Page 219 - Robot Builder's Bonanza

188 ALL ABOUT BATTERIES

Table 18- 1 Batteries and Their Ratings

Battery Volts per Application Recharge† Internal Notes
Cell* Resistance

Carbon- zinc 1.5 Low demand, No Moderate Cheap, but not suitable
flashlights—not robots for robotics or other
high- current
applications
Alkaline 1.5 Small appliance motors No High Available everywhere;
and electric circuits can get expensive
(replacement costs)
when used in a
high- current
application like
robotics
Rechargeable 1.5 Substitute for Yes High Good alternative to
alkaline nonrechargeable variety nonrechargeable
alkalines
High- capacity 1.5 Same as other alkaline No Low More expensive than
alkaline cells, but can handle standard alkaline; keep
larger current demands for emergencies
NiCd 1.2 Medium and high Yes Low Slowly being phased
current demand, out because of their
including motors toxicity
NiMH 1.2 High current demand, Yes Low‡ High capacity; still a
including motors bit pricey
Li- ion 3.6§ High current demand, Yes High Expensive, but
including motors lightweight for their
current capacity
Lead- acid 2.0 Very high current Yes Low Heavy for their size,
demand but very high
capacities available

* Nominal volts per cell for typical batteries of that group. Higher voltages can be obtained by combining cells.
† Some nonrechargeable batteries can be “revitalized” by zapping them with a few volts over several hours. However, such batteries are
not fully recharged with this method, and are redischarged very quickly.
‡ Internal resistance of NiMH batteries starts out low when the cell is new, but increases significantly as it is recharged over many times.
§ Li- ion cells have different voltage characteristics, depending on manufacturer; 3.6 volts per cell is common but is not considered a
standard. Li- ion batteries are almost always used in “smart” battery packs (they contain control circuitry). Packs designed to provide
7.2, 10.8, or 14.4 volts are typical.

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