Diy mppt? - Page 8

fabieville · 12-29-10, 03:19 PM

i just look at the charge controller and i am seeing just one light now. I was seeing the 2 lights on when i push the setpoint for the mini max up to about 16V.
Also i am hearing a very very very tiny sound coming from my charge controller due to the fact that the setpoint of the mini is so high at 15V. It sounds like the relay that is used to switch the current to dump load is moving rapidly between charge/full charge but the 2 lites are not on is just the charge lite alone is showing.
If i adjust the setpoint down to the battery voltage then the sound stops or if i manually send the current to the dump load by pressing a switch the very tiny sound stops which would indicate that its the relay creating that tiny sound.
Any suggestions/recommendations.

Xringer · 12-29-10, 03:37 PM

You should post some more info about your system. Like what kind of equipment
you are using, and what you are using for a dump load?
Perhaps some pictures too??

My charge controller makes a high-frequency sound, that I can hardly hear..
If your have a relay that's being pulsed hard at an audio frequency,
it's going to be chattering very loudly. Unless it's very tiny..
Fast cycling is bad for relays. It will wear them out quickly..

Like I said.. It's hard to reply when I don't even know what kind of batteries & you are using.. Are they 18v Ni-cads??

http://ecorenovator.org/forum/solar-...html#post10012

I'm just starting to learn about charging batteries. So, maybe someone else can
tell you about the finer points in that area..

fabieville · 12-29-10, 05:04 PM

i am using lead acid battery and i dont have any thing on the dump load section cause its not really necessary right now, where i live the wind hardly blow and thus my wind turbine hardly operate and the solar energy does not have to be dump, whenever the battery reaches full charge the controller just open the pv voltage on the dump load section. thats all.
I have a 60 amp/hr battery, 130watt solar power and a windblue 540 low wind turbine.

fabieville · 12-30-10, 07:30 AM

If I put the target voltage to be 14.5V. Will the battery ever get to go over that when its charging so that my charge controller can sense when it reaches 14.8V and then stop the charging process?

Xringer · 12-30-10, 07:49 AM

Quote:

Originally Posted by fabieville

If I put the target voltage to be 14.5V. Will the battery ever get to go over that when its charging so that my charge controller can sense when it reaches 14.8V and then stop the charging process?

"The board is going to act like a 14.5v (and above) voltage regulator.
It will not put out less than 14.5v. It's output will always be 14.5 or greater."

If the PV gets sun, the battery is going to see 14.5 and above..
Like 14.6, 14.7 & 14.8v. Where I guess the charge controller will cut off
the connection to the battery..?.

Let me ask you, how is it working?

fabieville · 12-30-10, 08:53 AM

my charge controller is sensing my mini max voltage and is cycling between charging and full charge very rapidly. My relay is clicking like a 100times per sec. When the sun comes up good its more of a in between click that you can count but now when the time is overcast you see both lites on at the same time(the charge lite and the full charge lite) which shows that its cycling very fast. What can I do to balance or stabilize the switching? What if I put back my big cap at the output of the mini?

Xringer · 12-30-10, 10:25 AM

The big cap will probably just charge up and stay charged.

Your problem is, you have one set of devices that makes high voltage/power.
And it's feeding a device that wants to limit high voltage/power.

I don't see an easy solution. You might have to reconfigure your system,
if you want to use the mini.

Perhaps replacing the Relay with a MOSFET would quite things down..
Or maybe a diversion load would help?

fabieville · 12-30-10, 03:38 PM

f i connect my solar pv straight to my charge controller plus use 2 other wires from my pv and connect it to the mini also with the mini output going to the controller too what would happen?

The thing is that my charge controller does not really monitor the voltage coming from the solar. The charge controller just monitor the battery voltage and when it sees the battery voltage reach a certain limit then it sends the panel voltage to dump load by using a relay. If i connect the solar to the battery straight and the battery is charging then just connect the charge controller to the battery terminals it still will monitor the battery voltage. That is why when the mini is pumping that high voltage in the battery the controller keeps on flicking between charge and full charge as it is seeing the battery voltage rising so fast and when it see it goes to the controller cutoff point it sends the mini max voltage to dump load but when it realize that the battery voltage drops again it open back again to received the mini max high voltage output.

If i put the mini max target voltage below the cut in and cut off point for my charge controller then that does not happen.

What if i put the big cap at the output of the mini max then put a blocking diode between it and my battery. So that the battery only pull from the cap but doesn't charge it up will my charge controller perform better?

Also with all those in between clicking of my relay. How long do you think my relay will last and will my charging rate will be of a higher efficiency than just connecting the PV straight to my battery?

Xringer · 12-30-10, 09:38 PM

Sorry, I'm not able to follow your ideas, without seeing a diagram it's too hard.
Maybe you can tell me what model charge controller you have, so I can find the manual.?.

That relay is going to wear out pretty fast. A couple of us DIY guys have found out
that relays on a solar tracker wear out real fast.. Too much clicking..

IIRC, A diversion charger uses PV panels tied directly to the battery.
The diversion charger measures the voltage across the battery.
When the PV voltage is nearly over-charging the battery,
the charger connects the battery &PV to the diversion load. (Dump-Load).

The diversion load can be a heating element in a hot water tank.
It's a low resistance, and it absorbs all the excess wattage from the PV..

I've read it's used on windmills a lot, because they can suddenly produce a lot of power.
And on many windmills, that power needs to be used.. Using it will provide
braking to the turbine, keeping it from flying apart at high RPMs..

fabieville · 12-30-10, 09:43 PM

This is what someone tell me i can do to smooth out the current so that the clicking stop.
The missing ingredient in the mini max is an LC filter at the output to smooth the output current. That means an inductor is placed in series with the output of the minimax and your big cap is connected between the inductor output and ground.
So what do you think about that?

