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Author Topic: Solar Charged LIPO Battery Kit For EMCOMM or Remote Communications  (Read 23303 times)
KB1GMX
Member

Posts: 1338




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« Reply #15 on: July 09, 2016, 12:45:34 PM »

For portable (back packed) lithium is of great value for it lower weight.
If you have to travel with it is light but costly.

For a toteable, that is drive to then setup, possibly with assistance, go with
lead as its reliable and lower in cost.

For fixed station go with lead as well.  The batteries in the 60-200Ah range
will not break the bank, charge controllers for lead systems are common
(lots of choices), and solar pnels are generally cheap (1$ watt or less these days).

My current home system is 400W of panels, an RF quiet charge controller,
150AH wet NiCd (expensive to buy I got lucky to find them free).  The charge
controller was a build it my self as I could not find anything commercial. This
runs 100W hf and 100W VHF/UHF all modes.  A suitable battery for less cost is a
good pair of marine or other VRSLA/AGM 100Ah in parallel.  Also with lead there
are a dozen or more charge controllers that can be used.  Panels, two 130W
should be enough in sunny areas.  Here in New England we get more gray days
so excess capacity is required to ride through those times.  With what I have and
the solar I can run for a long time (days) without exhausting the battery at 100W
and far longer at QRP levels.  This does not move easily as the big battery (10
150ah industrial NiCd cells) are 160 pounds alone.

A smaller system was used for FD.  it was 110 W of solar, a commercial charge
controller (morningstar), two U1 33ah AGM batteries in parallel to run a radio
and amplifiers for 24 hours at 100W level (all modes of 6 and 2M).
This can be moved easily, the two 33ah AGM are easy to carry in their case
(about 40pounds total).

For true portable a FT817 (all modes DC to daylight) and a 11AH Lion pack
(3S4P 18650 cells with CMB) that fit in a pocket.   I can charge with with
a 20w or 50W panel and a custom charge controller that matches the battery.
The voltage of a 3 cell series pack matches the FT817 needs much better
than it would other mobile gear that are more for nominal 13.8V mobile use
as the FT817(ND) tolerates lower voltages well (it works fine at 10V or less).

None of this mentions antennas, masts, coax and auxiliary gear.
For that I have matching home, movable (example FD), and portable antenna
gear for whats needed and based on weight and space.

Allison
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N4UE
Member

Posts: 401




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« Reply #16 on: July 19, 2016, 12:04:50 PM »

Rick, if I may comment.....
We have several solar powered deer and fish feeders at the farm. I recently replaced the solar panel on one. The nominal output is stated as 12 VDC. Even out of the direct sun, it was measuring over +20 VDC on my DVM.

However, there is a cheap alternative! Several sellers on eBay offer a small DC-DC adjustable converter.
This is a small, finished converter, 43mmX21mm. It uses an LM2596 chip. Very well made. I buy 10 or so at a time.
Input - 3.2-40 VDC
output - 3.5-35 VDC
The NICE thing is it's also a regulator. So, pick your maximum output voltage, say, 13 VDC. Set it via the precision 10 turn pot and regardless of the input voltage (up to 40 VDC) and your output will be 13 VDC.

The BEST part? < $1 each! PLUS, FREE shipping.
Yes, they are from China, sigh.
However, these items, like most Chinese items, come very quickly and the sellers are WAAAAY more pleasant than our own sellers are. Usually get a thank you note, etc......

FWIW

roin
N4UE
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W9IQ
Member

Posts: 538




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« Reply #17 on: July 19, 2016, 01:01:15 PM »

Ron,

These are nice converters but be aware that they employ a switching frequency of ~ 150 kHz. There is no filtering on the output of these modules. They may be fine for deer and fish feeders (as a rancher, I understand...) but when utilized within an RF transceiver environment, more attention to EMI/RFI is warranted. Given the low cost, an EMI/RFI filter added to the converter may still form an acceptable solution.

Here is a link to such a converter: http://www.ebay.com/itm/1pcs-1-23V-30V-DC-DC-Buck-Converter-Step-Down-Module-LM2596-Power-Supply-Output-/400985220074. Even a cursory inspection of the board shows no EMI/RFI filtering.

Here is an example of a low cost low pass filter that would prove beneficial with these converters:





- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
N4UE
Member

Posts: 401




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« Reply #18 on: July 19, 2016, 02:19:40 PM »

Hi Glenn. Sorry about the confusion, but I don't use the DC-DC converters at the farm.
I was just pointing out that the solar panel put out a lot more voltage than I expected. It was a bit larger than the original (Sweeney brand) solar panel on the feeder. It just connects to the battery and timer.
I'll look at a converter with a scope tomorrow. I'm building a 4 preamp distribution system from a nice Decibel Products unit.

Now if I can just protect my catfish from the Eagle that keeps clawing them. ha ha

ron
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W9IQ
Member

Posts: 538




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« Reply #19 on: July 19, 2016, 02:27:33 PM »

Hi Ron,

The scope won't show you anything. A spectrum analyzer would be needed.

