Battery Comparison: LiFePO4, Li-Ion and Lead/Acid

How is it possible that a lithium battery has a capacity (Ah = ampere-hour) of about 1/3 that of an equivalent lead/acid battery? How is it possible that, despite this lower capacity, its starting current (CA = Cranking Ampere) is 50% higher than that of lead-acid batteries?

Battery Comparison: LiFePO4, Li-Ion and Lead/Acid

To understand these data, reported in the tables and in the graph, it is necessary to introduce the concepts of energy density (Wh/L) and maximum discharge current. In fact, LiFePO4 batteries have an energy density up to five times higher than equivalent lead/acid batteries.

Construction typology Lead/
Acid 		LiCo (Lithium
Cobalt) /
Li-Ion 		LiFePO4
BC-LITHIUM
Nominal voltage [V] 2.1 3.6/3.7 3.2
Energy Density [Wh/L] Average High High
Specific energy [Wh/Kg] Average High High
Max. discharge current
(Discharge rate) [C] 		15 ND 50
Safety Discreet
(presence of
toxic materials) 		Low
(risk of fire
and explosions) 		Excellent
(no risk of
fire/explosion)
Life cycles > 400 > 500 > 2000
Product
eco-friendly 		No No YES

The result is that, for the same occupied volume, a lithium battery will have up to five times the energy compared to an equivalent lead/acid battery. Lithium Ion batteries (Li-Ion or LiCo) have an even higher starting power, but at a level of safety not comparable to LiFePO4 technology for automotive uses.

Furthermore, the maximum discharge current of a lithium battery is 50C, which is fifty times the battery capacity, more than three times that of lead-acid batteries.
Therefore, if a motorcycle requires a starting current (AC) of 300 A, if with traditional lead/acid batteries it would be necessary to use a battery of at least 20 Ah (15x20), if using a lithium battery a 4 Ah (50x4) battery will be sufficient.

BC-LITHIUM
BATTERIES
Main models 		Drums
lead/acid
corresponding 		BC
LITHIUM
Capacity
(Oh) 		Drums
pb/acid
Capacity
(Oh) 		BC
LITHIUM
Weight
(Kg) 		Drums
pb/acid
Weight
(Kg) 		Reduction
of weight
(Kg) 		BC
LITHIUM
CA
(Amp)		 Drums
pb/acid
CA
(Amp) 		Increase
Cranking
Amps (%)
BCTX5L-FP-S YTX5L-BS 1.6 4.0 0.5 1.6 1.1 105 70 50%
BCTX7L-FP-S YTX7L-BS 2.0 6.0 0.6 2.3 1.7 160 85 88%
BCTX9-FP YTX9-BS 3.0 8.0 0.8 2.5 1.7 180 120 50%
BCTZ10S-FP YTZ10S 4.0 8.6 0.8 3.2 2.4 240 150 60%
BCT12B-FP YT12B-BS 5.0 10.0 1.1 3.4 2.3 300 190 58%
BCTZ14S-FP-S YTZ14S 4.5 11.2 0.9 3.9 3.0 290 230 26%
BCTX20H-FP-SQ YTX20HL-BS 7.0 18.0 1.4 5.6 4.2 420 270 56%