--- Jerry Clough <jclough@...> wrote:
From: "Jerry Clough" <jclough@...>
The battery on my 47 CJ-2A doesn't seem to be
charging as fast as it should.
The battery is brand new although the battery store
gave one that was low on
charge. I charged it up and fired up my Jeep. Then I
checked the amount of
volts and my reader said the battery was putting out
6.7-6.9 volts. I also
checked the generator and that was putting out a
steady 7.2 volts. After
about 30 minutes of running, the battery was at 7.1.
I am totally ignorant
on 6-volt systems. Are these good numbers? Is there
a way of determining if
the battery is crap? Could it be the voltage
regulator? How can I determine
if it's the regulator?
Thanks,
Jerry Clough
Green Bay, WI
Dear Friends,
Let me crank up my Advice-O-Matic and see what
happens. If I understand you correctly, these numbers
sound pretty good. Remember a 35 amp 6v generator is
the equivalent of a 17.5 amp 12 generator, which isn't
a whole lot for output. Remember generators don't put
out much at low speeds, unlike alternators. About
15-20 minutes at cruising speed is required just to
recharge what energy was expended for starting.
To see a generator putting out about 7.2 volts sounds
good right after starting. As the battery is slowly
recharged, it will drop back into the 6.5 to 7.0
range. This is comparable to a 12 volt system, which
typically operates from 13-14 volts.
There is a quick way to check if your battery is OK.
Charge it fully and check with a hydrometer to make
sure. Turn on your headlights for about 10 seconds.
This kills what is known as a surface charge. Next
you need to apply a heavy load. If you can borrow a
battery load tester, that would be great. Even your
starting motor with the ignition disabled would work.
With your meter connected, load the battery via the
tester or your starter for 15 seconds. The minimum
after 15 seconds while still under load should be 4.8
volts. (Or 9.6 volts on a 12volt system) Some folks
use 5.0 as a minimum (10 on a 12volt system)
I was a bit confused, though, where you said your
battery was putting out 6.7-6.9 volts, but the
generator was putting out 7.2 volts. Was this at the
same time, or several minutes apart? Where did you
have your test leads during the two measurements? If
your generator was truly putting out 7.2 while at the
same time your battery only showed 6.7, there may be
some voltage drop through the cables themselves, which
will need attention. Don't forget the ground side of
the circuit also, which has multiple connections just
waiting to get you. 6 volt systems are easily slowed
down by the slightest voltage drops.
If you really want to get confused, I can try to
explain how to check for voltage drop along the length
of any conductor under load. It is one of the most
helpful electrical troubleshooting techniques.
Let us know if we can help more. I really like seeing
that 6v battery and massive generator under the hood
of my jeep.
Regards,
Vern
48 CJ2A in Vancouver, WA
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