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TI IC for LI, NICD and NIMH Two-way Radio Batteries

Patrick Armstrong
Prodigy 80 points
Other Parts Discussed in Thread: BQ2000, BQ2002, BQ25892

We are looking for an IC that can detect chemistry of LI, NICd and NIMH two way radio batteries that can get up to 5000mah in size.   We are looking to redesign our two-way radio battery chargers that are availble in 1, 2,3 and 6 charging bay models. See link below.   We use AC and DC power supplies.  

We need the IC to charge each chemistry properly and to 100% capacity.   

Help?

www.impactcomms.com/universal-radio-chargers

  • 0
    TI__Guru**** 166176 points
    Patrick,

    Unfortunately, TI does not have an IC that can detect chemistry. We have battery charge ICs for either LiIon or Nixx; however, because the Nixx batteries terminate very differently, we do not have one charger that charges both chemistries. What is the maximum DC power that the charger will see?
  • 0 in reply to Jeff F
    Prodigy 80 points
    Hi Jeff, i will have to ask re: DC. Would there be a work around do you think to accomplish what we are trying to do? maybe one LI and one Nixx per charger bay and then we figure out a way to check for chemistry to then decide which TI IC we use in that particular instance?
  • 0 in reply to Patrick Armstrong
    TI__Guru**** 166176 points
    Yes, if you have separate bays, we can provide chargers for each. What is your DC power supply, 5V, 12V? How many of each type of battery are in series?
  • 0 in reply to Jeff F
    Prodigy 80 points
    well its not separate bays, so we would need to figure out what the chemistry it is before charging then tell the TI ICs (nixx or LI IC hooked up to each bay) to start to do its thing. We can have up to 6 bays.
  • 0 in reply to Patrick Armstrong
    Prodigy 80 points
    Hi Jeff, could we not use the chemistry detection method discussed in the TI paper below then based on that result use a TI nicd/nihm IC or TI Li IC - where we would have one of each IC installed per charging bay?
    method : measure battery’s impedance calculation along with its open circuit voltage (estimate of its charge state) to determine whether it is a NiMH battery or not....
  • 0 in reply to Jeff F
    Prodigy 80 points
    Hi Jeff, could we not use the chemistry detection method discussed in the TI paper below then based on that result use a TI nicd/nihm IC or TI Li IC - where we would have one of each IC installed per charging bay?

    method : measure battery’s impedance calculation along with its open circuit voltage (estimate of its charge state) to determine whether it is a NiMH battery or not.... www.ti.com/.../slap106.pdf
  • 0 in reply to Patrick Armstrong
    TI__Guru**** 166176 points
    Patrick,

    I had not seen this. Looks promising. Is there a more detailed schematic? Would you use the MSP430 to perform charging as well, instead of a standalone charger? You could still use one of my group's LiIon charger's and then add the additional termination stuff for Nixx with the MSP430.
  • 0 in reply to Jeff F
    Prodigy 80 points

    the schematic in the PDF i sent you is all i found so far.  I am envisioning 6 charging bays in 1 mechanical body each bay with:

    1. MSP430 - used to do impedance calculation along with open circuit voltage (estimate of its charge state) to determine whether it is a Nixx battery, then select which TI IC below to use

    1. TI LI charger IC

    1. TI NIxx charger IC

    What do you think?,  Can you suggest both TI charging IC?

  • 0 in reply to Patrick Armstrong
    TI__Guru**** 166176 points
    Patrick,

    That sounds reasonable. I think you could use one LiIon charger and then use the MSP430 to alter LiIon charging profile to include the extra stuff for Nixx termination. What is your input source voltage? How many cells in series of each type?
  • 0 in reply to Jeff F
    TI__Guru**** 166176 points

    Patrick,

    I did some research and the bq2000 family of controllers charges both Nixx and LiIon chemistry. This family is quite old but we still support. My idea for using a LiIon charger with the MSP430 to alter its profile is based on the app note here: www.ti.com/.../slua843. The algorithm in this app note is specifically for eCall but you could develop a similar one for your application and use a different LiIon charger.

  • 0 in reply to Jeff F
    Prodigy 80 points

    Hi Jeff,  the input source voltage is 10-12V,   So we would do chem detection with MSP430 then use a bq2000 to charge whether its nixx or LI?

  • 0
    Prodigy 80 points
    or is it that we put a bq2000 per charging bay (so up to six bays) in our two-way radio batt charger
  • 0 in reply to Patrick Armstrong
    TI__Guru**** 166176 points
    Patrick,

    The bq2000 does a crude chemistry detection but terminates the Nixx chemistries using a LiIon charge profile. The recommended termination method for Nixx for longest life is Negative dV and Peak Voltage Detection, which is provided by the bq2002. The bq200x family is quite old and, while we do support it, I recommend moving to a newer charger with improved performance. Unfortunately, TI does not have a newer Nixx charger with the preferred termination method. If you are planning on using the MSP430 for detection, I recommend using a LiIon charger like bq25892 and then use the MSP430 to alter the termination profile.