We have some eagles but I consider their fishing a worthwhile price to pay for the beauty of their flight. Now the blue herons are another story...

My most successful story with a solar panel was to use it to pump water from a creek, up a 300 foot head, to water fruit trees in an isolated pasture. It worked so well that I needed to add a timer to stop the watering cycle. I too added a DC to DC converter but had no RFI concerns as it was sufficiently remote from the operating position.

Glad to meet a fellow ham / rancher / farmer.

- Glenn W9IQ
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- Glenn W9IQ

I never make a mistake. I thought I did once but I was wrong.
N4UE
Member

Posts: 401




Ignore
« Reply #20 on: July 19, 2016, 04:41:47 PM »

OK Glenn. I've seen a lot of Bald Eagles here in North Florida. Big, big birds. There are a bunch of rednecks around here who poach ANYTHING they can and have NO doubt they would shoot an Eagle in a second.
I'm not sure this is what's after my catfish. It's spooked pretty easily and my 70 yr old eyes can't resolve like they used to! ha ha
It's a large bird with a white head, but has a lighter colored chest. We've had alligators in our ponds but this pond is only about 2 acres. Our big pond (10 acres) had a couple of 12-13 foot gators in it. The catfish being black, now have a bunch of 'scars' on their heads. Bummer.
I love nature and don't hunt anymore, just target shoot.

ron
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KB1GMX
Member

Posts: 1338




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« Reply #21 on: July 22, 2016, 01:39:28 PM »

I've used those regulator in an RF environment.  They are noisy, both conducted noise and radiated.

To use them it must be in a metal box low pass filter at input and output.  Easy to do but needed.
Then they work well, however that only can power things in the sun up to the current limit of the panel.

To charge LIPO, NiCd, NiMh, or LEAD one approach is the small boards that do both voltage limit
and current limit (constant current constant voltage) and that is suitable for charging a HT or other
gear to the power limits of the converter ( 1A maybe at 12.6V).  Their advantage is you set the max
open circuit voltage to match max voltage for the battery in use then set the current to something
that doesn't melt the battery or the power supply (and consistant with what the panel can do).

For running pumps doing the day a battey is not needed and voltage regulation us to protect
the pump. For radios its better to store any power harvested in battery for the cloudy day or night.

For example:

For MPJA part # 31562PS (LM2996 based) that is 2A max current and 35V max input.
FYI 2A is enough to run FT817 and most 5W hts with margin.

Based on a CC/CV (constant current and constant voltage) charging works like this.
The board is set to deliver the desired charge current using a low value resistor and a amp
meter.  Then the maximum voltage allowed is set so that you never "cook" the battery by
charging past its safe terminal voltage. This limits the charging current into a discharged
battery and also limits the highest voltage impressed on the battery.  In all cases when
the battery attains the charge voltage set the charge current will have dropped to a small
and usually safe value (lithium is not generally safe for trickle charge).

For 1P3S 2800mah LIPO (18650 cells with Battery protection board) 12.6V and .5A is safe
for any amount of time before fully charged.

For a 7.4V nominal radio pack (LIpo 1p2s) 18650 2200mah max Voltage 8.4) its 8.35V max and 400 ma.

For charging a 7AH gell (usually 10hour rate is .73A) so 14.1V (For the brand I use) and .73A.

For charging a tray of 10 NiMh 2200mAh 15V at 230ma (10 hours) or .7A for three hours
(use a timer to cut it off).

Note for charging lithium tech I set the voltage a about a .1V less than the full charge max
as that keep the battery in the save zone and also use the longer/slower charge rate
as that prevents heating of the cells.  Generally I do not like and its considered bad to
float Lithium cells (Lipo, LifePO4, a123...) so a charge current cut off is preferred but
I've found if you never charge to 100% they tolerate sitting on charge.

Worst case that requires a 10.5W panel (for that 4 volkswagon panels in parallel 12.8W)
or a small 12 to 20W panel works.

To protect the regulator its packaged and preset for the specific battery. or application with
matching connectors (usually anderson PP) and filtering.  Some cases I embed it in the
battery box.  Also I include a small LED panel meter to indicate the output voltage ( helps
gauge state of charge).

For low power portable ops (hts, and FT817 and others) this works well.  For higher power
there are commercial solar controllers and much larger batteries.


Allison
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N4UE
Member

Posts: 401




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« Reply #22 on: Today at 10:38:24 AM »

Just wanted to give a big 'thanks' to those that mentioned about the noise coming from those el-cheapo DC-DC converters. I had never even considered that they would make THAT much noise.
I don't have a SA, but I did test one for radiated noise using my IC-7300. I've done this before helping a fellow ham who was curious about noise coming from a PC PS he was using. I used my 756PRO at that time.
I connected a loop of wire to a length of coax to the 7300 and started around 30 kHz. Yep, up around 190 kHz or so, the noise really kicked in and although it was pretty attenuated up at 70 MHz, there were 'spikes' throughout the spectrum.

I changed my design to a much more simple Zener diode distribution system!

thanks again!

ron
N4UE
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