Date: Wed, 27 Jun 2001 22:20:08 -0700
Reply-To: David Marshall <vanagon@VOLKSWAGEN.ORG>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Marshall <vanagon@VOLKSWAGEN.ORG>
Subject: Re: 130Amp alternator upgrade?
In-Reply-To: <B75FFBDA.64F9%albell@uvic.ca>
Content-Type: text/plain; charset="US-ASCII"
The Bosch distributor was telling me about an adjustable voltage regulator
for the Bosch alternators - I think it could go up to 16V. The logic behind
this is on some vehicle, like our vans and most Audis, there is a long run
between the alternator and the battery. The battery wants to see 14.4V for
charging but with the long cable run the I^2xR losses result in a smallish
drop in voltage by the time it gets to the battery - by turning up the
output of the alternator you can make it so there is 14.4V at the battery
again. Anyhow ever try this?
Another link I remember seeing is installing a Ford external voltage
regulator in a Volvo (normally a Bosch alter with an internal reg) - I think
this could successfully done in the Vanagon and the mounting of the voltage
regulator would be at the battery so it could sense the voltage where it is
needed.
David Marshall
Fast Forward Automotive Inc.
4356 Quesnel Hixon Road
Quesnel BC Canada V2J 6Z3
mailto:info@fastforward.ca <mailto:info@fastforward.ca>
http://www.fastforward.ca <http://www.fastforward.ca>
Phone: (250) 992 7775 FAX: (250) 992 1160
. Vanagon Accessories and Engine Conversions
. Transporter, Unimog and Iltis Sales
. European Lighting for most Audi and Volkswagen models
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of Alistair Bell
Sent: June 27, 2001 9:09 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: 130Amp alternator upgrade?
TBerk,
well I have to agree and disagree with you on one point! (hows that for a
Canadian response!)
I agree that the alternator output will drop when a load is applied but...
My alternator states a nominal output of 14V, I measured 14.1 or
thereabouts. With a 450W load, (2X100W headlights plus one 250W aux light)
the voltage only dropped to 13.8 - 13.9. All measurements done at the
battery, which is in the engine compartment in my van.
BTW, the two previously mentioned loads are on separate supplies, 2 X 8
guage wires, the headlights using 2 40 amp relays (one for lows, one for
highs) and the aux light has a single 70 amp relay.
on 27/6/01 2:20 PM, T Berk at tberk@mindspring.com wrote:
> Good point Alister, just wanted to add-
>
> When calculating the output it is best not assume 14 volts, there is
> voltage drop and other reasons why you hardly ever actually _see_ 14.5
volts.
>
> Even so, if you calculate out (12v*90A)*.667 = 720.36 watts. Still a
bunch.
>
> The other thing to consider is it takes mechanical energy to 'generate'
> the electricity. This means you will loose more HP to the Alt the higher
> amperage you choose.
>
> I also think if you RELAY all those lights and make the travel of
> electrons efficient around the car you will be fine with the 90A unit.
>
> hth,
> TBerk
>
>
> Alistair Bell wrote:
>>
>> A couple more points...
>>
>> Alternator output is listed on the alternator, for example my 90A Bosch
has
>> this bit of code: N1-> 14V 34/90, which translates to 14 volts at 3400
rpm
>> (alternator speed, faster than crankshaft speed due to pulley size), and
90
>> Amps.
>>
>> But it is commonly assumed (i love that phrase) that maximum continious
>> alternator output is at best only 2/3 of their max rating.
>>
>> So with that in mind:
>>
>> - Dave C. will have 460W of light producing apparatus up front
>> - A 90 A alternator will continiously produce 0.667(90A*14W) = 840W
>>
>> Leaving 380W "spare"!
>>
>> (the 55A alternator will be able to produce 0.667(55A*14V) = 514W)
>>
>> Also remember that this doesn't take into consideration losses due to
wiring
>> resistance etc.
>>
>> BTW Dave C., my alternator is currently (!) handling a 450W light load
with
>> no
>> problems, don't have the killer stereo though.
>>
>> Alistair
>>
