Lipo Batteries - Basic Information

ENPH 253 Lipo Battery Video

Rechargeable batteries we use for robots:

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2-cell, 8.4V / 300mAh 2-cell, 8.4V / 500mAh 4-cell, 14.8V / 1.3Ah

What’s inside a Lipo battery?

Never use without alarm.

Lipo alarm sounds when any one cell voltage gets below the set threshold.

Set alarm level to to 3.5V (here is how)
Never deep-discharge Lipo batteries, it damages them internally. Deep-discharge level is 3V or less.
Even just once is enough to cause substantial and lasting damage. Recycle battery if that happens.

How to “Park” your Lipo at the end of the day

Unplug everything (including the alarm) over night.
Every day, put batteries in “parking position” before going home (purpose = easy to see for instructors).
Parking position is top shelf on your bench, center isle. Tails hang out! Make it look like this:

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Battery on fire?

Put smoking battery into one bucket.
Cover with sand from second bucket.
Carry outside. Don’t inhale the smoke.
Carry down the stairs, no elevator!

Video of a lipo battery on fire.

Connecting the large battery to your system:

Additional info - important detail:

Some of the small batteries have a self-resetting fuse in the negative main wire.
These fuses will not allow currents higher than 500mA.
If a load tries to draw more current than 500mA, the fuse will increase its impedance.

With fuse. No fuse.

Symptom: voltage “collapses” when a high current is drawn from battery, but recovers when load is removed.

Problem: This might be an intermittent occurrence. For example, if you attach a motor to this battery and it runs fine under “no load” conditions, the motor might still draw more current than allowable when it is doing more work such as lifting a mass or driving up a hill.

Solution: Only use these fused small batteries for items with low power consumption, like the Blue Pill board. Also, don’t use them for items with highly variable load. Run all items with high power and variable power needs from the large battery.