Dji spark charging hub issue

[Ariyanoe]

Hi guys
I have problem with my sparks charging hub , when I connect one of my batteries to hub it charges to 100% but when I connect both of batteries to it , it's charge until 96% or 97% .
Is it normal ? If not please help me how to fix this issue

 

[irvine]

How old are the batteries and how many times have you charged each one this may be the cause that battery doesn't fully charge

 

[Ariyanoe]

How old are the batteries and how many times have you charged each one this may be the cause that battery doesn't fully charge

Hi Irvine
Both of my batteries have been charged for five times and I'm sure that the batteries are heathy because when I connect one of them to the hub it will fully charge it, and you know once I used usb cable for it and it charges to 100 percent.