If you currently have lead-acid batteries on your RV, you have likely thought about converting to lithium. The advantages are undeniable, lithium batteries are more efficient,longer-lasting, and lighter weight. Unfortunately, your friends urging you to go with lithium often are not talking about the peripherals that go along with it. The fact is, it’s not as easy as simply dropping in lithium batteries and hooking up the wires.
For example, motorhomes generally store the house batteries under the steps. This compartment is often sized specifically for two group 27-sized 100Ah deep cycle batteries. But, not all lithium batteries will fit here.
Unfortunately, that could the least of your problems when upgrading to lithium. Lithium batteries are not the only thing that will cost you thousands of dollars.
You Might Need a New Solar Charge Controller
If you’ve already installed solar, you’ll need to see if your charge controller will work with lithium batteries. Fortunately, many charge controllers can handle either lithium or lead-acid batteries, but not all charge controllers.
Charging lead-acid batteries involve three different stages, known as bulk, absorption, and float. Charge controllers for use with lead acid go through these stages, based on battery voltage and internal resistance.
For deep-cycle, lead-acid batteries, during the absorption stage, the charge controller maintains a voltage high to force the current into the batteries. On the other hand, lithium batteries don’t need this absorption stage.
However, a charge controller designed for lead-acid batteries can charge lithium batteries safely. But, the lithium batteries will never fully charge. In fact, they may only charge up to 80-90%.
Your current solar charge controller might be appropriate for both lithium and lead-acid if you’re lucky. If your charge controller is programmable, check if it can be programmed to work with lithium. If it’s not, you’ll need to think about replacing it with a lithium charge controller.
Finally, if your solar charge controller has an automatic equalization feature, it definitely needs to be replaced. This is because the equalization phase can damage lithium batteries.
Most Inverters Work with Lithium Batteries
Generally, most AC-to-DC inverters work fine with lithium batteries. But, if your inverter has a low-voltage cutout, look to see if you can change the setting. See if your lithium battery manufacturer has a recommended setting for the low-voltage cutout.
You’ll Need a Shunt Battery Monitor
Using a shunt battery monitoring system with lithium batteries is recommended. Only a shunt type of battery monitor accurately registers the state of charge for lithium.
If Your Batteries are Charged by Your Engine’s Alternator, Watch Out!
Motorhomes charge the house batteries off its engine. Likewise, travel trailers and 5th Wheels often charge the batteries through the cable attached to the tow vehicle.
Most vehicle alternators can not handle the high loads produced by lithium batteries for long. The lower internal resistance of lithium batteries can burn out fuses and even the alternator. Lithium batteries can be a great option for boondocking, but not if they burn out your alternator, leaving you stranded.
If your alternator will be charging your lithium batteries, you’ll need to install a DC-DC charge controller. This will maintain the electrical current at a safe level. Also, you’ll need a programmable DC-DC charge controller so that you can set it to the right voltage and current limit.
Also, a lithium battery isolation manager needs to be installed. This allows you to disconnect the batteries when you turn off the engine. This ensures that your alternator won’t overheat.
These parts are not cheap, you can expect to pay more than $300 for a lithium battery isolation manager and a DC-DC charge controller. Also, unless you’re a decent backyard mechanic, you’ll need to find an RV mechanic who can do the work.
Do your homework before you rush out and buy lithium batteries for your RV. Lithium batteries might be superior to lead-acid, but it’s not a simple, one-to-one swap. Many other electrical parts in your RV and tow vehicle also come into play. If a lithium upgrade isn’t done right, it could cost you thousands of dollars in damage.