BQ2004H: Charge pending

Thank you Kedar, I will check it.

TCO is at 1.8 V, from my calculations VLTF=2,0V and VHTF=1,728

Can I just connect/short/ TCO and TS pin?

My second question is:

How do I know if the charging process was terminated due to the dV or due to the timer?

Hello Kedar,

How about connecting TCO and TS together? Then only one divider is needed.

I have set the TCO at 1.52V and TS at 1,86 V

VLTF=2,0V VHTF=1,67

and charge pending is active on a battery which is 3,945V( before putting to the charger).

When I put a second battery  which is 3,975 then after two, three blinks it starts charging and after five minutes Led1 is on Led2 is OFF. During the charging the charge current is like 1/8 fast charge current, only.

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My VBAT divider had swapped resistors, under test now.

Hi Christopher, 

C/8 charging rate looks like the part is charging with top-off rate.When in top-off verify if VEDV<VCELL<VMCV and VHTF < VTEMP < VLTF. In top-off charging continues at a reduced rate after fast-charge termination for a period of time equal to 0.235∗ the fast-charge safety time

Hello Kedar;

Vcell is always between 2,0 and 4,0V, I have about 2.4 -2.6 at VBAT pin when cells are discharged. VTCO is 1.85V, almost in the middle between 1.52VLTF and VHTF=2.0V

I did extensive tests. I have a 3 cells batteries( I wrongly written 2 before ).

I have a battery which is  rated 2200mAh, how ever from my tests they are 2200mAh at 0.2C and 1850mAh @ constant power 8W discharging. Never mind, let assume they are 2000mAh.

1. I set a fast charge current as 0.9A, and following config: Tm1-High TM2 =low >> c/2 154min safety timer

2. It seems that battery charging works. It has terminated either by the timer or DV, it is hard to say. Normal charging time should be around 2.2hrs

3. To check if it terminated by the dV, not by a timer I have charged battery to (let say) 50% and then after one hour brake I tried to charge it full, to see if it will be terminated faster than safety timer, what means dV works fine. And i was terminated after about 1.5hr.

4. Then I inserted and old type battery rated as 1200mAh, and what strange it has stopped charging after 10 minutes of fast charge. I have repeated it with a second 1200mAh battery and the behavior was the same. I am wondering why they terminated fast charge so quickly ? ( they were discharged before both, sure)

5. Once I had Same situation with second 2000mAh battery, It was charged to 50%, after one hour brake I  reinserted it to finish charging at 100%, but then I have had the same situation. After 10minutes it has finished fast charging. When I reinserted it again it has started charging ok and finished at 100% due to dV.

My question is;

1.What could be the reason that the smaller batteries have problem with charging or a bigger when they does not start from complete discharge?
What I mean as full discharge is discharge to cut off voltage 3,0V; later on the voltage get self back to about 3.5 3.6 V.

2. Is it ok that before every fast charge I have Top-off charge for about 10 minutes with 1/8 C rate and then after fast charging?

Kedar: I do not understand; if my Vcell is within correct range and temperature as well should I always have on the beginning Top-off charge (before fast charge)? State diagram shows it should goes immediately to fast charge. I have everytime 1/8C rate, thus I assume it is top-off and then after about 10 minutes fast charge.

Hi Chris,

   Can you test with TM1=TM2=GND? This will disable the top-off period.

You mean it will disable Top off or pulse trickle?

I have right now TM1= high TM2 = Low; what means Top off is disabled, according to Table 1.

It always works for the first  5to 10 minutes in kind of warm-up mode, about 1/8C rate and then after 5-10 minutes fast charge. this wondering me.

Hi Christopher, 

    This looks like it is the initial hold off period. From the datasheet section Temperature and Voltage Termination Hold Off: 

A hold-off period occurs at the start of fast charging. During the hold-off period, -∆V and ∆T/∆t termination are disabled. The MOD pin is enabled at a duty cycle of 260µs active for every 1820µs inactive. This modulation results in an average rate 1/8th that of the fast charge rate. This avoids premature termination on the voltage spikes sometimes produced by older batteries when fast-charge current is first applied. Maximum voltage and maximum temperature terminations are not affected by the hold-off period.

Does the state diagram include this initial hold-off? I do not see this.