CHAPTER 7 ■ NINE-VOLT BATTERIESFigure 7-12. Non-rechargeable lithium 9 V batteries
Lithium 9 V batteries have a couple of downsides: they’re expensive, they can’t provide significant
bursts of electricity (no more than 80 mA or 120 mA depending on brand), and their high-rated capacity
(1200 mAh for 9 V) only holds true if you use the electricity in very small amounts. These disadvantages
make lithium unsuitable for most motor-driven robots.
Don’t confuse single-use lithium batteries with rechargeable lithium-ion or lithium-polymer batteries.
The rechargeable varieties offer higher current bursts without the same caveats.
Not Recommended
Carbon and Zinc
Poor “heavy-duty” battery! The greatest benefit I could come up with is they are the least expensive to buy for
a single use. This might make a good choice for a robot that dives off cliffs or unsuccessfully explores lava pits.
Despite their low initial cost, the total lifetime price of carbon-zinc, magnesium-carbon, and
zinc-chloride batteries (see Figure 7-13) is much higher than rechargeable batteries. This is because
the rechargeable batteries can be recharged, but the carbon and zinc batteries cannot.
Figure 7-13. Classic and super heavy-duty 9 V batteries