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People spend a LOT of time talking about how various RV lithium batteries work in the cold.
- “How cold can you charge it?”
- “How do you warm it up if it’s cold?”
- “How long can it stay at X temperature?”
- “I can imagine my RV getting colder than yours, and so now I’ve given myself an excuse to ignore how lithium batteries are fifty-billion times better than lead-acid batteries because I could think of one special edge-case that would happen once every thirty-four years and would cause me a temporary inconvenience.”
You get the idea.
But for as much as people talk about lithium batteries getting hypothetically too cold, you don’t see the same amount of chatter about them getting too hot. Well, I’m talking about it today, because it happened to us… sort of.
When we installed the lithium battery in Lance in the first place, I wanted to make sure to keep it inside. My thinking was to avoid this too-cold/too-hot discussion altogether. Because, if it’s comfortable in the van for humans, it’s comfortable for the battery. But just putting the battery inside wasn’t enough. I hadn’t counted on two things.
First, the battery was installed inside a closed compartment. This keeps it somewhat (but not completely) isolated from the temperature inside the van. That’s what I rectify with the project in this video.
Second, I’ve learned that charging the battery – especially at rates of 100 Amps or more – can really cause the battery to heat up. In fact, charging the battery causes it to heat up more than dis-charging it.
So on a recent trip we were:
- driving across the desert
- charging the battery at over 100A
- keeping the battery sealed up in its compartment near the skin of the van.
And our battery got really hot. In fact, it got up over 131 degrees Fahrenheit, and the Battery Management System (BMS) shut the show down. When the battery’s internal temperature dropped back down to a safe level, it just turned itself on again. So I did some checking with Lithionics, who makes our battery, and found out that their BMS enforces two over-temperature conditions.
- At temperatures of 114 degrees Fahrenheit and above, charging the battery is not allowed.
- At temperatures of 132 degrees Fahrenheit and above, discharging the battery is not allowed.
It does this through a battery temperature sensor that is internal to the battery (not just surface temperature or the temperature in the battery compartment). These limits are set by Lithionics to prevent damaging the battery. I had no idea that our battery got that hot, but now I know. Time will tell how well my venting solution works.
The Key Takeaway
But here’s the big point. If my battery was NOT protected by the BMS, I could have done serious damage to it. SO – if you’re spending the money to upgrade to lithium batteries, it really pays to make sure that your batteries are protected by a solid BMS.
I know that the systems offered today by Winnebago and Coachmen (Volta and Xantrex systems, respectively) are protected by a BMS. Other manufacturers? Maybe, but I simply don’t know. Drop-in lithium replacements? I don’t know. “Roll your own” buy-a-bunch-of-cheap-cells-and-wire-them-together-yourself systems? Probably not.
So there you have it. I’ll be watching my battery’s internal temperature closely in the coming months, so we’ll see how well this mod works.
Was the heat coming from the batteries themselves or the charge controller?
Some of the heat was certainly generated by the battery as it charged. They do get warm.
But the bulk of the heat was coming in from the outside with nowhere to go.
Has anyone on here found a reasonably low energy solution to keeping the temperature near AGM/Lithium batteries + inverter within safe parameters while parked? I travel for work and am trying to find safe solutions using uncovered airport parking in los angels without trying my batteries. Or better yet, starting a fire. Ideas anyone?
Fans and passive cooling would be your friends here.
Intake air down low. Exhaust air up high.
Add a computer fan or similar to improve the airflow when you need it.
I’d try something like that first, and see how far that gets you.
BTW – any decent lithium battery should come with a BMS that will shut things off if the temperature gets too high.
Question: Where is your inverter in all of this, and why did your battery shut down before your inverter? Was it simply because you were charging without a significant load imposed at the same time? (With temps like you describe, I think I would have been running the roof a/c as I was driving!).
We have experienced high-temp shut-downs, but the inverter has been the rate-limiting device. And because our 2,000 watt Xantrex inverter is situated on a floating shelf directly above the battery in the same cabinet, I have been assuming that it would serve as our battery’s canary in the coalmine (we have a DIY system – my husband is a mechanical engineer).
