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Author Topic: Seeking voltage limiter recommendations  (Read 3633 times)
W8JX
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Posts: 13268




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« Reply #15 on: August 18, 2018, 07:56:39 AM »

A regulator itself is going to consume some energy so not sure if you will gain much if any with one. 
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Ham since 1969....  Old School 20wpm REAL Extra Class..
K5LXP
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Posts: 6147


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« Reply #16 on: August 18, 2018, 04:42:37 PM »


Does your panel put out 3A?  If not, no dropping regulator will fix that, and even a low dropout regulator would have some drop vs input voltage below its setpoint, which translates to an output below battery voltage when the panel isn't pulling it up.  A DC-DC converter would maintain whatever output voltage you wanted as long as you satisfied the input voltage and current requirements of the converter.  Some are noisy but some are pretty quiet.  There would be a bit of efficiency penalty but if it allowed you to use the full capacity of the battery at whatever output power you need it might be viable at the system level.  I use a DC-DC converter this way to run a laptop at 16V, and another one to keep a 100W transceiver gel topped off from a bank of gel cells and solar.

Mark K5LXP
Albuquerque, NM
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K6AER
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Posts: 5728




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« Reply #17 on: August 19, 2018, 08:16:14 PM »

You did not mention what the output wattage from the panel is , the unloaded voltage and your battery size in amp hours. Solar charge controller for up to 20 amps can be had on the internet fore under $35. Your battery should be of a capacity to run the radio for three hours. I would suggest at least 35 amp hours.
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KD2JIP
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Posts: 28




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« Reply #18 on: August 21, 2018, 07:23:30 PM »

Does your panel put out 3A?
Yes.

Quote
A DC-DC converter would maintain whatever output voltage you wanted as long as you satisfied the input voltage and current requirements of the converter.
This is what I want.  Any recommendation for a quiet one?
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KD2JIP
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Posts: 28




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« Reply #19 on: August 21, 2018, 07:47:56 PM »

You did not mention what the output wattage from the panel is, the unloaded voltage and your battery size in amp hours. Solar charge controller for up to 20 amps can be had on the internet fore under $35. Your battery should be of a capacity to run the radio for three hours. I would suggest at least 35 amp hours.

I have a 60W panel.  Max Voc is 21V if i recall correctly.  I have shied away from cheap controllers because my assumption is that highly reputable equipment is more likely to be reliable than no-name, cheap equipmenti.  A 35 Ah battery is too heavy for man portable.
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KD8SKM
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Posts: 19




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« Reply #20 on: August 28, 2018, 04:09:48 AM »

Our Apollo Charge controller would work well here with a 60 watt panel and have room to grow up to 280 watts of Solar Power.

It also pairs nicely with a 20 amp hour Lithium Iron Phosphate battery at 6.5 pounds weight... and that's a true 20 amp hour usable capacity.

Check out the controller at:  http://www.diysolarforu.com

Battery can be found from http://www.batteryspace.com
I use the 20 amp hour 12.8 volt packs for shows LiFePO4 or LiFeMnPO4.

Cheers,

Rob
KD8SKM
DIY Solar for U
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KC4ZGP
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Posts: 1961




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« Reply #21 on: August 28, 2018, 11:03:59 AM »


Oh forget that fancy-pants solar charging thingy.

Use car batteries.

Kraus
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LYFAN
Member

Posts: 53




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« Reply #22 on: February 14, 2019, 07:37:34 PM »

"I would still like to put a voltage regulator between the controller and the load, no longer to protect the load, but to keep it powered at >= 13V as long as possible when running on battery."

Ain't gonna happen. You'e got something grossly wrong in the setup, and I think you are also under some misimpressions about how it can all work.

First of all, you will never have the battery powering the radio at more than 12.8 volts, which is about the maximum you'd eer see on a lead acid battery of any type. (Lithium might go higher, but that's a whole other kettle of worms.)

Anything over 12.8 volts (typically 12.6) on a lead acid battery is a float charge, which disappears after just a few minutes under any load. So, your battery is not going to give your radio anything above 12.6-12.8 volts.

Second, putting a regulator after the controller is totally counterproductive. The controller is supposed to have a regulator built into it. Either it works, so no second regulator is needed. Or it is broken--and it needs to be fixed, not kludged with a second regulator.

What you might want to do is replace the charge controller with an "MPPT" type controller. They can be 15% more efficient than pure DC simple controllers. And they may gain another 15% because they can take the low voltage in the early/late hours, or if the panels are partly shaded, and still boost it to effective charging voltage.

From what the OP is posting, there's just too much wrong, it needs to be redone right, not kludged on the kludges.
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KB8VUL
Member

Posts: 297




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« Reply #23 on: June 20, 2019, 04:47:49 AM »

There are DC to DC buck converters on eBay that will take 12 to 60 volts and output a solid 13 volts at all times with a reasonable current rating.
You could design something, but if it's a shelf item from China for 10 bucks, why bother?
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KD8SKM
Member

Posts: 19




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« Reply #24 on: July 30, 2019, 03:49:30 PM »

There are several issues with using a 10 dollar DC-DC converter...

1) Probably the most significant is the amount of RFI it will produce - making a DC-DC to be RF quiet takes great care in the design and selection of components along with PCB layout.

2) It will not know when the Battery is at full charge and stop charging

3) Without MPPT that converter will just pull down the Solar Panel Voltage to the minimum input of the converter - likely pulsing on and off all the while.  This results in a significant loss of power likely over 50%.

4) Reliability is another big one - 10 bucks is real cheap and will have cheap parts used in the design... probably will not last.

All of the above reasons are why I started DIY Solar for U 6 years ago and developed a Solar Charge Controller that would be RF Quiet,  have Maximum Power Point Tracking to get every last watt out of the panel, and know when the battery is full to go into standby.

Designed, and made in the USA with Automotive / Military grade components sourced in the USA.  Built to last 40+ years too.

Check us out at https://www.diysolarforu.com

Cheers,

Rob
KD8SKM
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N8AUC
Member

Posts: 625




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« Reply #25 on: July 30, 2019, 07:19:14 PM »


Oh forget that fancy-pants solar charging thingy.

Use car batteries.

Kraus
That is a bad idea on so many levels, it defies description.
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