Date: Thu, 8 Sep 2011 08:41:19 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: 91 Westfalia ground points, battery charging amps
In-Reply-To: <4E684E98.3000008@williamsitconsulting.com>
Content-Type: text/plain; charset="US-ASCII"
Battery charging is a bit of a complex process and it is not linear. As the
alternator is somewhat a constant voltage source charging current varies
with the voltage, charge acceptance of the battery, and the resistance of
the charging circuit. The most current will be drawn during the "bulk" phase
which is up to about 80%. The last 10-20% take a long time especially
without the ability to raise the voltage. A proper charge also includes the
off gassing stage which doesn't really happen at 13.8 volts.
Again there are variable but the group 41 battery will take somewhere around
20 amps during the bulk stage. A major limitation is the undersized wiring
from the alternator. This should be improved.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Steve Williams
Sent: Thursday, September 08, 2011 1:12 AM
To: vanagon@GERRY.VANAGON.COM
Subject: 91 Westfalia ground points, battery charging amps
Hi,
I am starting to familiarize myself with my 91 Westfalia's (2.1
standard) electrical system in preparation for a bit of a road trip.
I have been a lurker/occasional poster on this list and from my
eavesdropping, it seems like there are the following ground points:
- Engine to chasis
- Transmission to chasis
- Fuse block
- Battery negative cable (?)
I intend to remove the ground connection (both ends, one end at a time),
clean wire and ground point (wire brush), thin coating of dielectric
grease and re-assemble. Have I missed anything?
I am also curious about what current the battery (or batteries if I put a
2nd one in) charge at. I realize that it changes over the charging cycle,
but what current would generally be expected to end up running down the wire
with the battery at maximum discharge (60% or whatever, not FLAT) with a
standard (90 amp?) alternator? Ballpark kind of figure... this would be
regular lead acid batteries. (Assume good grounds/cables and full
alternator voltage getting to the batteries, which I understand is not
always the case).
Does the "charge time" roughly correlate to "discharge time"? For example,
if I used 5 amps out of the battery for 4 hours and the alternator recharges
at 20 amps, would it take (ballpark +/-50%) 1 hour to "replace" the juice I
used?
I'm trying to figure out driving time vs. recharge time.. bit new to this
all.
Thanks,
Steve Williams
