Skip to content

Latest commit

 

History

History
116 lines (63 loc) · 3 KB

battery.md

File metadata and controls

116 lines (63 loc) · 3 KB

HRB LiPo Battery

Battery specs

Capacity: 5000mAh

Voltage: 11.1V 3S

Discharge rate: 50C

XT60 Connector with 4 adapter parts.

Balance connector: JST-XH

Carbon fibre rigid case: 155×44×24mm (0 - 3mm Unterschied)

Weight 376 g

Safe charging rate: 0.5-1C (i.e. in my case 5A)

Rationale for the choice of battery

cfr: https://articulatedrobotics.xyz/mobile-robot-5-power-theory/

Requirements

Consumers @5V:

  • RPi 1.5A
  • Arduino 0.1A
  • Lidar 1A
  • PiCamera 0.1A
  • Motor driver 0.1A
  • LCD 1A

Total: 3.8A @5V --> 1.6A@12V --> 2A

Consumers @12V

2 motors x1.5A = 3A

Total requirement

5A @12V during 40'

Explanation of the specs

S-number

e.g. 2S 3S 4S is the number of 3,7V cells in series

3.7 is the storage level, fully charged each cell is 4.2V

e.g. in our case:NEED 3 (11.1V avg)

Capacity in mAh

The maximum continuous current in mA that fully discharges the battery over 1h.

Measures the run time from a single charge, but in practice one should use maximum 2/3 of the charge.

Therefore minutes to safe discharge @5A = CAPACITY mAh/ (5A * 1000mA/A) * 60min(h) *2/3 = 0.008 * CAPACITY

i.e. in our case to achieve approx 40' usable time @5A: NEED 5000mAh

C-number

The discharge rate is how fast you can discharge the battery without harming it.

C-number is the maximum current expressed as a multiplier of the capacity. Typically two values: continuous and burst.

e.g. in our case 50C * 5000mAH *1A/1000mA= 250A (more than enough!)

Battery basics

cfr : Battery basics, LiPo guide for beginners

Pros/Cons LiPo vs NiCad, NiMH etc

Pros: Lighter, higher capacity, high discharge, various sizes

Cons: Shorter life (100-200 cycles), risk of fire

Safety

  • Never use a puffed or damaged battery

  • Never leave a charging battery unattended. Never leave a battery plugged in (either in the robot or in the charger)

  • Never charge any cell above 4.2V or below 3.0V

  • Never leave a Lipo batttery fully charged or fully dischared more than 3 days: charge them to storage level (3.7V per cell)

  • Never immediately use or charge a warm LiPo battery

  • Never store batteries in a hot environment. Heat kills batteries.

Charging

See How to charge lithium batteries for the charger I bought.

Recommended to charge slowly (at 1C)

4 settings: Charge, Balance, Storage, Discharge

  • Charge may lead one individual cell to overcharge

  • Use Balance to increase the life, uses balance connector to ensure all cells are charged evenly (). Different connectors for 2S, 3S 4S cells.

  • Use Storage to charge to 3.7V per cell if you wont use the batteries for months

Storage

Store in a tin box or lipo pouches

Connectors

XT60 connector is better than older T or Dean's style connector

Balance connector: to ensure all cells are charged equally. Different connectors for 2S, 3S 4S cells