Magneto vs Battery draw for accessories and AMP

[Sopher]

I was at a motocycle show today and asked about installing an AMP and its wiring from an Audio for Motocycle vendor.
He stated that the current draw would come from the charging system when the bike is running and NOT the battery.

IS this true? WHat is the power capabilities of the Spyder (I have the RTS)?
Will it handle an audio AMP that can supply 70rms watts to 4 channels?

Specifics will help.

Thanks!

[NancysToy]

The electrical draw is off the system...not specifically the battery or the alternator. If the charging system output exceeds the draw, part of that output is used for the machine, and the rest (if any) charges the battery. When the output is less than the current draw, the battery is used as a supplement, and is discharged in the process. All the juice originates at the alternator, some is just stored in the battery

At idle, and even well above that if your amp, heated gear, or other accessories draw enough current, your charging system will not be able to keep up and the battery will become depleted. Think of it as a reservoir in a water system, when you open the faucet the water tank supplies your needs, until the pump kicks in and replenishes the system. At higher rpm, the charging system will hopefully keep up...unless your draw exceeds the capacity of the alternator at the speed. If you have a chronically large load, that exceeds the alternator capacity, no matter how many batteries you have, they will eventually become discharged. It is like drawing 120 gallons per minute from a water system that can produce only 100 gpm...eventually the tank becomes empty. The only way to refill is to reduce the load on the system, while you continue to charge.

[BajaRon]

I agree with Scotty (afterall, he is right so why not).

I think what the saleman may be inferring is that the AMP draw is going to be substantial and as such will probably be exceeding what your battery can suppy, requiring the charging system to make up the difference.

You need to know how much the sound system draws to know if you're going to have an issue. Knowing what the amp supplies to the speakers is not helpful. There is a lot of loss between input and output.

Once you know how many amps the system draws, you can then compare it to the output of your charging system. You will need some headroom to allow for other current drawing systems that are installed on your Spyder.

You may be able to find a more efficient audio system that would go a little easier on the electrical capabilities of your Spyder. The problem is, most audio systems are designed for cars which have bigger charging systems than our Spyders.

One way to lessen the current draw is to switch to HID or LED lighting. Especially if you're running the fog lights. Halogen draws a fair amount more than HID's. And incandescent draws a lot more than LED. Expensive but they are brighter and last longer too.

[Sopher]

Great replies!! thanks guys!

I would not have guessed that HID lamps draw less then the current lamps. I would have thought the other way around. How do I find the draw of the amp?
So your also saying that I must add another mod to my bike by replacing the lamps with HID. Thus to give the AMP more feed.

I wish other Spyder ryders that have done substancial audio systems would chime in. I hate being the first to discover the pitfals.

[BajaRon]

Great replies!! thanks guys!

I would not have guessed that HID lamps draw less then the current lamps. I would have thought the other way around. How do I find the draw of the amp?
So your also saying that I must add another mod to my bike by replacing the lamps with HID. Thus to give the AMP more feed.

I wish other Spyder ryders that have done substancial audio systems would chime in. I hate being the first to discover the pitfals.

No, I'm not saying to change your lighting necessarily. Just that there are more than 1 way to skin the cat. The Amp should have specs.

I looked at the Boston Acoustics GTA-704 — 70 watts RMS x 4 amp. This rating is at 14.4 volts which means it's going to draw more current at lower voltages (like idle or whenever your charging system is putting out less than 14.4v). This may be what your salesman was referring to. If you don't have the Spyder running it's really going to suck the juice, though you won't need the volume up nearly as high so that would reduce the draw somewhat.

I could not find an input or power consumption for the amp so I just did some ballparking. This amp requires 2 25A fuses. Obviously you fuse for more amps than you expect to ever draw and you have to factor in the draw at less than 14.4v. So let's say you're drawing 1/2 the fused current or 25 amps. at 14.4v. That's 360 watts. At 75% of fused capacity you're looking at 540 watts used.

I agree that the best advise would be from someone with a system installed. Then you'd have some real world data to work with.

[Smokinspyder]

See I would be able to give you a professional installers view and suggestion but I have yet to install a stereo in my Spyder . Having done normal motorcycles before I guess i can go off that , but they also dont have the electronics that the spyder does. I have pictures somewhere of the previous installs I have done on bikes on a old road pi.. Road king I had put a small 4 channel like yours, obviously with a small sub and speakers then a fold out monitor. As far as hurting anything electrical like its charging system as far as I know its still on the road( well when its warm out in chicago its out on the roadand he hasnt had to change anyhting except we put a different battery in at the original install . But since the spyder has much more electrical technology I dont know, I do know someone who did a small stereo like yours or the one i described above and that install went fine with no negative effects . But again I have no stereo experience with the spyder personally so I couldnt tell you if you need to add a battery , or cap or any other mobile electronics "tricks" to help keep power to the rest of the bike .

[Smokinspyder]

All very good equipment. For a extremely basic system 2 speakers and a sub a single 4 channel is more than needed. use the 2 front channels for your JL slam pack one per speaker, then bridge the rear outputs for the sub and you should be happy with the install . Now someone else might be able to help with how much the spyder can handle LOL . I guess I need to get off my rear end and install some kind of stereo so I can be of better help LOL .

[Sopher]

Update:

Well the Alpine KT445 is not going to work. I beleive the output to the speakers is less than the 2volts needed for this amp to AMP up the signals.
I tested on on speaker. no sound.

I am researching Arc audio, Massive audio or JBL Amps.
Some specs I am looking for:
Smallest size possible, 4 channel, speaker level inputs, etc.
Some models: ARC KS125.4
JBL MS-A1004

[AMTJIM]

I haven't seen the problem on this Spyder Rotax, it seems to be a good stator and electrical system. The Buell Rotax has a weak stator and this problem seems to be occuring in other fairly current machines. Watch the amps, outside of draining the battery keep in mind the possiblity of buring up your stator. I was suprised to see some of the Goldwings of all machines having some problems with this. Not sure what the difference is in the number of winds on the coil or the gauge of copper wire is between machines, just consider all the amps with each addition.

[docdoru]

Great replies!! thanks guys!

I would not have guessed that HID lamps draw less then the current lamps. I would have thought the other way around. How do I find the draw of the amp?
So your also saying that I must add another mod to my bike by replacing the lamps with HID. Thus to give the AMP more feed.

I wish other Spyder ryders that have done substancial audio systems would chime in. I hate being the first to discover the pitfals.
The HID's draw less power except the first 10-20 seconds (over draw for ballasts). In time, you're looking at 35W (HID) vs. 55W (halogen).
For 3 years I'm running 4 HID's on the RS: http://contour.com/stories/4xhid