Paralleling bulk caps with a Li-ion battery to mitigate battery voltage droop

Hi All,

If I have a one cell Li-ion battery and it goes to a boost conveter with transient loads at the boost's output.

I want to minimize the droop at V_batt. Can I place several bulk caps (such as 220uF, 470uF, ect) in parallel with the battery when the boost has its transient at the output?

If the battery is a normal DC power source, placing bulk caps at this voltage source will function to suppress the droop. However, I never see people use this way with the battery. Is there any specific reason for not doing this?


Thank you!

bhl3302 said:

Hi All,

If I ha
...
However, I never see people use this way with the battery. Is there any specific reason for not doing this?
View attachment 153032

Thank you!

Click to expand...

You can do that, there's nothing wrong with that. Use the inductor current ripple to calculate the minimum value for the boost converter input capacitance.

bhl3302 said:

Hi All,

If I have a one cell Li-ion battery and it goes to a boost conveter with transient loads at the boost's output.

I want to minimize the droop at V_batt. Can I place several bulk caps (such as 220uF, 470uF, ect) in parallel with the battery when the boost has its transient at the output?

If the battery is a normal DC power source, placing bulk caps at this voltage source will function to suppress the droop. However, I never see people use this way with the battery. Is there any specific reason for not doing this?

Thank you!

Click to expand...

Will lower ESR Caps help?
Initial inrush may be a concern, especially if there is a fuse between the battery and caps

summitville said:

Will lower ESR Caps help?
Initial inrush may be a concern, especially if there is a fuse between the battery and caps

Click to expand...

A softstart circuit will help control your duty cycle to increase from 0 gradually to dutyoperate. This helps control the inrush.