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BQ33100 EVM board Q1 temperature problem during measure 4 3000F supercapacitors

Yi Zhang2
Prodigy 40 points
Other Parts Discussed in Thread: BQ33100, BQ24640

Hi,

I tried to measure 3000F maxwell supercapacitors by BQ33100 EVM plus EV2300. The Q1 on the BQ33100 EVM temperature increase very high in seconds. Wondering whether the BQ33100 EVM has the capacitor limit? And how to adjust R1 and R2 to meet higher charging current like 100A or more?

The 3000F supercapacitor came from maxwell. The test condition is:

1. 4 series connected

2. maximum charging current < 2A, the current shown the software is around 1200mA

3. Voltage is 12V

Thanks

 

Yale

 

   

  • 0
    TI__Genius 13700 points

    Hello Yi,

    I am looking into the device GUI to determine for certain what the capacitance limit is for this device. However looking at the device webpage and supporting information it should be able to support 3000F bank.

    The reason for the increased heat in the Q1 is that assuming you are starting with a near zero capacitor bank voltage there will be nearly a 12V differential across Q1 at a charge rate of even just 1.2A means it is dissipating about 14W.

    If you are trying to achieve 100A charging on the EVM that will not be possible. Truly if you are interested in charging at that sort of current you will need to consider moving to a switching topology for your charger since a linear charger at that current is simply not feasible.

    I would recommend looking at the BQ24640 which is a switch-mode charger for multi-cell super capacitor applications.