12-30-10, 08:53 AM	#76
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	my charge controller is sensing my mini max voltage and is cycling between charging and full charge very rapidly. My relay is clicking like a 100times per sec. When the sun comes up good its more of a in between click that you can count but now when the time is overcast you see both lites on at the same time(the charge lite and the full charge lite) which shows that its cycling very fast. What can I do to balance or stabilize the switching? What if I put back my big cap at the output of the mini? Last edited by fabieville; 12-30-10 at 02:00 PM..

12-29-10, 03:19 PM	#71
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	i just look at the charge controller and i am seeing just one light now. I was seeing the 2 lights on when i push the setpoint for the mini max up to about 16V. Also i am hearing a very very very tiny sound coming from my charge controller due to the fact that the setpoint of the mini is so high at 15V. It sounds like the relay that is used to switch the current to dump load is moving rapidly between charge/full charge but the 2 lites are not on is just the charge lite alone is showing. If i adjust the setpoint down to the battery voltage then the sound stops or if i manually send the current to the dump load by pressing a switch the very tiny sound stops which would indicate that its the relay creating that tiny sound. Any suggestions/recommendations.

12-29-10, 03:37 PM	#72
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	You should post some more info about your system. Like what kind of equipment you are using, and what you are using for a dump load? Perhaps some pictures too?? My charge controller makes a high-frequency sound, that I can hardly hear.. If your have a relay that's being pulsed hard at an audio frequency, it's going to be chattering very loudly. Unless it's very tiny.. Fast cycling is bad for relays. It will wear them out quickly.. Like I said.. It's hard to reply when I don't even know what kind of batteries & you are using.. Are they 18v Ni-cads?? http://ecorenovator.org/forum/solar-...html#post10012 I'm just starting to learn about charging batteries. So, maybe someone else can tell you about the finer points in that area..

12-29-10, 05:04 PM	#73
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	i am using lead acid battery and i dont have any thing on the dump load section cause its not really necessary right now, where i live the wind hardly blow and thus my wind turbine hardly operate and the solar energy does not have to be dump, whenever the battery reaches full charge the controller just open the pv voltage on the dump load section. thats all. I have a 60 amp/hr battery, 130watt solar power and a windblue 540 low wind turbine.

12-30-10, 07:30 AM	#74
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	If I put the target voltage to be 14.5V. Will the battery ever get to go over that when its charging so that my charge controller can sense when it reaches 14.8V and then stop the charging process?

12-30-10, 10:25 AM	#77
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	The big cap will probably just charge up and stay charged. Your problem is, you have one set of devices that makes high voltage/power. And it's feeding a device that wants to limit high voltage/power. I don't see an easy solution. You might have to reconfigure your system, if you want to use the mini. Perhaps replacing the Relay with a MOSFET would quite things down.. Or maybe a diversion load would help?

12-30-10, 03:38 PM	#78
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	f i connect my solar pv straight to my charge controller plus use 2 other wires from my pv and connect it to the mini also with the mini output going to the controller too what would happen? The thing is that my charge controller does not really monitor the voltage coming from the solar. The charge controller just monitor the battery voltage and when it sees the battery voltage reach a certain limit then it sends the panel voltage to dump load by using a relay. If i connect the solar to the battery straight and the battery is charging then just connect the charge controller to the battery terminals it still will monitor the battery voltage. That is why when the mini is pumping that high voltage in the battery the controller keeps on flicking between charge and full charge as it is seeing the battery voltage rising so fast and when it see it goes to the controller cutoff point it sends the mini max voltage to dump load but when it realize that the battery voltage drops again it open back again to received the mini max high voltage output. If i put the mini max target voltage below the cut in and cut off point for my charge controller then that does not happen. What if i put the big cap at the output of the mini max then put a blocking diode between it and my battery. So that the battery only pull from the cap but doesn't charge it up will my charge controller perform better? Also with all those in between clicking of my relay. How long do you think my relay will last and will my charging rate will be of a higher efficiency than just connecting the PV straight to my battery?

12-30-10, 09:38 PM	#79
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	Sorry, I'm not able to follow your ideas, without seeing a diagram it's too hard. Maybe you can tell me what model charge controller you have, so I can find the manual.?. That relay is going to wear out pretty fast. A couple of us DIY guys have found out that relays on a solar tracker wear out real fast.. Too much clicking.. IIRC, A diversion charger uses PV panels tied directly to the battery. The diversion charger measures the voltage across the battery. When the PV voltage is nearly over-charging the battery, the charger connects the battery &PV to the diversion load. (Dump-Load). The diversion load can be a heating element in a hot water tank. It's a low resistance, and it absorbs all the excess wattage from the PV.. I've read it's used on windmills a lot, because they can suddenly produce a lot of power. And on many windmills, that power needs to be used.. Using it will provide braking to the turbine, keeping it from flying apart at high RPMs..

12-30-10, 09:43 PM	#80
fabieville Helper EcoRenovator Join Date: Dec 2010 Location: Jamaica Posts: 59 Thanks: 0 Thanked 0 Times in 0 Posts	This is what someone tell me i can do to smooth out the current so that the clicking stop. The missing ingredient in the mini max is an LC filter at the output to smooth the output current. That means an inductor is placed in series with the output of the minimax and your big cap is connected between the inductor output and ground. So what do you think about that?