BQ24610EVM: New board, charging slowly, then stops after 30 minutes

Christopher Nguyen

Part Number: BQ24610EVM

I just got a new evaluation board. It's currently in its default configuration.

18VDC input, 1p4s battery connected, 12W load on Vsys, 1.7V power supply connected to TS.

At first, the battery will charge slowly (with and without the load).

Then, at the 30 minute mark, the battery stops charging. If the load is connected, the battery drains. Disconnect battery, load stops.

I have to disconnect/reconnect Power Supply to TS and the 18VDC to resume charging.

over 6 years ago

0 Joel Hernandez II over 6 years ago

TI__Mastermind 25800 points

Hey Christopher,

What is the voltage of the 4S battery pack as measured on the SRN node of the charger?

Can you also monitor the ACDRV pin voltage?

Can you take a waveform capturing the event when the charge current goes to zero?
The waveform should show the following:
IBAT (trigger on the falling edge of this waveform)
VSRN
VBUS
ACDRV

Regards,
Joel H

0 Christopher Nguyen over 6 years ago in reply to Joel Hernandez II

Prodigy 90 points

Hi Joel,

Don't currently have access to the equipment to get the waveforms. But the Voltage on SRN seems to match the voltage of the battery pack.

Based on the thirty minute timeout, do you think it's in the precharge phase and the safety timer is kicking in? I've grounded the TTC pin, but it's still stopping after 30 minutes.

0 Christopher Nguyen over 6 years ago in reply to Christopher Nguyen

Prodigy 90 points

Still don't have a working scope right now, but using a couple multimeters:

	Before	After
Ibat	0.290 A	0.003 A
ACDRV	12.62 V	12.96 V

Vsrn was the same as Vbatt (within 0.05 V)

0 Joel Hernandez II over 6 years ago in reply to Christopher Nguyen

TI__Mastermind 25800 points

Hey Christopher,

What is the battery voltage (as measured from the SRN pin of the charger)? If the battery voltage is less than 15.6V using this EVM, the charger is in pre-charge mode. The EVM was designed around a 5S configuration. I would recommend adjusting R25 to a lower value for the battery regulation voltage you are looking for. You can use the datasheet to determine the value you need.

Regards,
Joel H

0 Christopher Nguyen over 6 years ago in reply to Joel Hernandez II

Prodigy 90 points

I've determined the R25 and R28 values I'd need for 4S.

But for the safety timer, my reading of the documentation is that by grounding the TTC pin (lo on the TTC Jumper) it should disable termination and the safety timer. Is that incorrect?

0 Joel Hernandez II over 6 years ago in reply to Christopher Nguyen

TI__Mastermind 25800 points

Hey Chris,

Termination is still disabled and the fast charge safety timer is disabled. However, the Pre-Charge safety timer cannot be disabled. Realistically, charger should not remain in the pre-charge region for that long unless something is wrong with the batteries.

Regards,
Joel H

0 Christopher Nguyen over 6 years ago in reply to Joel Hernandez II

Prodigy 90 points

Ok.

To clarify then, does that mean there was something wrong with the previous board we had? That one didn't time out during precharge.

What would I look for to verify?

0 Joel Hernandez II over 6 years ago in reply to Christopher Nguyen

TI__Mastermind 25800 points

Hey Chris,

For the pre-charge timer to not take effect, make sure the feedback voltage (VFB) is above 1.55V. If your previous board had a different resistor divider ratio that set the regulation voltage to a 5S configuration, most likely the VFB on your 4S battery was less than 1.55V.

Regards,
Joel H

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BQ24610EVM: New board, charging slowly, then stops after 30 minutes