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4 procedure, 1 pre-charge, 2 max charge – Texas Instruments BQ24450EVM User Manual

Page 4: 3 charge termination, 4 re-charge, Figure 2

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Procedure

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Replacement circuit for a 3-cell lead acid battery. BAT+ to BAT– voltage tracks the power supply input
voltage, minus 1 diode drop

Figure 2. Battery Load Circuit – PR1010-2

4

Procedure

4.1

Pre-charge

Turn on PS #1, preset to 10 VDC. Verify voltage on VM #1.

Turn on PS #2, preset to 5.2 VDC.

Adjust PS #2 such that VM #2 shows 5 VDC.

Using VM #3, measure the voltage across the current sense resistor on Load #1. Multiply this value by a
conversion factor of 10A/V. This is the pre-charge current.

4.2

Max Charge

Adjust PS #2 such that VM #2 shows 6 VDC.

Using VM #3, measure the voltage across the current sense resistor on Load #1. Multiply this value by
a conversion factor of 10A/V. This is the max charge current.

4.3

Charge Termination

Adjust PS #2 such that VM #2 shows 7.5 VDC.

There should be no charge current in this condition.

4.4

Re-Charge

Adjust PS #2 such that VM #2 shows 6 VDC.

Using VM #3, measure the voltage across the current sense resistor on Load #1. Multiply this value
by a conversion factor of 10A/V. This is the max charge current.

4

bq24450EVM

SLUU464 – November 2010

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