Hybrid Power Generation System

Thread Starter

milenjacob

Joined Apr 15, 2020
8
Hi,

I had a school project to do and my team was thinking about designing a system where there are 3 sources of energy (Solar, Wind & Wave), we are quite unsure on how to integrate the 3 into a single battery. The solar and wind generators produce around 12V and the wave has something around 9 - 10v. It is a very small project:). Would love if someone could assist me with the integration part.

Thanking you for your valuable time.
 

Audioguru again

Joined Oct 21, 2019
1,508
You did not say what battery chemistry you are using or if you have a proper charger circuit for it. For a 12V battery the input to the charge probably must be about 15V or more that you do not have. Each source of energy must have a series diode that also needs some extra input voltage to the charger circuit.
 

Thread Starter

milenjacob

Joined Apr 15, 2020
8
You did not say what battery chemistry you are using or if you have a proper charger circuit for it. For a 12V battery the input to the charge probably must be about 15V or more that you do not have. Each source of energy must have a series diode that also needs some extra input voltage to the charger circuit.
No i do not have a proper charger circuit
 

Papabravo

Joined Feb 24, 2006
13,759
Sorry. But I have less to none knowledge about chargers, could you assist me more with that?
Not really. I don't use Li-Ion batteries and know next to nothing about chargers. I do know that I am not knowledgeable enough about those batteries or their charging requirements. If I was you I'd buy one recommended by the battery manufacturer. Once we have the battery and the charger we can figure out how to utilize the three power sources -- that I can help you with.
 

Audioguru again

Joined Oct 21, 2019
1,508
The student said he has a Lithium-ion battery and no knowledge about chargers.
Then the teacher should have taught the student about the dangers of a Lithium-ion battery and the proper way to charge it, or change the project.

Was the teacher sleeping on the job? Do you expect a student to learn about things the hard way (kaboom, oops my hand got blown off and my clothes are on fire) without a teacher?
 

PaulNewf

Joined Mar 24, 2020
10
When you hit a wall change the question...

a) Use a safer battery, maybe a Motorcycle battery (6V) or a telephone/alarm system backup battery (12V).
Avoid the lithium chemistry.
Maybe your teacher has or knows someone who might have access to such batteries, often one in someone's garage.
Depending on size of your power sources you might find a tiny rechargable battery is sufficient for the prototype, but sticking to standard motorcycle/phone/alarm/car batteries will make it easier to find charger circuits with DC inputs (AC powered circuits not useful for this project).

b) Find on the web a charger circuit for the battery (appropriate voltage for the battery, 6V or 12V)
You need a circuit that will stop charging when battery full, or the battery will overheat and die.
These "more common" batteries have simpler charge circuits.

*Actually if you have a solar panel they often come with a 12V battery charger module.

c) Choose the sources (solar, wind, wave) that provide sufficient voltage for charger circuit above (b)
*Careful to check the maximum current output of the sources, the combined output (add all together) should be well under the chargers current rating, or you could destroy the charger.

d) Build a circuit to combine the sources together
d1) common Gnd/Negative (Wire together the Source's Out- pins to Charger Input-)
d2) wire charger Out- to Battery-, wire Charger Out+ to Battery+
d3) start with one Source Out+ wired to Charger In+, Test it works safely (Source, Charger, Battery) else disconnect immediately.
d2) Using a multiway switch or alligator clip lead: connect only one Source Out+ at a time to the charger and check that each Source does indeed provide enough and appropriate power to charge.
d3) Inefficient but OK for first prototype: Big diode from each Source Out+ to the Charger Input+ (The diode will allow only the one with highest voltage to drive charger, but may allow current from multiple sources to simultaneously provide some power if voltages are similar under charging load). Diode rated for double voltage of highest voltage source (safety in case polarity connected wrong) and current greater that max of source. The big diodes will have a voltage drop (0.6V ~ 1.2V) and get hot and waste power, but should be OK for a test. Heatsinking may be needed if used for more than a few second.
d4) Future: Create an "ideal diode" circuit to 'OR' the Sources together. The Ideal diodes do similar to Diodes in (d3), but don't have a voltage drop so don'tr get hot and don't waste charging power. Ideal diodes can be assembled from FETs that have their gate biased 'on'. Search web for some examples. Use FET with sufficient voltage/current for the power source, and with a low RDSon for efficiency.

*) Fair bit of terminology in above, you will need to search for the various circuits mentioned, and hit things like wikipedia and this websites for the terminology and examples. The more you do the more people here will be willing to help. Sorry, but no free ride.

*) ref: I often end up going back to the pamphlet series "Engineer's Mini-Notebooks" which someone scanned and put online: http://thelukens.net/science/electronics/Engineer's Mini-Notebooks/

Paul
 

Toughtool

Joined Aug 11, 2008
63
I believe these assignments are more a proof of concept than engineering a complete system from scratch. Unless of course they are in an electrical engineering class at a university. One (of many) ideas would be to make a useful system that is not expensive and made of "off the shelf" components. Maybe create a power source to charge every ones cell phone. I agree, an Li-Ion battery would not be my choice. Battery chemistry described on the web site batteryuniversity.com will bear that out.
1. They are a very real fire hazard. Remember the pocket fire videos if electronic cigarettes, the cell phone fires, hoverboards, and Li-Ion battery computer fires.
2. Li-Ion chargers require sophisticated circuits and temperature monitoring.
3. They are expensive.
My choice would be the lead acid battery because charging can be controlled by varying the voltage. Since the stated power sources are wind and solar at 12 V and Wave is at 10 volts, He should consider a common working voltage of 5 to 6 volts. All these DC outputs can be connected quite easily by using inexpensive DC to DC buck converters, (5 to 30 volts input, adjustable output up to 3 amps max @ $2.00 each) each isolated by a barrier diode for steering currents, to a battery for energy storage. then using a DC to Dc buck converter adjusted to 5 volts for a charging cable to the phones. So the students need to read up on battery, battery chargers, DC to DC buck converters, and steering diodes (see example schematic) and why they are needed. This is just one idea.



