately somewhat common, our Airstream came with "pre-tortured" batteries from the dealership, meaning that they were allowed to go completely dead because nobody plugged the trailer into power while the trailer was sitting.
That's Strike One against the longevity of the batteries. You don't get to do that to lead-acid batteries too many times before they are dead forever. Lead-acid batteries should be maintained at a minimum of 12.2-12.3 volts.
The batteries went flat again a few months later while the trailer was in storage. Strike Two. This took less than two weeks even with the Battery Disconnect switch in the “STORE” position, so I suspected that the batteries were already in rough shape. Normally they'll hold their charge longer than that, if there's nothing turned on. I moved the trailer to a storage lot that had power, to avoid this problem happening again.
But then came Strike Three, earlier this year, when we took the Airstream in for service and it sat for 6 weeks waiting for a part to arrive. Again, nobody plugged it in. When I got the trailer back, the batteries were utterly useless and would hold no charge at all.
In fact, the batteries were so damaged that they began to swell.
That was an ominous sign and it meant those batteries needed to go to recycling immediately. If you aren’t already aware of this, you should never use batteries that are swollen or that get hot when they charge.
In summary, it took only 20 months to destroy a $600 pair of AGM batteries that should have lasted 6 years. It was time for a better solution.
Why we chose Renogy LiFeP04
Although there are several types of "lithium" batteries out there, Lithium Iron Phosphate chemistry (or LiFePO4) is the type RV'ers use, for several reasons:
It's safe: very tolerant of heat and vibration, won't leak, non-toxic, doesn’t burn
It has great longevity: you can recharge LiFePO4 batteries many more times than traditional lead-acid batteries
It holds its charge while in storage for a long time (i.e., it has a low "self-discharge" rate). It's no big deal to leave LiFePO4 batteries in storage mode for 6-12 months.
Deep discharging isn’t a problem: these batteries can go to zero and still come back strong
And there's another benefit: you can pack a lot more power with lithium compared to lead-acid batteries.
In our case, our Airstream came with two Interstate AGM batteries that each held 62 Ah (amp-hours), which was OK for 2-3 days of camping if we weren't plugged in. Note that our usable power wasn't 62 x 2 = 124 Ah, because lead-acid batteries like these should only be discharged about 50%. So two 62 Ah batteries is still only 62 Ah usable.
Battle Born brand batteries are recommended by Airstream, and they are a great product. But given our needs, I chose Renogy as an economical but still respectable alternative. After doing some careful measuring, I was able to determine that we could fit two Renogy RBT100LFP12S batteries in the same space as the Interstate batteries. Like the commonly-prescribed Battle Born GC2 batteries, they have a capacity of 100 Ah each, meaning that a pair of them yields 200 Ah usable. In our case that more than tripled our battery power—and lightened the trailer by about 43 pounds.
Battery heaters were another key decision. LiFePO4 batteries don't want to charge below about 25°F, and for this reason some manufacturers offer a self-heating option. This adds about $50 per battery.
For our purposes, I didn't see the need. We live in southern Arizona and we don't camp in freezing temperatures. On those rare occasions where we have a freezing night, we can still use the batteries all the way down to -4°F and they'll charge back up during the daytime when it's warmer.
How much did all this cost?
Honestly, it wasn’t cheap. This is the downside of lithium, of course. Even the relatively inexpensive Renogy batteries were $720 each when I bought them. On top of that, my Airstream's built-in converter/charger would need an upgrade to be able to correctly charge lithium batteries. (Some Airstreams have converter/chargers that have a switch for lithium.) The upgrade added another $288.
With tax, the total was $1,879—and there would be additional costs later for small parts and tools, which I'll document in a moment.
Whether this is "worth it" depends on you. I would not switch to lithium for the weight savings alone, but for our needs, lithium makes sense. We will make good use of the additional power when we are boondocking, and it will be a relief to pick the Airstream up from storage and find the batteries ready to go, rather than dead.
With the decision of which batteries to buy complete, I was ready to begin the DIY install of the Renogy batteries, and upgrade the WFCO converter/charger. It seemed like it would be a straightforward process–but I encountered a few "gotcha" challenges along the way.
Hire or DIY?
Only you can answer that question, based on your skill level, comfort working with batteries, and budget. I chose to do the upgrade myself because:
These days it's hard to get an appointment at an RV service center
My self-assessment was that I had enough skill to do the work myself without frying electronics, hurting myself, or doing a crappy job
But without an experienced technician looking over my shoulder, I needed to think carefully about the parts I'd buy, the tools I'd need, and the process of installing everything. For weeks I researched the options and best practices, which is always a task fraught with confusion because there's so much incorrect information on the Internet.
If you decide to DIY, here are a few critical points about safety:
Flip the battery disconnect switch to "STORE" before you start work. This will ensure that when you re-connect the batteries later, the power won't go to the rest of the Airstream. This might save you from sparks or bigger problems if you've accidentally made a connection on the batteries you didn't mean to.
Unplug the Airstream from external power. Put the power cord away so nobody else can plug it back in.
