solar charging regulators - Page 2 - Electronic Circuits Projects Diagrams Free

Hero999 · 15th March 2009, 08:49 PM

The solar cells self limit the current, you could probably safely short circuit them and the current won't be high enough to do any damage.

As long as the batteries can handle the constant current then I don't see the problem. The solar panels I have connected up to my batteries give 23V each or 46V both in series when nothing is connected but the voltage drops when the batteries are connected.

If the batteries can't handle the current then you need something to limit the battery voltage. This is a problem I'm trying to solve myself, the LM317 will probably work and so will a comparator connected to a relay to disconnect the cells when the battery voltage exceeds a certain level.

Thunderchild · 15th March 2009, 09:03 PM

Quote:

Originally Posted by ericgibbs

hi,
Do you need any help with a charger design, I have used 12V SLA 7AH and 20AH battery chargers on a number of projects.?

so what is SLA ?

basically i want to make as much use of the power availablr as possible

Thunderchild · 15th March 2009, 10:42 PM

so basically the output needs to track the baterry voltage and be just a little over than in real life applications

Hero999 · 15th March 2009, 11:29 PM

Quote:

Originally Posted by Thunderchild

so basically the output needs to track the baterry voltage and be just a little over than in real life applications

That's exactly what happens if you connect the solar panel directly to the battery. The trouble is you need to ensure the battery voltage doesn't rise above a certain point to prevent venting.

SLA, just means Sealed Lead Acid battery and means you don't have to worry about filling it with water. Most SLAs have a recombination system to react any hydrogen produced with oxygen to form water thus prolonging the life of the battery and limiting the venting of explosive gasses. The trouble is more hydrogen tends to be produced at higher voltages to it's good to limit the voltage to 2.3V per cell when float charging.

wombweller · 15th March 2009, 11:32 PM

Hi all

I am following this thread with interest as I have thought about solar cells as an alternative power supply and charger.

I have a shed full of electric clocks that use very little power to make them run so I too would like to trickle charge an 12v SLA battery safely and productively.

Would the solar trickle charger stay connected all the time and if yes does this mean when I connect the load up to the battery it will take the power from both the battery and the solar panel in other words how do we separate the connection so it's only the battery that's being drained?

Is it possible to have say a bank of two batteries and use a battery swapper circuit that only trickle charges one battery at a time and when one battery is in use IE. connect to supply to my clocks it's not being charged until required? or am I over complicating things?

I found this on youtube any good?

YouTube - battery swopper (TheDaftMan)

I look forward to the outcome of this thread as like I say there must be good and bad methods to connect up the Solar charger to the batteries.

Cheers Mark

nickelflippr · 16th March 2009, 12:10 AM

An interesting thread the Otherpower.com Discussion Board || Small 25A MPPT Controller Progress May have to rethink whether the MPPT thing is really worth it for one panel.

wombweller said:

Quote:

Would the solar trickle charger stay connected all the time and if yes does this mean when I connect the load up to the battery it will take the power from both the battery and the solar panel in other words how do we separate the connection so it's only the battery that's being drained?

Yes the solar panel and battery both stay hooked up in a parallel configuration. Your little trickle charger is going to have little effect on a single battery, much less a bank of batteries. Most trickle chargers don't even bother with electronics, or controllers, because there output is so low.

HarveyH42 · 16th March 2009, 03:11 AM

Batteries are kind of expensive, and a charge controller is well worth the investment. You can't really know when the battery will get a full charge, sun doesn't always sine the same all day, every day, nor the drain on the battery be the same daily. The charge controller takes care of maintaining the proper charge, and cuts out before it over charges.

Thunderchild · 16th March 2009, 07:29 AM

so I'd have to check the battery voltage now and then and reset the SMPS to just above that.... trick seems to be making a SMPS that can be controlled so easily......

ericgibbs · 16th March 2009, 03:10 PM

hi TC,
This is a solar panel controller using a miniPIC, maybe worth a look thru.

Solar Panel controller using PICmicro and PIC BASIC

Thunderchild · 16th March 2009, 06:18 PM

hm I'm not sure what that circuit is doing ? looks like is just stopping charge when full, I don't see anything that looks like a SMPS voltage reduction.

nickelflippr · 16th March 2009, 07:35 PM

More reading Allegro hall effect current sensing article. Looks like the ACS712 would work for my 75W panel, and would be easier than the Maxim devices I've sampled (which still require a shunt).