"Engineer's Mini-Notebooks" which someone scanned and put online: http://thelukens.net/science/electronics/Engineer's Mini-Notebooks/
I love the Engineer's Mini-Notebooks. Joe
 
Last edited:

Thread Starter

milenjacob

Joined Apr 15, 2020
8
When you hit a wall change the question...

a) Use a safer battery, maybe a Motorcycle battery (6V) or a telephone/alarm system backup battery (12V).
Avoid the lithium chemistry.
Maybe your teacher has or knows someone who might have access to such batteries, often one in someone's garage.
Depending on size of your power sources you might find a tiny rechargable battery is sufficient for the prototype, but sticking to standard motorcycle/phone/alarm/car batteries will make it easier to find charger circuits with DC inputs (AC powered circuits not useful for this project).

b) Find on the web a charger circuit for the battery (appropriate voltage for the battery, 6V or 12V)
You need a circuit that will stop charging when battery full, or the battery will overheat and die.
These "more common" batteries have simpler charge circuits.

*Actually if you have a solar panel they often come with a 12V battery charger module.

c) Choose the sources (solar, wind, wave) that provide sufficient voltage for charger circuit above (b)
*Careful to check the maximum current output of the sources, the combined output (add all together) should be well under the chargers current rating, or you could destroy the charger.

d) Build a circuit to combine the sources together
d1) common Gnd/Negative (Wire together the Source's Out- pins to Charger Input-)
d2) wire charger Out- to Battery-, wire Charger Out+ to Battery+
d3) start with one Source Out+ wired to Charger In+, Test it works safely (Source, Charger, Battery) else disconnect immediately.
d2) Using a multiway switch or alligator clip lead: connect only one Source Out+ at a time to the charger and check that each Source does indeed provide enough and appropriate power to charge.
d3) Inefficient but OK for first prototype: Big diode from each Source Out+ to the Charger Input+ (The diode will allow only the one with highest voltage to drive charger, but may allow current from multiple sources to simultaneously provide some power if voltages are similar under charging load). Diode rated for double voltage of highest voltage source (safety in case polarity connected wrong) and current greater that max of source. The big diodes will have a voltage drop (0.6V ~ 1.2V) and get hot and waste power, but should be OK for a test. Heatsinking may be needed if used for more than a few second.
d4) Future: Create an "ideal diode" circuit to 'OR' the Sources together. The Ideal diodes do similar to Diodes in (d3), but don't have a voltage drop so don'tr get hot and don't waste charging power. Ideal diodes can be assembled from FETs that have their gate biased 'on'. Search web for some examples. Use FET with sufficient voltage/current for the power source, and with a low RDSon for efficiency.

*) Fair bit of terminology in above, you will need to search for the various circuits mentioned, and hit things like wikipedia and this websites for the terminology and examples. The more you do the more people here will be willing to help. Sorry, but no free ride.

*) ref: I often end up going back to the pamphlet series "Engineer's Mini-Notebooks" which someone scanned and put online: http://thelukens.net/science/electronics/Engineer's Mini-Notebooks/

Paul
Thank you sir for the response, I will discuss this with my faculty and hopefully get a result.
 

Thread Starter

milenjacob

Joined Apr 15, 2020
8
I believe these assignments are more a proof of concept than engineering a complete system from scratch. Unless of course they are in an electrical engineering class at a university. One (of many) ideas would be to make a useful system that is not expensive and made of "off the shelf" components. Maybe create a power source to charge every ones cell phone. I agree, an Li-Ion battery would not be my choice. Battery chemistry described on the web site batteryuniversity.com will bear that out.
1. They are a very real fire hazard. Remember the pocket fire videos if electronic cigarettes, the cell phone fires, hoverboards, and Li-Ion battery computer fires.
2. Li-Ion chargers require sophisticated circuits and temperature monitoring.
3. They are expensive.
My choice would be the lead acid battery because charging can be controlled by varying the voltage. Since the stated power sources are wind and solar at 12 V and Wave is at 10 volts, He should consider a common working voltage of 5 to 6 volts. All these DC outputs can be connected quite easily by using inexpensive DC to DC buck converters, (5 to 30 volts input, adjustable output up to 3 amps max @ $2.00 each) each isolated by a barrier diode for steering currents, to a battery for energy storage. then using a DC to Dc buck converter adjusted to 5 volts for a charging cable to the phones. So the students need to read up on battery, battery chargers, DC to DC buck converters, and steering diodes (see example schematic) and why they are needed. This is just one idea.




I love the Engineer's Mini-Notebooks. Joe
Thank you sir, I realize that lithium ion is quite dangerous to work with and I will reaserach more on battery, battery chargers, DC to DC buck converters, and steering diodes.
 

Thread Starter

milenjacob

Joined Apr 15, 2020
8
The student said he has a Lithium-ion battery and no knowledge about chargers.
Then the teacher should have taught the student about the dangers of a Lithium-ion battery and the proper way to charge it, or change the project.

Was the teacher sleeping on the job? Do you expect a student to learn about things the hard way (kaboom, oops my hand got blown off and my clothes are on fire) without a teacher?
Sorry sir, this was actually my idea not the teachers, she had given me a heads up saying that it will be difficult to do, but I took up this project regardless. I understand the difficulties of this project but I wanted to learn about power integration, hence this project
 
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