We are using an ElectroDacus BMS, which gives temp read-outs of the battery itself on its frontpage display. I’ve never seen lithium temps as high as you describe here, but I’ve never really made it a point to watch for that. I will now!!
We have a perforated aluminum theme going in our DIY mods (rather than carbon fiber), so I made an analogous compartment face which is held on using the kind of neodyms that have a hole in the center so they can be screw-attached to the face plate, which then sticks to the cabinet. I do believe that we will also need to retrofit a fan into our cabinet to circulate air, but we haven’t done it yet.
Here’s a pic of the face plate I made – my first real woodworking project of any kind. Not perfect craftwomanship, but I was satisfied with it. It’s two-layered because our van was born with a conventional electrical converter, which we removed when installing the lithium system. The original cabinet opening was the size of the converter face, so I had to account for that with the oak mask which I painted gray to match the rig’s countertop.
The inverter is in a separate compartment, and was not running at the time of the shutdown. We don’t typically run the roof AC while driving. We find the cab AC gets the job done for the front of the van, where we usually are.
I like the perforated vent you made. I went for off-the-shelf parts from the home center. Time will tell if I’ve done enough to keep the battery cool – though I expect I will have to wait until next summer to know for sure.
Hi! Just finished watching your video about care and nurturing of lithium ion batteries.
A couple of days before I had watched a PBS show on Netflix, “The Search of the Superbattery”, …. very, very informative about forms of lithium batteries and safety. I would highly recommend it to you and subscribers – gives good info, albeit in silly ways at times, with lots of industry laboratory demos.
I enjoy your vids. Thanks for doing them!
Glad you like the videos. I’ll see if I can check out that PBS show.
Excellent video as always. I have a couple slightly unrelated questions, but now that I see your talking batteries again…
Do you think your system is something anyone off the street could buy?
Is there a reasonably priced (OK oxymoron for Lithium) commercially available aftermarket lithium battery system you know of that you’d be inclined to recommend?
If you had it to do over again, would you be inclined to go with one of these higher voltage systems like 48 Volt?
We have the EcoTrek modules in our van, and I’ve seen a lot of people asking about lithium upgrades in general. I’m curious with your experience if you’d be inclined to take a factory setup, or look at aftermarket solutions. I wish when I got into the Lithium that I’d thought forward to post warranty support. Its not like a fridge that you’d just replace with a similar fridge. Lithium is evolving.
Could anyone off the street buy one? Maybe? I’m pretty sure you could buy the inverter, cabling, fuses, etc. No problem there.
The folks at Lithionics would probably have some questions for you to make sure you got the right battery. And if you didn’t seem like you knew what you were doing, they might refer you to a knowledgeable installer.
You could try calling Xantrex about their branded system that uses the same components. I don’t know if it’s available aftermarket, but it’s worth asking.
If I were to do it again, I’d be inclined to take a factory setup, but that would depend on features and functionality. I’d certainly at least evaluate one. It’s would be nice to get a new rig and not feel like I had to immediately tear it apart just to get back to where I was before… 😉
Would a small thermostatically-controlled fan be a good addition back there too?
Well, it wouldn’t hurt. But I’m going to wait and see if I need it first.
Glad to hear there was no damage James. Well designed system. Since the battery is now dumping heat quickly into the coach, have you noticed any difference in how hard your AC is working to keep up on hot days? Should be a nice boost on cold days though!
Well, I actually *just* did the mod, so we don’t have much road-time with it yet. Just by watching the battery temperature, I’ve noticed that unless we’re really hitting it hard, the temperature stays pretty constant with mellow changes. So I’m hopeful there won’t be much impact. Time will tell, though.
Hi, and greetings from Norway ! I just want to say good work with what you do. I liked the quality of this video. super cut and edited. And useful info. Carry on, we camper / bikers follow you.
Norway!! I think you are our first commenter from Norway!
Thanks for checking us out, and we’re glad you like the video.
