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Author Topic: Battery question for Yaesu 817/ICOM 7000  (Read 13408 times)

AC2EI

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Battery question for Yaesu 817/ICOM 7000
« on: March 20, 2010, 01:19:09 PM »

I am a new ham and am trying to set up a battery operated station.  I am not sure how to size a battery for my 100W ICOM 7000, and another battery for my Yaesu 817, 5W.  Batteryplus has sealed lead acid batteries named Werker with a trickle charger, from 2.5 Ah up to 15 Ah.  I would like to have a system where the radio runs off the battery, and the trickle charger keeps the battery full.  Assuming I had two separate systems, what size battery would I need for each of the two radios?  Should I keep a meter between the battery and radio to monitor the current voltage?  Any help you can give would be appreciated. -   Steve  KC2TGP
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K5LXP

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RE: Battery question for Yaesu 817/ICOM 7000
« Reply #1 on: March 22, 2010, 05:58:14 AM »

Before you can answer the size question you need to first know how long you want it to run for, and what portion of that time will be spent transmitting vs receiving.  

Then you determine the current draw for transmit and receive, and also find out at what voltage your radio no longer functions (almost surely before the battery does).

Next you'll apply a battery capacity function known as peukert constant for your particular battery, combined with your anticipated TX/RX duty cycle and low voltage cutoff, and you'll have it.

A spreadsheet makes this trivially easy to manage and calculate.


Mark K5LXP
Albuquerque, NM
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KD4LLA

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RE: Battery question for Yaesu 817/ICOM 7000
« Reply #2 on: March 24, 2010, 11:13:18 AM »

I have the cheapest Wal-Mart deep cycle battery I could find.  To keep it charged I use a 10 amp charger on a timer.  The battery and charger are located near my feet.  I use a FT-890 (100 watt) HF and two FT-2500 (50 watt) VHF radios.  This setup have been in use for five (plus) years.

Or, you can do all sorts of calculations and such (if a battery works in my car, why won't it work in the shack?).

Mike
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AJ4WC

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RE: Battery question for Yaesu 817/ICOM 7000
« Reply #3 on: March 26, 2010, 04:52:21 PM »

It depends on your intended use.  It would be okay if you're more interested in portability than functionality.  For home back up, I think 15 AH is too small.  I have two 190 AH in parallel, which I'll admit is overkill, but I can run an HF and VHF/UHF radio for days without power.  Obviously, it depends on duty cycle, but a 100W HF radio draws about 22A in TX.  So a 15 AH battery wouldn't provide even an hour of TX time.
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AJ4WC

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RE: Battery question for Yaesu 817/ICOM 7000
« Reply #4 on: March 26, 2010, 05:01:26 PM »

Also, don't worry about an Ammeter, they are a pita to hook up and also can add resistance to your high current leads depending on how its done.  An voltmeter by itself is sufficient.  I got a nice digital off ebay that only draws 20mA for under $10.

How do you like that IC-7000?  It's on my short list for a new radio?
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K4FH

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RE: Battery question for Yaesu 817/ICOM 7000
« Reply #5 on: March 28, 2010, 07:06:29 PM »

Purchase a Watt's Up from Powerwerx.  You can also get them from HRO.  This will allow you to monitor your battery usage and can help you save your batteries if you intend to drain them to 10.5v.

During a typical day use the Watt's Up on a standard power supply and get a sample of what your power usage was.  You now have a baseline to design a portable system with.  

I'm hunt & pounce so my TX is low compared to RX.
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