Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: Radios and alternators  (Read 27313 times)
AF5CC
Member

Posts: 1018




Ignore
« on: September 03, 2013, 07:43:39 PM »

Our 2007 Chrysler Town and Country Minivan (123,000 miles) had to have the alternator replaced today.  The battery warning light came on Sunday when we were driving back from an out of town trip, but luckily we got back ok.  I have been doing more mobile operating in the past year than I ever have before (got a better mobile antenna) and wonder if that can damage or shorten the life of an alternator?  I usually run the radio at 35-40 watts, as I am powering it thru the cigarette lighter.

73 John AF5CC
Logged
NO2A
Member

Posts: 841




Ignore
« Reply #1 on: September 03, 2013, 10:34:08 PM »

I`ve never heard of that damaging an alternator. I would watch running the radio from the cigarette lighter,as the car`s wiring can get awlfully hot. As well as the cigarette plug itself. Unless you were running an amp from your car,a standard alternator is fine.
Logged
WB2EOD
Member

Posts: 219




Ignore
« Reply #2 on: September 03, 2013, 10:58:25 PM »

At 35-40 watts output the radio is probably pulling around 10 to 12 amps from the car's electrical system. 
This is not too much for the electrical system and probably did not directly contribute to the alternator failure. 

Having said that, you should NOT be drawing that kind of current from the lighter socket regardless of it's published rating. 
Best practice is to run a pair of wires directly to the battery with fuses in both positive and negative lines. 
The fuses should be as close to the battery as possible, (within 6 inches).  Depending upon what the rig draws you may be looking at #8 or #10 wires

K0BG's website shows some rather graphic and disturbing examples of what can happen when the lighter socket is overloaded.

73
WB2EOD
Logged
K1CJS
Member

Posts: 6061




Ignore
« Reply #3 on: September 04, 2013, 06:33:25 AM »

No, that in itself wouldn't cause alternator failure.  Could be that overheating caused the diode pack to cook itself, could be that a bad brush in the alternator is causing the problem.  Could even be that the battery/charging/electrical system inadvertently wasn't properly maintained causing undue stress on the alternator sensing circuitry.  But just using a ham radio connected to the van electrical system?  Not likely.
Logged
KJ4OBR
Member

Posts: 104




Ignore
« Reply #4 on: September 04, 2013, 07:54:32 AM »

 Alternators wear out. Nothing you did killed it early. 123,000 on a Mopar alternator is doing really good. Do note that if you deep discharged the battery limping home you can expect to replace that soon too.. you might want to put some pennies away to cover that cost.

73
Dave

Our 2007 Chrysler Town and Country Minivan (123,000 miles) had to have the alternator replaced today. 
Logged
WX7G
Member

Posts: 6322




Ignore
« Reply #5 on: September 04, 2013, 09:17:49 AM »

A 100 watt radio that draws 20 amps at 100 watts, and assuming 2 amps for housekeeping, will draw 13 amps at 40 watts.

   I = 18 x (40/100)^0.5 + 2 = 13.4
Logged
AF5CC
Member

Posts: 1018




Ignore
« Reply #6 on: September 04, 2013, 12:18:36 PM »

Thanks for the feedback. Great to know that is wasn't my fault.  THe battery was bought new from Sam's club in March, 2012, so if it does fail soon, it should have most of a prorated warranty left. The replacement alternator is supposed to have a lifetime warranty.  Too bad the original one didn't

Mobile operating and handing out counties while driving sure is fun!

73 John AF5CC
Logged
M6GOM
Member

Posts: 1012




Ignore
« Reply #7 on: September 04, 2013, 06:36:41 PM »

I usually run the radio at 35-40 watts, as I am powering it thru the cigarette lighter.

73 John AF5CC

K0BG and myself disagree quite a lot about powering transceivers with the cigarette lighter socket but we would both be in agreement that 35-40W is seriously pushing it, especially on FM. I bet you see the display light dimming as you talk? That's because you're exceeding the current rating of the cable and getting significant voltage drop.
Logged
W8JX
Member

Posts: 6664




Ignore
« Reply #8 on: September 06, 2013, 09:32:48 AM »

If you like to use cigarette lighter plug there is a option that was not mentioned. You could place a 50 to 100,000 ufd capacitor in parallel with power cord near rig. This would reduce peak draw on socket during modulation and stabilize voltage.  It will surprise how well something so simple can help
Logged

--------------------------------------
You can embrace new computer/tablet technology and change with it or cling to old fall far behind....
AA4PB
Member

Posts: 13032




Ignore
« Reply #9 on: September 06, 2013, 11:51:05 AM »

If you like to use cigarette lighter plug there is a option that was not mentioned. You could place a 50 to 100,000 ufd capacitor in parallel with power cord near rig. This would reduce peak draw on socket during modulation and stabilize voltage.  It will surprise how well something so simple can help

It may work for CW or SSB but I don't see how it could help for a 100% duty cycle mode like FM. If your transmit time is 5 minutes then the capacitor would have to be large enough to supply power to the transmitter for 5 minutes in order to maintain the voltage - not likely.
Logged
K1CJS
Member

Posts: 6061




Ignore
« Reply #10 on: September 07, 2013, 04:56:49 AM »

If you like to use cigarette lighter plug there is a option that was not mentioned. You could place a 50 to 100,000 ufd capacitor in parallel with power cord near rig. This would reduce peak draw on socket during modulation and stabilize voltage.  It will surprise how well something so simple can help

It may work for CW or SSB but I don't see how it could help for a 100% duty cycle mode like FM. If your transmit time is 5 minutes then the capacitor would have to be large enough to supply power to the transmitter for 5 minutes in order to maintain the voltage - not likely.

