Homemade NiMH Charger working not correctly

[DanielEurope]

Last week I assembled NiMh charger by below mentioned diagram. Charger working good, except LED indicator - it should light during charging, but nothing happened. I measured voltage on this LED, it is only 0.7 V........So I replaced resistor with lower resistance, but no success Is there anyone who can help me to figure out, why Led isn't lighting during charging, please? Thanks, Daniel

www.circuitdiagram.org/automatic-nimh-battery-charger-circuit.html

 

[JimB]

At a first look at that circuit, be happy that it is charging the batteries.

As for the LED, the design of that circuit as a charge indicator is ay best marginal and very dependant on component and battery characteristics.
In my opinion, it is not worth worrying about.

JimB

 

[alec_t]

The LED indicator part of the circuit as shown won't work. If you want a LED indication of when the battery voltage reaches a target value then a voltage comparator should be used, with a switchable threshold voltage according to how many cells are in the battery. But as Jim says, it's probably not worth it.

 

[Legardo]

Diode 1

Last week I assembled NiMh charger by below mentioned diagram. Charger working good, except LED indicator - it should light during charging, but nothing happened. I measured voltage on this LED, it is only 0.7 V........So I replaced resistor with lower resistance, but no success Is there anyone who can help me to figure out, why Led isn't lighting during charging, please? Thanks, Daniel

www.circuitdiagram.org/automatic-nimh-battery-charger-circuit.html

N

 

[Legardo]

• Diode 1N4001 was connected backwards anode should be connected to ground of 5V Reg then cathode to + side battery so diode is in fwd bias .

 

[crutschow]

Diode 1N4001 was connected backwards anode should be connected to ground of 5V Reg then cathode to + side battery so diode is in fwd bias .

Diode is connected correctly.
Lm7805 is being use as a current regulator, not a voltage regulator.

 

[crutschow]

Charger working good, except LED indicator

What battery are you charging when this happens?

 

[JimB]

This is a two year old thread, revitalised by someone providing incorrect information.

Thread closed.

JimB