2000mAh LiPo Battery Quickstart Guide


Overview

Thanks for purchasing a SparkFun 2000mAh Lithium Ion Polymer (LiPo) battery! This page will give you some tips and tricks for using your new battery effectively and safely.

Why Choose LiPo Batteries

Batteries come in all different shapes, sizes and chemistries. Each has its own advantages and disadvantages- price, size, weight, rechargeability, life, self-discharge characteristics, and maximum current are all things to be taken into account when selecting a chemistry for your project.

Lithium ion polymer batteries offer a good balance, as you can see in this comparison table of three very common rechargeable battery chemistries:

Sources: batteryuniversity.comiccnexergy.com

Parameter NiMH Sealed Lead-acid LiPo
Price1 $1/Wh $1.08/Wh $2.50/Wh
Volume2 400 100 540
Mass3 60-120 30-50 100-130
Charge cycles4 300-500 200-300 300-500
Self-discharge5 30% 5% 10%
Max current6 5C 5C 2C
Cell Voltage7 1.2V 1.5V 3.6V
  1. Comparison of SparkFun's AA NiMH cell, this 2000mAh LiPo battery, and a 4.6Ah SLA battery from Interstate Batteries website. Larger numbers mean more expensive batteries for similar battery life.
  2. In Watt-hours per liter (Wh/L)- bigger numbers mean a smaller battery for similar battery life.
  3. In Watt-hours per kg (Wh/kg)- bigger numbers mean a lighter battery for similar battery life.
  4. Number of times you can charge and discharge the battery before its capacity is reduced to 80% of its initial capacity.
  5. Percentage of capacity lost to internal chemical reactions each month in storage.
  6. Maximum current, in terms of the battery's capacity, which can safely be delivered to the load. For this battery, that would be 2000mA.
  7. Batteries are typically formed by stacking cells together to create higher voltages. LiPo batteries have a higher cell voltage, which means fewer cells must be stacked for most applications, which has an advantage in both discharge rate and in the number of charge cycles.

Finally, some words on the way batteries are rated. This is a 2000mAh battery, and a glance at the datasheet suggests that the method for reaching this value was discharging the battery at .2C (where "C" is the capacity of the battery, 2000mAh) until the battery voltage was 2.75V. Thus, the battery lasted at least 5 hours at 400mA discharge rate. It also tells us that if we discharge it at C (2000mA) we can only expect 51 minutes of discharge time- in other words, discharging the battery more slowly allows us to eke out more capacity.

Requirements

You'll need a charger, of course- this battery cannot be "trickle charged" the way older sealed lead acid batteries could, and attempting to charge it without appropriate charge circuitry could fail in several ways, ranging from failure to charge to a damaged battery to serious risk of very bad fire. SparkFun offers a very simple, inexpensive LiPo charge board designed to charge from any USB port. It's available with a mini-USB connector, as well as a micro-USB connector which will mate with most recent, non-iPhone cellular phone chargers.

Recommended Uses

Obviously, you need something to power with this battery. SparkFun sells a number of things that come with the 2mm JST connector this battery mates to:

We also sell a few boards which can enhance the usability of your LiPo battery:

  • LiPower shield will provide 5V for the more standard Arduino boards, which require more than the 3.7V which the LiPo battery normally provides
  • Power Cell provides a 5V step-up supply and a charger in one handy board
  • LiPower Boost board gives you just the 5V step-up circuitry in a minimalist footprint
  • LiPo Fuel Gauge allows your circuit to monitor the battery life left to it
  • "Uh-oh Battery Level Indicator" gives you a visual on whether the battery has slipped below a pre-set level

Safety Precautions

Never cut the positive and negative leads at the same time. This will briefly short circuit the battery, resulting in sparks flying, unnecessary excitement and, frequently, exhortations inappropriate for certain situations. It can also damage the battery and even the cutting tool.

Charge using a designated LiPo charger only. Using chargers designed for other types of batteries (even other lithium chemistries) can damage the battery, the charger, or even cause a fire.

Batteries can explode. LiPo batteries are less toxic than other kinds, but they still contain substances best left safely inside. It's also worth mentioning that a burning LiPo battery cannot be easily extinguished without specialist fire fighting equipment and burns much hotter than most fires, so try not to set it aflame.

Resources

We've got a couple of tutorials you can turn to for more information. Nathan did a "care-and-feeding" tutorial for LiPo batteries that has a lot more tips and tricks for making use of your new LiPo, and Jim wrote a tutorial going into greater detail about the types of batteries you have to choose from for your projects.

Now that you've been introduced to your new battery, go make something cool!

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