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#1jess
Samba Member
Joined: May 15, 2018
Posts: 4
Location: Walnut
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 Posted: Tue May 15, 2018 12:22 pm Post subject: Alternator upgrade |
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| Hello vw family. I have a 68 bug , I'm going to upgrade from generator to alternator, and I would like to know if anyone can recommend a reliable alternator. I'm going to be installing a sound system, 1,000 watt amp and a air compressor for air ride. I'm new to vw's. Thank you. |
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Wayne S. Johnson
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Joined: April 12, 2006
Posts: 1265
Location: GILROY, CA
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#1jess
Samba Member
Joined: May 15, 2018
Posts: 4
Location: Walnut
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| Posted: Tue May 15, 2018 2:47 pm Post subject: Re: Alternator upgrade |
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| Thank you sir |
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mukluk
Samba Member
Joined: October 18, 2012
Posts: 7028
Location: Clyde, TX
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| Posted: Tue May 15, 2018 3:23 pm Post subject: Re: Alternator upgrade |
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At full output your amplifier will be consuming right around 80 amps. Add on the amp draw of your air ride compressor plus roughly 20-25 amps for normal engine and lighting requirements for a stock car to figure out how large of an alternator you'll need to keep the battery from depleting with everything up and running. Just a rough estimate, but I'd say you're looking at something right around 125 amps to cover peak draw -- a figure you're not very likely to see often or for much of a time period anyway.
The highest output VW alternator available that I'm aware of is 90 amp, so your best bet will be to run that size alternator with a good deep cycle battery and a voltmeter to monitor when it's time to dial back on the volume. Running a decent size air tank to cut down on the frequency of the compressor kicking on will also help.
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#1jess
Samba Member
Joined: May 15, 2018
Posts: 4
Location: Walnut
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| Posted: Tue May 15, 2018 6:05 pm Post subject: Re: Alternator upgrade |
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| mukluk, thank you for the information, I really like your idea and it makes sense. |
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evillrdnikon
Samba Member
Joined: February 26, 2014
Posts: 180
Location: Las Vegas
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| Posted: Thu May 17, 2018 8:24 am Post subject: Re: Alternator upgrade |
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| So I am sort of dealing with this myself. I just bought a 90 amp alternator from CB Performance. I have a sound system in my car (nothing to big and not 1000 watts) and i have noticed that when my (2) 380cc air compressors kick on to fill my 3 gal tank my retro sound radio will turn off for a second. this is on my 55amp alternator. This 90amp upgrade should be perfect since 1) the air compressors are not running all the time and 2) the 2 systems will rarely be running at the same time. I have converted all my light and everything to LEDs so my draw is extremely low. The only draw is from my stereo, compressors, and starter. They can add up. Hope this helps. I know the 90 amp alternator will run 45amps at idle so keep that in mind. |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Thu May 17, 2018 10:08 am Post subject: Re: Alternator upgrade |
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What about a second deep cycle battery connected thru an RV battery isolator. The isolator allows the one alternator to charge two batteries and not allow one weak battery from discharging the other. Make your second battery a large capacity one w/ an additional capacitor to handle power spikes and you should be able to avoid any power sags.
Will the 90amp alternator be able to keep up with the constant draw of the amp and the air compressors... not sure.
One idea I had been tossing around for a while.... add a second HO alternator (120A+?) in the engine compartment. Something like this:
From a thread on common hacks when VW replacement parts are not commonly available. In the above pic the second alternator compromises the original generator (notice how little belt contacts the generator pulley) which actually compromises the cooling fan (not good). The belt slips at higher rpms and you get less cooling where you need it most.
I would go with a serpentine belt system (wider belt) and somehow add an extra tensioner pulley in between the two alternators to get more belt contact surface area on the pulleys. Might need an extra pulley to the right of the second alternator so the belt can clear and make it back to the crank pulley.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 76939
Location: Sneaking up behind you
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| Posted: Thu May 17, 2018 10:46 am Post subject: Re: Alternator upgrade |
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
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AlmostHeavenWV_VW
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Joined: October 12, 2017
Posts: 1966
Location: WV
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| Posted: Thu May 17, 2018 12:32 pm Post subject: Re: Alternator upgrade |
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Wut?
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vwkirb
Samba Member
Joined: January 16, 2007
Posts: 812
Location: Athens, GA
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| Posted: Thu May 17, 2018 12:50 pm Post subject: Re: Alternator upgrade |
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thats a sweet set up glen, but good luck findng it.
