Solar Battery Charger, AC/DC Adapter Changeover Relay Circuit Diagram

The enclosed circuit of an solar battery controller, AC/DC adapter automatic changeover circuit was requested by Mr.Juan. Let's learn more about the request and the circuit from the below given discussions:

Hi Swagatam,

Your information and circuits are great.

But I want to ask for a special circuit.

I've a little solar panel with a solar/battery controller and a battery.

My load is connect to the load-pins of the controller, so when the battery voltage drops, the controller cuts off the output in load-pins immediately (from 11V-14V to 0V)

As hobby, I want to solar power from this system to a 12V led strip in my kitchen. But in case the light is on and the battery falls off, I want to autoswitch to a 220AC/12DC adapter that I have. So if my light is on, I will notice a little flick but nothing more, the light will be on all the time I want.

I don't want to "auto charge" battery with de AC/DC adapter in that case, because the main utility of my project is to use solar power.

I want to ask you several questions/circuits

1. I think I can't put together my controller ground and my AC/DC adapter ground, so I need a DPDT LATCH RELAY ("latch" in order not to waste lots of power from de battery system). And because of I can't put them together, I can't use the AC main switch of the kitchen to control all the system (I mean, the AC main switch of the kitchen will control the light, while the battery/controller powers the light either the AC/DC adapter)

2. What I want is that when my controller's load-pins output goes to 0V, the RELAY will turn to AC/DC power adapter. And when that output returns to 11-14V, the RELAY will turn to battery/controller system in order to waste "solar power" in my lights.


3. It doesn't mind if the relay is a single o dual coil, but the circuit has to be ultra low power consumption.

4. The ultra low power consumption is the reason for use a latch relay. It will only drain power when it has to activate o deactivate. I expect it not to activate never, so means that my solar system has a good battery capacity.

5. How can I control the light only with the AC main switch of the kitchen ?

Do I explain correctly ?

Before I knew about not to join grounds of the to systems (AC/DC adapter and controller output) I design this circuit with a simple SPDT normal relay. I have attached to you as a guide to understand this long post. but I suposse I can't do this way.

http://dl.dropbox.com/u/33152873/LowBatteryTrigger_presentar.pdf


Hi Juan,

I am little confused, I couldn't understand the procedure correctly. There are three parameters:

The solar panel,

The battery,

And the AC/DC adapter.

I couldn't understand how you want to integrate these together.

According to me it should be like this:

During day time the solar panel charges the battery and also stays connected to the LED strip, so that it can be lit through solar panel.

At night, the LED strip gets automatically connected to the battery and uses the battery power for illumination.

And during overcast conditions or in absence of sunlight, if the battery voltage drops below 11v, the battery gets connected to the adapter so that it is able to get charged from the AC/DC source....


Is it that way you want??

First of all, thanks for your help.


Excuse me for my English.

The led strip is NOT always ON. It's a secondary light in my kitchen.

The solar panel is connected to a solar/charger/battery controller (it has 2 inputs and 1 output: solar panel, battery, and load).

The battery is also connected to the controller.

The load attached to the controller is the led strip.

What I want to do is give 2 power supplies to my led strip. The main supply is the one that comes from the controller (it's using solar power or a battery charged with solar power). The secondary supply is the one that comes from the AC/DC source.

I don't want to charge my battery with the AC/DC source (I've found some circuits for that).

I want to use the solar-battery-controller group to supply my led strip, but, just in case the controller cuts off the output (to protect the battery because of 3 or 4 four cloudy days or whatever), the led strip will be supplied by the AC/DC adapter.

Then, the next sunny day, the battery will be charged again with solar power (solar-battery-controller group).

I've to check the output of the controller, and when that output is 0V, I have to change to the AC/DC adapter. The battery remains "untouched".


May be this picture helps.


http://dl.dropbox.com/u/33152873/simple_paint.jpg

There's also a handicap, the switch on the wall has to "control" the led strip (either supplied by controller, or by the ac/dc adaptor).(You will understand my previous post's pdf, the coil was energized by the AC/DC source, in order not to energized it if the wall switch is open)


NOTE: In future, I will also get a USB female in order to charge mobiles, and similar. (I've already get circuits to step down 12 V to 5 V). May be this USB female connector will have the same "AC/DC source as emergency" or not). but this doesn't matter now.

I got it now, the circuit will be very simple, I'll draw it and publish it in this blog as a new post, with the above discussions included....I'll inform you when it's posted....soon.

Thanks a lot,

Remember that is very important to drain a very "ultra low" power from the battery to make the circuit/relay/or whatever work. The solar system is little, so I can't have a constant drain of 30-50 mA, 24 hours per day. (that is because my first try was power the relay's coil directly with ac/dc source).

I will be using transistors instead of a relay, so the consumption will be negligible....


Done...here's the circuit requested by Mr.Juan, designed by me:






The following circuit goes in response to the added comment by Juan.




