PRC-104 BB-2590 Battery Protector

[Augi]

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

 

[cagosti]

I have an interest . Have you tested the board for hf RFI .?

 

[Augi]

I've run the radio with my prototype and not had any problems. I don't have a spectrum analyzer to check it for real, but what I see on my scope is clean.

Augi

 

[Augi]

I've got an update on this project. Enough people have shown interest that I will be ordering a batch. If anyone else is still interested there are a few left unclaimed. The final cost is $130 + $7 for shipment in a small USPS flat rate box.


Here is a rehash of the project and some additional details:


This is a PCB that will allow safe use of BB-2590 Lion batteries in a PRC-104 radio. It is a drop-in replacement for the BB-390 charging circuit board in the base of the BB-x90 battery box, picking up the same mounting standoffs. It regulates any input voltage above 28.5V from the battery connectors down to 28.5V. If the battery voltage is lower than that, it just passes it straight through without any parasitic drop. There is a trim pot that allows about 2V of output level adjustment.


Output ripple is about 50mV at RX and jumps to about 100mV under the TX load. It's been nice and quiet through all of my tests and there is no change in the audio or any RFI that I can detect. It appears to be a transparent modification.


The 3-pin power connector on the side of the battery case is retained as an input and is diode blocked so there is no worry of back-feeding whatever external supply you may choose to connect. This input bypasses the regulator and goes directly to the radio so whatever supply is connected to it must meet the 22-30V that the radio requires. I typically use a bench supply to power the radio through this connector when I'm at home.


Applying 22-30V to the 3-pin power connector automatically shuts down the regulator and a MOSFET blocks the batteries so they are not fed from the external supply. This means that the batteries can be left in the case when running on external power without worry of inappropriately charging them. Removing the external supply automatically restarts the regulator and brings the batteries back online. There is an unavoidable brownout during these transitions which will usually reset the radio. It's best to turn it off first.


I estimate the efficiency to be in the mid 90%'s when bucking and high 90%'s when running at 100% duty cycle. Idle current is about 5mA, so a pair of 7.5Ah batteries in the box with the radio off will take about 100 days to completely discharge from full charge.

Augi

 

[M114]

I've got an update on this project. Enough people have shown interest that I will be ordering a batch. If anyone else is still interested there are a few left unclaimed. The final cost is $130 + $7 for shipment in a small USPS flat rate box.


Here is a rehash of the project and some additional details:


This is a PCB that will allow safe use of BB-2590 Lion batteries in a PRC-104 radio. It is a drop-in replacement for the BB-390 charging circuit board in the base of the BB-x90 battery box, picking up the same mounting standoffs. It regulates any input voltage above 28.5V from the battery connectors down to 28.5V. If the battery voltage is lower than that, it just passes it straight through without any parasitic drop. There is a trim pot that allows about 2V of output level adjustment.


Output ripple is about 50mV at RX and jumps to about 100mV under the TX load. It's been nice and quiet through all of my tests and there is no change in the audio or any RFI that I can detect. It appears to be a transparent modification.


The 3-pin power connector on the side of the battery case is retained as an input and is diode blocked so there is no worry of back-feeding whatever external supply you may choose to connect. This input bypasses the regulator and goes directly to the radio so whatever supply is connected to it must meet the 22-30V that the radio requires. I typically use a bench supply to power the radio through this connector when I'm at home.


Applying 22-30V to the 3-pin power connector automatically shuts down the regulator and a MOSFET blocks the batteries so they are not fed from the external supply. This means that the batteries can be left in the case when running on external power without worry of inappropriately charging them. Removing the external supply automatically restarts the regulator and brings the batteries back online. There is an unavoidable brownout during these transitions which will usually reset the radio. It's best to turn it off first.


I estimate the efficiency to be in the mid 90%'s when bucking and high 90%'s when running at 100% duty cycle. Idle current is about 5mA, so a pair of 7.5Ah batteries in the box with the radio off will take about 100 days to completely discharge from full charge.

Augi

Hi Augi, So what is the latest on this build as I am interested. Thanks, Pat

 

[M114]

I've got an update on this project. Enough people have shown interest that I will be ordering a batch. If anyone else is still interested there are a few left unclaimed. The final cost is $130 + $7 for shipment in a small USPS flat rate box.


Here is a rehash of the project and some additional details:


This is a PCB that will allow safe use of BB-2590 Lion batteries in a PRC-104 radio. It is a drop-in replacement for the BB-390 charging circuit board in the base of the BB-x90 battery box, picking up the same mounting standoffs. It regulates any input voltage above 28.5V from the battery connectors down to 28.5V. If the battery voltage is lower than that, it just passes it straight through without any parasitic drop. There is a trim pot that allows about 2V of output level adjustment.


Output ripple is about 50mV at RX and jumps to about 100mV under the TX load. It's been nice and quiet through all of my tests and there is no change in the audio or any RFI that I can detect. It appears to be a transparent modification.


The 3-pin power connector on the side of the battery case is retained as an input and is diode blocked so there is no worry of back-feeding whatever external supply you may choose to connect. This input bypasses the regulator and goes directly to the radio so whatever supply is connected to it must meet the 22-30V that the radio requires. I typically use a bench supply to power the radio through this connector when I'm at home.


Applying 22-30V to the 3-pin power connector automatically shuts down the regulator and a MOSFET blocks the batteries so they are not fed from the external supply. This means that the batteries can be left in the case when running on external power without worry of inappropriately charging them. Removing the external supply automatically restarts the regulator and brings the batteries back online. There is an unavoidable brownout during these transitions which will usually reset the radio. It's best to turn it off first.


I estimate the efficiency to be in the mid 90%'s when bucking and high 90%'s when running at 100% duty cycle. Idle current is about 5mA, so a pair of 7.5Ah batteries in the box with the radio off will take about 100 days to completely discharge from full charge.

Augi

Augi, This is a older post, any update ? I am interested. Pat

 

[Augi]

Sorry, these were all gone years ago and unfortunately nobody else has asked for one since so I doubt I'll be making any more. I need to make at least 20 at a time.


Augi

 

[M114]

Sorry, these were all gone years ago and unfortunately nobody else has asked for one since so I doubt I'll be making any more. I need to make at least 20 at a time.


Augi

Hi Augi, I was one of the guys that purchased one of these. I am sorry to learn that there was not more response. Do you have any boards or parts still available? A schematic? What is you start a new thread on the nodule? Thanks Augi, pasquale.nj@gmail.com