Solar chargers

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ShowMaster
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Solar chargers

Postby ShowMaster » Fri Dec 23, 2016 4:35 pm

I can use some advice. I'm building a solar powered RC charging station at a remote flying field, no shore power.
Ive run into an issue with the controller outputting DC that hovers at 15v dc and pulses at high as 19v DC?
I'm using a 2 panel (120W ea) 20v setup into a $12 30A Chinese controller and (2) 130A heavy duty batteries used in buses that are in good condition
I'm thinking the controller is defective or damaged? I took a chance on a $10-20 range controller. It seems to be a pwm type controller by design.
.
I'm also using the 12v battery buss to power a link radio setup and its seeing this 15v + pulsing and not happy.

This also is what a smart charger will see and I'm sure, be very unhappy!

The charge regulator has a 12v output that's managed to shut off if too high or too low. I would expect this to be cleaner but it too is going too high.

This leads me to think the controller is defective or damaged!

Some facts!

The sparse info manual does mention to always connect the battery first then the panels, I'm sure I messed up there! I also found info saying to not use a battery or power supply as a substitute for the panels. Finding out to late, I did that bench testing.

So accepting I messed up, I've ordered another $15 brand to try again. This time I'll follow all the info supplied.

My questions for this post are,
Is this pulsing type controller actually too dirty for electronic equipment? Shouldn't the charge buss and especially the managed output port, be clean and under 15v?

I'm assuming these controllers are used with panels for clean 12v camping power?

Is there another type I should try that's still inexpensive?

Has anyone reading this built up a portable or fixed solar charging system using these pwm Chinese controllers?

Do I need to look into the $100-200 range for a controller and if yes, a certain type for clean 12v DC output?
Thanks

I'm going to try this one next.
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Re: Solar chargers

Postby ShowMaster » Sun Dec 25, 2016 7:02 pm

Just in case someone is following this.
From what I'm reading I actually need to connect a 12v 150w type panel to test the controller. By design a12v panel is actually around 18v open circuit and drops to the 12 volt range when loaded. This puts it J to the 12-14v range the pwm controllers maintain.
So to really test this I'll have to take my setup to where panels are already in service and do a real test with a battery and a the panels. The paralleled panels at closer location can have 1 or 2 taken off line to connect to my setup.
Hopefully it'll show that it's my miss use/bench testing, that's the issue here and not a faulty controller.




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andrewju
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Re: Solar chargers

Postby andrewju » Mon Dec 26, 2016 2:51 pm

I don't have experience with solar power equipment (except for the calculators). :) But can you cover your panel with something to reduce its voltage until your controller and the batteries are connected (to avoid excessive voltage without load)?

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Re: Solar chargers

Postby ShowMaster » Tue Dec 27, 2016 2:06 am

Thank you for taking the time to reply.
I need all the panel current so shielding the panels would limit test.

I made a real test with 2 paralleled 12v 150w solar panels and a 12v car battery today. Not the final panels or battery setup, but available for a test.
What I found out is...
The "12v" panels output 18-20v until loaded. Then they drop down to 14-16/18v. The pwm type controller turns on and off the panel connection, putting the full loaded panel voltage across the battery. This pulsing on and off is what charges the batteries. As they charge up to 14.2v, the pluses get less.
In any case, the so called 12v output buss does see quick voltage spikes higher than 14.2v. My transmitter is very critical on anything higher than 14.2v and won't transmit. It wants to see 12-14v.
The type of pwm controller seems to all work this way. Especially if under $100.

So after my testing this is my next attention at a fix. I'm going to use a 5A peak buck boost regulator to stabilize my 12v buss to 12v. The buck boost regulator I have will hold 12v out with 6-35 volts in, that's it's job. This will allow the charge controller to do its job, while the 12v buss stays constant.
The opentracker APRS device I'm using to report the wx info to the Internet will handle up to 24vdv input. This I'll power off of the unregulated controller buss because it measures the battery buss voltage and adds it to its outgoing packets. Handy to remotely see the charge on the batteries 24/7, day and night.
Spend a little $, spend a lot of time making it work. There's A reason why higher end solar controller cost so much I'm finding.




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Solar chargers

Postby ShowMaster » Mon Jan 09, 2017 4:19 pm

Followup
I replaced the original pwm charger with a different 30A one, still $15 range from BG.
It's working much better so I must have damaged the first one by bench testing it as well as applying a non solar source voltage first before a battery. These mistakes seem to be bad!
I did go ahead and use the 5A ($5) Buck boost regulator for all the critical 12v circuitry like relays and a aprs link wx transmitter. The transmitter will not tx if over 14.2v and the 12v 120A and 40A relays I'm using get real hot over 12v. So setting the regulator to 12.8v is perfect and it smooths out the pwm pulse noise on the supply buss.
Under one 12v 150w panel and one 12v 100A battery test, 8.8A at 14v was being supplied to the battery.
I have 2 panels and 2 batteries for the final install.
This will live in /on a container at a remote new private RC field, and be used for RC battery charging and wx reporting to the Internet via the APRS network.
As members and funds increase, more solar and batteries will be added as well as a 60A higher end solar controller.
For now, heaver weekend usage with weekdays sparse, giving the system time to recharge.
If anyone is interested in providing solar charging and on site wx conditions and remote voltage monitoring, I'll be happy to share my setup.






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mmilan
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Re: Solar chargers

Postby mmilan » Wed Jan 11, 2017 1:09 pm

Please do, your work here looks great!


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