Believe it or not, getting up to Scandinavia has been on our bucket list for quite some time. If we make it there, we’re bringing bikes!!
Indeed keeping a battery from overheating is very important for longevity. Our hybrid car has multiple temp sensors on the battery that I can read from the OBD connector as well as an air inlet and fan to keep it cool.
The scariest thing that can happen with these types of batteries is a thermal runaway, which is probably why your system includes overheat protection. https://www.sciencedirect.com/science/article/pii/S2405829716303464
Our battery is a lithium-iron=phosphate battery. I’m no battery chemist, but I believe that particular chemistry is not able to experience the thermal runaway.
Other chemistries would have different properties with respect to thermal runaway.
Regardless, the warning against over-temperature is good advice for any lithium battery.
Hello James and Steph – we’ve learned so much from you guys as we’ve done our own conversion. Is there any way that you could run a vent pipe up from the battery compartment, behind or in front of the wall and then through the roof? We did ours as part of the conversion and ended up aiding the natural thermal current with a small house fan. We turn it on when the compartment temp reaches 80 degrees F. (As read by a small remote wx station.) Thanks again.
I suppose I *could* run a vent pipe up through the roof if I wanted to. That would require a *LOT* of work. I redid that whole cabinet when I replaced our refrigerator, so I’m not too eager to crack it back open. (It was a bear!) Plus, there’s the opposite, winter-time problem to consider, and that cabinet also contains plumbing. I’m going to run with this for a while, and we’ll see where it gets us.
My planned power installation has the lithium battery doing double duty as a bench seat in the dining area and the inverter/charger in an externally vented compartment that draws cooling air from the interior. Your experience suggests this may work out well.
I think if you just make sure to not box the battery in too air-tight (perhaps adding a similar vent) you should be fine. At least, I hope so, because I’m kind of counting on it.
What happened to your shop ?
Everyman needs HIS shop… (Steph it’s a proven fact)
Well, we moved.
Ultimately, the space I have for a shop will be bigger than what I had before, but right now, it’s a mess.
I’m told we have other “priorities” now. Like new towels and decorative pillows.
Are you guys still in Utah?
Whether or not a DIY lithium battery has this sort of protection is entirely up to the builder and how advanced the BMS they use is. The 123SmartBMS for instance is extremely configurable. It individually monitors the temperature of each cell and can be setup with relays to stop charging or discharging based on a number of different criteria including over or under temperature. As for drop in replacements battle born says their BMS will protect from over temperature.
There is also another reason to worry about high temperatures. Even if you aren’t outside the safe operating range of your batteries you are still accelerating wear and aging. Technomadia for instance saw greater then expected capacity loss with a DIY LiFeYPO4 setup due to installing the inverter and batteries in the same bay.
Oh James you could spend a lot of time geeking out with a DIY lithium setup a good BMS has a ton of settings to play with.
I’m sure a DIY BMS could be as sophisticated as the builder’s capability. I just don’t know how many DIY solutions include one.
Before we settled on Lithionics, I was looking at SmartBattery and similar. It was incredibly difficult to get a straight answer out of them.
And yes, the temp will decrease the lifespan, but I doubt we’ll use up even half of ours before upgrading! 🙂
Besides the initial cost of the litium battery, the fussiness of the things kept me in the AGM battery camp in my newest overland vehicle. We are frequently in tempreture extremes, from zero up to 110 degrees. I have enough problems keeping our systems going in those conditions without having to learn a whole new battery protocol. Thanks to you guys, and others, for being lithium pioneers. I’m sure that within a few years we’ll have lithium batteries that will be as tough as AGMs while providing crazy amp hours of power.
Lithium batteries, AND eventually exterminating propane refrigeration…
That was a nice and easy fix for a potential $ catastrophe $.
Don’t let the OCD get to you … A shop is anywhere the tools happen to be!!!!
Hope to see you at the Pomona Show this year,
Andy & Kim
We’re planning on being there.
Likely the first weekend as usual.
See you there!