[SCCC] portable contesting power

Wed Jan 20 00:59:47 EST 2021

Do not let the perfect be the enemy of the good.
I would cut to the chase and phone Kevin Zanjani at Bioenno Power in Santa Ana. He’ll walk you through all of this. 
https://www.bioennopower.com/pages/support
Jim WI6X

> On Jan 19, 2021, at 8:42 PM, Drew Arnett <arnett.drew at gmail.com> wrote:
> 
> A bit of follow up.  (I'm not done, yet.)
> 
> Peter's suggestion of using 24 V battery pack and an Astron 24 to 12 V
> DC-DC switcher is a very intriguing one.  That can supply a rig with
> an alternator voltage (13.8V) and would reduce the worry of drooping
> too low on the rig supply voltage due to wire I*R drop.  Some DC-DC
> loss sure, but might be best solution depending on situation.
> 
> I had a friend reply to me that he knows two guys who tried those
> Renogy batteries and found problematic RFI on the 2m band.  I guess
> EMC applies to everything (both RFI and susceptibility).
> 
> I see Home Depot has another brand for 100 amp-hour 12 V LFP in the
> $600 range.  That vendor has no real specs on their webpage, so trying
> to ask them for more.  I see HD also says 180 day returns on both of
> these products.
> 
> If I had to trigger pull today without doing more research, seems like
> 24V battery + Astron DC-DC is lowest risk.  (lead-acid or Bioenno)
> Toss in a panel and Genasun charge controller if I want to extend run
> time that way.  Otherwise, seems like a research project.  How much
> would I be willing to pay a vendor who did this homework for me?
> 
> It's been fun to read and learn about though.  If you haven't seen it,
> in the recent RATPAC series of presentations, Bruninga, WB4APR, has an
> awesome slide deck (and recorded talk) on solar.  I very highly
> recommend it.
> 
> Best regards,
> 
> Drew
> n7da
> 
> On Sun, Jan 3, 2021 at 5:57 AM Peter Putnam <ni6e at twc.com> wrote:
>> 
>> Drew,
>> 
>> I've found several common Icom radios (IC-706, IC-7000) that are not
>> happy with your anticipated supply voltage range of 12.0 to 12.8 volts.
>> Complaints range from distorted audio to doing a complete power-on reset
>> on the first voice peak. Voltage drop in the wiring from the battery to
>> the radio plays a role in this issue, so your mileage may vary...
>> 
>> You might find the range of 13.0 to 13.8 to be more suitable. A series
>> set of 6 LTO (Lithium-titanate) cells initially charged to 14.0 volts is
>> worth considering.
>> 
>> An MPPT solar controller for a "12-volt" system barely outperforms a PWM
>> controller when the open-circuit panel voltage is in the range of 21 to
>> 22 volts, typical for a 100 watt panel. The MPPT controller becomes the
>> obvious choice when the panel voltage is two or three times higher than
>> the battery voltage.
>> 
>> Don't be tempted to use one of the $15.00 PWM controllers from China.
>> They connect the positive panel output to the positive terminal of the
>> battery and do the switching on the negative terminals, making a common
>> ground connection impossible.
>> 
>> Paralleling solar panels gives disappointing results. If one panels
>> voltage is a few millivolts higher than the other, it will deliver most
>> of the output while the other panel loafs along. My experiments with two
>> identical 150 watt panels in parallel maxed out at only 200 watts. You
>> get what you expect if you put the panels in series, but that requires a
>> controller that can handle the higher input voltage. The Morningstar
>> SS-MPPT-15L, for example, can accept panel voltages up to 60 volts,
>> efficiently accommodating two 100 watt panels in series.
>> 
>> 73,
>> Peter
>> NI6E
>> 
>> 
>> 
>> On 1/2/2021 12:54 PM, Drew Arnett wrote:
>>> I've been burning holiday time researching a few things.  Due to not
>>> fantastic radio home location, portable is the way to go for me for
>>> any serious contest effort.  I haven't purchased a genset, yet.  I had
>>> a hypothesis that battery or battery + solar might be a good move.
>>> 
>>> I'm only considering LiFePO4 (aka LFP) and not lead-acid.  Lead-acid
>>> are cheap as heck, but wow, those things are just what you need for
>>> boat ballast.  Lifetime is supposed to be a lot better for LFP.
>>> (Thousands of cycles!  How do I recoup the $ value of all the unused
>>> cycles if I only use a dozen times a year contesting?  Email me if you
>>> have good ideas!)  No need for battery V boost converter.  90% depth
>>> of discharge at 12.0 V and 12.8 V roughly for much of the discharge.
>>> I think battery efficiency for a cycle is 90%.
>>> 
>>> I'm factoring in a lot of things, but still rough numbers.  Need some
>>> margin, but margin is easy to get.  Reduce PA power by 1 dB is 80% for
>>> example.  Assuming camping someplace without shade during day and
