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Author Topic: automobile starter spike  (Read 1078 times)
KG6WLS
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Posts: 507




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« Reply #15 on: October 18, 2006, 02:26:34 PM »

"Wouldn't it be easier to just turn off your radio than add circuitry to eliminate the potential problem."

I agree! That's why I mentioned earlier the simple toggle switch method.

KISS ;-)

73
Mike
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K1CJS
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Posts: 6055




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« Reply #16 on: October 18, 2006, 03:03:02 PM »

Your battery may not be large enough to safely supply both the starter and the radio.  If the battery is a couple of years old, it may be weakening and you may have a starting problem soon.

The first thing I would do is check all the starting and charging connections.  Yes I did say starting, and especially ALL.  One loose or corroded connection point can increase the power needed for starting from the battery by many times.  

Take all the connections apart, check the ends of all the cables--especially inside the cable ends, wire brush them and the terminals to remove oxidation and reassemble them.  Make sure the alternator to engine mount is also clean and tight, although that point is seldom a problem.  Keep checking the battery terminals also, every time you open the hood.  Be sure they're clean and tight.

You may find the vehicle starts faster--and runs better too.  If not, it may be time for a new battery, and/or maybe even a new starter.  Oh, and I do agree, a larger capacity battery may be a good idea.  Just make sure the alternator is good and will keep the battery fully charged--a test that can be done at the battery sales center.
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K1CJS
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Posts: 6055




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« Reply #17 on: October 18, 2006, 03:14:33 PM »

One thing I forgot is I once had a problem similar to yours, a drastic drop of voltage when starting the car.  I did all the things I mentioned and the cables were seemed good, but the problem remained.  Finally I found the cause, the end of the negative cable attached to the chassis was badly corroded--inside the terminal end.  I replace the cable, and no more problem--the battery held near 11 volts even when cranking the engine.
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K0BG
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Posts: 9883


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« Reply #18 on: October 19, 2006, 07:27:08 AM »

Well, we've all come close, but no cigar.

Most all vehicle starters nowadays are wired in a shunt configuration. This is done primarily to reduce their size and weight. As a result, their inrush current is very high; in the order of about 300 amps albeit for a short duration. This causes the battery voltage to drop.

Depending on the temperature, the battery's age, and a few other factors, this could be below the cutoff voltage for the 706 which is 11.6 volts. You can use a 1 Farad cap mounted close to the radio to buffer the drop (it is NOT a spike), but due caution should be exercised.

Alan, KØBG
www.k0bg.com
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K4JJL
Member

Posts: 501




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« Reply #19 on: October 19, 2006, 07:59:24 AM »

The reason I said "add circuitry" was the CONVENIENCE factor.  Your radio has a TR switch right?  Why don't radio manufacturer's make manual TR switches.  That way there's 4+ switches to throw when you want to switch from RX to TX.  It's much less likely to fail.  Probably cheaper too.  But no, people like convenience.  That's why I tore apart the dash of my Mini Cooper to hook up the ignition sense wiring of my Motorola Spectra.  I like the fact it cuts the radio off when I take the key out.

If he was truly cheap and liked extra work, he could go with a couple toggle switches to isolate the radio completely, or he could install something to make this more CONVENIENT and AUTOMAGIC.  

Marty's device (I think it came straight out of QST or Nuts&Volts) shuts off power if the voltage goes above 16V or below 10V.  It also protects you from hooking stuff up backwards and burning up traces in the radio.  I think it also has some current limiting abilities as well.  It also incorporates a couple indicator LEDs to show the state.

If this is too complicated, choose some other method.  I'm not forcing you to try this.
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WA4MJF
Member

Posts: 1003




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« Reply #20 on: October 19, 2006, 11:31:42 AM »

I've been running radios in
vehicles ever since I've been
a ham.  The best way is the
Army way, turn off all radios
before engaging starter.  I've done
this for 44 years and never had a
problem.

BTW, it doesn't sound like a voltage
spike problem, but rather a voltage
sag problem that you're having.
However, you never know when that
spike will hit you!

73 de Ronnie
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K1CJS
Member

Posts: 6055




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« Reply #21 on: October 19, 2006, 01:52:18 PM »

Just pointing this out--When you start a vehicle, the 'sag' could be considered a reversed spike.  However, when the engine actually starts and the load is removed from the starter, a voltage feedback could occur, causing a real spike.

With that said, turning off the radio is the best way to avoid damage to it--from any spike.
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W9PMZ
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Posts: 575


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« Reply #22 on: October 19, 2006, 02:14:41 PM »

This happens in my Ford Explorer.

Installed a power pole distribution box.

Charged a 1F capacitor.

Connected it to the distribution box, along with the 706.  They are mounted underneath the rear passanger seats.

Problem solved.

Do not attach the 1F capacitor (directly) until it is charged.  If your distribution block has a fuse it will likly blow.

73,

Carl - W9PMZ
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AA4PB
Member

Posts: 12980




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« Reply #23 on: October 19, 2006, 05:15:52 PM »

Where is KD4HLV's device. I found his web page but no mention of the device. He's not listed in the QST articles index.
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K4JJL
Member

Posts: 501




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« Reply #24 on: October 20, 2006, 11:43:01 AM »

I mentioned that you should email him.  I've only seen it at his house and he demonstrated to me how it worked.

He said it's called a startup delay out of a 2005 QST (not sure which month).  I think he made some mods to it to provide over-voltage protection.

Email him.  His address is on his website.
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KB4QAA
Member

Posts: 2445




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« Reply #25 on: October 30, 2006, 08:06:40 AM »

I have the same problem with my 706.  They are not tolerant of low voltage condtions.  The correct solution is to turn off the radio for startup.

However, I did find a work around.  If I turn the key to the intermediate "accessory" position for a few seconds before going to start, the voltage doesn't sag as much and the 706 doesn't blink.   The air condition fan and all the other electronics in the car probably draw way more power than the radio and the battery needs a moment or two to supply the load.

73, bill
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