Today, we’re looking at the details of upgrading to lithium. Many of the things that we hear repeated about upgrading to lithium aren’t always 100% accurate, so we have some tests to get to the real-world use case.
Because this 150-buck battery that I just picked up—it’s a 100—amp—hour battery—used to cost us right around $1,000. So, with that price change, as lead-acid batteries are dying off, people who thought they would never switch to lithium might actually be considering it now.
Let’s get into the nitty-gritty. Do you need to replace everything to switch to lithium, or is it just a drop-in replacement? Let’s have any time—let’s look into it.
To start, I set up a couple of batteries to be able to do a side-by-side test because the four or five things we want to consider when doing a battery upgrade are:
- The converter
- Is our battery monitor even going to work anymore?
- Alternator charging—are we going to fry that alternator?
- Our solar charge controller
- Outside temperature
So, let’s let’s tackle the converter and charge up the battery because we all know that lithium charges slightly differently than lead acid. I was shocked the other day when I was charging these up—one had a lead acid converter, and the other one had a lithium converter charger—and it only took about 10 minutes between them to get a full charge on both of them. Which is pretty much nothing, considering these are 280Ah batteries. I even did a capacity test, and it did pull over 280 amp hours.
So what’s the truth here? I’ve heard it repeated that it can take days to bring your lithium battery up with a lead acid battery charger up to full charge. Why did it do it in just about the same amount of time? Do I need to swap out my converter for a lithium converter?
So, let’s look into that. I recommend having a lithium charger for your batteries—but you might already have one. I’ll tell you what to look for, but my long-term recommendation is a lithium charger. If you have an inverter setup like the Multiplus that handles the charging, you wouldn’t have a converter, and a lithium upgrade isn’t anything. Our RV has a moderate system, but there are also budget options. Many like to do these upgrades in stages—that way, it’s a significant one-lump sum for an upgrade.
Let me give you an example of what you would expect if you could get batteries and weren’t to upgrade your charger initially. It has a hard time with a lead acid charge control system because it doesn’t know what to do. It depends on voltage and whether it can receive a charge. The language between the battery and the converter maintains the battery and gives it the voltage and charging profile it needs.
It charged it up all the way the first time because it recognised it as a severely depleted battery. The voltage was low enough, so it put it into a boost mode. If you look at the charging for this unit, we can see that it goes up to 14.4 for boost, which is excellent—that battery wants to be able to charge up and balance those cells inside.
The problem is that when it goes into normal mode, we’re at 13.6. But then, after that, it goes into either storage or float, which will put it around 13.3 or 13.2. So, let me show you what’s happening to your battery when it goes into that mode.
This power supply represents our converter and will be plugged into the bit’ sry. It is supplying 13.3 like it’s in the storage mode, but you can see that the voltage on there is actually 13.69 when we connect the battery because the battery’s resting voltage is higher than the battery’s converter is going to supply to it.
So when we pull a load off of this—like turning on lights and a fan—it will take that energy from the battery rather than it’s our converter. So even though you might be connected to shore power, you will be using what’s inside your battery, bringing that down what’s 100%. So you might be plugged into power thinking that you’re getting ready to go boondocking at 100%you’reyou, and you find out that your battery has been depleted because it’s pulling that power from the battery ratheit’san your converter—which can be a problem if you’re expecting a fully charged battery.
Your problem is that under normal circumstances for charging—rather than a fully depleted battery—it will be charging at 13.6, not 14.4. So, at 13.6, it won’t bring it up to 100%. That’s where we get that it’s 90%, typically 80–90%. That does not bring it up enough to balance the cells inside that battery.
But the next thing we’ll check out is connecting a lithiwe’rettery to an alternator. You’ll often hear that it doesn’t matter—or sometimes that it does your alternator or you out. So, it’ll see where the truth is on that.
The firslet’stwo RVS we will examine is the towable RV. The towable setup is different from the drivable setup. In the towable, the power from the alternator is typically protected with a fuse and wired all the way back to the 7-way connection on the truck, which delivers the power back to charge the RV batteries while connected and driving.
