Racal , again.

[panserv]

From what I remember, years ago the rechargables I used gave good service and might have indeed been Li ion.
I had 2 which I used all the time, but aftyer a while I bought alot of a dozen PRC128's from GovLiquid and sold the Racals.
I now regret it because the while looking like cool mil radios they are too large to be carried around, and now we have this situation and would prefer the P25's.
Anyway, thats history.
Another look at underneath the radios, shows just one tiny pin, ( dont forget I dont have a rechargable batt), so prcguy, where would the other tiny pin connect ? And if I understand you correctly, on the battery, from either tiny pin to batt negative you get nothing , and to batt positive you read + 8 volts , right ?
I might give this a shot, via a current limiting resistor, thats right starting 10k. And maybe also use an 8 volt zener.

 

[wildbillx]

From what I remember, years ago the rechargables I used gave good service and might have indeed been Li ion.
I had 2 which I used all the time, but aftyer a while I bought alot of a dozen PRC128's from GovLiquid and sold the Racals.
I now regret it because the while looking like cool mil radios they are too large to be carried around, and now we have this situation and would prefer the P25's.
Anyway, thats history.
Another look at underneath the radios, shows just one tiny pin, ( dont forget I dont have a rechargable batt), so prcguy, where would the other tiny pin connect ? And if I understand you correctly, on the battery, from either tiny pin to batt negative you get nothing , and to batt positive you read + 8 volts , right ?
I might give this a shot, via a current limiting resistor, thats right starting 10k. And maybe also use an 8 volt zener.

I sent a PM message to you. I also have an old battery that is dead if you are interested.

 

[prcguy]

The radio only has one extra pin but the batteries have two so you can put the battery on either way and it will still make contact.

From what I remember, years ago the rechargables I used gave good service and might have indeed been Li ion.
I had 2 which I used all the time, but aftyer a while I bought alot of a dozen PRC128's from GovLiquid and sold the Racals.
I now regret it because the while looking like cool mil radios they are too large to be carried around, and now we have this situation and would prefer the P25's.
Anyway, thats history.
Another look at underneath the radios, shows just one tiny pin, ( dont forget I dont have a rechargable batt), so prcguy, where would the other tiny pin connect ? And if I understand you correctly, on the battery, from either tiny pin to batt negative you get nothing , and to batt positive you read + 8 volts , right ?
I might give this a shot, via a current limiting resistor, thats right starting 10k. And maybe also use an 8 volt zener.

 

[panserv]

Ok, understood about the two pins. Might have a try putting 8 volts + on the tiny pin and see what happens.

 

[prcguy]

It would be 8 volts less than the full battery voltage. I mentioned its not referenced to ground and with a voltmeter + lead on the battery + and the meter - lead on the extra pin the meter reads 8 volts.

Ok, understood about the two pins. Might have a try putting 8 volts + on the tiny pin and see what happens.

 

[panserv]

It would be 8 volts less than the full battery voltage. I mentioned its not referenced to ground and with a voltmeter + lead on the battery + and the meter - lead on the extra pin the meter reads 8 volts.

So that means there is some inverter in the battery. Complicated. Who dreams them up ?
back to the drawing board

 

[mancow]

There is no inverter or any other crazy stuff. It's 3 18650 Panasonic type liion cells with a small charge controller board that load balances each cell and monitors voltage. The board talks to the radio through that extra pin using (I think) one-wire protocol but I would have to go look at a board again to be sure. This is howthe radio gets the battery level status and also know whether to default to 2 watts or not.

 

[panserv]

There is no inverter or any other crazy stuff. It's 3 18650 Panasonic type liion cells with a small charge controller board that load balances each cell and monitors voltage. The board talks to the radio through that extra pin using (I think) one-wire protocol but I would have to go look at a board again to be sure. This is howthe radio gets the battery level status and also know whether to default to 2 watts or not.

Ok, but how then could prcguy measure a negative 8volts, NOT referenced to the negative, on the small pin ?

 

[mancow]

I think he said he measured 8 volts not negative 8 volts.

