Problem with HB: Battery issues or?

[DanielTERRAN]

Have 16 X-Gen taggers + HB (Belts)... About 10 months old.
HB#9: HB starts, everything fine... after game starts, it turns off... Voltage: 4.13V (this has a new main board installed)
HB#3: HB starts, everything fine... after game starts, it turns off... Voltage: 4.05V
HB#2: HB starts, everything fine... after game starts, it turns off... Voltage: 4.06V
HB#1: HB starts, everything fine... after game starts, it turns off... Voltage: 4.11V  (This one a has NEW battery installed)
HB#10: HB starts, everything fine... after game starts, it turns off... Voltage: 1.44V

HB#4: once turned on, will not turn off, only if battery is disconnected. Changed Board + Battery... Still not lasting more than 10mins in  the game... Voltage: 1.74V (!!after new battery installed!!!)

HB#12: everything fine.... Voltage: 3.99V
And the rest of the HB have voltages between: 3.71 - 3.74v... , and 4.01 - 4.04V, and they work fine... they last an entire day.

Chargers have been checked. Firefly Charger: 8.2V under load.

What is the problem?

[Support]

Hello,

We discussed it by Skype. The problem should be in the batteries and/or power controllers. Do everything is ok now with these headbands?