Are Lithium Batteries Worth It? Cost of AGM vs Lithium

Battery Life

Lithium batteries last longer than lead-acid batteries. In this comparison, we use the number of charge/discharge cycles to calculate battery life.

• 50% Depth of discharge. At 50% DOD, AGM batteries average 800 cycles. Lithium batteries will last more than 8000 cycles.

• 100% Depth of discharge. At 100% DOD, AGM batteries average 400 cycles. Lithium batteries will last more than 4000 cycles.

In this comparison, the life of Lithium batteries is at least 10 times that of lead-acid batteries.

 

 

NOTE

It is not recommended to regularly discharge AGM Lead Acid batteries greater than 50% DOD.

 

As for the available energy, the AGM battery is rated at 120 Ah, and the Lithium battery is rated at 130 Ah. Since these values are so close, they are not factored into the comparison.

Initial Cost of Batteries

The retail price of the AES Lithium battery ($4500) is significantly more expensive than the AGM battery ($300). However, in our comparison, the AGM battery is a 12V battery, which means four AGM batteries, connected in series, are required to equal the voltage of one Lithium 48V battery. This brings the initial cost of the batteries closer.

• AGM Battery (4 x 12V = 48V): 4 x $300 per battery = $1200

• Lithium Battery (48V): $4500

The set of 4 AGM batteries costs $1200, whereas the Lithium battery costs $4500.

Lifetime Cost of Batteries

Although the Lithium battery is more expensive, it also lasts much longer. As evidenced by our battery life comparison, AGM batteries will be replaced TEN times by the time the Lithium battery approaches its end of life. Over the life of the batteries, the cost of using AGM lead-acid batteries is significantly more than the cost of using Lithium batteries.

• AGM Battery (10 sets of 4 batteries): 10 x $1200 = $12,000

• Lithium Battery: $4500

In addition to the dollar cost of the AGM batteries, there is also the hassle and the installation cost related to replacing the batteries, which we do not cover here.

Summary

 

 

Absorbed Glass Mat

(G27-12V 120 Ah)

Lithium

(AES 48V 130 Ah) 

Battery Parameters

Voltage

           48 V

• 4 batteries in series x 12 V

48 V

 

Capacity (Amp Hours)

          120 Ah

130 Ah

Initial Cost

 

 

• Price/Battery

          $300

$4,500

• Price/48V

          $1200

• 4 batteries in series x $300/battery

$4,500

Lifetime Cost

 

 

Lifespan

           4000 cycles @100% DOD

• 10 sets of batteries x 400 cycles/battery

4000 cycles @100% DOD

Lifetime Cost

           $12,000

• 10 sets of batteries x $1200

$4500

 

Conclusion

When directly comparing the cost of Lead Acid batteries versus the cost of Lithium batteries, in most cases, Lithium batteries cost much less. Add in the convenience of replacing the batteries less frequently, makes Lithium batteries an easy choice over the cost and hassle of Lead Acid batteries.

Lead is dead