Our test example is a halfway depleted SFK lithium battery with a cable of the same length and gauge found just like in our fifth wheel. The results are a shocker for many people—at idle, we only see two amps get to the battery for charging, which is not much. Even taking it on the road to get the RPMs up and seeing a bit more voltage increase, the highest I saw was 2.3 volts. So, this is not a stress on the alternator, the battery, or any systems there. That’s why I’ve been keeping it like that. For that, I need to disconnect it from the truck. It’s not that much. I’m not getting many benefits. I’d rather have that power back at the 7-way in other situations.
This one’s simple: you don’t need to change one’s back there unless you’re going to try to get a more substantial you’re to the back, and then there are options to do that. But you’re not needed if you’re trying to do a simple setup.
Now, for the drivable RVs, typically, the battery is closer to the alternator and with a thicker gauge wire, which changes quite a few things. So that’s exactly what I’m doing here: testing, and that’s precisely what it does.
Okay, here we go. When we flip the switch, we hit over 100 amps and quickly drop down but steadily climb back up. Giving it a high idle, closer to what driving would be, it’s well over 100 until I back off, and it writes back down but steadily comes back up.
This is more stress than I want to put on my alternator over time. And depending—if you only had one 100 amp hour battery—typically, it will stress that out, and the BMS will step in and shut everything down to protect the battery.
That brings us to a piece of advice that I hear isn’t necessarily true—and it’s that the BMS isn’t and regulates the chits. It won’t set up the charging profile to charge your baptistery correctly. The two most significant functions of the BMS are to protect your battery and to balance the cells. It’s basically like a big safety net for the battery—if there’s something wrong or it needs to shut safety, it will just disconnect and shut it down.
When charged up, it will balance its sales on the inside. It usually does that as a top balance, so when that battery gets full, it will make sure that all those cells are balanced with each other. That’s why having a converter that will work for your lithium battery in that term is essential.
All of that is a lot of information. So, I want to break this down into a really simple format—basic recommendations—because there are a thousand ways to set it up. But what is the basic way to start?
Number one—you probably guessed it:
Make sure you have a lithium charger and a converter that’s lithium-compatible. Look at your existing server—it might already be an auto-detect. So it will detect if there is lithium or if you collect lithium as we did on the one we got from Etrailer. Typically, you’ll see something with a two-stage charging you’ll for charging it up and 13.6 for float. That’s general for lithium charging, so it’s a simple long-term solution.
Now fit alternator charging:
Towables—you see, we didn’t need to do anything.
If you have a driver, I recommend having a DC-to-DC charger. They’re not difficult to set up, and you can see how the battery charges.
Number three is your battery monitor in your RV:
If you have a voltage-based battery monitor, it won’t do much for you because the voltages are different from lithium. So there are usuit’sithwon’tptions that people go with:
- They either do without,
- They get an upgraded battery that has Bluetooth built into it—so you can open up the app and see what the status of that battery is, what percentage it is at,
- You can also install a shunt-based monitor, which will be the most expensive but is an option.
Moving on to number four is solar charging:
Everyone has moved to MPPT solar charge controllers, which are the most popular. Almost all of those are programmable for lithium, so just select the right charging profile, and you’re good to go.
This brings us to the number of low-temperature protection:
I have a battery buyer guide, and every single one on there is going to give you low-temperature charge protection. I wouldn’t buy a lithium battery without low-temperature charge protection—even though (I’m going to put a little asterisk on there) I put ours in our front bay, which is not heated or cooled, and we’ve never had the low-temperature charge protection kick in while we’re using the RV.
Many people have heard that our lithium batteries don’t do well in cold climates—which isn’t the don’t story. You’re going to have loisn’tperature charge prYou’reon. You can still use them in very low temperatures—you don’t want to charge it up when it’s below the front. But if you get one with lit temperature protection, it will take care of that. So you don’t even have to think about it. If it’s just cold, it won’t charge. When it is up, it can charge. Those are the five significant considerations when you are considering upgrading to lithium. We used not to have the option of having Bluetooth inside of batteries. We didn’t have converters that came where you candidate different battery types already in our RV. So those are things that you can look for.
So, upgrading to lithium might be easier and more affordable than ever. That battery that I got for 150 bucks—I think right now it’s 160, depending on the sales that will be—is more affordable and achievable than it used to be.
I hope some of this information helps if you consider upgrading to lithium. You know you’re what to expect and what to look for.