All component comparisons
Lead-Acid vs Lithium Battery
Battery (lead-acid / NiMH) and Battery (Li-ion / LiPo / LiFePO4) compared — what each is better at, and which one the job actually calls for.
Lead-acid is cheap per amp-hour, tolerates float charging indefinitely, and is recycled everywhere — but it is heavy, and repeatedly taking it below about half discharged kills it. Lithium gives several times the energy per kilogram and many times the cycle life, and will genuinely use its rated capacity, but it needs a BMS and a charger that respects it. LiFePO4 sits between the two: less energy density than Li-ion, far more cycles, and much better behaved thermally.
What each one is
Battery (lead-acid / NiMH)
The old reliables of rechargeable storage. Lead-acid: cheap, heavy, delivers huge cranking currents, hates deep discharge. NiMH: benign chemistry in AA form, tolerant of abuse, self-discharges faster.
Battery (Li-ion / LiPo / LiFePO4)
A rechargeable lithium cell with high energy density. Powers phones, tools and packs - but needs protection and correct charging to stay safe.
Key specs
Battery (lead-acid / NiMH)
- Voltage(V)
- Lead-acid: 2 V/cell (12 V = 6 cells); NiMH: 1.2 V/cell.
- Capacity(Ah)
- At a stated discharge rate — capacity shrinks at high current (Peukert).
- Cycle life(cycles)
- Strongly depends on depth of discharge; shallow cycles = long life.
- Charge voltage/current(V / A)
- SLA: 13.6–13.8 V float, 14.4 V absorb; NiMH: −ΔV terminated.
Battery (Li-ion / LiPo / LiFePO4)
- Nominal voltage(V)
- ~3.6-3.7V Li-ion/LiPo, 3.2V LiFePO4 per cell.
- Capacity(mAh / Ah)
- Charge stored; runtime = capacity ÷ current.
- C-rate(C)
- Safe charge/discharge current as a multiple of capacity.
- Charge/cutoff voltage(V)
- 4.2V full, ~3.0V empty (3.65/2.5V for LFP). Don't exceed.
- Cycle life(cycles)
- Charges before notable fade; LFP lasts longest.
Types you will meet
Battery (lead-acid / NiMH)
- Flooded lead-acid (car)
- SLA/AGM (sealed, alarm/UPS)
- Gel
- Deep-cycle
- NiMH AA/AAA
- Low-self-discharge NiMH (Eneloop class)
Battery (Li-ion / LiPo / LiFePO4)
- Li-ion cylindrical (18650/21700)
- LiPo pouch
- LiFePO4 (LFP, safer/long-life)
- Prismatic
- Coin (rechargeable)
How to choose
Battery (lead-acid / NiMH)
SLA for cheap standby power and inverters; deep-cycle (not car) batteries for solar; low-self-discharge NiMH for anything that took alkaline AAs.
Battery (Li-ion / LiPo / LiFePO4)
Match voltage (cells in series) and capacity/C-rate to the load. Use a matching charger/BMS (CC-CV for Li-ion, LFP profile for LiFePO4). Choose LiFePO4 for safety/longevity, LiPo for light high-current.
How each one fails
Battery (lead-acid / NiMH)
Sulfation from sitting discharged (the #1 killer), dried-out cells in old SLAs, one weak cell dragging a pack down; NiMH: crystalline memory-ish capacity loss and vented cells from overcharge.
Battery (Li-ion / LiPo / LiFePO4)
Over-discharge kills capacity; overcharge/puncture/short -> swelling, fire or venting; cell imbalance in packs; capacity fade with age.
Full reference for each part
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