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Eneloop charging requirements with bq2004E

derek koonce
Prodigy 160 points
Other Parts Discussed in Thread: BQ2004E

I am looking at the BQ2004E battery charger for two AAA eneloop batteries in series. Questions:

1. For the resistor divider in the data sheet on page 3, RB1 and RB2, is having a 510k for RB1 and leaving RB2 open acceptable?

2. What is the best termination method for the eneloop batteries? Is it Peak Voltage Detection or minus-delta-V?

3. Since eneloop batteries ask for a long charge time, but I do not always have a lot of time, my goal is to have a C/2 charge rate. Is this the best rate for the eneloop?

I  have asked Panasonic for months, but have not gotten any response. I am now hoping someone on this forum can answer.

Other settings:

A. No discharge-before-charge implemented.

B. No concern on LED indication since my processor is busy with other actions. I expect the charger to do its job once the INH goes high to initiate the charge.

C. Supply voltage is 4.9V and charger supply voltage is over 15V, with a maximum of 30V. I have a 100uH inductor that is in the charge path for current control.

 

A fast response is requested since I need to close quickly on this project.

  • 0
    TI__Guru 56650 points
    1. For RB1 and RB2 value: I don't see any issue with "510k for RB1 and leaving RB2 open". But, there is note on datasheet page 3: " This resistor-divider network input impedance to end-to-end should be at least 200kΩ and less than 1MΩ." So, please keep RB2 space. In case, we need it.
    2. When -ΔV termination is selected, if VCELL is lower than any previously measured value by 12mV ±4mV (6mV/cell), fast charge is terminated. When PVD termination is selected, if VCELL is lower than any previously
    measured value by 6mV ±2mV (3mV/cell), fast charge is terminated. I would like to use PVD for small charging rate.
    3. I don't have enough knowledge to decide the charging rate for eneloop batteries. Please keep checking Panasonic or select another vendor who can provide enough parameter.
  • 0 in reply to Wang5577
    Prodigy 160 points
    1. I did see the conflict with the note on page 3; but the divider is for more than 2 batteries, yet the data sheet says it can handle down to 2. Problem with adding RB1 and RB2 is that they end up loading the battery pack; does it not?

    2. Thank you for your view on fast charge termination. Since I am trying to keep charge rate at C/2, it looks that the PVD is best method.

    3. Yes, Panasonic is seemingly tight lipped about any charging information on their Eneloop product. Multiple requests always seem to come back with "cannot answer". Yet someone HAS to know about the product. I have selected their product since the batteries have a very long shelf life after charging, which is key to my application. Eneloop looks to be the longest; unless anyone knows of a better product.