Today, we are going to go over the differences between lithium batteries and sealed lead-acid batteries to explain why lithium is the better and cheaper choice over the lifetime of your battery.
Before we begin, it’s true that for some situations sealed lead-acid batteries are perfectly fine, maybe even preferable. If you only need to discharge your battery around 10 to 20% then an AGM battery is perfect for you. If, for instance, you have an RV or van that you do not live in full time, then a sealed lead-acid battery can be a smart decision. If your power requirements are minimal, maybe only needing to power a few lights, a USB charger, and a laptop, then some sealed lead-acid batteries will work perfectly fine and the upfront cost will be much lower than lithium. However, if you rely on your solar system heavily or live full-time in your RV, skoolie, or van and plan on doing so for extended periods, then Lithium batteries are the smarter choice.
- Below we have outlined the six main reasons why Lithium batteries are the best choice in any off-grid situation.
1. Cycle Life
The first and possibly biggest benefit to lithium batteries are their significantly larger cycle life. The cycle life refers to how many times you can discharge and recharge the battery. In a sealed lead-acid battery, you can maybe get 500 to 800 cycles before having to replace them. With a lithium battery, your cycle life is somewhere in the range of 2000 to 5000. Some batteries, like the Simpliphi, boast a cycle life of 10,000+. For example, with our best-selling portable solar generators, the Bluetti from MaxOak or the Inergy Apex, you can get around 2,000 cycles or 10+ years of use from them. After the 2,000 cycles, your battery still works perfectly; it just operates at 80% of what it was capable of.
2. Depth of Discharge
With most sealed lead-acid batteries, your discharge rate is somewhere between 70 to 80%, meaning that you can only discharge the battery down around 30% before you need to recharge it because you will damage the battery if you don't. Therefore, in a 100aH sealed lead-acid battery, you essentially only have 30aH available. By comparison, lithium batteries can discharge down to 0% while keeping the same voltage and with no damage to the battery itself. Also, since you can discharge lithium batteries down, you get significantly more real-world use, meaning that you don't need as physically large a battery bank to get the same amount of useable power.
The efficiency of lithium batteries is also significantly greater than their flooded lead-acid counterparts. When you put electricity into an FLA or AGM battery and take it back out, you will lose around 10 to 15%. If the battery is older or damaged, you can lose even more than that. Lithium batteries, on the other hand, have about 99% efficiency, meaning that whatever you put into the battery, you can use.
A great real-world benefit for lithium batteries is their overall weight and size. Lithium batteries are much lighter than FLA or AGM batteries. In fact, they are about 30% lighter in general, which is of huge significance if you want a battery for any type of mobile function like RV’s, vans, or skoolies. If you plan to drive around or want the ability to do so, the lighter your battery bank, the better. Not to mention, since they are only 30% of the weight, they are also smaller in size, another reason they are more beneficial for mobile situations.
5. Constant Voltage
In SLA or AGM batteries, when you lower the capacity. the voltage drops. In a lithium battery, the voltage stays constant right up until the point where it is completely dead. You’ll really notice this if you’re running a larger load because performance drops when the voltage lowers, and you’ll have a constant voltage with your lithium battery bank.
The last benefit is one of simple practicality. Lithium batteries require almost zero maintenance and won’t give off any toxic fumes. You can essentially install your lithium batteries and forget about them. With an FLA battery bank, you have constant upkeep and work to do to keep them functioning. Lithium batteries are the modern-day plug-and-play battery option. A lithium battery with a BMS (battery management system) will cut off power if the battery is too low in capacity, meaning that once the battery is at 0% capacity, the BMS will cut off the power to the appliances. It also cuts off the power when the battery is fully charged to prevent over-charging. The only way to damage a lithium battery is to damage the battery itself, for example, rupturing one of the cells or over-discharging it too quickly, or if you short circuited it for a prolonged time, the cells could puff up. For most applications, if you have a file on the battery or a BMS that has a circuit breaker installed, you don't need to worry about this. Contrast that with an AGM, FLA, or SLA battery where if you discharge it past 50% even one time, you will cause permanent damage.
In closing, a lithium battery is:
- Packed with higher discharge capabilities for its size
- Capable of a higher cycle life
- Higher performing due to higher voltages while discharging
- Easier to use
- Easier maintenance
Lithium batteries are more expensive up front, so this leads many people to purchase FLA or AGM batteries because of the cost factor. However, over the lifetime of the battery, the cost of lithium is SIGNIFICANTLY less. Lithium batteries will last up to ten times as long and are more efficient, too. If you plan to use your batteries consistently, we strongly suggest lithium.