Date: Sun, 13 Feb 2011 11:06:56 -0500
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Charging system questions.
In-Reply-To: <AANLkTi=xMz-+J==+J8Qo8=V2-4+6Uh01tWJwzQqgR8qg@mail.gmail.com>
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I don't know if this was answered yet so here goes.
A battery with 10 volts at rest is either extremely discharged or a cell is
shorted.
With a shorted cell the system voltage will be sucked down as that battery
will draw an excessive amount of current.
14.02 volts at the alternator is fine. Design is 13.8.
Batteries used for deep cycle (even starting batteries) should occasionally
be tested for performance. A battery with a shorted cell can also overheat
and make quit an acid mess during a long drive.
Group 41 batteries are larger and will still fit in the boxes under the
seats.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Don Hanson
Sent: Tuesday, January 25, 2011 1:43 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Charging system questions.
Hey all,
I am having issues with my aux battery taking and holding a charge that is
adequate for how I am using my van right now.
My "set-up", which has been satisfactory for my needs for three years now,
is as follows: I have a 60amp Bosch Alternator, replaced with a rebuild
about 2yrs ago. At that time, I replaced one of my 2 identical NAPA Sure
start 65 (#5042) BCI 42 batteries with a new one, installing the new one
into the starting (vehicle) battery box under the passengers seat and taking
the older one (about 3 yrs old, minimum) to the aux. battery position (under
the driver's seat) I have the two batteries connected with a large RV
cannister style relay, which is activated by current from the ignition
switch, after the engine cranks and catches.
So, with the engine off, all my electrical widgets are powered by the
coach battery (the one under the drivers seat). The starter battery is kept
out of the circuit by that relay... When the ignition is activated....that
happens using only the starter battery..passenger's side...and then once the
engine starts, I hear the relay click and the current goes to both
batteries. I also have a toggle switch to control that relay, should I want
to put the full alternator output back into the starting battery, only.
So, a fairly simple system...one I have used with success for a few years
and identical to other RV systems I've used in the past.
Recently, my auxillary battery hasn't been up to my demands. I mainly
use that to keep my laptop charged, to listen to some sirrius sat radio for
a few hours in the AM and to power my water pump at the sink...Not a large
constant draw.
I am thinking my little BCI 42 battery is finally wearing out, but in
order to learn something...I took some numbers and would appreciate some
knowledgeable input on the numbers. I did order up a new battery and it is
coming. I am considering also getting a new voltage regulator...I will
probably put that in the alternator and keep the one I currently have as a
spare. I want to have a spare anyhow.
So with the engine running and the starter battery taking a charge....I
get a reading of 14.02 v at the alternator
at the starter battery, I get 13.72v
With the second battery in the charging loop...the relay activated...I
get a reading of 13.58 at the starter battery....at the coach (aux) batt. I
get about 12.xx when charging...but that battery is really quite
dead...reads about 10.2 volts at rest and will not run my stereo right
now. When I run the vehicle, both charging..I can get enough power in the
Aux battery to make the stereo run for maybe 15 minutes...or bring my
laptop battery up about 3/4 charged.
I cleaned all the connections and have topped up the electrolytes before
taking these numbers with a radio shack digital multimeter...
So is 14.02 at the alternator good? Is that voltage drop between there
and the starter battery near acceptable? Am I on the right track, thinking
my older aux battery is needing replacement? Worthwhile swapping in a new
voltage regulator and putting the present one into my spares box?
Thanks, Don Hanson
