Battery over discharge & other indicator circuit

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rajaram04

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Hello Sir

I have 3 batteries each of 4 volts 1 amp 1.0 Ah & combining all them in series to make an output of 12 volts

Other info labelled on battery :-

Standby use : 4.70 v - 4.90 v
Cycle use : 5.00 v - 5.20 v
Maximum charching current 0.21 A
Sealed lead acid


Now i want to make circuits for the indications of

1.over discharge (due to overload etc)
2.Normal discharge (due to usage)
3.charge complete (While charging)

please help in designing a single or multi circuits for the combination

Too please tell that is if its a good idea to combine all 3 batteries in that way ??

I searched indicators in google but very proper circuits are available for
6 Volt 4.5 Ah Sealed Lead Acid Rechargeable Battery

so . . . .
 

You are living in ancient history.

I have never used an old lead-acid battery except to start my car.
Years ago I used Ni-Cad (Nickel-Cadmium) battery cells in a portable sound system I made. Later I used and still use Ni-MH (Nickel-Metal-Hydride) cells.
Today I use Li-Po (Lithium-Polymer) battery cells which are small, lightweight and very powerful.
 




ya i know and i am proceeding just like you said but . .

This time i've tried to configure some old systems like emergency lights fans etc

and the options i found in them are either 6v or 4v or 3.6v

Ok leave lead acid part , assume its a diffrent battery with parameters i explained

then how to design indicators ?
 

I believe someone at this forum posted this 12V battery monitor.

Three led's indicate battery voltage.
Red = low (below 11.5 V)
Green = normal (11.5 to 14)
Yellow = high (above 14)

 
BradtheRad said:
I believe someone at this forum posted this 12V battery monitor.

Three led's indicate battery voltage.
Red = low (below 11.5 V)
Green = normal (11.5 to 14)
Yellow = high (above 14)

Click to expand...




hmm that preety cool

so should i use normal BJT ?

a diode is in the middle of the circuit , so 1N4148 is ok for it ?
 

rajaram04 said:
so should i use normal BJT ?
Click to expand...
Yes. All they do is turn on LEDs.

a diode is in the middle of the circuit , so 1N4148 is ok for it ?
Click to expand...
Look at its symbol, it is NOT an ordinary diode, it is an 11V ZENER diode (it even says "znr").
 
Re: Battery over discharge & other indicator circuit

Audioguru said:
Yes. All they do is turn on LEDs.


Look at its symbol, it is NOT an ordinary diode, it is an 11V ZENER diode (it even says "znr").
Click to expand...




ya godfreyl is right i am talking about that one connected to one end of green LED

i know about zener,tunnel etc sign

well thanks

- - - Updated - - -

godfreyl said:
I guess he meant the other one. 1N4148 is OK for that.
Click to expand...



kk sir thanks a lot , let me proceed first . .

- - - Updated - - -

godfreyl said:
I guess he meant the other one. 1N4148 is OK for that.
Click to expand...



sir one more thing here , i am applying 15v zener in place of 13 v . . is that ok ?
 

The circuit is just a simple voltmeter that is not a battery charger.
With a 13V zener diode then the yellow LED lights at about 14V to warn that the charging voltage is too high.
If you change it to a 15V zener diode then the battery might be destroyed by over-charging and the yellow LED will never light.
 



i see , ok then . . hv to proceed that way only
 

BradtheRad said:
I believe someone at this forum posted this 12V battery monitor.

Three led's indicate battery voltage.
Red = low (below 11.5 V)
Green = normal (11.5 to 14)
Yellow = high (above 14)

Click to expand...



sir you told for

Green = normal (11.5 to 14) as we are applying 15v for charging purpose

but is it possbile to apply 12 volts for charging ?

if no then why ??? & if yes then what would be the modified circuit configurations ?
 

A lead-acid battery at only 12.6V is almost dead. They are charged at 13.8V to 14.1V. A charger DOES NOT charge a lead-acid battery to 15V!
The simple voltage meter (it is not a charger) is powered from 15V because the base-emitter diode in the PNP transistor needs 0.7V and has other voltage losses.

Go to www.batteryuniversity.com and read all about it.
 
rajaram04 said:
sir you told for

Green = normal (11.5 to 14) as we are applying 15v for charging purpose

but is it possbile to apply 12 volts for charging ?

if no then why ??? & if yes then what would be the modified circuit configurations ?
Click to expand...

12V will only charge a 12V battery to 12V. It will not be fully charged.

You need to apply more than 13V in order to fully charge the battery.
 
BradtheRad said:
12V will only charge a 12V battery to 12V. It will not be fully charged.

You need to apply more than 13V in order to fully charge the battery.
Click to expand...




ok got it , so in that case i am applying 15 volts . . is it all correct ?
 

If you apply 15V to a lead-acid battery then it will severely over-charge, get corroded, get sulphated and probably boil away its fluid. Your little battery will be destroyed.
You need a proper charger circuit for it.
 
Re: Battery over discharge & other indicator circuit

Audioguru said:
If you apply 15V to a lead-acid battery then it will severely over-charge, get corroded, get sulphated and probably boil away its fluid. Your little battery will be destroyed.
You need a proper charger circuit for it.
Click to expand...



ya thats what i need actually . . well pease suggest a circuit as per my requirment . . thanks

well i got one . . please verify



with link : http://staff.um.edu.mt/rlib1/charger.htm

may be the transistor would be an issue after the diagram is confirmed . .


one more here

http://www.electronicecircuits.com/electronic-circuits/12-volts-lead-acid-battery-charger



please verify



one more automatic type

**broken link removed**





one more again

http://www.circuitstoday.com/lead-acid-battery-charger



- - - Updated - - -

BradtheRad said:
12V will only charge a 12V battery to 12V. It will not be fully charged.

You need to apply more than 13V in order to fully charge the battery.
Click to expand...



hmm ya okk , well verify some of charger diagrams i posted above

& too check this level indicator link below

http://www.circuitstoday.com/12v-battery-level-indicator-circuit-led-bargraph

please tell your opinion
 
Last edited:
Most of the battery charger circuits you found are simple voltage regulators that do not limit the charging current (the 4th one does but its high current does not match your little battery).
None of them detect then change the topping charge voltage to a float charge voltage or turn off when the battery is fully charged.

The LM3914 battery voltage monitor is a good circuit. But why do you need it? My car does not have a battery voltage monitor.
 




O i see ,

no no not for car , actually i am trying to apply the same for my battery pack

& its better if you can allot a proper one sir . .

& what is topping charge voltage ?
 

You are using a very old fashioned lead-acid battery that is used only in cars here. Do you use lead-acid batteries in power tools, laptop computers and cell phones?
Look at my post #12. It has a link to The Battery University where they tell you the details about charging batteries.
 
Re: Battery over discharge & other indicator circuit




hm ya ya refering that one , & no i am not using it in power tools , just have to operate LED lights manually & automatic small inverting circuits to drive LED chains , some ready made some home made . . .

- - - Updated - - -




sir you said "the 4th one does but its high current does not match your little battery"

In explanation below the diagram , an adjustment option to get required charging current by means of R5 (1k) is there . .
& too my battery current rating is 1 Amp. & 1.0 Ah

please comment . .
 

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