Lithium-Ion vs Lead-acid battery

Lithium-Ion vs Lead-Acid battery

Let’s consider a 12V battery to store energy from a solar powered system (ie: Off-Grid). For this application, we need a storing capacity of 105Ah.

If we equip the system with a Lead-Acid battery, the actual capacity of the battery will be 2 x 105Ah = 210 Ah (no more than 50% DOD).

Let’s take as an example the 12V lead-acid battery for power applications: DAIJIN SG. This device measures 50cmx25cmx24cm, weighs 76Kg and has a capacity of 210Ah. The useable capacity is 105Ah (depth of discharge 50%), and for high discharge applications, actual capacity will be only 65Ah.

For comparison, a Lithium-ion equivalent to our lead battery will have a capacity of 110Ah. We will take general products as an example to compare the characteristics of both batteries.

The table below summarizes the characteristics of the two batteries for our application:

Specifications Li-ion Lead-acid (AGM)
Real Capacity 110Ah 210Ah
Useable Capacity 105Ah 105Ah
Life cycles >2000 500
Weight 15.8Kg 76Kg (X4.8)
Size / Volume 26cmx17.2cmx22.5cm = 10.0L 52.1cmx26.9cmx23.3cm = 32.7L (x3.2)
Charging Fast to 100% Fast to 80%
Wasted 0% 15 à 20%
Peukert’s Losses No Yes
Voltage sag No Yes
Maintenance No Yes

Lithium-ion vs Lead-Acid cost analysis

We take the example of a solar installation for a standalone building (Self Sufficient Home). The storage capacity for the battery is 50KWh.

The application need is summarized in the above table:

Specifications Value
Stored Energy 50KWh
Discharge Power 10KW (or 5 hours running time at C/5)
Cycling frequency 1 charge discharge/charge per day
Average ambient temperature 23°C
Expected Lifespan 1900 Cycles, or 5.2 years

The costs of delivery and installation are calculated on a volume ratio of 6:1 for Lithium system compared to a lead-acid system. This assessment is based on the fact that the lithium-ion has an energy density of 3.5 times Lead-Acid and a discharge rate of 85% compared to 50% for AGM batteries.

Based on the estimated lifetime of the system, the lead-acid battery solution-based must be replaced 3 times. Lithium-Ion solution-based is not replaced during operation (2000 cycles are expected from the battery)

The cost per cycle, measured in US$ / kWh / Cycle, is the key figure to understand the business model. To calculate it, we consider the sum of the cost of batteries + transportation and installation costs (multiplied by the number of times the battery is replaced during its lifetime). The sum of these costs is divided by the net consumption of the system (50kWh per cycle, 365 cycles per year, 5.2 years of use). The result is summarized in the table below:

Lead-Acid AGM Lithium-Ion
Installed capacity 100 KWh 58 KWh
Usable capacity 50 KWh 50 KWh
Lifespan 500 cycles at 50% DOD 1900 cycles at 90% DOD
Battery cost US$16,400 ($164/KWh) (x 4) US$44,497.00 (700€/KWh) (one shot)
Installation cost US$1,095 (x 4) US$1,095.00 (one shot)
Transportation cost USD30.70per KWh (x 4) US$10,959.00 per KWh (one shot)
TOTAL COST US$83,500 US$40,229.16
Cost per KWh per cycle US$83.30 / kWh / cycle (+81% vs Li-Ion) US$46.03 / kWh / cycle

* Others Information

hemistry Voltage  Energy Density  Working Temp.  Cycle Life  Safety Environmental Cost based on cycle life x wh of SLA
LiFePO4 3.2V >120 wh/kg  -20-60 °C  >2000(0.2C
rate, IEC Standard)
Safe Good 0.15-0.25
lower than SLA
Lead acid 2.0V > 35wh/kg  -20 – 40°C >200 Safe Not good 1
NiCd 1.2V > 40wh/kg  -20 – 50 °C >1000 Safe Bad 0.7
NiMH 1.2V  >80 wh/kg  -20 – 50 °C  >500 Safe Good 1.2-1.4
LiMnxNiyCozO2 3.7V >160 wh/kg  -20 – 40 °C  >500 better than LiCo OK 1.5-2.0
LiCoO2 3.7V >200 wh/kg  -20 – 60 °C  > 500 Unsafe w/o PCM OK 1.5-2.0