Remove rings, watches, and dangly jewelry before working on the batteries. It will minimize the chance of getting zapped.
Before working on the power converter, take the additional step of switching off the circuit breaker that controls the converter. The breaker assignments should be printed on a label inside the fuse panel area.
Don’t skimp on tools & technique. Proper crimping of wire ends is crucial. Loose connections can be dangerous.
Take precise measurements
Starting with model year 2016, Airstream changed the depth of the battery storage box on trailers to 12 inches. This gave me plenty of options for batteries. (Earlier model years were only 8.25 inches deep.)
Given that I was about to spend about $1500 on the batteries, I wanted to be absolutely sure they'd fit without any surprises. As the saying goes, “the good carpenter measures twice and cuts once,” but in my paranoia I measured about 7 times.
I checked not only the box dimensions but also accounted for the smaller size of the lid opening, wires inside the battery box, the space required by the hold-down bracket, and even minor intrusions like rivet tails poking through. TIP: Keep in mind you don't want the batteries to fit too snugly in the case, or you will have trouble arranging the wires and lifting the batteries out later.
The photo below shows my initial test-fit of the batteries. It was a perfect fit once I removed the battery tray (which isn't needed for lithium batteries).
The first challenges cropped up immediately once I had the old batteries out. Renogy (and some other lithium batteries) don't have traditional battery posts—everything connects to a screw-down M8 bolt, which means the fat wires that have clamp connectors have to be cut off and replaced with ring terminals.
Also, the battery cross-connect wires were far too short to reach, as you can see in the photo. The Renogy batteries could only be positioned as shown, because of the tabs you see on the top and bottom of the photo. Those tabs are access points for a switch that takes the batteries out of "storage mode" and so I couldn't position the batteries in any other way or one of those tabs would interfere with the hold-down bracket.
The solution: make new, longer cables.
In fact, cables were the bulk of the challenge. Measuring, cutting and crimping wires is necessary at several points. You'll need a good wire cutter and crimping tool capable of handling 4 and 6 gauge wire, plus of course some wire, and an assortment of ring terminals. The posts on these batteries were M8 bolts, which means I needed a few 5/16" ring terminals for both 4 and 6 gauge wires. Some heat shrink and a heat gun will be needed to put on the final touches.
While planning, you'll probably encounter "might as well"-type choices. In my case, I decided to spring for another $130 to get an amp-hour meter so I'd really know what was going on with the batteries. The built-in volt meter that comes with most RVs just doesn't cut it.
I chose the Victron Smart Shunt. I didn't want to snake wires into the Airstream and find a place to mount a monitor, so the Smart Shunt was perfect for me. Instead of a monitor, you connect with Bluetooth and can view the status of the batteries on your phone.
Best of all, the installation of the Victron Smart Shunt was dead simple. You just connect the battery negative terminal to one end, and all of the negative cables to the other end, then plug in a pair of wires (not pictured) that go to the positive battery connection. The only slight catch was that the Smart Shunt uses larger M10 bolts, so I needed yet another set of ring terminals for various wire gauges in order to connect all the negative wires to it.
The photo shows another test fitting, before I finished wiring and securing it to the top of the battery with 3M VHB tape. The trick here was to find a spot where it wouldn't interfere with any other cables or the battery hold-down bracket. Since there's not much free space in the battery box, I recommend taking plenty of time to test-fit every cable, fuse holder, and device before fastening it all in place.
The other major challenge was the need to replace part of the power converter/charger.
Airstream has used several models of converters recently. Some of them have a convenient switch to change charging mode from lead-acid to lithium, some of them need a simple jumper wire to be installed, and others have to be swapped out. Mine fell in the latter category. You can get more details about upgrading late-model power converters to lithium charging on Airstream's support site.
Ours was a 30 amp WFCO 8955-PEC, which needed the lower section (the main board assembly) replaced with the WFCO WF-8950L2-MBA. While this is far easier than replacing the entire converter, it was still expensive: $288.
This was a fairly easy job, involving 4 screws and 5 wires. Still, if you don't have experience at working with AC wiring, and proper tools, I would recommend getting a technician to do the job. A full converter replacement would be considerably more complicated.
IMPORTANT! If you have solar installed, there's another step to take: updating the solar charge controller. For factory-installed solar:
2021 model year: Airstream installed a Victron charger and display. It has a dial indicator on the side that can be switched to position 7 for Lithium batteries. Easy!
2017 to 2020 model years: Airstream installed a Sun Explorer controller and display. The controller will have to be replaced with an updated model that has the option to choose the battery type, which is available. You can use the current display.
2016 model year and earlier: Both the factory-installed controller and display will need to be replaced with something lithium-compatible.
We don't have factory-installed solar. We use our 170-watt Portable Solar Kit instead, which doesn't need any update to charge LiFePO4 batteries, so I was able to skip this step.