How the above circuits function:

In the upper circuit the transistor remains switched OFF by the +V from the solar panel during day, and switch ON during night via a the 1K resistor illuminating the LEDs. The diodes keep the voltages from the two sources isolated for correct functioning of the circuit

In the lower diagram, the left transistor conducts due to the presence of the solar voltage which grounds the base of the right transistor switching it off....during night the opposite takes place illuminating the LEds. The relay diode is a freewheeling diodes in order to protect the transistor from relay coil back emf.

the resistors are all 1/4 watt rated

If you liked the post, Please Share it

Related Posts

Previous
Next Post »

42 comments

comments
Anonymous
March 17, 2013 at 3:34 PM delete

Hi Swagatam, i need your help in doing my solar project, im stuck at doing mppt, please help me,guru_ram86@yahoo.com

Reply
avatar
June 5, 2013 at 2:35 AM delete

hi swagatam

if i would like to replace the bc557 for bc547 in the first circuit can it be used as a changeover circuit...?

Reply
avatar
June 5, 2013 at 10:48 AM delete

Hi JP,

no it won't work that way.

Reply
avatar
June 6, 2013 at 3:58 AM delete

i tried the second circuit practically for charging my LA battery(6v4.5ah) from panel it charge perfectly upto 6.46V(9hr charging) with using 6v relay. the panel needs to be above 6 to cut off the dc supply from wall.. but the one thing it makes lot of noise(relay keeps clicking) when the panel volatge is around 5v.. what i want to make a relay free circuit.. please suggest me idea or circuit..
only want to modify the second circuit...

thankyou

Reply
avatar
June 6, 2013 at 10:56 AM delete

you may try the first circuit given in the above article.

Reply
avatar
October 4, 2014 at 12:15 AM delete

what if we have a PV and acdc adapter only(two power sources)

Reply
avatar
October 4, 2014 at 9:40 AM delete

what is your exact requirement? please specify...

Reply
avatar
October 4, 2014 at 10:24 PM delete

thanks for reply.
I have an LED tube 12v dc. I want to operate this light on a 12v solar panel during a sunny day. So, when there is not enough power to light led tube from the solar panel due to sunset or cloudy days, the acdc adaper will come into operation.
the reason to use this schematic to operate the led is to avoid using battery.

Reply
avatar
October 5, 2014 at 2:43 PM delete

you can use any of the above designs for the mentioned application, both are fine and will execute the changeover actions from solar panel to adapter and vice versa..

Reply
avatar
October 6, 2014 at 9:51 PM delete

thanks for support.
I need a short description on the selected components. such as , the diode, the fet components operating method in ur circuit.

Reply
avatar
October 7, 2014 at 9:28 AM delete

in the upper circuit the transistor remains switched OFF by the +V from the solar panel during day, and switch ON during night via a the 1K resistor illuminating the LEDs. The diodes keep the voltages from the two sources isolated for correct functioning of the circuit

In the lower diagram, the left transistor conducts due to the presence of the solar voltage which grounds the base of the right transistor switching it off....during night the opposite takes place illuminating the LEds. The relay diode is a freewheeling diodes in order to protect the transistor from relay coil back emf.

the resistors are 1/4 watt rated

Reply
avatar
October 7, 2014 at 9:41 AM delete

thanks.
The description you mention related to the circuit with a 12 v relay?

Reply
avatar
October 7, 2014 at 9:44 AM delete

The led draws 4.5 to 9 Ah. do I have to change the diode specs only to handle this load?

Reply
avatar
October 7, 2014 at 5:44 PM delete

i have written for the upper and the lower diagrams both, in the lower diagram the LEDs are illuminated through the relay contacts....

Reply
avatar
October 7, 2014 at 5:45 PM delete

i have written for the upper and the lower diagrams both, in the lower diagram the LEDs are illuminated through the relay contacts....

Reply
avatar
October 7, 2014 at 5:49 PM delete

please specify the exact wattage of the LEds, is it 15 watt rated??

Reply
avatar
October 31, 2014 at 9:01 PM delete

18 watt and 50 watt led tubes of 12 volt system.

Reply
avatar
November 1, 2014 at 9:29 AM delete

if you are intending to use the first circuit, the diodes will need to be rated at 10amps each, and TIP127 replaced with a TIP34 or TIP36

Reply
avatar
February 4, 2015 at 11:50 PM delete

hi,
Thank you. finally I have recieved the stuff.
I've created the curcuit board, but used AC 12 volt instead of solar charger for testing purposes. suddenly the main breaker is down

Reply
avatar
February 4, 2015 at 11:52 PM delete

can I use AC 12 volt instead of solar charger?

Reply
avatar
February 5, 2015 at 9:27 AM delete

hi,
can I use AC 12 volt instead of (solar or battery)?