>>> sunny skies, etc.  Overall, I think my ballpark figuring isn't far
>>> off.
>>> 
>>> Baseline:
>>> Renogy 100 amp-hour 64 lbs $212 @ Home Depot
>>> --> $2/amp-hour
>>> 
>>> LFPs data points:
>>> Renogy 100 amp-hour 26 lbs $765 shipped, can be paralleled
>>> --> $8.5/amp-hour, figuring 90% usable depth of discharge
>>> Renogy 170 amp-hour 48.5 lbs (tempting!) $1275 shipped, can be
>>> paralleled (but why?)
>>> --> $8.3/amp-hour
>>> 
>>> Does Renogy offer discount for will-call at their SoCal location?  For
>>> hams like that other brand?  For group buy quantity?  I haven't asked,
>>> yet.  I picked Renogy at random, mostly because Home Depot sells them.
>>> 
>>> These batteries have BMS to keep the battery healthy.  Can be set to
>>> shelf mode for safety, perhaps during transport, assembly,
>>> disassembly.  They offer an inexpensive display panel to show load,
>>> capacity and current charge/load rate.
>>> 
>>> If willing to try random brands, I see stuff as low as sub $6/amp-hour
>>> shipped.  (If someone has info or has done homework, let me know,
>>> please!)
>>> 
>>> For solar, I don't have time this year to chase down RFI.  Genasun has
>>> a stellar reputation.  (If someone has info or has done homework, let
>>> me know, please!)  So, another data point:
>>> 
>>> Genasun GV-10-Li-14.2V $135
>>> 
>>> That wants to be paired with a 100W panel.  (Their support is good,
>>> talking to them about options.)
>>> 
>>> Grape 100W panel at Home Depot $72
>>> 
>>> No RFI to mitigate (I hope!) unlike even the great Honda gensets.
>>> 
>>> For each panel/controller pair above, can supply load and/or charge at
>>> up to 100W per set.  Parallel those to retop batteries.
>>> 
>>> Using a couple of web tools, I was able to get the amount of charging
>>> for fixed position (tipped per time of year) or move several times
>>> through the day for SoCal for some of the big events during the year.
>>> Ranges from 5.3 to 8.7 equivalent hours a day.  (Nice to be in SoCal!)
>>> 
>>> Interestingly, the time of day of start does have an impact on
>>> battery/panel tradeoff.  FD is about the easiest and CQ WW the
>>> toughest out of the events I analyzed.
>>> 
>>> Assumed 90W load.  RPi/KX3/KXPA100 100W TX 25% duty cycle
>>> 
>>> 100 amp-hour + 0 W panel --> 12.9 hours runtime for $764
>>> 170 amp hour + 0 W panel --> 21.9 hours runtime for $1274
>>> 200 amp hour + 0 W panel --> 25.7 hours runtime for $1528
>>> 
>>> A pair of 100 amp-hour batteries paralleled for 24 hour portable
>>> contests looks not bad at all.  Just top off a month before you go.
>>> Use $200 of solar charge capability at home.  Hard mount in your
>>> vehicle?  Takes up little space.  Drag out the panel, too, to run the
>>> fan during the day.
>>> 
>>> FD (24 hr) 100 amp-hour + 100 W (sleep 2 hours)
>>> SS (24 of 30) 100 amp-hour + 200 W (sleep a bit less than 4 hours the
>>> first night)
>>> CQP (24 of 30) 100 amp-hour + 100 W (designed for solar!, sleep the
>>> same 5 hours as everyone else)
>>> IARU HF (24) 100 amp-hour + 200 W (maybe 2 hours of downtime, not
>>> designed for solar for our time zone)
>>> CQ WPX (48) 100 amp-hour + 200 W (sleep 5 hours a night)
>>> CQ WW (48) two choices:
>>> 100 amp-hour + 300 W (39 hours, sleep 5 hours a night)
>>> 200 amp-hour + 200 W (don't sleep)
>>> 
>>> There may be a mistake above.  I'd calculate before a specific event,
>>> anyway, as I'd want planning notes.  Tilt angle, power budget over
>>> time & strategy, etc.  (If anyone knows of a writeup of this sort of
>>> analysis that I could use instead of doing this myself, let me know!)
>>> 
>>> No RFI.  Possibly very little bulk, at least for 24 hour contests.  A
>>> couple of panels for longer contests.  No RFI.  No gas can.  No gas
>>> engine maintenance.  Bulk of a couple of panels versus generator &
>>> jerry can.  (Those thin monocrystalline panels offered by several
>>> vendors for $200 for 100W would be easier to stow.)  More criteria for
>>> choosing location.  More susceptibility to weather.  :-)
>>> 
>>> Really no significant price difference, unless scaling up for CQ WW
>>> (in the dark of winter) or for other reasons.
>>> 
>>> No QRO, but as a CW op, I'd be thinking class E amplifiers.  (How come
>>> no commercial class E CW amps on the market?  So great for portable
>>> power.  And think about the lack of heatsink/fan/weight/bulk.
>>> 
>>> Hmm.  If I'm writing my own contest logging software, I could have it
>>> display the power situation, too.  Perhaps throttle the rig power 10
>>> or 20% when needed.  Etc.  :-)
>>> 
>>> Best regards,
>>> 
>>> Drew
>>> n7da
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>>> 
>> 
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