# How much wattage do I need to run my ham radio

Registered Users Posts: 2
Hello, I am new to the solar world and I need some help on my first project. I am my ham radio operator and a backpacker and am trying to design a radio package for backpacking keeping it as light as possible. My question is how much wattage of by rollup type solar panel do I need to run my radio and keep the 13.2 V battery charged.
The specifications of my radio are on receive my radio uses one amp on transmit it uses 22 A at 100 W. Not transmit to receive time is less than 20%.
When I transmit or in a conversation it rarely goes over one minute in length. So that using 22 A and 100 W for a minute. My little 13.2 lithium battery that I have will last me on 100 W for about 30 minutes of normal talk time. My goal is to have a solar panel with enough wattage and voltage to keep my little battery charged.
Any help would be greatly appreciated as well as mathematical equations on how to figure this stuff out.
Thanks

• Solar Expert Posts: 9,363 ✭✭✭✭✭
You are a Ham Operator and cannot figure out watt hours consumed ?    Something is very fishy here......

But to answer your question, 22A @ 13V is 286 watts consumed.   That is a full size Grid tie panel.  You might get away with a 100w of pv panel and limit your talk time even more.

Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,

• Registered Users Posts: 43 ✭✭
When I read this I hope he meant 2.2 Amps not 22 amps. Something didn't sound right maybe I'm wrong lol
• Registered Users Posts: 2
Yes I am a ham operator. I'm new to the hobby. I have Run portable operations all across the southwest, southeast, northeast and Midwest.
Nothing fishy here. I have over 440 portable contacts. I'm looking to keep my batteries charged with solar power. I am just trying to figure everything out. When I am using 100 W of transmit power out I am consuming 22 amp hours. My receive time is only one amp hour.
I'm just attempting to configure all this and don't need any slack jawed comments. I'm now to solar and my long term goal is running my camp on solar power. Like I said my first project is to make sure I can have emergency communications.
• Solar Expert Posts: 3,739 ✭✭✭✭

"Watts" is a rate of energy use.  WattHours is an amount of energy.  Thus 150 watts for 3 hours is 450 watthours of energy.

Amps is a rate that charge (electrons) are moving.  AmpHours an amount of charge.

A battery with an amphour rating holds a certain amount of charge... but you need to multiply that by the voltage in order to get the amount of energy that the battery stores.
When I am using 100 W of transmit power out I am consuming 22 amp hours.
This quote, for example, makes no sense to me.  Are you trying to say that when your transmitter is using 100 watts, the battery is supplying 22 amps at about 13.2 volts?  If so, your battery is providing 290.4 watts.  Where's the other 190.4 watts?

Or, are you trying to say that using 100 watts for a period of time draws 22 amphours from your battery?  If so, the period of time is:  100 watts ÷ 13.2 volts = 7.58 amps.   22 amphours ÷ 7.58 amps = 2.9 hours.

In order to answer your question about what size solar array you need, I need to know your loads.  Because of terminology issues, I can't figure out from your posts how much energy you consume in a day.

--vtMaps
4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
• Solar Expert Posts: 3,113 ✭✭✭✭

Hi martin ..,

Welcome to the Forum.

Martin probably has a Ham Transciever which uses a 12 V battery,  and is able to produce about 100 Watts of RF power output,  into an antenna.   In doing so,  it consumes the relatively customary amount of DC current from the 12 V source  --  22 - 23 ADC.

I DO wonder,  if you have considered running somewhat less power ...   although the current required to produce 50 W RF  is often about 75% of that needed to produce 100 W of RF.

Your transmissions seem quite short.   Are you a VHF Backpacker?

Most roll-up PVs are not very efficient,  although,  guess that you have little choice for a packed setup.

Why not consider a QRP radio that might be able to run about 10 - 15 watts output,  and try to make your antennas a bit better?

FWIW,  73,  GL,    Vic

Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
• Solar Expert Posts: 1,218 ✭✭✭✭
The specifications of my radio are on receive my radio uses one amp on transmit it uses 22 A at 100 W. Not transmit to receive time is less than 20%. When I transmit or in a conversation it rarely goes over one minute in length. So that using 22 A and 100 W for a minute. My little 13.2 lithium battery that I have will last me on 100 W for about 30 minutes of normal talk time.
Example anaylsys for one day, tweak as you need to:

Radio RX :  12.8V * 1A =  12.8W for 0.5 hours is 6.4Wh/day
Radion TX: 12.2V * 22A = 268W for 0.1 hours is 26.8Wh/day
Total for the day is 39.6Wh

To recharge that (assuming a sunny day), you are going to need a variation on these:

-10Wp PV:  40Wh/10W/0.77/0.8 = 6.5 sun hours (small panel strapped to backpack)
-30Wp PV:  40Wh/30W/0.77/0.8 = 2.2 sun hours (med sized panel at camp)
-80Wp PV: 40Wh/80W/0.77/0.8 = 0.8 sun hours (go for broke)

Sun hours here are equiv full sun hours, ie a hour at midday, longer teh further you go from midday. Cloudy/rainy, multiply everything by 5.  The two deratings are for your information, 0.77 for losses from  teh panel and controller, and 0.8 for the battery cycle efficiency.

1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar

• Solar Expert Posts: 1,218 ✭✭✭✭
BTW, the smallest portable PV at the moment are the foldable units using sunpower back contact monoC cells. Theres a lot of rubbish out, do your homework.

1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar

• Solar Expert Posts: 6,034 ✭✭✭✭✭
mike95490 said:
You are a Ham Operator and cannot figure out watt hours consumed ?    Something is very fishy here......

But to answer your question, 22A @ 13V is 286 watts consumed.   That is a full size Grid tie panel.  You might get away with a 100w of pv panel and limit your talk time even more.

Well, my wife has been an extra class since the mid-nineties. She memorized the answers and learned 20 words per minute of code
for about 3 weeks. All she knew about watts was that there better be enough to run the hairdryer on our sailboat in the tropics.
"we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
http://members.sti.net/offgridsolar/
E-mail [email protected]

• Solar Expert Posts: 117 ✭✭✭✭
All she knew about watts was that there better be enough to run the hairdryer on our sailboat in the tropics.
Well she has the important stuff down, hey good buddy what's it look like in your neck of the woods.

What more is there.

General Class, or as my XYL tells me, No Class...

Rancher
• Solar Expert Posts: 6,034 ✭✭✭✭✭
It looks like the humidity is rising out the window in the Merced river basin!   Where are you Ranching?
"we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
http://members.sti.net/offgridsolar/
E-mail [email protected]

• Solar Expert Posts: 117 ✭✭✭✭
It looks like the humidity is rising out the window in the Merced river basin!   Where are you Ranching?
SE AZ
• Solar Expert Posts: 6,034 ✭✭✭✭✭
Since the OP is not back yet....  South East Arizona came very very close to where we built our home. I go back there as much as I can.
The birds, friends/clients and desertcsape are just a few of the reasons.  Nice!
"we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
http://members.sti.net/offgridsolar/
E-mail [email protected]