Here is a Microchip appnote on a switchmode? regulator using a PIC 16HV785. The 16HV785 has two op amps, very interesting. Going to have to read read this one a few times to decipher.

Thunderchild · 18th March 2009, 11:00 PM

Would this be a good regulator, unfortunately none of the regulators have proper explanations of their technology

NEW SOLAR PANEL CHARGE REGULATOR BATTERY 12V 30A 360W on eBay, also, Solar Panels, Gadgets, Consumer Electronics (end time 31-Mar-09 16:23:42 BST)

nickelflippr · 19th March 2009, 07:29 PM

Quote:

Originally Posted by Thunderchild

Would this be a good regulator, unfortunately none of the regulators have proper explanations of their technology

NEW SOLAR PANEL CHARGE REGULATOR BATTERY 12V 30A 360W on eBay, also, Solar Panels, Gadgets, Consumer Electronics (end time 31-Mar-09 16:23:42 BST)

Might very well work with flooded lead acid batteries. Without any sort of data sheet it's hard to tell.

For perhaps a little more money? you get a data sheet, from Xantrax, Morningstar, or other well known PWM controller mfr. Included would be a 3 stage battery charger, plus equalization charge (if required). Also, you usually get a selection for battery chemistry, flooded, agm, gel or a variable setpoint voltage.

Here's a home brew peak power tracker? link with an atmel controller.

**bryan1** · 20th March 2009, 08:29 AM

G'day Thunder,
All I use in my shed for my main 700ah battery bank is a LM358 based shunt controller. The output is 2 169amp fets in parrallel and they dump 18 amps into a heat based dumpload. I went for the bigger fets as I kept blowing boards up when my wind gennie maxed out. It's a simple circuit that works on most voltages by simply changing a few resistors and if you want it just singout and i can email it to you.

As far as open circuit on PV panels dont worry about it as soon as you hook them upto a battery the voltage will drop to the battery voltage. Most commercial PV charge controllers simply short out the pv panels when the battery is charged which personally I consider a waste of energy.

Cheers Bryan

Thunderchild · 20th March 2009, 02:54 PM

HI Brian, well from what you say you are just switching the panels on and off when the battery charges, what I'm tring to do is adapted the panels power to the battery as best as possible so as to get the most out of them. will the panel automatically output more current when less voltage is required ? I don't think so in which case power is being lst, hence me wanting a SMPS/PWM controller

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15th March 2009, 08:49 PM	#16
Hero999	The solar cells self limit the current, you could probably safely short circuit them and the current won't be high enough to do any damage. As long as the batteries can handle the constant current then I don't see the problem. The solar panels I have connected up to my batteries give 23V each or 46V both in series when nothing is connected but the voltage drops when the batteries are connected. If the batteries can't handle the current then you need something to limit the battery voltage. This is a problem I'm trying to solve myself, the LM317 will probably work and so will a comparator connected to a relay to disconnect the cells when the battery voltage exceeds a certain level. __________________ I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong. Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

15th March 2009, 10:42 PM	#18
Thunderchild	so basically the output needs to track the baterry voltage and be just a little over than in real life applications __________________ I AM the exeption that disproves the rule in many ways but the rules still apply (unfortunately) www.simonsphotography.org.uk/ - My other hobby www.rushdenrotaract.org.uk/ - make a difference and have fun ! Never buy "Trust" products, all mine broke !!!

15th March 2009, 11:32 PM	#20
wombweller	Hi all I am following this thread with interest as I have thought about solar cells as an alternative power supply and charger. I have a shed full of electric clocks that use very little power to make them run so I too would like to trickle charge an 12v SLA battery safely and productively. Would the solar trickle charger stay connected all the time and if yes does this mean when I connect the load up to the battery it will take the power from both the battery and the solar panel in other words how do we separate the connection so it's only the battery that's being drained? Is it possible to have say a bank of two batteries and use a battery swapper circuit that only trickle charges one battery at a time and when one battery is in use IE. connect to supply to my clocks it's not being charged until required? or am I over complicating things? I found this on youtube any good? YouTube - battery swopper (TheDaftMan) I look forward to the outcome of this thread as like I say there must be good and bad methods to connect up the Solar charger to the batteries. Cheers Mark

16th March 2009, 03:11 AM	#22
HarveyH42	Batteries are kind of expensive, and a charge controller is well worth the investment. You can't really know when the battery will get a full charge, sun doesn't always sine the same all day, every day, nor the drain on the battery be the same daily. The charge controller takes care of maintaining the proper charge, and cuts out before it over charges.

