0 Beach Cities Robotics FRC Team 294 Summer Academy Batteries and Soldering July 20, 2008 Rick Wagner, Mentor, Beach Cities Robotics FIRST Team 294.

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Beach Cities RoboticsFRC Team 294 Summer Academy

Batteries and Soldering

July 20, 2008

Rick Wagner, Mentor, Beach Cities Robotics

FIRST Team 294

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Batteries and Soldering Outline

Concepts:

• Batteries

• Types

• Characteristics

• Charging

• Soldering

• Theory

• Practice

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FRC Battery

Lead-acid (H2S04) sealed motorcycle battery can supply more than 40 amperes for two minutes

Heaviest single component in the robot Wear safety glasses when charging and handling

A battery explosion can ruin your whole day (and blind you for the rest of your life)

A shorted battery will heat up rapidly and explode Wear no rings or watches when handling batteries

A short across a ring will heat it red hot: you will lose your finger

Unlike the VEX battery (Nickel-Cadmium, NiCad), a lead-acid battery does not need “conditioning” to take a full charge

A Ni-Cad battery needs to be deep discharged before recharging for a maximal charge

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2006 BatteryES18 Mfr Spec

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AGM Type Automotive Sealed Lead-Acid Battery

AGM is “Active Glass Mat”

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NiCd Batteries

The principal advantages of NiCd over other rechargeable types is lower weight for a given quantity of stored energy, good charging efficiency, small variation in terminal voltage during discharge, low internal resistance, and non-critical charging conditions. (Wikipedia)

Certain usage patterns may cause a "false bottom" effect. Specifically, if the battery is consistently discharged to the same level, then fully recharged, the battery will eventually stop discharging on its own upon reaching this threshold. (Wikipedia)

When not under load or charge, a NiCd battery will self-discharge approximately 10% per month. (Wikipedia)

If the battery is going to be stored unused for a long period of time, it should be discharged down to at most 40% of capacity (some manufacturers recommend fully discharging, or even short-circuiting), and stored in a cool, dry environment. (Wikipedia)

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Soldering

Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point. Soft soldering is characterized by the melting point of the filler metal, which is below 400 °C(800 °F). The filler metal used in the process is called solder.

Applications: Attaching electrical components to circuit boards Electrical wiring attachment Plumbing with copper pipes Food cans Rain gutters Automotive radiators Jewelry Joining stained glass Small mechanical parts

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Soldering Concepts

Oxidation Wetting Capillary action Flux Electronic solder (63% tin, 27% lead (eutectic)) with

rosin core flux Unsoldering

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Soldering Techniques

Wear safety glasses Make a good mechanical joint

first Solder provides permanent

corrosion protection Do not rely on solder to

provide mechanical integrity Tin the iron (apply solder), then

wipe off oxide on the wet sponge

Apply the clean hot iron tip to the joint

When the joint is hot, flow in the solder to the joint, not to the iron