## What Type of Batteries?

There are several types of batteries to choose from.  The leading types are Lithium-Ion and Lead-Acid.

### Lithium Ion

Lithium Ion batteries are the superior battery for most applications.  They are lighter, more energy dense, can cycle deeper than the best Lead-acid batteries, they have more usable energy, they are more efficient and have a longer life expectancy.

There are only a few drawbacks to them. They are expensive and they burst into flames when the electrolyte is exposed to air. They are less scalable, meaning the startup cost is high.

Lithium-Ion batteries can use about 85% of the energy stored in them. (Depth of Discharge)  Using more will shorten the battery's life.

A 12 V, 100 Ah Lithium Ion battery runs about $1100 and you can use about 85 Ah from it. ### Lead Acid The Lead-Acid family can be broken into several other categories, like sealed/un-sealed and deep-cycle. Anything but the best deep-cycle marine batteries will become an unacceptable recurring expense. Sealed batteries cannot be serviced, but most common lead-acid battery problems cannot be fixed by normal servicing. Lead-acid batteries can only use about half of the stored energy in them. For this reason, you will need a battery array that is twice as big as you might expect. The biggest advantage of lead-acid batteries is that they scale well. I can start a 48 VDC battery array with 4 batteries, then add 4 more to the array later to increase storage capacity. I can continue to add groups of 4 batteries until I have an array storage capacity I want. A 12 V, 75 Ah Lead Acid battery costs about$110 and you can use about 32.5 Ah of its stored energy.

For \$1100 in lead acid batteries, you could get about 325 Ah of usable energy from them.  That is over 4 times the energy storage of Lithium-Ion for the same amount of money. However, this array takes up 10 times as much space.