The battery talks bi-directionally to the radio. It reads the voltage and power capacity remaining. It is read out at power up and and every minute after that and after every transmit session. The chargers also talk to the batteries via the same bus via bottom contacts. Chargers are all over ebay. I threw several in the trash not long ago.

Do some reading here if inclined. I can't guarantee it's the exact same part without looking again but it should be similar enough to get you most the details you might be interested in.

https://www.ti.com/lit/ds/symlink/bq2050.pdf

LOL Unitrode, reminds me of Office Space but I think that was Initrode some went to work at after the fire.

 

[panserv]

I think he said he measured 8 volts not negative 8 volts.

The battery talks bi-directionally to the radio. It reads the voltage and power capacity remaining. It is read out at power up and and every minute after that and after every transmit session. The chargers also talk to the batteries via the same bus via bottom contacts. Chargers are all over ebay. I threw several in the trash not long ago.

View attachment 83627

"its not referenced to ground and with a voltmeter + lead on the battery + and the meter - lead on the extra pin the meter reads 8 volts. "
Scratching my head now....voltmeter + on battery+ and voltmeter - on extra pin reads 8 volts !

 

[mancow]

It's irrelevant anyway because it's a data bus and nothing you can reference to voltage to glean anything useful without decoding it and in turn talking over it to the radio with the correct information to spoof it into thinking it's a regular pack. You could probably read up on that datasheet and get one of those parts or sniff it with a logic analyzer and perhaps build a spoof board, or code one from a tiny duino board.

 

[mancow]

The bq2050 includes a simple single-pin (DQ plus return) serial data interface. A host processor uses the interface to access various bq2050 registers. Battery characteristics may be easily monitored by adding a single contact to the battery pack. The open-drain DQ pin on the bq2050 should be pulled up by the host system, or may be left floating if the serial interface is not used. The interface uses a command-based protocol, where the host processor sends a command byte to the bq2050. The command directs the bq2050 to either store the next eight bits of data received to a register specified by the command byte or output the eight bits of data specified by the command byte. The communication protocol is asynchronous return-to one. Command and data bytes consist of a stream of eight bits that have a maximum transmission rate of 333 bits/sec. The least-significant bit of a command or data byte is transmitted first. The protocol is simple enough that it can be implemented by most host processors using either polled or interrupt processing. Data input from the bq2050 may be sampled using the pulsewidth capture timers available on some microcontrollers.

 

[prcguy]

It would be easier to just rebuild an original battery with new cells and keep the electronics intact.

It's irrelevant anyway because it's a data bus and nothing you can reference to voltage to glean anything useful without decoding it and in turn talking over it to the radio with the correct information to spoof it into thinking it's a regular pack. You could probably read up on that datasheet and get one of those parts or sniff it with a logic analyzer and perhaps build a spoof board, or code one from a tiny duino board.

 

[mancow]

It would be easier to just rebuild an original battery with new cells and keep the electronics intact.

Which is exactly why old dead batteries are still in fairly high demand. Three tabbed 18650s, some kapton tape, some copper tape and a bit of patience and luck and you can have one that rates better than the OEM.

 

[panserv]

I think thats what I will go for.
Have not seen any chargers on ebay though, maybe they all got trashed.
Let me know if you know where I can get some.
Thank you guys, you have just pulled me from the abbyss.

 

[mancow]

I might have a charger to sell. I'll check.

 

[panserv]

I might have a charger to sell. I'll check.

Thank you

 

[prcguy]

I have two stock old batteries and one that went to a rebuild company and they screwed it up.

Thank you

 

[mancow]

I have two stock old batteries and one that went to a rebuild company and they screwed it up.

What did they screw up?

I haven't messed with my T25 in ages. I just dug it out. I see I put a label on the battery indicating repack 9-6-16. I hope it charges. I haven't charged it in a year probably.

 

[prcguy]

Everything. I sent them a T25 and MBITR battery, both weak but working. They hacked them up, glued them back together crooked and the T25 would not charge. I suspect they shorted out the internal circuit boards or hooked a cell up backwards. I wish I could remember the name of the company so nobody else makes the same mistake.

What did they screw up?