Author |
Message |
gilg Samba Member
Joined: April 17, 2020 Posts: 62 Location: Fayetteville, AR
|
Posted: Mon May 10, 2021 8:06 am Post subject: Generator + audio system questions |
|
|
Hi guys,
I'm resurrecting a 1972 Super Beetle. It still runs a generator, but I've installed a brand new Wolfsburg West harness and upgraded the fuses to a blade-style block.
I'm now trying to design a decent audio system for it. I'm thinking about a 1200w Blaupunkt 4 channel amp along with a 4-speaker setup and two small subwoofers. I am retaining the old style head unit, and want to conceal most everything else either under the hood or behind the rear seat.
My question: how much power can this generator and harness really support, and what do I need to do to mitigate future problems?
Secondary battery, capacitors, deep cycle battery? _________________ '72 Super Beetle - 1776cc w/ dual Weber 134 ICT carbs, Pertronix ignition, glasspack, Rally+ lift springs |
|
Back to top |
|
|
mukluk Samba Member
Joined: October 18, 2012 Posts: 6985 Location: Clyde, TX
|
Posted: Mon May 10, 2021 9:52 am Post subject: Re: Generator + audio system questions |
|
|
P=IV
Power (in watts) equals Current (in amps) times Voltage.
So we have a stock VW generator which is rated 30A/14V, giving us a maximum possible output of 420 watts. Safe to say this isn't going to support running the car, lights, charge the battery, and come anywhere near to supporting the max output of the stereo you're envisioning. _________________ 1960 Ragtop w/Semaphores "Inga" |
|
Back to top |
|
|
gilg Samba Member
Joined: April 17, 2020 Posts: 62 Location: Fayetteville, AR
|
Posted: Mon May 10, 2021 11:18 am Post subject: Re: Generator + audio system questions |
|
|
Sure, that makes sense - totally wouldn't be running the amp at max watts. However, I'm wondering how much extra wattage a generator has to work with.
I found threads like this which indicate people are running 100-250w systems on a 30a generator without a problem: https://www.thesamba.com/vw/forum/archive/index.php/o-t--t-165714--.html
How many watts does the car itself draw? If I can work with a few hundred extra watts, I think I could have a 1.0-2.0 farad stiffening capacitor and be safe, however that's the big question for me. _________________ '72 Super Beetle - 1776cc w/ dual Weber 134 ICT carbs, Pertronix ignition, glasspack, Rally+ lift springs |
|
Back to top |
|
|
AirHead1966 Samba Member
Joined: October 17, 2019 Posts: 561 Location: Triad Area NC
|
Posted: Mon May 10, 2021 1:09 pm Post subject: Re: Generator + audio system questions |
|
|
gilg wrote: |
How many watts does the car itself draw? If I can work with a few hundred extra watts, I think I could have a 1.0-2.0 farad stiffening capacitor and be safe, however that's the big question for me. |
Well, that depends on what you are running. The coil and distributer, plus choke, etc. (all engine compartment stuff) will not draw more than 10 amps, probably 8. The lights etc. will have some draw, you can calculate that by looking at the wattage on your bulbs. Add wipers, 7 amps ball park as it is on an 8 amp fuse.
For estimation, I would say you could draw up to 20 amps with lights on and wipers going, to run the car. Ballpark additional 5 amps would go to keeping the battery charged. That leaves you with about 5 amps to play with on a 30 amp generator. Also note that the generator will not be producing full 30 amps all the time the car is running.
This is all theoretical ballpark estimation. I would go with a bigger alternator. |
|
Back to top |
|
|
EVfun Samba Member
Joined: April 01, 2012 Posts: 5446 Location: Seattle
|
Posted: Mon May 10, 2021 3:37 pm Post subject: Re: Generator + audio system questions |
|
|
I ran a Sony 250 watt 3 channel amp on a '65 Dodge Dart with a stock 36 amp alternator. If I cranked it up I could watch the dash lighting flicker and the amp meter dance to the drums.
I would figure on 20 amps for the car, plus the amps. I would take their stated wattage and divide by 12 to get peak amps then divide by 2 to estimate the addition current you should have available from the alternator or generator.
If it's really a 1200 watt amp go for a 70 amp alternator. Another option is class D (digital) amps, you get more volume for less power because they are more efficient. It might be possible to faintly hear artifacts, but since most of us are playing compressed digital music I bet not. _________________
Wildthings wrote: |
As a general rule, cheap parts are the most expensive parts you can buy. |
|
|
Back to top |
|
|
jeffrey8164 Samba Member
Joined: January 06, 2018 Posts: 3804 Location: Georgia
|
Posted: Sun May 16, 2021 7:41 am Post subject: Re: Generator + audio system questions |
|
|
I don’t have any digital images because it was so long ago but back in the day I have a generator to power the car and I use an AC bracket with a cut up generator stand bolted to it to run an alternator to the power battery for the stereo. Worked well enough except at idle.
In my current version I’m running about 1150 watts with two amps. I have a 90 amp alternator. You don’t need a deep cycle battery that’s for when you want to run it dead and still be able to charge it reliably. You will want a capacitor so your lights don’t dim to the beat.
_________________ Volkswagen!
Turning owners into mechanics since 1938.
“Let he that is without oil throw the first rod”
(Compression 8.7:1) |
|
Back to top |
|
|
|