Alternator Output not keeping up with audio system |
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Alternator Output not keeping up with audio system |
Kansas 914 |
Oct 25 2011, 11:14 AM
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#1
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
I installed a Boston Acoustics GTA-504 and since install I have not been able to charge the battery during long drive with the music cranked up. I really thought the 55AMP alternator would have been fine for the small amp.
I am running 6.5" separates on 2 channels and bridged the other 2 channels to mono for the sub. All speakers are 4 ohm. There are two 25A fuses on the amp and I added a single 60A in-line at the battery for the power to the amp. No fuses have ever blown - but I wondered if the alternator is actually cranking out 55 Amps. If I don't drive with the music on it works and charges the battery fine. I think I might just install a bus alternator (75Amps) unless others think it is a mistake. Link to install manual: http://www.bostonacoustics.com/PDFs/manual..._2_4_Ch_Man.pdf Quick Specs: |
Mike Bellis |
Oct 25 2011, 11:24 AM
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#2
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None |
You can try adding additional grounds from the battery to the engine.
Bottom line, alternator to small to keep up with demand. |
VaccaRabite |
Oct 25 2011, 11:26 AM
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#3
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En Garde! Group: Admin Posts: 13,441 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Lots of things here
Corrosion at connectors force more current draw then expected. It may not be enought to pop a fuse, but a little will add up when the alt is at the limit. The alt may not actually produce 55 amps any more. If you have better headlights, horns, fuel pump, oil cooler, AC, they are all sapping more power then was designed. Voltage regulator may be slightly wiggy. Too many variables. Do a load test and see what kind of power you are really making. |
Kansas 914 |
Oct 25 2011, 11:27 AM
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#4
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
You can try adding additional grounds from the battery to the engine. Bottom line, alternator to small to keep up with demand. Hi Mike - thanks - I was hoping I would be okay - moving to plan B (Bus alternator). I don't think spending the big bucks to have the alternator re-wound makes sense for this small system. |
Kansas 914 |
Oct 25 2011, 11:30 AM
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#5
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
Lots of things here Corrosion at connectors force more current draw then expected. It may not be enought to pop a fuse, but a little will add up when the alt is at the limit. The alt may not actually produce 55 amps any more. If you have better headlights, horns, fuel pump, oil cooler, AC, they are all sapping more power then was designed. Voltage regulator may be slightly wiggy. Too many variables. Do a load test and see what kind of power you are really making. Connections are all new - regulator is not. I will get an ammeter and see what I am truly working with. Thanks Zach - cheers! |
Mike Bellis |
Oct 25 2011, 11:40 AM
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#6
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Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None |
You need to add up all the differet demands from your system. The factory alternator was sized just big enough to run the car with a cheezy AM radio. Once you add load you need to upgrade. First, you can up size the charge wire from the alternator. This will help current flow more freely to the battery. Upgrading or adding grounds will also help. Car manufacturers size all the wiring just big enough to prevent fires. Not for electrical performance.
I don't have a T4 engine. I run a 185 Amp Powermaster alternator. I never run out of juice. |
stugray |
Oct 25 2011, 01:12 PM
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#7
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
Who drives a 914 while NOT listening to the engine? ;-)
Just curious? Stu |
Spoke |
Oct 25 2011, 01:39 PM
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#8
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Jerry Group: Members Posts: 6,978 Joined: 29-October 04 From: Allentown, PA Member No.: 3,031 Region Association: None |
Not charging the battery with the amp can be tested with a voltmeter on the battery.
You can test this by running the car at about 2k RPM with all electrical appliances off and a voltmeter on the battery. Monitor the battery voltage and turn on electrical appliances one by one; lights, amp, etc. and see when the battery voltage drops. |
messix |
Oct 25 2011, 02:09 PM
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#9
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
the head lights draw more power than that amp would, does your batt drain when driving with the lights on?
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Rod |
Oct 25 2011, 02:29 PM
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#10
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Senior Member Group: Members Posts: 616 Joined: 1-January 08 From: Farnham UK Member No.: 8,526 Region Association: England |
That amp should not flatten the battery whilst driving, when driving the amp takes it's current from the alt, not the battery so I reckon there is actually something up with your battery - what does it float at??
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stugray |
Oct 25 2011, 02:47 PM
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#11
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
"when driving the amp takes it's current from the alt, not the battery"
The amp will take the current from whichever supply is at the higher voltage. When running the whole system is at the same potential, so all share the load. If the car pulls 60 amps, and the alt is only putting out 50 amps, then 10 amps is coming from the battery until loads are shed to below 50 amps. Even then, if the alt puts out 50 amps, an the load is exactly 50 amps, then there is not enough left to charge the battery. Stu |
Rod |
Oct 25 2011, 03:08 PM
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#12
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Senior Member Group: Members Posts: 616 Joined: 1-January 08 From: Farnham UK Member No.: 8,526 Region Association: England |
That amp will be drawing 26.6 amps when driven really hard - no more. His alt surely still puts that out??
I have a theoretical 133 amp drain on my battery using the same watts/voltage equation (1600w system) and never struggled with the 55 amp alt once I changed to an Optima battery. Check earths (especially on the amp to chassis cable) and make sure your batts upto scratch (IMG:style_emoticons/default/smile.gif) |
Cap'n Krusty |
Oct 25 2011, 03:28 PM
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#13
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
Good luck finding anything other than the 55amp version. The major wholesalers of Bosch remans don't even list it, and it was pretty rare when it was more-or-less available.
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Drums66 |
Oct 25 2011, 03:43 PM
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#14
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914 Rudiments Group: Members Posts: 5,321 Joined: 15-January 03 From: Coronado,Cali Member No.: 151 Region Association: Southwest Region |
......What about a 911 alternator?...but I think everything in the circuit
have to be comensurate no? (IMG:style_emoticons/default/idea.gif) (IMG:style_emoticons/default/bye1.gif)( may be over KILL) try some of the suggestion's before you get drastic! |
Kansas 914 |
Oct 25 2011, 03:51 PM
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#15
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Advanced Member Group: Members Posts: 2,999 Joined: 1-March 03 From: Durango, Colorado Member No.: 373 Region Association: Rocky Mountains |
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hcdmueller |
Oct 25 2011, 04:02 PM
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#16
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????????????? Group: Members Posts: 542 Joined: 4-February 06 From: UK Member No.: 5,527 Region Association: England |
The bus/912e alt is 70amp and available from places like Autozone or NAPA. I can't guarantee if they are great quality. You are supposed to use a different pulley with a cooling fan but they are NLA so you will have to use your regular 55amp pulley. The cooling boot is different but available from Bus Depot. I have an old Bosch 70amp in my 914. The biggest difference I noted was when I added a ground wire straight from the alt to the chassis. I would try that with the 55amp first.
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stugray |
Oct 25 2011, 04:18 PM
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#17
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Advanced Member Group: Members Posts: 3,824 Joined: 17-September 09 From: Longmont, CO Member No.: 10,819 Region Association: None |
"The biggest difference I noted was when I added a ground wire straight from the alt to the chassis. I would try that with the 55amp first."
OR a ground straight from the alt to the Amp. If the Amp is pulling the highest current then that would make the biggest difference. Stu |
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