Solar Panel + LCR6V4P Sealed Lead Acid battery Charging....

[ikelectro]

To alec_t and MikeMl


by studying your's post nos. #15 to #19, I think that I don't have to concern about the current as far as i'm using the solar panel {(which i mentioned earlier), am i right?}.

 

[ikelectro]

Here's a simple possibility (not optimised for maximum energy extraction from the panel):-
View attachment 74024

and thanks for the circuit........

 

[MikeMl]

...I don't have to concern about the current as far as i'm using the solar panel...

Measuring the current flow into the battery is the easiest way of automatically terminating the charging process when the battery is fully charged, thereby preventing the battery from damage due to long-term overcharging. You do not need to worry about protecting the battery from excessive charge rate early in the charge cycle.

 

[ericgibbs]

Posts #1 and #9

hi alec,

You may find this zipped LTS PV + SLA project interesting.

You can use a PWL to vary the [VLUX] 'sunshine' on the PV panel

Sim created using LTS_Yahoo group models.

Edited the 12v SLA to 6v SLA

Eric

PS: the major divisions along the Xaxis are hours.

 

[alec_t]

Thanks Eric. Duly downloaded.

 

[ikelectro]

Thanks Eric. Duly downloaded.

but I can't download the zip file!!!!!!! (may be this is not for me!!!!!!).

 

[ikelectro]

Hi MikeMl

You do not need to worry about protecting the battery from excessive charge rate early in the charge cycle.

1. I have to make a 7.2V power supply (with solar panel).

2. A current sensor for measuring the current which goes through from 7.2V V. Reg to battery.

3. At the time of sensing less than or equal to 20mA current the circuit should be able to swift 7.2V regulator to 6.8V

4. and finally cut off the battery after full charging....


Please make correction if I'm wrong...... thanks.

 

[MikeMl]

Hi MikeMl


1. I have to make a 7.2V power supply (with solar panel).

Yes

2. A current sensor for measuring the current which goes through from 7.2V V. Reg to battery.

Yes

3. At the time of sensing less than or equal to 20mA current the circuit should be able to swift 7.2V regulator to 6.8V

swift=switch

4. and finally cut off the battery after full charging....

No, it is ok to keep the 6.8V applied to the battery forever (or at least while the sun shines.

This process to start again whenever the battery load is turned on. The cycle will complete after the load is turned off if the sun is still shining. Next day, charging cycle can begin again battery is accepting charging current. It will terminate automatically when the charging current drops to less than 20mA again...

 

[ericgibbs]

but I can't download the zip file!!!!!!! (may be this is not for me!!!!!!).

hi ike,
I have just done a test download of the zip, it all ok here.?

E

 

[ikelectro]

hi ike,
I have just done a test download of the zip, it all ok here.?

E

hi eric, it is ok now... don't know what was happened then...

 

[ronv]

What is your battery going to be used for? Backup? Will it be used every day or maybe once a week?

 

[ikelectro]

it'll be used for emergency light..... all most every day...........

 

[ikelectro]

Lm317 or MC34063 will be best for the V regulator or charging...??????

can any one help me in the circuit for the sensing of 20mA current......????

 

[MikeMl]

...can any one help me in the circuit for the sensing of 20mA current......????

Was in the earlier referenced forum thread.

 

[ikelectro]

Was in the earlier referenced forum thread.

ok, i'm searching it for now....

 

[ronv]

solar charger

I bet the shunt regulator that Eric suggested would work for you.

 

[alec_t]

it'll be used for emergency light..... all most every day.........

In that case will a fixed shunt regulator at 6.8V allow rapid-enough charging to maintain the battery at full charge? I think something more elaborate is called for. Perhaps a 7V reg which shuts off, or reduces the regulated volts, once the charge current has dropped down to 20-30mA, then turns on/reverts to 7V again when the battery voltage has dropped down to 5.5V or so?

 

[ronv]

In that case will a fixed shunt regulator at 6.8V allow rapid-enough charging to maintain the battery at full charge? I think something more elaborate is called for. Perhaps a 7V reg which shuts off, or reduces the regulated volts, once the charge current has dropped down to 20-30mA, then turns on/reverts to 7V again when the battery voltage has dropped down to 5.5V or so?

It's really hard to say, but here is my thinking... The panel can only put out 3 watts at high noon on a sunny day so it won't be able to charge a dead battery in one day no matter what we do. By the time you add something like a 317 and a diode to keep the battery from flowing backwards into the panel almost 30% of the power would be lost to heat not to mention the dropout voltage that would have the effect of shortening the charge time. I guess we could build a MPP charge controller and do a little better or maybe a buck boost with some battery management, but is it worth the complexity and expense?
The simple circuit would get the battery back to about 80% about as fast as anything and for less money

 

[alec_t]

Ok, I'll go along with that thinking. With a 6.8V shunt should we be able to leave the charger on indefinitely without harm to the battery, just float charging? Or is it still worth trying to chop it off once 20-30mA is reached?

 

[ikelectro]

Hi alec_t,,,

I'll go along with that thinking. With a 6.8V shunt should we be able to leave the charger

MikeMl has said in the post no. 15 >>>> 6.8V will take more than 5 to 10 (and that is I think take more than 10 days to fully charged a dead battery) times longer than a 7.2V Reg take....



So will it be a good idea to charge the battery with 6.8V ???????