16th March 2009, 07:29 AM	#23
Thunderchild	so I'd have to check the battery voltage now and then and reset the SMPS to just above that.... trick seems to be making a SMPS that can be controlled so easily...... __________________ I AM the exeption that disproves the rule in many ways but the rules still apply (unfortunately) www.simonsphotography.org.uk/ - My other hobby www.rushdenrotaract.org.uk/ - make a difference and have fun ! Never buy "Trust" products, all mine broke !!!

16th March 2009, 03:10 PM	#24
ericgibbs	hi TC, This is a solar panel controller using a miniPIC, maybe worth a look thru. Solar Panel controller using PICmicro and PIC BASIC __________________ Eric " Good enough is Perfect " I will NOT answer PM's requesting technical help, please use the Forum PIC tutorials: Nigel's www.winpicprog.co.uk/ Bill's: www.blueroomelectronics.com/

16th March 2009, 06:18 PM	#25
Thunderchild	hm I'm not sure what that circuit is doing ? looks like is just stopping charge when full, I don't see anything that looks like a SMPS voltage reduction. __________________ I AM the exeption that disproves the rule in many ways but the rules still apply (unfortunately) www.simonsphotography.org.uk/ - My other hobby www.rushdenrotaract.org.uk/ - make a difference and have fun ! Never buy "Trust" products, all mine broke !!!

16th March 2009, 07:35 PM	#26
nickelflippr	More reading Allegro hall effect current sensing article. Looks like the ACS712 would work for my 75W panel, and would be easier than the Maxim devices I've sampled (which still require a shunt). Here is a Microchip appnote on a switchmode? regulator using a PIC 16HV785. The 16HV785 has two op amps, very interesting. Going to have to read read this one a few times to decipher.

18th March 2009, 11:00 PM	#27
Thunderchild	Would this be a good regulator, unfortunately none of the regulators have proper explanations of their technology NEW SOLAR PANEL CHARGE REGULATOR BATTERY 12V 30A 360W on eBay, also, Solar Panels, Gadgets, Consumer Electronics (end time 31-Mar-09 16:23:42 BST) __________________ I AM the exeption that disproves the rule in many ways but the rules still apply (unfortunately) www.simonsphotography.org.uk/ - My other hobby www.rushdenrotaract.org.uk/ - make a difference and have fun ! Never buy "Trust" products, all mine broke !!!

20th March 2009, 08:29 AM	#29
bryan1	G'day Thunder, All I use in my shed for my main 700ah battery bank is a LM358 based shunt controller. The output is 2 169amp fets in parrallel and they dump 18 amps into a heat based dumpload. I went for the bigger fets as I kept blowing boards up when my wind gennie maxed out. It's a simple circuit that works on most voltages by simply changing a few resistors and if you want it just singout and i can email it to you. As far as open circuit on PV panels dont worry about it as soon as you hook them upto a battery the voltage will drop to the battery voltage. Most commercial PV charge controllers simply short out the pv panels when the battery is charged which personally I consider a waste of energy. Cheers Bryan __________________ " The only way to avoid human error is to avoid the use of humans"

20th March 2009, 02:54 PM	#30
Thunderchild	HI Brian, well from what you say you are just switching the panels on and off when the battery charges, what I'm tring to do is adapted the panels power to the battery as best as possible so as to get the most out of them. will the panel automatically output more current when less voltage is required ? I don't think so in which case power is being lst, hence me wanting a SMPS/PWM controller __________________ I AM the exeption that disproves the rule in many ways but the rules still apply (unfortunately) www.simonsphotography.org.uk/ - My other hobby www.rushdenrotaract.org.uk/ - make a difference and have fun ! Never buy "Trust" products, all mine broke !!!