Is Lithium right for my RV?
Is Lithium right for my RV?
Lithium can be economical choice for those with heavy use.
Let’s first start off with the benefits. Lithium does not have a Peurkert effect (the bigger the load on a battery the less capacity it has), this is huge for people with inverters! Lithium will also charge more effectively than other types of batteries. By mostly skipping the absorption cycle, Lithium can charge 1-5 hours faster than equivalent flooded or AGM batteries depending on the State of Charge (SOC) when solar starts charging. This can be critical when using solar to charge on cloudy or short sun days. Battle Born Lithium states 98% efficiency and Lifeline AGM states 97% efficiency and Trojan Flooded states 94% efficiency. Lithium laboratory tests yield >2800 cycles compared to flooded laboratory tests yielding around 850 cycles, more on this below. Lithium will allow you to use ‘all’ of the advertised capacity and weighs ⅓ to ¼ less than AGM or Flooded batteries.
One downside of Lithium is that they don’t like the cold. You can discharge them at temps from -4 to 140 degrees F but if you do charge them at <32 degrees F, there can be permanent damage. So if you leave your RV and the battery temperature drops too low and your solar charger or converter charger starts to charge your Lithium battery bank on its own you could destroy the battery. You can spend some time and build an insulated chamber for the battery, add a battery heater and/or locate the battery in a living compartment to keep the battery temperature above 32 degrees. Maybe you will never have your RV battery get that cold!
The cost of Lithium is also a factor. Trojan Trillium Lithium will cost you about $1450 for a useable 100 Amp Hours-(AH) while Deka flooded golf cart batteries will run $210 for useable 150AH. Now if you do the math with cycle life and shop Lithium prices, the gap gets much smaller. In the real word most people achieve 1/3 to 1/2 the laboratory cycle rate of AGM and flooded batteries. We don’t know how many cycles Lithium will yield in the real world yet.
There can be more parts required when switching to Lithium. Lithium manufactures make ‘drop in replacement batteries’ (just means it will fit most RV’s battery locations) and these are OK for the converter charger made by Progressive Dynamics. You will need to push and hold the converter button for 2 seconds after you connect shore/generator power so that it will charge the battery with 60 amps at 14.4 volts (boost mode) for 4 hours before going back to normal mode at 13.6 volt. If you do not push the button the charge wizard will not put out more than 13.6 Volts, this will not charge your lithium battery completely. You can always purchase the lithium version of the converter charger from Progressive Dynamics, it will do the 14.4 V until charged, then switches to 13.6 all on its own.
Thermal runaway is where the battery temperature rises out of control and is more common with Lithium than AGM or flooded batteries. A battery can melt, catch on fire or even explode. If you discharge Lithium too far, it will not take a charge. It is critical not to over charge, over heat or let the cells get out of balance. There needs to be a Battery Management System (BMS) to take the battery offline before things get out of control. Most drop in replacements have some form of a BMS on board the individual battery but still recommend that it is not the only form of protection. There are many ways to add a BMS and those parts can cost $400 or more. I myself would never install Lithium without using a stand alone BMS system, even if it was redundant.
Lithium is bleeding edge technology for RV’s. It is a very exciting time for batteries and the future has hints of doubling the wh/kg! Technomadia built their own battery bank out of prism lithium cells. They have experienced measurable capacity loss in the first 3 years(<1095 cycles). They are not the only ones to report capacity loss with Lithium and it is believed to be directly related to high battery temperatures and charging to 100% SOC. Real people that use Lithium in RVs seem to believe that the battery is happier at ~75% SOC and important to keep battery temperatures below 100 degrees.
The big players with drop in replacement Lithium seem to be Trojan, Relion, LifeBlue, Battleborn, and many others popping up faster than one can count. Battleborn is the only manufacturer that I am aware of to claim their on board BMS is stand alone safe. They also seem to have a good price vs performance ratio. Others can require low voltage cut off, high voltage cutoff, low temp cutoff, high temp cutoff and of course balance checking/charging. Battleborn use 26650 cylindrical cells to make their batteries here in the US. Tesla currently uses 18650 and 21700 cylindrical cells and I believe there is more reliability to these type of cells.
I live off grid in my ATC toy hauler year round and my personal money was spent about a year ago on a useable 480AH of Lifeline AGM battery bank. I have not had my batteries below 40 degrees even when the outside temperatures dipped to 25 degrees. My battery bank is underneath the sink, next to the heat duct which helps them stay warmer. If I were to purchase new batteries today I would definitely lean towards Lithium batteries. For weekend warriors my advice would be to look very hard at AGM and put any extra money towards solar to keep battery topped off.