This is a subject that has been hashed out here before, and the same people keep claiming the same fallacious things.  Pulling more amperage through a circuit or a wire than the circuit or wire is rated for is asking for trouble--and no amount of capacitors or other "load evening" devices can get around that, period.  Those cigarette lighter plugs were made for a very short time intermittent useage, not for a longer time heavy useage.

Older vehicles with the cigarette lighter plugs had heavier wiring than today's vehicle "power outlets" do, and even though those outlets may be rated at 20 amps, if you try using them to pull a constant 20 amps--especially through the wires connecting them to the electrical system--you're asking for trouble.  Add to that, most rig installation instructions warn against using the factory wiring for power purposes in the first place!

Capacitors for smoothing power are fine, as long as the wiring that has to carry the load is large enough to actually carry the load safely!  Any heating of the wiring means that the wires aren't large enough to carry the load on them and the insulation may melt to the point of letting the wires short.  That is exactly what may well happen if you try to run a FM rig that draws 16 to 20 amps through those power outlets for an extended time.

Hey, it's your vehicle--do what you want to.  Just because you've run a rig through the factory wiring before with nothing happening doesn't mean that nothing ever will happen.  If you have and nothing has happened just means you've been lucky.  Don't expect your luck to hold out forever.  73.  
Logged
W8JX
Member

Posts: 6664




Ignore
« Reply #11 on: September 07, 2013, 09:20:27 AM »


This is a subject that has been hashed out here before, and the same people keep claiming the same fallacious things.  Pulling more amperage through a circuit or a wire than the circuit or wire is rated for is asking for trouble--and no amount of capacitors or other "load evening" devices can get around that, period.  Those cigarette lighter plugs were made for a very short time intermittent useage, not for a longer time heavy useage.


It is amazing how much some slam capacitor trick that they have never tried. Yes it will not help with FM (though it will soften surge load on source). I works great for SSB and CW.  I remember doing a portable battery powered field day station about 15 years ago using two 12v car batteries in parallel. I also had a 120,000 ufd cap in parallel near rig. We ran hard all night long and into morning running 100 watts with a TS 140. Display on rig was solid and no dimming when talking. It was not till morning when we did a key down tune check did we see how low batteries were when display dimming and output sagged a lot. Yet, it would still do about 100 watts PEP SSB voice.  Try it before you knock it.
Logged

--------------------------------------
You can embrace new computer/tablet technology and change with it or cling to old fall far behind....
K1CJS
Member

Posts: 6061




Ignore
« Reply #12 on: September 07, 2013, 01:13:32 PM »

Two wires that are not in a harness is a different thing altogether than wiring that is bundled together.  And if you noticed, I didn't 'slam' any capacitor trick.  Better re-read the post I made.

Wires that get warm when a device is powered off them are not heavy enough to carry the power the device is carrying--tricks or no tricks.  That is just a plain fact.
Logged
AD5X
Member

Posts: 1437




Ignore
« Reply #13 on: September 07, 2013, 01:32:20 PM »

...It is amazing how much some slam capacitor trick that they have never tried...

Yes - Take a look at the tiny Gamma HPS-1a power supply.  It uses a 5-farad capacitor bank at the output of a 13.8V 5-amp power supply and powers a 100W SSB transceiver just fine.  

I've also played around with a MFJ-4403 powering an IC-706MKIIG from an auto accessory plug.  The MFJ-4403 has a 4.3 farad capacitor bank on its output.  The auto accessory plug handles the 5-8 amps average current needed by my IC-706MKIIG operating CW or SSB, and the 4.3 farad capacitor bank handles the 20-amp peak current necessary for full output.  The MFJ-4403 places a large resistor in series with the capacitor bank when it is first turned on so as to limit the current charging that 4.3 farad capacitor bank.  When the capacitor bank is charged (takes about 60 seconds), a relay shorts the resistor.  Of course, wiring directly to the battery is cheaper - but these are interesting techniques.

Of course, these techniques only work with low duty cycle applications like CW and SSB.

Phil - AD5X
Logged
W9MMS
Member

Posts: 121




Ignore
« Reply #14 on: September 09, 2013, 05:20:44 PM »

Isn't there an old CLICHE that goes something like?

IF IT'S WORTH DOING?
THEN DO IT "RIGHT" THE FIRST TIME!!!!!!!!

Why not run the correct size wire from the Battery to the radio in the first
place once and for all?

An electrical repair in a vehicle can be very costly.

((((73)))) Milverton
Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!