Once I had everything wired up, I did a double-check of everything including tugging hard on all the cables I'd made, then powered up in this order:
Activated the batteries using the switch Renogy provides (pictured above)
Battery Disconnect in the Airstream switched back to "USE"
Double-checked for popped fuses in the battery box and fuse panel
Plugged the trailer into shore power with my Progressive EMS in line so I could monitor the power draw.
The batteries arrived about 2/3 charged. Once power was flowing I could hear the cooling fan in the new power converter go on, and the batteries began to charge at about 9 AC amps (about 1,000 watts). I left the Airstream to charge for a couple of hours and came back in the morning to test and calibrate the Smart Shunt (described below).
Initial impressions and what I’ve learned so farI have always recommended that frequent boondockers, solar users, and full-timers strongly consider installing an amp-hour meter to replace the factory-supplied voltage meter. There are many on the market, andI discuss what they do in more detail in this blog.
It makes a lot of sense to install an amp-hour meter when you're doing any battery upgrade, since you're already into the wiring. I chose the Victron SmartShunt for ease of installation this time, but in my previous Airstream I used the Bogart Engineering Tri-Metric 2020 and it worked just as well.
The Bluetooth range of the SmartShunt has been disappointing. I can only connect to it reliably when standing within a few feet of the battery box, and the signal doesn't reach inside the Airstream even when standing by the front window. Having to go outside to check the battery status is inconvenient, but I've decided I'll put up with it for now.
However, the information provided by the SmartShunt is invaluable. There's a small amount of tweaking needed to the settings in the app before it will read accurately, but that's simple.
TIP: For LiFePO4 batteries you should adjust several settings:
Set Battery Capacity to match your battery bank (mine is 200 Ah)
Set Charged Voltage Value to between 13.4 - 13.6 volts (depending on manufacturer)
Set Peukert Exponent value to 1.05
Set Charge Efficiency to 99%
Set Discharge Floor to the minimum you want to let the batteries get to in normal use before the SmartShunt sends an alert (Victron recommends 10-20%, and I set mine at 10%).
IMPORTANT! Although you can use all the rated capacity of your new LiFePO4 batteries, they can still be damaged by over-discharging beyond that point. This can happen if you put your Airstream in storage for a long time—even with the Battery Disconnect switch in the "STORE" position!
This is where an amp-hour meter comes in handy. The SmartShunt told me that with everything switched off in my Airstream, there was still a stand-by ("parasitic") draw of 0.81 amps (about 11 watts), all the time. At that rate, my fully-charged lithium batteries would be dead in about 10 days!
When I switched the Battery Disconnect to "STORE", the draw dropped to 0.19 amps (about 3 watts)—which is obviously still not zero. This means my fully-charged lithium batteries would be dead in about 5 weeks. (This also demonstrates why the previous AGM batteries were going flat while the trailer was in storage—they would be discharged below their safe minimum in about 2 weeks.)
I often store my Airstream for more than 5 weeks, and I don't want to come back to murdered batteries, especially not with a $1500 replacement cost. Renogy provides an activation switch which theoretically can be used to put the batteries back into "shelf mode" but in practice it doesn't work when you have two batteries wired in parallel.
Since I keep my Airstream in covered storage (thus eliminating the possibility of solar) the only solutions for my situation are to keep the trailer plugged in, or electrically disconnect the batteries while in storage, which fortunately is easy to do. With just a screwdriver I can remove the main negative cable from the battery in seconds. Once disconnected, the batteries should hold their charge for a very long time (only 2-3% self-discharge per year.)
I expect the batteries to be trouble-free, based on reports from others. Moreover, we should have no worries about camping without an electric hookup. In this case we went from 62 Ah to 200 Ah and thus have tripled our off-grid camping time, without requiring a complicated custom battery installation.
For our purposes, 200 Ah (2,560 Watt-hours) is all we'll need for our typical trips. This will easily power all our needs including two laptops for a few days. If we need more, we can easily pick up another 400-500 Watt-hours per day with our Portable Solar Kit.
Lithium definitely has advantages that make sense for Airstream use, whether in trailers or motorhomes:
Battery Management Systems are built-in to every lithium battery to ensure the battery is protected from various conditions like overloading, high/low temperature, incorrect charging, etc.
LiFePO4 batteries are particularly long-lived (8-10 years expected)
LiFePO4 batteries are safer: They don't contain toxic metals or acid, don't spill, don't emit flammable or corrosive gas, and aren't prone to catching fire even if damaged.
LiFePO4 batteries charge more quickly and efficiently.
As mentioned previously, LiFePO4 batteries can be stored for long periods of time without needing charging.
Lithium batteries are generally much lighter (about half the weight) compared to the batteries they replace.
Whether any of these advantages are worth the much higher cost of lithium is a call only you can make. In my case the total cost of this project was about $2,100 including taxes and miscellaneous tools and supplies. A big expense indeed, but one that I expect will pay dividends in convenience and enhanced ability to use our Airstream the way we want to.Our products
Swollen batteries like this one are dangerous
Our batteries needed to go to recycling immediately. If you aren’t already aware of this, you should never use batteries that are swollen or that get hot when they charge.