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20 Ni-MH cell battery design

Mario Jimenez
Prodigy 200 points
Other Parts Discussed in Thread: BQ24610

Hello,

I was wondering if there is an IC capable to charge a 20 cell Ni-MH battery pack. Single battery spec is this:

In short, the charger for this battery pack must provide more than 24V at 2.6A maximum, when quick charge is desired.

I saw a couple of IC's only capable of charging 4 cell's at most. I would really like this design to use a TI IC (I like Webench a lot).

Thanks in advance.

  • 0
    TI__Guru 56650 points
    We don't have a dedicated NiMH charger can charge 24V/2.6A NiMH battery. What is the maximum input voltage? If it is lower than 31V, you may use bq24610 to charge this NiMH battery and use safety timer to do the charging termination.
  • 0 in reply to Wang5577
    Prodigy 200 points
    Yes, input voltage is around 30V. That is a very interesting IC, but I have doubts about the maximum charge voltage(26V). I think 20 Ni-MH batteries will require around 20*1.4V=28V to truly charge. Could bq24610 provide more voltage by increasing the switching frequency?
  • 0 in reply to Mario Jimenez
    TI__Guru 56650 points
    The maximum output voltage is limited by the sleep comparator (VCC to SRN comparator). VCC need higher than SRN about 0.675V. Plus the VCC series diode forward voltage drop. So, the input voltage has to be higher than 29V. Increasing the switching frequency cannot change the sleep comparator threshold. 30V input should be OK. But, bq24610 could trigger input OVP at 31V. So, the input source voltage tolerance would be very challenge.