ok, my thoughts.
It is recognized that it can be a little rough on an alternator to use it to
charge up a low battery.
I'd say they are not actually designed for that.
They are designed to replace the voltage used starting the vehicle, then
maintain nice charging voltage on the now-fully charged battery ( say after
the first few minutes of running ) and to keep up with any electrical load
the car can through at the battery ..
like say both heater fans on, wipers on, and rear window heater on, and high
beams ....keep up with all that.

I would say the safer thing to do is charge the battery some first.
I have not found trickle chargers to of much use for that though myself.  I
make it a regular part of my vanagon tools to have a common 2/10/50 amp 12
volt battery charger . Then I'd just do 20 minutes to  a half hour at 20
amp, then start it up with new alternator.

I liked that thinking about the new brushes needing to break in, and don't
push them too much at first.  Good thinking there, whether that's true or
not.
Scott
www.turbovans.com
----- Original Message -----
From: "John Rodgers" <inua@CHARTER.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, April 24, 2010 10:39 AM
Subject: Re: alternator installation

> It's been a long time since I have thought on this - but I seem to
> recall that a strong charge from the battery(or jumper battery) is
> required to activate the field of the Alternator or the thing won't
> charge, even if it is turning. If your battery is strong enough to turn
> your starter motor - which takes a whopping amount of amps to turn
> against the load of the engine - it should be charged sufficiently to
> activate the field.
>
> John Rodgers
> Clayartist and Moldmaker
> 88'GL VW Bus Driver
> Chelsea, AL
> Http://www.moldhaus.com
>
>
> On 4/24/2010 11:41 AM, Bill MacLachlan wrote:
>> Hi all
>> List wisdom&  experience needed:
>> I'm installing a new alternator.
>> Label on the new alternator says have the battery fully charged before
>> hooking up the alternator.
>> My battery is low.
>> How critical is the warning?
>> Do I have to dig out the trickle charger and recharge the battery first?
>>
>> thanks
>>
>> Bill M
>> 82 GL I4
>>
>>
>>