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RE: voltage issues

To: "Mackay, Steve" <steve.mackay@analog.com>
Subject: RE: voltage issues
From: "Stephen L. Hanselman" <tr6@kc4sw.com>
Date: Mon, 13 May 2002 16:26:03 -0700
The time delay for the terminal voltage to come up to 14.2 is probably OK.
A lead-acid battery is a set voltage device (a ni-cad for example is a set
current device).  This means you select the voltage you want to charge to
and pump current in.  When the terminal voltage reachs your set point the
current into the battery approachs zero and the battery is charged.   When
seting stationary batteries we usually ended up taking two or three days
tweaking the charge circuit to "float" the battery where we wanted it.

The terminal voltage is somewhat variable based on the ambiant temprature,
and I haven't a looked up the coorelations lately).  Generally as temp goes
up the nominal voltage goes up. A single lead-acid cell is generally
considered fully charged at 2.2 volts leading to 13.6 for a standard 6 cell
auto battery.  One thing you should do is invest in a hydrometer and measure
the specific gravity of each of the cells in the battery.  With the temp
conversion chart that will tell you if your battery is properly charged.

The Ampmeter should be moving more towards zero as the DVM voltage gets
closer to the steady state terminal voltage.

If I read the drawings right there MAY be a way to adjust the regulator, but
I kinda doubt it'll be easy.  In the bad old days you could bend the relay
arm(in the regulator)to adjust the set point, but not anymore.

>From your description, I'd be a bit concerned that your alternator (assuming
it is the one with the built in regulator) is set at too high a terminal
voltage.  Even though you have a new harness, you still might want to check
all connections including the battery cables themselves.

The other thing to do is get a battery box so the overspill goes in a nice
plastic (read not affected) box.

Steve Hanselman
tr6@kc4sw.com

-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net]On
Behalf Of Mackay, Steve
Sent: Monday, May 13, 2002 12:40 PM
To: 6pack@autox.team.net
Subject:


Charging question. I noticed a very small amount of battery acid on the
battery
shelf next to the battery. I inspected the battery for cracks with negative
results. Removed the battery, naturalized the area and installed the
battery. At
this point I believe I have an over charging problem. I did the following
checks. DVM across the battery with everything disconnected battery read
12.9 v.
With the DVM meter connected I started the car. During starter cranking
period
DVM reading dropped to 11.9 v (Normal) as soon as the car started the  DVM
meter
went to 13.5 volts and climbed over the next 60 seconds to 14.2v @ 1900
rpm's.
After driving the car for over an hour the meter on the dash and the DVM
never
dropped below 14.2v. My question

1. Should it take 60+ seconds for the DVM and the amp meter on the dash to
climb
from 13.5v to 14.2 volts?
2. Regardless of the run time should the meter always be reading > 14.v when
running. Doesn't the system drop back to 12.5v at some point?
3. What is the most common problem, Alternator?

History - New battery, Rebuilt alternator, New wire harness, The car has 5k
on a
total frame off rebuild

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