Lead Acid vs Lithium Ion: How Do You Choose? 

Lead acid has over 150 years of proven reliability powering everything from automobiles to backup generators, while lithium ion, despite being the go-to battery technology for the last 30 years, is still rapidly gaining ground and is now widely used across applications ranging from smartphones to EVs.

‍

So which chemistry provides the most longevity?

‍

Experts say lithium ion generally offers a longer lifespan thanks to their higher energy density and their more durable, compact designs. Lithium ion batteries beat lead acid in performance, lifespan, usable capacity and efficiency, making them superior for most solar storage and regular deep cycling applications.

‍

Lead acid's key advantages are low upfront cost, high power output, and extreme temperature tolerance. Lithium ion boasts faster charging, greater efficiency, a lightweight form factor, and a longer life that offsets the higher price tag.

‍

When you compare the hard numbers, a typical lithium ion battery lasts 2 to 5 years, while lead acid averages 3 to 5 years, and everything from temperature to usage patterns to maintenance can impact this lifespan. The reason lithium ion batteries are considered to last longer comes down to the energy density...

‍

The key advantage of lead acid is lower upfront cost. Lead acid is cheaper, but you may need to replace them more often. But the longer lifetime and other benefits of lithium ion typically make it the most economical and effective choice overall. So ultimately, the choice depends on the application and key priorities. For sheer affordability in vehicles and backup power, lead acid remains a stalwart.

‍

Here is the full round-up of the key takeaways regarding lead acid vs lithium ion (LiFePO4) batteries.

Advantages of Lithium (LiFePO4) over Lead Acid:

1. Longer cycle life - LiFePO4 can handle 2000+ full discharge cycles vs only ~400 for lead acid if discharged to 50% capacity. Lifespan is 3-4x longer without losing effectiveness over time‍
2. Lighter weight - LiFePO4 batteries are much lighter than lead acid for the same capacity, at only 10 to 20% of the weight.‍
3. Higher usable capacity - LiFePO4 provides nearly 100% usable capacity, while lead acid is limited to 50% depth of discharge, which is to prevent life reduction.‍
4. More efficient - Lithium ion batteries are typically 95% (or more) efficient while lead acid is 80 to 85% efficient. This means lithium ion charges faster and has higher effective capacity.
5. ‍Superior cold weather performance - LiFePO4 can still function in lower temperatures that are problematic for lead acid.‍
6. Faster charging - LiFePO4 batteries can be charged at higher currents than lead acid.‍
7. More consistent voltage output - LiFePO4 maintains steady voltage through the full discharge while lead acid voltage drops more as it discharges.

‍

Advantages of Lead Acid over Lithium:

1. Lower upfront cost - Lead acid batteries are cheaper to purchase initially, about 1/2 to 1/3 the price of lithium for the same rated capacity.
2. Easier to install - Lead acid batteries are less complicated to set up than lithium-ion systems.

‍

In the end, it comes down to what power purpose you actually need the battery for. The general consensus from Reddit, a valuable source for real-world information, is that if budget allows, LiFePO4 is the superior choice for a portable power application like a pellet grill due to the significantly longer lifespan, lighter weight, greater usable capacity and more consistent performance.

‍

Other Considerations:

• ‍Pilot Group recommends to make sure to use the proper charger chemistry for the battery type selected. A LiFePO4 charger is required for LiFePO4 batteries.

• An inverter used with a battery will draw roughly 10x the DC current from the battery compared to the AC output current it provides, so size the battery capacity accordingly for the expected run time.

• For simplicity, an integrated "power station" with built-in LiFePO4 battery, charger and inverter may be an easier plug-and-play solution than assembling separate components.

• Proper battery chemistry chargers must be used for each type (lithium vs lead-acid).

• For infrequent use in off-grid applications like RVs, the lower cost of lead-acid can make it preferable.

• But for regularly cycled use, the longer lifespan of lithium-ion makes them more cost-effective in the long run

Let us know what you think, or if you have other insights to add to this analysis!