Amplifier/current draw

[Rocketman]

As some of ya'll know, I've been  having some trouble with my alternator(s).  I have fried four or five of them since I bought this Valkyrie in October of last year.  I pulled the bike apart this weekend to look for excess current draws that I might not know about.  The previous owner had put an amplifier in the fairing (it's an IS), and I had assumed that he had spec'd it properly.  I am beginning to have my doubts.  The amp has a tag on it that states it is rated at 75 W X 4 with a four output system, or 300 W X 2 for a two output system.  By my math, that gives either 300 or 600 total watts (at full output).  With a pair of headlights, at 60W(?) each, a couple of running lights, and other miscellaneous draws, I'm at either at ~450 or ~750 W, and that doesn't even include the engine itself.  If it's 750, I'm way over the 540 W spec that I recall the stock alternator putting out, and if it's 450, I'm too close for comfort without knowing how much the engine firing system draws.

Am I interpreting the amp numbers properly?   Is this likely my problem, that I am overworking the alternator, and it just can't handle it for long term usage, and eventually dies?

The other thing I found was that some of the wires were not well attached to the output of the amp, and could have had a problem with intermittent short or open.

There are some other "extras" he had on there, inccuding FIAMM air horns, but those aren't used for a long enough period to cause a problem, I would think.

Discuss.

Mark

[roboto65]

Well just a thought and I say thought LOL On a cage the altenators put out what 130 amps give or take not sure of the wattage and also maybe a bigger battery but I have a 91 Suburban that has a 1000w amp in it well it is my sons  anyhow does the Amp do the work converting that 12 volts to the wattage it needs some what because it does not go thru Alternators just thinking out loud !!!!  Very Dangerous

[Kingbee]

Most likely those stated wattages are PEAK watts. The amp itself draws very little current unless it's making VERY loud music.

Why not eliminate the amp, if in doubt, and use the system as stock?  I had one of those add-on amps rated at 600 watts/2ch (peak) and didn't think it really did that much & threw it out..........

Are you sure the amp switches off with the ignition?  If there's enough drain on the battery when the bike is off, there would be an additional strain on the alternator charging the battery up each ride.

Have you disconnected a battery cable and measured the current draw with the ignition off?  S/B just a few milliamps for the radio & CB memories.

Is your battery recent?  Some older batteries draw a lot of energy trying to be charged, & never really get fully charged, so the drain on the alt keeps on.

[Steve K (IA)]

What your talking about is the amp's "output" wattage.  It shouldn't use much power running it at reasonable levels.  I would hook it up to a switched power source.  That will make sure there is no current draw when the bike isn't running.

[humshark]

Kingbee is on the right path here with his info - I simply wanted to add that not only are the WATTAGE RATINGd usually stating peak power, the wattage is not directly comparable to your 60W headlamps and the amount of current it will draw.  That scenario would look like this - 60W @ 12V = 5 Amps of draw.

Musical Amplifiers are measuring wattage based on an acoustical signal that varies in VOLTAGE & Frequency.  If a 600 watt amp pushes it's power out and reaches voltages of 40 to 60 volts peak - that's a five fold division of the current needed to produce the wattage stated.  This is an example only.  Maybe the Amp is having issues.  Wouldn't be the first one I've seen.  What is it fused at?

If you have gone through so many alternators - why not even temporarily fix a AMP METER to the bike and cruise around a bit to determine the draw / Amperage you are demanding on your alternator. -

A battery with a bad cell might seem fine - as long as it doesn't sit very long between rides - and your bike starts easily, but is VERY hard on an alternator. 

Hope you find your problem.  This would get old quickly for me    Keep us posted!

[Rocketman]

I was hoping that it wouldn't be pushing 300 W or more, but wasn't sure.  It's fused at 30A on the power line, and has two 30 A fuses in the body of the amp itself.  By my math, that's just enough over 300 W to make it a good safety.  Of course, if it might occasionally pull 300 W but doesn't pull it very often, that still makes sense.

