Re: Any use of a battery eliminator/charger device?

Donald Sanders

Yes, The 7809. It requires at least 3 volts input higher than the output as I remember . 
I have used several of this series in various regulator applications and as current sources.
Old technology but reasonable cost. 
I usually add the protective diodes to the regulator as depicted in many schematics.

Dr. Don W4BWS

Ego is the anesthesia that deadens the pain of stupidity.

On Tue, Feb 6, 2018 at 1:37 PM, Frank Perkins <N6CES.r@...> wrote:
Hi Don, I assume you were thinking of the 7809 regulator. I'll try it.
Thanks, Frank

On Feb 6, 2018 9:07 AM, "John Lonigro" <jonigro@...> wrote:
I don't think the one I'm familiar with is sold anymore.  However, Harbor Freight has a newer version, model 62376.  Looks like the trouble light is now LEDs (vs incandescent) and they got rid of the expanded scale voltmeter.  It also now has a USB port for powering your phone.  The battery is 17 Amp Hr.  Before buying, you might look for a sale coupon, either online or in their catalog.  A lot of times they have 20% off coupons.

If it is truly a 17 AmpHr gelcell (as advertised), you can calculate about how long it should last.  The Amp Hr rating is always based on a 20 hour discharge rate.  You should be able to draw 850 ma continuously for about 20 hours (20 x .85 = 17).  Most QRP rigs draw a lot less than 850 mA on receive and not much more than that on transmit. Estimate your transmit duty cycle.   Measure the receive and transmit current of your rig, compute a weighted average current drain, and you can come up with a good approximation of how long the battery will last, as long as the computed current isn't too much higher than 850 mA.  I'll bet it is less than 850 mA if you have a QRP rig (not a QRO rig turned down to 5 Watts).

Hope this helps.

John, AA0VE

On 02/06/2018 10:33 AM, Michael McEwen wrote:
Do you have a model name or number I can Google?

On Feb 5, 2018 12:21 PM, "John Lonigro" <jonigro@...> wrote:
I'm assuming you are referring to one of those Jump starters like those sold at Harbor Freight?  They have a 15 Ah (approx) gel-cell inside, nothing fancy.  Mine used to be in the car until the insulation on the short jumper cables cracked and fell off.  I removed the defective jumper cables from the old one, and added a cable with Anderson Powerpoles on the end.  It should easily last for most of Field Day  with a 5 Watt QRP rig attached.  My model includes a cigarette lighter socket, a built-in trickle charger, a trouble light, a heavy duty on-off switch, the ability to charge it from your car, and an expanded scale voltmeter.  When they are on sale, they are hard to beat, other than being large and on the heavy side.  it's old technology, but I believe gelcells are safer to handle than the newer Lithium batteries.  If they are kept charged with the built-in charger, they seem to last a pretty long time.  Mine is at least 12 years old.

John, AA0VE

On 02/05/2018 12:04 PM, Dr Jim Kennedy via Groups.Io wrote:
Have any of you QRP'ers who operate from outside locations ever used a 12V 15000mAh Multi-Function Car Jump Starter Battery Charger as a power source transceivers? If yes, how long does it last and would you recommend?

72/73, Doc - K2PHD

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