Internal Resistance Tester Schematic
Abstruct
CASE1 バッテリー用内部抵抗計
この回路は、容量が 20Ah を超える鉛蓄電池およびゲル電池の状態をチェックするように設計されています。
CASE2 バッテリテスター回路
この回路は、電源や高価な可動コイル電圧計を必要とせずに、高速バッテリ テストを実行します。2 つの範囲を備えています。SW1 が回路図に示すように設定されている場合、デバイスは 3V ～ 15V のバッテリーをテストできます。SW1 を他の位置に切り替えると、1.5V セルのみをテストできます。
CASE1 LEARNING ELECTRONICS
Internal Resistance Tester For Batteries Circuit Diagram
This circuit is designed to check the condition of lead-acid and gel cell batteries with capacities greater than 20Ah. It switches a load of about 18A at a rate close to 50Hz
Internal Resistance Tester For Batteries
This circuit is designed to check the condition of lead-acid and gel cell batteries with capacities greater than 20Ah. It switches a load of about 18A at a rate close to 50Hz so that the internal resistance of the battery can be measured using a digital multimeter across the battery terminals. The measured AC voltage in millivolts divided by 10 (ie, a shift of the decimal point) is approximately equal to the battery's internal resistance in milliohms. As shown, the circuit is quite straightforward and is based on two 555 timer ICs (IC1 & IC2) and power Mosfet Q1. IC1 operates as a monostable timer with a period of 10s.
When switch S1 (Test) is pressed, IC1's pin 3 output goes high for 10s and this enables IC2 which operates as a 50Hz astable oscillator. IC2 in turn drives power Mosfet Q1 which is connected across the load in series with three 0.22W 50W resistors. IC2 then turns off again after 10s - ie, at the end of the monostable timing period. LED1 provides power indication when the circuit is connected to a battery, while LED2 (green) comes on during the test period. The thermostat is not necessary unless the unit is to be used repeatedly (the Jaycar ST-3823 70°C unit is suitable) and you want to protect the output circuit against overheating.
Note:
The power Mosfet does not need cooling but the thermostat and the 0.22W 50W resistors should all be mounted on an aluminium heatsink at least 2mm thick. In practice, the internal resistance of car batteries can vary from about 15mW down to about 3mW. Before testing the battery, check that the electrolyte level is correct and that the voltage across its posts exceeds 12.5V for a nominal 12V battery; ie, close to full charge. That done, switch on the car's headlights and measure the DC voltage between each battery post and its connecting terminal. It should be less than 10mV in both cases; if not, the terminals need cleaning. Once you've done that, you can turn off the headlights, connect the tester and proceed with the internal resistance test. Be sure to connect the multimeter's test probes directly to the battery posts, to read the internal resistance (not the battery terminals).
CASE2 Self-Powered Fast Battery Tester Schematic
Self-Powered Fast Battery Tester Schematic - EEWeb
This circuit runs a fast battery test without the need of power supply or expensive moving-coil voltmeters. It features two ranges: when SW1 is set as
Tests 1.5 to 15 Volt cells, Two-LED display, No Power Supply Required
This circuit runs a fast battery test without the need of power supply or expensive moving-coil voltmeters. It features two ranges: when SW1 is set as shown in the circuit diagram, the device can test 3V to 15V batteries. When SW1 is switched to the other position, only 1.5V cells can be tested.
Circuit Diagram:
Parts:
Resistors
R1 = 2.2K
R2 = 3.3R
R3 = 10R
R4 = 4.7K
R5 = 33K
R6 = 100K
R7 = 100K
R8 = 220K
R9 = 330K
R10 = 500K
Capacitors
C1 = 10nf-63V
C2 = 10nf-63V
C3 = 100nF-63V
C4 = 100nF-63V
C5 = 100nF-63V
C6 = 100nF-63V
C7 = 100nF-63V
C8 = 220uF-35V
Semiconductors
Q1 = 2N3819 FET General purpose FET
Q2 = BC337 NPN 45V 800mA NPN Transistors
Q3 = BC337 NPN
D1 = 5mm Red LED
D2 = 1N4148
D3 = 1N4148
D4 = 1N4148
D5 = 1N4148
D6 = 1N4148
D7 = 5mm Red LED
IC1 = 7555or TS555CN CMos Timer ICs
IC2 = 7555
Miscellaneous
SW1 = DPDT Switch
BUT = Battery Under Test
P1 = SPST Pushbutton
Testing 3V to 15V Batteries:
- Switch SW1 as shown in the circuit diagram.
- Place the battery under test in a suitable holder or clip it to the circuit.
- Wait some seconds in order to let C8 reach its full charge.
- LED D1 illuminates at a constant intensity, independent of battery voltage.
- If D1 illuminates very weakly or is completely off the battery is unusable.
- If D1 has a good illumination, press P1 and keep an eye to LED D7.
- If D7 remains completely off, the battery is in a very good state.
- If D7 illuminates brightly for a few seconds, the battery is weak. This condition is confirmed by a noticeable weakening in D1 brightness.
- If D7 illuminates weakly for a few seconds but D1 maintain the same light intensity, the battery is still good but is not new.
Testing 1.5V Batteries:
- Switch SW1 in the position opposite to that shown in the circuit diagram.
- Place the battery under test in a suitable holder or clip it to the circuit.
- Wait some seconds in order to let C8 reach its full charge.
- LED D1 illuminates very weakly only in presence of a new battery, otherwise is off. Press P1 and keep an eye to LED D7. If D7 remains fully off the battery can be in very good state. If D7 illuminates brightly for a few seconds, the battery is weak. If D7 illuminates weakly for a few seconds, the battery is still good but is not new. If you are suspecting a 1.5V cell to be completely discharged, a better test can be made wiring two 1.5V batteries in series, then running the 3V test.
Circuit Operation:
FET Q1 provides a constant current generator biasing LED D1 and Q2 Base. In this manner D1 illuminates at a constant intensity, independent of battery voltage from 3 to 15V and Q2 (when P1 is closed) applies a constant current load of about 120mA to the battery. IC1 is a square wave generator oscillating at about 3KHz. IC2 acts as an inverter and drives, together with IC1 but in anti-phase, Diodes D2-D6 and Capacitors C4-C7, obtaining a voltage multiplication.
C8 is charged by this raised voltage and R8-R10 form a voltage divider biasing the Base of Q3. When P1 is open, a very light load is applied to the battery under test and Q3 Base is biased in order to maintain LED D7 in the off state. Closing P1, a 120mA load is applied to the battery under test. If the battery is not fully charged, its output voltage starts reducing: when this voltage fall 0.6V below the battery nominal voltage, Q3 Emitter becomes more negative than the Base, the transistor is hard biased and D7 illuminates.
Obviously, this state of affairs will last a few seconds: the time spent by C8 to reduce its initial voltage to the new one, proportional to the voltage of the loaded battery. If the battery under test is in a good charging state, its output voltage will not fall under a 120mA loading current, so LED D7 will stay off. When testing 1.5V batteries, the circuit formed by Q1, Q2, D1, and R1 & R2 does not work well at this supply voltage, so a 150mA load current is applied to the BUT by means of the 10 Ohm resistor R3 after switching SW1A. Q3 bias is also changed via SW1B.
Notes:
To set-up this circuit applies a 6 to 7.5V voltage source to the input and trim R10 until LED D7 is completely off (without pushing on P1). 1.5V test position needs no set-up. CMos 555 ICs must be used for IC1 & IC2 because they are the only cheap devices able to oscillate at 1.5V supply or less. Source: Red Free Circuit Design