It IS hard wired to the battery (through its own inline fuse).  It may be drawing power full time, I haven't done the tests to determine that.  I also intend to load test the battery, and am hoping Autozone has the capacity to load test a MC battery.  Maybe I'll just buy a new one on principal.  I don't think the battery is very old, but since I didn't buy it personally, I can't know for sure.

I have been intending to install a voltmeter, as an early warning system of future failures.  An amp meter would probably be a good idea as well, but not sure where I would put it, as there are at least three lines connected directly to the battery:  Stock positive cable, amplifier power, and horn power (through a relay, and, I believe,  also through a fuse).  I have never put an amp meter in.  I am assuming it's an inline meter, between the positive battery terminal and the load.  Hmmm.  Maybe it's supposed to go between the neg. terminal and the frame ground.  That ought to capture all at once...

I think at this time, I intend to pull the amp and restore the audio system to stock.  That leaves me with one concern:  The previous alternator failures have been anywhere from 100 to 3000 miles into the lifetime of the alternator.  I want to be sure I've solved the problem before I button it up and ride it again.  I'm hoping to take a trip in a month or so, and if I can't be sure my alternator will survive, I'm not going to be comfortable leaving home, especially with the wife on the back, and a hard deadline for my arrival.
I need to be sure I've fixed the problem, rather than simply suspecting I have, since I may not know till I get 500 miles from home.

[Kingbee]

Interesting that you said the amp is connected directly to the battery.........................

[Rocketman]

Interesting that you said the amp is connected directly to the battery.........................

I had assumed that there was another signal wire that turned on when the radio turned on, but that may not be the case.  I have not had trouble starting the bike after sitting for a long time.  I believe it was all hooked up when I was recovering from knee surgery, although it might not have...
I plan to check ignition-off amp draw tonight.

[roboto65]

Well most car radios DO have an extra lead that when you turn the key on it turns the amp on most likely blue so yes most amps are connected directly to the battery..  I do not know weather the Valk has such a lead so yes the amp could be on all the time not Good!!!!

[Rocketman]

Well, I didn't get around to the battery load test tonight.  Maybe tomorrow.  I did, however, do the ignition off current reading.  I measured between the neg. terminal and the neg. cable.  It read an initial spike of ~80 mA, but very quickly settled to ~3 mA.  I got the same readings whether the amplifier was plugged in or not.  That sounds an awful lot like radio/clock keep-alive power to me.  If the battery tests out good, it's back to the drawing board.

Mark

[Andy]

Here's a good link to car audio: http://www.bcae1.com/

My amp is wired direct per the instructions but doesn't turn on until it senses power to the radio. I've had zero problems with the original alternator.

[Rocketman]

Well, the results are in.  The battery, despite being "somewhat" new, was showing bad on the load test.  It started up fine each and every time, but after charging it for several days with a trickle charger, then letting it just sit there for a week, only hooking it up for a total of ~1/2 hour, and with the key on for only a few minutes total, O'Reilly's reported that it was only 54% charged.  They charged it again for me, then tested it.  Showed up as bad.  I have a new AGM battery, ready to install.
So:
Can I blame all my problems on a bad battery?  Should I keep looking for other things?  I'm not keen on assuming this is the right answer, and then finding myself on the side of the road again in a few days or a few weeks.

[humshark]

Because of the HISTORY - I would still be cautious, but that's me.  It COULD be possible that you started this whole thing off with a good battery and the process of blowing up alternators adversely effected the battery resulting in it's current state.

I would have to ultimately convince, myself however, that you can worry about it, or get on the bike and ride! 

You have a good charging system, and a good battery. ( 1st time maybe since you bought it? ) This is the best place to start over again.  Since you have already verified the current draw with the ignition off, then unless you have some sort of intermittent short ( curious to not blow a fuse / fusible link ) that is taking the alternator out, I'd say you have to put your trust in it and GO!

IF you have more trouble, then you'll have to figure out a way to monitor what's going on.  Until you can see and then figure out when it's happening - riding conditions, temperature, load, etc,... we will all continue to guess.