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#1jess
Samba Member
Joined: May 15, 2018
Posts: 4
Location: Walnut
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| Posted: Thu May 17, 2018 6:06 pm Post subject: Re: Alternator upgrade |
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| All great ideas and information, I see this getting up there in price. I just want to do it right the first time. I really appreciate everyone's ideas and time. |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Fri May 18, 2018 7:52 pm Post subject: Re: Alternator upgrade |
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I modified the earlier pic to show the tension pulleys I mentioned. Notice how much more contact the generator pulley has with the belt.
(sorry about the rushed mspaint job)
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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vwkirb
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Joined: January 16, 2007
Posts: 812
Location: Athens, GA
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| Posted: Sat May 19, 2018 10:26 am Post subject: Re: Alternator upgrade |
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| ashman40 wrote: |
I modified the earlier pic to show the tension pulleys I mentioned. Notice how much more contact the generator pulley has with the belt.
(sorry about the rushed mspaint job) |
That would be a great way to route it, too often we end up seeing belts routed funky ways that don't have good contact on the driven component pulley.
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Wayne S. Johnson
Samba Member
Joined: April 12, 2006
Posts: 1265
Location: GILROY, CA
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| Posted: Sat May 19, 2018 8:15 pm Post subject: Re: Alternator upgrade |
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Don't worry about your VW alternator. First of all, amp companies lie about the power output. Sure running an amp on a resistive load and sine wave will pull a lot of current, but music is far from a sign wave and the average current that is supplied to the 12V input is a lot less with music.
Take a look at my 6V power amp. the average current is about 8 amps driving 15" speakers. The current with a 12V amp would average about 4 amps under the same test conditions as seen in my video. The analog meter on the left is 12A full scale.
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mark tucker
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Joined: April 08, 2009
Posts: 23937
Location: SHALIMAR ,FLORIDA
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| Posted: Sun May 20, 2018 7:12 pm Post subject: Re: Alternator upgrade |
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| I wood just get a 75 or 90 amp alt and stick it on....and do the required gen to alt mods if required. I had a new(put on new bosch) that lasted about 2 years.. the china one has lasted.....14 or more years...and was working when I parked yesterday. |
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EVfun
Samba Member
Joined: April 01, 2012
Posts: 5481
Location: Seattle
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| Posted: Fri Jun 29, 2018 1:53 pm Post subject: Re: Alternator upgrade |
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OMG Wayne, with that setup you could recharge your electric car while you drive. 
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| Wildthings wrote: |
| As a general rule, cheap parts are the most expensive parts you can buy. |
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ashman40
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Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Fri Jun 29, 2018 11:06 pm Post subject: Re: Alternator upgrade |
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| mark tucker wrote: |
| I wood just get a 75 or 90 amp alt and stick it on....and do the required gen to alt mods if required. I had a new(put on new bosch) that lasted about 2 years.. the china one has lasted.....14 or more years...and was working when I parked yesterday. |
Part of the reason I came up with the crazy idea to add a generic alternator next to the stock generator was because of how difficult it can be to removed/replace the alternator/generator.
If you buy an aftermarket stock style rebuilt alternator and it fails on you after a few days/weeks you will need to remove the alternator from the fan shroud, disassemble the fan and then put it all back together. I feel this is one of the motivations to buy expensive NOS alternators instead of rebuilt ones. The time/cost of swapping out a bad replacement discourages buying rebuilt units.
In the above concept pic above, replacing the generic alternator should only take 15min and the fan remains mounted in the housing. So even if you buy a rebuilt generic alternator and it goes bad the next day you can get a replacement fro the FLAPS and not have to spend the next weekend R&R the alternator.
The old generator should actually be gutted and only the bearings and shaft that drives the fan should remain. I was looking for a way to build a generator sized shell that allowed the pulley to drive a shaft that spun the fan. The empty generator housing could be purposefully modified to mount the generic alternator.
When I first started to think if this years ago the cost of alternators was rather low so such a mod would not be cost effective. But as the cost of replacement alternators rise this mod becomes more cost effective. The only question is whether it could be reliable?
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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bluebus86
Banned
Joined: September 02, 2010
Posts: 11075
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| Posted: Sat Jun 30, 2018 9:52 am Post subject: Re: Alternator upgrade |
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My 63 Microbus had three electric system driven by a triple crank pulley. stock 6 volt generator to run the Bus, 12 volts alternator for the camper fridge, hotwater heater, sink pump, camper lights, and 110 volts alternator for the microwave oven.
This was installed back in 1973 or so, got me and family thru a month long Alaska road trip, including several hundred miles of dirt logging road, all with a 1500 cc 50 HP motor.
Bug On!
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