Product details


Cell chemistry Lead Acid Battery capacity (Min) (mAh) 1000 Battery capacity (Max) (mAh) 327000 Implementation Pack External capacity indication LED Operating temperature range (C) -40 to 85 open-in-new Find other Battery fuel gauges

Package | Pins | Size

HTSSOP (DDW) 44 85 mm² 14 x 6.1 open-in-new Find other Battery fuel gauges


  • Designed for Use with 12-V Lead Acid Batteries in Consumer UPS Systems
  • Programmable Cell Models for Enhanced Pb-Acid Gas Gauging Performance
  • Provides 10-LED Bar Graph of Run-Time Remaining During Discharge and
    % Capacity During Charge
  • Can Be Easily Integrated Into Battery Cover
  • Works with Pb-Acid Batteries Up to 327 Ah
  • Records Cumulative Usage Data Internally for Warranty Return Analysis
  • On-Chip Temperature Sensor
  • Data Interface for Retrieving Warranty Information
  • Fully Programmable Features and Thresholds via UART Serial Interface
  • State-of-Health (SoH) Determination and Status Reporting
  • Includes Configurable Audible Indicator for Low-Capacity, Low-Voltage,
    and Overvoltage Warnings
  • Addressable Commands for Use in Multi-Battery Systems
  • Optional Infra-Red Communications Interface
    • Stand-Alone Uninterruptible Power Supplies
    • 12-V Pb-Acid Battery Monitors
    • Battery Warranty Data Logging Equipment

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The bq78412 Pb-Acid Battery State-of-Charge (SoC) Indicator with Run-Time Display is a complete stand-alone battery gas-gauge solution designed for single 12V Pb-Acid batteries. The bq78412 displays remaining Run-Time-To-Empty during discharge and Percent (%) capacity during charge using a 10-LED (light-emitting diode) bar graph.

The bq78412 monitors battery voltage, current, and ambient temperature to calculate state-of-charge and determine remaining runtime-to-empty. Measured values can be recorded and tracked for later retrieval for warranty purposes.

Programmable cell models allow the bq78412 to be customized to a variety of Pb-Acid formulations and capacities.

Current measurements and Coulomb-counting for gas-gauging are also automatically performed by the bq78412. Current measurements use a small value sense resistor placed in the negative power path and calibrated in-circuit. This allows the precise, continuous, real-time calculation of battery capacity and run-time-to-empty values.

Temperature sensing augments gas-gauge and capacity information using a firmware algorithm to compensate for the temperature effects on capacity.

A serial port is available for configuring various programmable parameters including cell models, calibration values, serial number and date of manufacture. The serial port can operate an infra-red (IR) interface to allow connector-less data acquisition. The bq78412 is easily configurable, is fully programmed and requires no algorithm or firmware development

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Technical documentation

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Type Title Date
* Datasheet Pb-Acid Battery State-of-Charge Indicator datasheet Aug. 04, 2010
User guide BQ78412EVM Board Quick-Start Guide May 04, 2011
User guide BQ78412 Application Programming Interface Jan. 20, 2011

Design & development

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Software development

SLUC256.ZIP (2257 KB)
SLUC257.ZIP (0 KB)

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HTSSOP (DDW) 44 View options

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