BEST TO YOU!

[Rocketman]

I put my trust in it 3000 miles ago, and it left me stranded again.  I had a friend look at the amplifier.  He doesn't know much about motorcycles, but he knows more about amps than I do.  He commented on the bad-looking wiring job, and the oversized amp for the application.  Additionally, he pointed out that while wiring it directly to the battery is standard practice, it's also standard practice to include a signal wire that tells the amp when to turn on.  That signal wire did not exist.  By his reckoning, it should have been on full time, even with the key out of the ignition.  We can't figure out why I wasn't reading more than 3 mA current, though.
Of course, as I was pondering this just now, I wonder why it ever turned on at all.  My understanding of the signal wire is that it gets 12V when the ignition is on (or however you want to wire it), and the amp then turns on.  So, if there's no wire, there's never any 12V signal.  The amp should never turn on.  Maybe there's a setting somewhere where you tell it whether you're using a signal wire or not.  But, if it's such a bad idea to not use a signal wire, why have a factory installed option to not use it?

Bottom line:  I pulled the amp.  Put it back to as close to stock as I could get it before 1AM, and rode it in this morning.  First time since June, and she started a little hard, and wanted to die when I gave her throttle initially.  When she warmed up, everything was great.  Headlight was strong when I entered the parking garage at work.

[Kingbee]

I had an amp one that "sensed" when there was an audio signal, then turned on fully.  Current drain when in the "off" mode was insignificant.

[Scott from FL, now in Maine]

I felt I just had to add a blip about my experience with an amp.  I had a Mazda RX7 and installed a killer stereo setup I loved. About 2 months later my Alternator died, I replaced it (not cheap on those cars) and another 2 months later it died again and this time I had it rebuilt. 2 months again and the same story! I am an auto electrician and started to smack my head on missing the obvious! I didn't test the draw from the main and largest of two amps I had installed.
Here is the best way I found to test it. First I found my Alternator was rated for 65 amp load. Get an amp meter, preferably one that  goes against the wire your checking or clamps around it. Be sure it can read and handle up to 100 amp load.  Put it on the power lead coming from the alternator. An amplifier has the largest draw with heavy bass sounds so find music with a deep bass beat. Start the vehicle and the check the draw on you system with the meter and get a base reading from a full load on your bike (all accessories on) it should of course fall below the draw rating on the alternator. With the Valk you may want to bring the rpm up a bit for that base reading, around 1200 rpm. Then turn on your stereo and the volume up a bit higher than you normally set it at and check the draw on the amp meter. It will spike upwards on the bass beat. I found that I was spiking the load between 80 and 85 amps!!!! This is what was killing my alternators!! My amp had a adjustment knob for amplification that was scaled 1 to 10. While still testing the amp load I turned the adjustment down and watched the results. I found that at a setting of 7 to 8 or so the spikes dropped to about 60 amp spike. NEVER had to replace the alternator again over the next 5 years I owned the car.  Remember it's the Bass that draws biggest. Hope this helps!
I would test it as soon as possible and look for an adjustment know on the amp   

[humshark]

Kingbee beat me again,

I had an amp one that "sensed" when there was an audio signal, then turned on fully.

This is most likely the case. 
The additional sensing wire could be used in the case of CASCADING POWER ON /OFF sequencers.  When using outboard AMPS, those ON/OFF schemes eliminate the "THUMP" you hear when you turn on your radio.

Nice input from the post above on current draw and his experience with amplifiers.  If it's really a big monster, then I'm with you for pulling it!

[Rocketman]

Well, the amp is out, the alternator is in, and I now have a voltmeter to serve as an early warning system for alternator failure.
I would love to have more confidence that I've solved the problem by removing the amp.  Currently, I'm not sure how I'm going to be confident of that, since the problem appears to have been intermittent.  I'm just worried that my alternator will last several thousand more miles, and will die in the middle of my trip next month, when I'm too far from home to recover gracefully.