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Battery monitor indicator ??

Angy15

Nov 18, 2015
27
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Nov 18, 2015
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I have working circuit of battery monitoring (ref attach) using LM339.I want to redesign for my application .
The outputs conditions required are:

i.At 27.5 V LED 1,2,3 glows
ii.At 25.5 V LED 2,3 glows
iii. At 23.5 V LED 3 glows
iv. At 22.5V LED 6 glows

What resistors values for input of comparator should i set to get thiese desired outputs
 

Attachments

  • BATTERY MONITOR_WITH_INVERTER.JPG
    BATTERY MONITOR_WITH_INVERTER.JPG
    51.7 KB · Views: 80

AnalogKid

Jun 10, 2015
2,884
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1. What are the trip points now?
2. What is the part number or the opamp/comparator?
3. Any particular reason you didn't use a quad comparator like the LM339?
4. T1 can be eliminated and LED6 driven the same way as the other three LEDs by reversing the inputs to OP4.
5. None of the comparators have hysteresis. Any problems with indicator flicker?

6. How did you calculate the resistor values for the current design?

ak
 

eetech00

Nov 17, 2014
95
Joined
Nov 17, 2014
Messages
95
I have working circuit of battery monitoring (ref attach) using LM339.I want to redesign for my application .
The outputs conditions required are:

i.At 27.5 V LED 1,2,3 glows
ii.At 25.5 V LED 2,3 glows
iii. At 23.5 V LED 3 glows
iv. At 22.5V LED 6 glows

What resistors values for input of comparator should i set to get thiese desired outputs

Hi

Just use an LM3914 and divide the input voltage down to provide the appropriate scaling.
 

AnalogKid

Jun 10, 2015
2,884
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Jun 10, 2015
Messages
2,884
A 3914 can't display the status pattern he wants.

ak
 

eetech00

Nov 17, 2014
95
Joined
Nov 17, 2014
Messages
95
I have working circuit of battery monitoring (ref attach) using LM339.I want to redesign for my application .
The outputs conditions required are:

i.At 27.5 V LED 1,2,3 glows
ii.At 25.5 V LED 2,3 glows
iii. At 23.5 V LED 3 glows
iv. At 22.5V LED 6 glows

What resistors values for input of comparator should i set to get thiese desired outputs

Hi

The easiest way to do this would be using an LM3914.
But the LEDs would need to light in linear increments.
Your power supply is 26v. LEDs would light like this:

25.5
24.5
23.5
22.5
21.5
20.5
.......
.....
...
Is that OK?
 

Angy15

Nov 18, 2015
27
Joined
Nov 18, 2015
Messages
27
1. What are the trip points now?
2. What is the part number or the opamp/comparator?
3. Any particular reason you didn't use a quad comparator like the LM339?
4. T1 can be eliminated and LED6 driven the same way as the other three LEDs by reversing the inputs to OP4.
5. None of the comparators have hysteresis. Any problems with indicator flicker?

6. How did you calculate the resistor values for the current design?

ak
I am using LM339.
 

Angy15

Nov 18, 2015
27
Joined
Nov 18, 2015
Messages
27
Hi

The easiest way to do this would be using an LM3914.
But the LEDs would need to light in linear increments.
Your power supply is 26v. LEDs would light like this:

25.5
24.5
23.5
22.5
21.5
20.5
.......
.....
...
Is that OK?
Hi

Just use an LM3914 and divide the input voltage down to provide the appropriate scaling.
LM3914 can't be used in this design because voltage limit for LM3914 is 25V
 

Angy15

Nov 18, 2015
27
Joined
Nov 18, 2015
Messages
27
1. What are the trip points now?
2. What is the part number or the opamp/comparator?
3. Any particular reason you didn't use a quad comparator like the LM339?
4. T1 can be eliminated and LED6 driven the same way as the other three LEDs by reversing the inputs to OP4.
5. None of the comparators have hysteresis. Any problems with indicator flicker?

6. How did you calculate the resistor values for the current design?

ak
resistor values were for
I am using LM339.
1. What are the trip points now?
2. What is the part number or the opamp/comparator?
3. Any particular reason you didn't use a quad comparator like the LM339?
4. T1 can be eliminated and LED6 driven the same way as the other three LEDs by reversing the inputs to OP4.
5. None of the comparators have hysteresis. Any problems with indicator flicker?

6. How did you calculate the resistor values for the current design?

ak

I am using LM339.
I will write the trip voltages on the circuit and upload
 

Attachments

  • BATTERY MONITOR_WITH_INVERTER.JPG
    BATTERY MONITOR_WITH_INVERTER.JPG
    53.4 KB · Views: 77

Angy15

Nov 18, 2015
27
Joined
Nov 18, 2015
Messages
27
I will change value of R2 from 10k to 11k and check if i get the results
 

AnalogKid

Jun 10, 2015
2,884
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Messages
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LM3914 can't be used in this design because voltage limit for LM3914 is 25V

The voltage can be scaled to something withing the 3914 operating range. The problem is condition iv in post #1. Without several external components, the standard 3914 circuit will not toggle between acting as a bar graph for one range of input values, and acting as a single comparator for another range of values, and (important) making the two ranges mutually exclusive. The action of OP4 (and its output transistor) is inverted from the action of the other three comparators. This is why a 3914 cannot meet all 4 operating conditions.

ak
 

eetech00

Nov 17, 2014
95
Joined
Nov 17, 2014
Messages
95
The voltage can be scaled to something withing the 3914 operating range. The problem is condition iv in post #1. Without several external components, the standard 3914 circuit will not toggle between acting as a bar graph for one range of input values, and acting as a single comparator for another range of values, and (important) making the two ranges mutually exclusive. The action of OP4 (and its output transistor) is inverted from the action of the other three comparators. This is why a 3914 cannot meet all 4 operating conditions.

ak

Can you not invert the output of the LM3914 to the 22.5v LED in the same way as shown in post #1 There would still be less components than post #1.
 

AnalogKid

Jun 10, 2015
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Messages
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Maybe. It would take some tricky input scaling and using every other output to hit the step values, plus keeping the external transistor that bugs me. The apparent complexity of the post #1 schematic is deceptive because he is using a quad comparator, not four individual opamps as implied by the reference designators. I think eliminating R11 and T1, and adjusting R3-R6 as needed for the new trip points probably is easiest since he already is familiar with this circuit.

ak
 

GPG

Sep 18, 2015
452
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Sep 18, 2015
Messages
452
The action of OP4 (and its output transistor) is inverted
As drawn the transistor will not turn on. A pullup is required. If the inputs of 4 are swapped the transistor and pullup are unnecessary.
 

Angy15

Nov 18, 2015
27
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Nov 18, 2015
Messages
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As drawn the transistor will not turn on. A pullup is required. If the inputs of 4 are swapped the transistor and pullup are unnecessary.
Yes you are right. I have already added a pullup resistor to feed current into the base of transistor.
 

Angy15

Nov 18, 2015
27
Joined
Nov 18, 2015
Messages
27
after changing R2 to 11k. and adjusting the pot my readings are
i.At 27.5 V LED 1,2,3 glows
ii.At 25.3 V LED 2,3 glows
iii. At 23.1 V LED 3 glows
iv. At 21.1V LED 6 glows
 

GPG

Sep 18, 2015
452
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Sep 18, 2015
Messages
452
Yes you are right. I have already added a pullup resistor to feed current into the base of transistor.
Then get rid of the transistor etc by reversing the inputs of the relevant comparator and wiring the Led as the others
 
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