Reply
avatar
February 5, 2015 at 7:02 PM delete

Hi, the circuit is entirely a DC based circuit, AC will damage it instantly, you should have used a DC input for testing, because a solar panel is strictly a DC source.

Reply
avatar
February 5, 2015 at 9:40 PM delete

Hi,
Thanks for reply.
today I was testing an led strip rated at 24 watt.
the results as follows:
1. the tip127 got burned when the solar panel volt about 14.5v.
2. Before sunset arround 1.5 hours the ratio taken from the adapter to the solar is arround 44% the volt was 10.5v. Is it reasonable?
note: I was installing an AC meter on the adapter

Reply
avatar
February 5, 2015 at 9:44 PM delete

it seams to me that the curcuit compensate the required load's power from the adapter.Is it write?

Reply
avatar
February 6, 2015 at 10:12 AM delete

Hi,

1) the solar panel voltage is supposed to keep The TIP127 switched OFF, so how can it burn it?

2) That will be difficult to predict without a practical check.

Reply
avatar
February 6, 2015 at 2:35 PM delete

how can i send to you the curcuit I have made? Just to verify

Reply
avatar
February 7, 2015 at 9:30 AM delete

you can upload it to any free online free image hosting site and provide me the link here.

Reply
avatar
February 12, 2015 at 10:08 PM delete

hi,
Thank you my friend for supporting me during my inhouse project.

I have another enquiry:
What I need to raise a solar panel from 4 volt to 15 volt with an expected solar panel generated amps arround 8 amps:
in another way : I need to operate arround 12 led 12v 5wat bulbs with a minimum solar cells.

Reply
avatar
February 13, 2015 at 8:10 PM delete

You can try any 555 based boost circuit for it, but remember the output from the booster can never exceed the voltage x current value of the fed input.

Reply
avatar
February 14, 2015 at 10:36 PM delete

Is it the same case with Juli Theif Coil method? I mean the same input VA equal out VA.

Reply
avatar
February 15, 2015 at 10:46 AM delete

it's as per the law of conservation of energy which states that in any energy system the output power can never exceed the input power

Reply
avatar
October 29, 2015 at 2:40 PM delete

Hi Mr. Swagatam, I would like to know how the circuit looks like for the problem that you have explained previously. But the application is little bit different.

There are three parameters:

The solar panel,
The battery,
And the AC/DC adapter.

During day time the solar panel charges the battery and also stays connected to a 1hp air conditioner, pendaflour tube and a computer so that it can be lit through solar panel.

At night, all 3 appliances gets automatically connected to the battery.

And during overcast conditions or in absence of sunlight, if the battery voltage drops, the battery gets connected to the adapter so that it is able to get charged from the AC/DC source....

Thank you in advance Sir.

Reply
avatar
October 30, 2015 at 7:57 AM delete

Hi Rina,

although I have a few relay changeover circuits in this site, your requirement is sightly different, therefore I'll have post it in a new article, I'll try to do it soon.

Reply
avatar
October 30, 2015 at 8:15 AM delete

Thank you very much Sir, I am looking forward to the solution. :)

Reply
avatar
October 30, 2015 at 4:39 PM delete

I have published it here:

http://www.homemade-circuits.com/2015/10/solar-panelbatterymains-changeover.html

Reply
avatar
January 11, 2016 at 8:02 PM delete

sir can you please give me the circuit for a solar hybrid inverter such that it uses solar for charging when available and otherwise uses 230v AC mains for charging...please

Reply
avatar
January 12, 2016 at 9:15 AM delete

Mohammed, please provide more details regarding the exact operating specifications, I'll try to help.

Reply
avatar
February 25, 2016 at 5:51 PM delete

Hi. Sir we have almost the same concept as this one but instead of using s solar panel, we are using a micro hydro turbine. When water is in use, this turbine generates power and then stores to the battery. Andwhen the battery reached to a certain voltage (6-8v) this will then switches its power from the ac/dc adapter to battery to boost our system.

I tried using this circuit, but when the battery reaches to 0 and/or not connected, the relay wont switch to the 12v supply from the adapter.

Hoping for your reply.

-Miguel

Reply
avatar
February 26, 2016 at 11:11 AM delete

Hi Miguel,

you mean to say you connected the charging battery at the solar input position of the last circuit?

but how can the battery voltage become zero?

however when not connected then definitely the relay has to switch ON....check your BC547 connections or whether it's faulty or not.

or you can also try connecting a 1K resistor across the base and emitter of the left hand side BC547 and see the response

when nothing is connected check the voltage across base and emitter of the left BC547...it must show 0V and the for the right side BC547 it should be 0.7V...and this situation will undoubtedly switch ON the relay.

or may be you have connected the relay contacts wrongly...check it.

Reply
avatar

Readers are requested not to include external links while commenting. For consulting a diagram, upload it on Google Drive and provide the link here.