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LED indicator

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E2K

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This is a circuit of a 6V 4.5Ah lead acid battery charger with LED indicator.
When battery connected LED indicate that & when there is no battery LED will go off.
I want to use this indicator for 12V 12Ah lead acid battery. What are the Resistors values should i use?
 

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E2K said:
This is a circuit of a 6V 4.5Ah lead acid battery charger with LED indicator.
When battery connected LED indicate that & when there is no battery LED will go off.
I want to use this indicator for 12V 12Ah lead acid battery. What are the Resistors values should i use?
Well I find the design even for 6V faulty for the following reasons.
In order for a normal low intensity red, yellow or green LED to light the voltage drop across the 3.3 ohm resistor has to be very close to 2.3 volts.
When it is the power rating of 1/2w watt is way low. The calculated power is very close to 1.6 watts.
 
The circuit shows a 6V power supply and a 6V battery. When both are exactly 6V then no current flows in the resistors and no current lights the LED.
 

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E2K said:
This is a circuit of a 6V 4.5Ah lead acid battery charger with LED indicator.
When battery connected LED indicate that & when there is no battery LED will go off.
I want to use this indicator for 12V 12Ah lead acid battery. What are the Resistors values should i use?

R1 is so much less resistance than R2, so current will always flow through R1. The LED will never light up.
 
If the 6V battery is nearly dead at 6.0V and it is 6.9V when fully charged then there is not enough voltage to light the LED unless the input voltage is much too high and will cause over-charging.

If the LED is a 2.0V red one, the battery is nearly dead at 6.0V and the input voltage is 9V then the charging current is 0.94A and the LED current is 26mA.
 
I've copied this circuit from a search Light. Did some one have another circuit for 12V 12Ah battery? tell me please.
 
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