NiMH - LTC4015 battery charger

I would like to use LTC4015 battery charger to charge a Nickel–metal hydride battery.

1) is this IC can support charging NiMH chemistry.

2) NiMH batteries nominally operate at 1.2 V per cell, do I need stacked cells (three cells = 3.6V) to be able to use the charger. 

Thank you in advance

  • 0
    •  Analog Employees 
    on Apr 13, 2018 9:22 PM

    Hello,

    LTC4015 does not support NiMH.

    It is theoretically plausible that it could be used to do this, but it would need to be set up to think it is charging an LiFePO4 battery in order to get the 3.6V target voltage. Also, bear in mind that the LTC4015 does not support the termination methods recommended for charging NiMH batteries. That said, the LTC4015 has a powerful telemetry system that could possibly be used to manually control the charging. For example, a processor monitoring the LTC4015's battery voltage and temperature measurements could manually implement negative delta v or delta temperature termination. However, all of this would be left up to the user to design and test safely.

    So, to summarize, NiMH is not supported but it seems like it could possibly be done manually if implemented carefully. It would be absolutely necessary to use a microcontroller in order to make it work properly.

    Regards,

    Zack

  • Give the complexity of using LTC4015 to charge NiMH, do you have any recommended IC that best fit in this application.

  • 0
    •  Analog Employees 
    on Apr 13, 2018 10:02 PM

    Hello,

    Yes, but I need more specifics about your application to recommend one. What is your input voltage, charge current, and cell count?

    In the meantime, here is a parametric search of all of our switching NiMH chargers:

    Selection Table for Switching Battery Chargers | Parametric Search | Analog Devices 

    Or if you don't need a switching charger, here are all of our NiMH chargers in general:

    Selection Table for Battery Charger IC | Parametric Search | Analog Devices 

    Some of these still do not include proper termination for fast charging, though, if that's what you need.

    Regards,

    Zack

    • input voltage 5V
    • charge current up to 1.5A (even though I don't need fast charging)
    • my system uses 5V/3A, so I still need a boost converter if I use one cell (1.2V) or three cells (2.4V), if the charger IC doesn't provide the boost feature. 
    • the battery used for backup power (10min). looking for ~500mAh NiMH 
  • 0
    •  Analog Employees 
    on Apr 16, 2018 6:23 PM

    Hello,

    I might recommend LTC4011 for your application. This is a NiMH charger with proper termination functions (which I recommend for charging at 1.5A). It is a buck charger without a boost feature, so you will need to follow it with a boost converter.

    LTC4010 is a slightly simpler alternative which would also work. I am recommending LTC4011 because it has an input ideal diode (INFET) which will help your charger to be more efficient at your low 5V input.

    Regards,

    Zack