In last week’s part one comparing the differences in RV lithium batteries, we covered the type of cell used such as Grade A, Grade B, and used cells, and how to tell the difference with a sealed box. The next issue we will look at is how those cells are connected and protected inside the box.
Less-expensive RV lithium batteries use a cheaper and less time-consuming method of fastening the cells and plates together with a soldered connection, which is a joining process of two different metals such as the wire and the contact by melting a metal alloy usually made of tin and lead. This type of connection will not hold up to the rigors of running down the road. This method may work in a climate-controlled room for a residential application but not for the temperature changes and road vibration an RV will encounter. A mechanical connection ensures a solid connection for years to come.
A customized case
It may sound like a minor issue, but the case design can also add to the longevity of the battery. A customized case that protects the cells, plates, and battery management system (BMS) is important. Built-in rubber feet, radius corners, larger connector pads, and plastic dividers rather than fiberboard also provide superior protection.
Battery management system (BMS)
Lithium batteries do not like cold weather. In fact, if the converter tries to charge below 32 degrees, it could ruin the battery. A good BMS will either eliminate low-temperature charging or, better yet, turn on a heater for cold-weather camping. It also regulates low and high charge voltage and other functions. It is the brains of a quality lithium battery that do all the thinking for you.
As stated in the first part, a quality battery manufacturer will only use Grade A cells and ensures the cells that are closely matched. However, even the best cells have their own specific characteristics for voltage and temperature. The BMS monitors each individual cell to ensure they are operating in a safe range and not charging or discharging at a different rate than other cells.
The BMS also monitors the state of charge and adjusts the charge coming to the battery from either a converter, inverter/charger, or solar panels. It can also provide information to the RV owner through a battery monitor, which can show the percent of capacity and available amp hours, and measures amps, watts, and voltage.
Cold weather usage
I stated earlier that lithium batteries do not like cold weather, which is not entirely true. Let me explain. A quality lithium battery can be operated in temperatures of between -20 degrees up to 120 degrees with a BMS; however, it is not advised to recharge the cells below freezing temperatures. This does not mean you will be stuck in the middle of Northern Iowa for six months until the temperature reaches 33 degrees!
One option is placing the batteries above floor level underneath a bed pedestal or under a dinette. Since they do not gas, they do not require venting like a flooded lead acid, so the onboard furnace will keep them warm enough to recharge.
The BMS will monitor the temperature and either shut down the charging process to protect the cells, which means a dead battery, or activate a heating option. The Expion360 batteries have an optional heat pad that the batteries sit on. Others have a built-in heater in specific models. If you are planning to camp in cold weather, make sure you research the option that works best for you.
Read last week’s part one here.
Read more from Dave here.
##RVT1103
Great! Thank you, Dave!
We needed a new house battery for our 5th wheel and though we don’t really plan to do extended boondocking or add much solar, we would like to be able to park overnight and have some power.
So we started researching. For the cost and features included, we went with a 100ah Weize LifeP04. We’ve had it installed for more than 6 months with great results and no issues.
Our WFCO converter keeps it charged (I contacted WFCO directly about our model and setup and anticipated battery, etc. They verified our converter would work fine. They were right.)
The battery has worked flawlessly even in close to zero degrees in February. It has a BMS that shuts off charging but continues to allow usage.
I’m hesitant to jump into Lithium batteries as new technology has advanced 2 new batteries using solid state technology and others have developed a sodium battery, both of which are nonflammable and nonexplosive and don’t have cold weather issues requiring heat to keep them from freezing.
The automotive industry is funding billions for the research that has developed these technologies and is working to utilize them within a couple of years.
2 years ago I looked into building my own batteries from salvaged Tesla vehicle batteries. I even sourced vendor who tested each cell they sold. I finally scrapped the project for health reasons but now I’m glad I didn’t go forward with it.
I’m waiting for better alternatives and I’ll keep using the generator for now.
FYI – Not all BMSs offer CHARGING freeze protection
Also, does it matter which of the 2 positive and negative terminals I clamp my portable 500w inverter to in a 2 12v lithium battery parallel setup?
When two 12volt batteries are connected in parallel, the ideal connection would be positive the one battery and negative on the other.
Thanks Carlos
Good article … One item I don’t think is correct about the BMS shutting down the charging means a dead battery. My Renogy batteries can still be drawn from down to 0% SOC or if -4°f is reached.
Great informative article, Dave. Especially since I chose the Expion 360 series of batteries for our trailer two years ago. I also had the Expion monitor installed so for the first time ever I am able to not only see how much we’re charging but how much we are discharging. The batteries were installed in our pass-through storage in the front of our travel trailer. Expion has excellent customer service and I’ve had numerous contacts with them, both with emails and phone calls. Battle Born is excellent too.
re: soldering vs mechanical connection
Are you referring to soldered vs spot welded? My guess is that on an automated production line spot welding is faster than soldering.
YouTube has videos of people opening the cases of lithium batteries to evaluate their construction. Search for “lithium battery teardown”.
Robert, are you an AI Bot that gets to write anything without facts? Yes I did highlight Expion 360 because they have done exhaustive research and are truly trying to educate people on the difference and provide proof. They are not owned by Dometic but there is a tie to Zamp and yes Battleborn is a good company but more established??? Really??? Wait for part 3 and thanks for reading and reaching out.
I find it disingenuous to highlight expion360, without mentioning they are owned by Dometic and that Dragonfly energy, thru Battleborn is more established, independent, and superior, offers more alternative sizes and such. I also find that Dometic has aquired Zamp solar who ONLY offers Expion.
History suggest that Domentic will continue to leverage Expion360 in an effort to exploit these shadow relationships until they corner the market and increase prices. I certainly hope Y’all are not leveraged in there to while toting your independence.
Dave I built my own Li-po batteries using 3.2 volt cells. To keep them from freezing I put RV water tank heaters under them. It’s only been 1 year but so far so good.
Dave,
Your article doesn’t answer your question, “Are expensive lithium batteries really worth it?”. I am a big fan, but I think the article should answer the title question.
Be patient, Dave is building up your anticipation for a climatic finish. This is only part 2. Slow down big boy!
Can’t wait to read part 3 !