Lithium vs Lead Acid Batteries: Which Is Better?
When buying backup batteries, you'll choose between lithium (LiFePO4) and lead acid (gel or AGM). Lithium costs more upfront but lasts much longer. Here's the full comparison.
Key Takeaways
- Lithium lasts 10+ years vs 3-5 years for lead acid
- Lithium gives you 90-95% of stored energy vs 50% for lead acid
- Lead acid is cheaper upfront but more expensive over time
- Lithium is lighter and smaller — easier to install
- For daily use (load shedding), lithium is the better investment
Upfront Cost
Lead acid batteries are much cheaper to buy. A 5kWh lead acid bank costs about R8,000-R15,000. The same capacity in lithium costs R20,000-R35,000. But this is only half the story.
- Lead acid 5kWh: R8,000-R15,000
- Lithium 5kWh: R20,000-R35,000
- Lead acid looks cheaper — but read on
Usable Capacity
This is where lead acid loses badly. You can only use 50% of a lead acid battery before damaging it. Lithium lets you use 80-95%. So a 5kWh lead acid battery only gives you 2.5kWh of actual power. A 5kWh lithium gives you 4-4.75kWh.
- 5kWh lead acid = only 2.5kWh usable
- 5kWh lithium = 4-4.75kWh usable
- You need DOUBLE the lead acid capacity to match lithium
Lifespan
Lead acid batteries last 500-1,000 cycles (charges). With daily load shedding use, that's 2-3 years before replacement. Lithium lasts 3,000-6,000 cycles — that's 8-15 years of daily use.
- Lead acid: 500-1,000 cycles = 2-3 years daily use
- Lithium: 3,000-6,000 cycles = 8-15 years daily use
- You'll replace lead acid 3-5 times in the life of one lithium battery
Total Cost of Ownership
When you factor in replacements and usable capacity, lithium is actually cheaper over 10 years.
- Lead acid over 10 years: R24,000-R45,000 (3 replacements)
- Lithium over 10 years: R20,000-R35,000 (no replacement needed)
- Lithium saves you money AND hassle in the long run
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