iONic
Member
My current understanding... correct me if I'm wrong.
Lead-Acid, including Gel Cells, both can be charged by the tenth rate method; that is, 1/10th the full power rating is used to charge the battery for 10 to 12hours. If we had a 32AHr battery we would charge it at 3.2A for 10 to 12 hours.
The idea of a trickle charger is that it can be left charging the battery continuously without fear of damage to the battery. To do this, the rate must be no more than 1/100th the power rating of the cell, and at least as high as the internal discharge rate of the cell. Thus If we had a 32AHr battery we would charge it at 320mA.
Therefore I need to alter the following circuit, from National Semiconductor, to do the following since I have both Lead-Acid and Gel Cells.
Given a 20V, 3A power source I would like to make a switchable charge-rate charger.
1) For Gel Cell(12V, 32AH) Initial charge current ~3A.
when the current falls below 320mA the charger switches to a lower "Float" Voltage(14.4) to prevent overcharging.
2) For Lead-Acid(12V, 32AH) Initial charge current of ~3A.
when the current falls below 320mA the charger switches to a lower "Float" Voltage(13.8) to prevent overcharging.
What would I have to do to make this dual circuit?
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Here is a description of the working of the circuit according to Tony Van Roon:
his high-performance circuit first quickly starts (and holds) the charge at 2 amp, but as the voltage rises the current will consequently decrease.
When the current falls below 150mA, the charger automatically switches to a lower 'Float' voltage to prevent overcharging.
At the point that a full charge is reached, Q1 will bias and the LED will light.
The LM301A is a 8-pin OpAmp. Transistor Q1 is a PNP, Silicon, AF-Out type with a TO-39 metal case and can be substituted for a NTE or ECG129. Diode D1, a Si, GP Det. type, can be substituted with a NTE177 or ECG177. The LM350 (U1) needs to be cooled.
The input voltage should equal or about 18volts.
R1's function is to bleed some of the input voltage to the output and vice-versa. A 1N4002 or similar diode can be used also.
R2 and R5 are actually metal-film type resistors. To get the 3K for R2 use two 1K5 (1500 ohm) resistors in series. For R5 use two 470 ohm resistors in parallel. Or whatever combination to get to these values. For R1, 500 ohm, you can use two 1K in parallel or 470 + 33 ohms in series.
R7, the 0.2 ohm resistor, is a 5 watt wire-wound type. Do not use the standard carbon type.
C4: This (optional) 0.1uF (100nF) Ceramic capacitor needs to be mounted over the power lines and as close to the LM301 (U2) as possible. It will filter off any possible residue hf ripple, which otherwise may prevent this op-amp from working properly. Use only if you have problems with the LM301 not switching off.
When the start switch is pushed, the output of the charger goes to 14.5 V. As the battery approaches full charge, the charging current decreases and the output voltage is reduced form 14.5V to about 12.5V, terminating the charging process. Transistor Q1 then lights the led as a visual indication of a full charge.
Lead-Acid, including Gel Cells, both can be charged by the tenth rate method; that is, 1/10th the full power rating is used to charge the battery for 10 to 12hours. If we had a 32AHr battery we would charge it at 3.2A for 10 to 12 hours.
The idea of a trickle charger is that it can be left charging the battery continuously without fear of damage to the battery. To do this, the rate must be no more than 1/100th the power rating of the cell, and at least as high as the internal discharge rate of the cell. Thus If we had a 32AHr battery we would charge it at 320mA.
Therefore I need to alter the following circuit, from National Semiconductor, to do the following since I have both Lead-Acid and Gel Cells.
Given a 20V, 3A power source I would like to make a switchable charge-rate charger.
1) For Gel Cell(12V, 32AH) Initial charge current ~3A.
when the current falls below 320mA the charger switches to a lower "Float" Voltage(14.4) to prevent overcharging.
2) For Lead-Acid(12V, 32AH) Initial charge current of ~3A.
when the current falls below 320mA the charger switches to a lower "Float" Voltage(13.8) to prevent overcharging.
What would I have to do to make this dual circuit?
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Here is a description of the working of the circuit according to Tony Van Roon:
his high-performance circuit first quickly starts (and holds) the charge at 2 amp, but as the voltage rises the current will consequently decrease.
When the current falls below 150mA, the charger automatically switches to a lower 'Float' voltage to prevent overcharging.
At the point that a full charge is reached, Q1 will bias and the LED will light.
The LM301A is a 8-pin OpAmp. Transistor Q1 is a PNP, Silicon, AF-Out type with a TO-39 metal case and can be substituted for a NTE or ECG129. Diode D1, a Si, GP Det. type, can be substituted with a NTE177 or ECG177. The LM350 (U1) needs to be cooled.
The input voltage should equal or about 18volts.
R1's function is to bleed some of the input voltage to the output and vice-versa. A 1N4002 or similar diode can be used also.
R2 and R5 are actually metal-film type resistors. To get the 3K for R2 use two 1K5 (1500 ohm) resistors in series. For R5 use two 470 ohm resistors in parallel. Or whatever combination to get to these values. For R1, 500 ohm, you can use two 1K in parallel or 470 + 33 ohms in series.
R7, the 0.2 ohm resistor, is a 5 watt wire-wound type. Do not use the standard carbon type.
C4: This (optional) 0.1uF (100nF) Ceramic capacitor needs to be mounted over the power lines and as close to the LM301 (U2) as possible. It will filter off any possible residue hf ripple, which otherwise may prevent this op-amp from working properly. Use only if you have problems with the LM301 not switching off.
When the start switch is pushed, the output of the charger goes to 14.5 V. As the battery approaches full charge, the charging current decreases and the output voltage is reduced form 14.5V to about 12.5V, terminating the charging process. Transistor Q1 then lights the led as a visual indication of a full charge.
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