Ok, you’ve got a lot going on here. Some advice: 1. Get a bench power supply to slowly charge each cell individually up to about 3.3Volts. Use 100mA, Don’t try to “jump“ them. When all five cells are 3.3V, Then put it in your Ryobi charger and see if it charges. If not, do the BMS reset trick to clear all error flags. Then try to charge with Ryobi charger. 2. Often you’ll find that you can charge the over-discharged cells back up to 4.20V but they will self discharge. The longer they were below 1.5V the more self discharge you will see. (One day, no problem. One year, good luck getting them to not self discharge.) 3. Another method I use is a TP4056 module with a variable 10K potentiometer +1K resistor in series, swapped in where the current setting resistor is located. This gives me adjustable current from 50mA up to 1000mA. I suggest 100mA for cells below 1.5Volts. When the cell reaches 2.5V , increase the current to 200mA. Charge only to 3.90V for the first charge cycle. Then discharge at 300mA until the cell is down to 3.3V . This time charge all the way up to 4.20V at 300 mA. Now at 4.20V…. Watch the self discharge for about 10 days. Weed out the bad cells. 4. Another issue with severely discharged 18650 cells is their capacity drops due to internal chemistry changes. For example : a 2000mAh cell might only measure 1500 mAh after being discharged to 1.0 volt, and left sitting at 1.0V for 3+ months. Unfortunately, neither self discharging nor loss of capacity can be reversed. (But…… I’m working on it)
I have new Ryobi HP 2ah battery not charging and one followed by four green light flashing, I check the voltage all the cell have 3.5 but one cell showing .35 volt. Any clue how to fix it.
the cells that were 4.2 while the others are 3.5 ish means the 3.5v cells should be brought up to 4.2 individually. it probably wont charge cause the 1 cell is already at 4.2v and is over charging?
![RYOBI 18V Battery Not Working? [Easy DIY Charging Hack]](http://i.ytimg.com/vi/sqeiOkSNRsU/mqdefault.jpg)
Ok, you’ve got a lot going on here.
Some advice:
1. Get a bench power supply to slowly charge each cell individually up to about 3.3Volts. Use 100mA, Don’t try to “jump“ them. When all five cells are 3.3V, Then put it in your Ryobi charger and see if it charges. If not, do the BMS reset trick to clear all error flags. Then try to charge with Ryobi charger.
2. Often you’ll find that you can charge the over-discharged cells back up to 4.20V but they will self discharge. The longer they were below 1.5V the more self discharge you will see. (One day, no problem. One year, good luck getting them to not self discharge.)
3. Another method I use is a TP4056 module with a variable 10K potentiometer +1K resistor in series, swapped in where the current setting resistor is located. This gives me adjustable current from 50mA up to 1000mA.
I suggest 100mA for cells below 1.5Volts. When the cell reaches 2.5V , increase the current to 200mA. Charge only to 3.90V for the first charge cycle. Then discharge at 300mA until the cell is down to 3.3V .
This time charge all the way up to 4.20V at 300 mA.
Now at 4.20V…. Watch the self discharge for about 10 days. Weed out the bad cells.
4. Another issue with severely discharged 18650 cells is their capacity drops due to internal chemistry changes. For example : a 2000mAh cell might only measure 1500 mAh after being discharged to 1.0 volt, and left sitting at 1.0V for 3+ months.
Unfortunately, neither self discharging nor loss of capacity can be reversed. (But…… I’m working on it)
I have new Ryobi HP 2ah battery not charging and one followed by four green light flashing, I check the voltage all the cell have 3.5 but one cell showing .35 volt. Any clue how to fix it.
They are hot because your over charging the 4.2v cells. Dangerous.
Get a p111 dumb charger. They were from the old blue models.
Great job!. And this is why I don't have much faith in the electric car hype!. 😐
the cells that were 4.2 while the others are 3.5 ish means the 3.5v cells should be brought up to 4.2 individually. it probably wont charge cause the 1 cell is already at 4.2v and is over charging?