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Solar, Field Day, or Emergency Response: Emergency Power Options. George Ure AC7X. Agenda. Outage Scenarios: When could the power fail? Power demands are band and mode dependent On-the-fly power Introduction to Generators Battery Basics – Charge and Discharge Parameters
Don’t forget the cable to connect to the radio!
A “Cell” is a single chemical reaction device.
A “Battery” is a collection of cells
“Cells” are measured in volts/per cell
“Batteries” are measured by terminal voltage
A single cell is just like a polarized capacitor:
EXCEPT instead of a dielectric there is a chemical reaction which delivers or absorbs energy!
Key Terminology to be aware of:
Energy Density: The “work to weight” ratio.
Cycle Life: How many discharge/charge cycles will a given battery deliver?
Discharge Rate: How many hours will a battery deliver how many amp? Typically 20 min., 1-hour, and 20-hour rates are cited.
Depth of Discharge: What is the recommended level of discharge beyond which cycle life rapidly declines?
Peukert Exponent: Effective shrink rate of a battery at high rates of discharge.
Carbon Rod (center)
Major difference between cells is the chemistry of the “goo” and whether the chemical reaction is reversible!
Never attempt to equalized SLA – sealed lead/acid batteries!!!!!! They tend to blow up.
Use plenty of ventilation (outside!) because Brown’s Gas is HIGHLY EXPLOSIVE
Usually Charging Voltage is increased to drive 2-5% of the battery’s 20-hour rate (in amps) into the battery. So a 100 AMP-Hour battery would equalize at the 2-5 AMP rate for 1 hour.
Monitor closely to prevent thermal runaway!
Safety timer! Safety Glasses! Do NOT overfill batteries (with distilled water only) if Equalizing!
Plate depth versus toal plate area determines it:
Typical good quality deep cycle battery is a Trojan T-105 which is a 6-volt standard.
Terms like “cold cranking AMPs” is only marginally useful as comparison information.
Most ham gear will operate to 10.5 Volts
Operating to 10.5 V was required for marine SSB type acceptance
10.5 V is when a 12V battery is “dead”
Batteries deliver less total energy on their way to 10.5V “dead” if discharged FAST
Where Cp is Peukert Capacity and both i and t are time and currents of two different discharges such as 10 amps for 20 hours (20-hour rate) vs. 20 amps for 1 hour (1-hour rate). The n is the exponent value.
Here’s what a T-105 weighs:
If you are down to two batteries in your shopping, pick the heavier battery if you’re after long cycle life – heavier means more plate material is being used!
From a gen-set: Simplest is a chain saw motor on a piece of plywood connected via a drive belt to an alternator. Add voltmeter and whatever if more control is needed.
Works good on a sailboat – such as the one we lived on.
BUT no significant power below 10 Knots/ 12 MPH
Generates some noise, besides PWR
Depends on swept area – bigger is better on wind gens.
Solar is not initially cheap, but over the long term is does have good payback – breakeven at between 10-18 years depending on how much you do yourself.
Single-Axis (panels are mounted on hinges so from March 21 to Sept 21 they are at 20° tilt otherwise (wintertime) they are at 45°
Full tracking systems
Which track E/W
I chose T-Post and
Rebar for ours…
Components are: Panel, Battery, Charge Controller. This plus an old ATV winch raises and lowers my tower.
Low NO maintenance!
HOW TO SELL SOLAR TO A SKEPTICAL XYL:
AvBlend.com or AircraftSpruce.com
RUN-TIME EQUALS FUEL AVAILABLE
Natural gas gens require lots of fuel but are a very long-life option.
Bad choice though if concerned about earthquakes or infrastructure damaged.
Very good unit reports WA7BRI – he uses the Econo Mode with Icom 7000 and now voltage sag problems from key down to listening.
‘BRI meticulously runs every month and uses STABIL in his gas, however! Runs 8-12 hours on a single fill in contest setting, 100 watt xmt class, no RFI issues
From Onan manual good list of watts.
Applies whether your are planning an inverter off batteries (sep. charger), solar (big or small) or buying a genset.
Add up peak loads and that’s your sizing.
More loads = More $$$
Typical 24-hour contest time: 6.7 gallons at 50% load.
Full Power 24-hours = 11 Gallons per day
Full load uses almost 3 times fuel of no load.
Ballpark: 50% load is 60% of max fuel use
85% of charge in Battery size divided by generator/alternator output.
Example: 100 AHr battery will be 85% full in one hour on 100+ Amp alternator or generator-run source such as charger.
Last 15% of charge takes about 2 ½ Hrs. regardless of size – “absorption charge rate” also called “finishing” charge.
Operate initially from 100% full to 60% depth of discharge.
Recharge to 85% of charge level
Resume ops to 60% depth of discharge
The 85% down to 40% of capacity is the “sweet spot” where batteries give up – and accept charge most readily.
When charging begins, battery may not begin charging right away.
Reason: Takes time for the battery chemistry to “change directions”
Delay in discharge to charging reaction is called ‘Coup de Fouet’ by battery gurus. (“crack of the whip”)
Read current after 5-minutes of charging, or so
Coup de Fouet is why active (charging braking) on electric vehicles is so problematic – energy can’t just “reverse and save” – takes time!
Plan on 10% transmit and 90% receive unless you are net control.
Turns off dial lights is available.
Use power output at minimum level to get the job done. V/UHF 1 watt often sufficient. HF use 100 to establish coms, then reduce to path requirements.
Keep mental picture of fluid situations, make notes if possible.
Keep Radiogram pads on hand if regional emergency – doing public service traffic – be sure to get delivery phone number and confirm them.
If a 100-watt station is S-9 and drops to 25 watts the result is S-8.
From 25 watts down to 6 Watts is about S-6
2W about S-4 etc.
100 W increased to 2 kW ≈ 1½ S-Units
One S-unit is a change of 6dB in signal strength, which corresponds to double the VOLTAGE or four times the POWER at the receiver input.
Is 6 DB over
Is 18 DB over
With S-6 Signals, Antenna Noise becomes a major factor in good communications…
Easiest to Install Quickly
160 Meter 1 λ Loop at 25’ or higher Used on 20 Meters where it has some gain…
NVIS low bands, 160/80 some gain on 40-& 20 Meters. Quiet (it’s a loop!).
Only problem is size and height and needs a tuner and open wire!
Verticals, Mobile Whips, and Long-wires need grounds
Signals Depend on Grounds
Keep all generators 50 -100 feet or more – and preferably downwind - from humans. Carbon monoxide is carried as easily as oxygen in the bloodstream.
Never work circuits hot even if they are 12V -12 V is enough to kill! It’s the current (less than 5 ma.) that kills!
When wiring wear rubber-soled shoes and trust no one.