Augi
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Hi All,
I've designed and prototyped a PCB that will allow safe use of BB-2590 Lion batteries in my PRC-104 radio. It is a drop-in replacement for the mystery charging circuit board in the base of the BB-x90 battery box and regulates any input voltage above 28.5v down to 28.5v. If the battery voltage is lower than that, it just passes it through.
This radio was originally used with a rechargeable silver battery. Also a battery box was made for BB-390 NiMH and BB-590 NiCAD batteries which both supply under 30v when fully charged.
Unfortunately the latest Lion batteries have a slightly higher cell voltage than their predecessors and fully charged they are about 32.5v. While they will function in the PRC-104 for a time, the radio is designed for a maximum input of 30v. One of the modules can get too hot and eventually sustain damage with extended use in this condition.
My goal with this project is to use modern electronics to implement as high efficiency a buck regulator as possible in order to minimize the impact on battery life. To achieve this goal the regulator must also be capable of 100% duty cycle operation so when the battery voltage falls below the regulator set point the FET is held on continuously. There is no point in boosting as the radio already does this internally.
I estimate the efficiency to be in the mid 90%'s when bucking and high 90%'s when running at 100% duty cycle. Quiescent current is about 3mA, so batteries in the box with the radio off will take about 100 days to completely discharge from full charge.
Now the sales pitch: I can have a run of 20 of these boards made and assembled by a PCB manufacturer if others find them useful. Making less than 20 is not economical unfortunately. I estimate the final cost at $125 each plus shipping.
Pictures attached.
Augi
I've designed and prototyped a PCB that will allow safe use of BB-2590 Lion batteries in my PRC-104 radio. It is a drop-in replacement for the mystery charging circuit board in the base of the BB-x90 battery box and regulates any input voltage above 28.5v down to 28.5v. If the battery voltage is lower than that, it just passes it through.
This radio was originally used with a rechargeable silver battery. Also a battery box was made for BB-390 NiMH and BB-590 NiCAD batteries which both supply under 30v when fully charged.
Unfortunately the latest Lion batteries have a slightly higher cell voltage than their predecessors and fully charged they are about 32.5v. While they will function in the PRC-104 for a time, the radio is designed for a maximum input of 30v. One of the modules can get too hot and eventually sustain damage with extended use in this condition.
My goal with this project is to use modern electronics to implement as high efficiency a buck regulator as possible in order to minimize the impact on battery life. To achieve this goal the regulator must also be capable of 100% duty cycle operation so when the battery voltage falls below the regulator set point the FET is held on continuously. There is no point in boosting as the radio already does this internally.
I estimate the efficiency to be in the mid 90%'s when bucking and high 90%'s when running at 100% duty cycle. Quiescent current is about 3mA, so batteries in the box with the radio off will take about 100 days to completely discharge from full charge.
Now the sales pitch: I can have a run of 20 of these boards made and assembled by a PCB manufacturer if others find them useful. Making less than 20 is not economical unfortunately. I estimate the final cost at $125 each plus shipping.
Pictures attached.
Augi
Last edited:
