Date: Tue, 25 Jan 2011 13:41:28 -0800
Reply-To: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM>
Subject: Re: Charging system questions.
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if you are changing both batteries at once..
how about disconnecting the starting battery after the engine is running and
alt changing ?
very low tech way to make sure you get full charging to the aux batt, which
I suspect could be tired anyway.
I'm low tech on things like this ..
I like KISS ..keep is simple stupid.
All I do is have to batteries each with a battery switch..
then I get to choose which battery to start off of,
which battery is getting charged etc.
there is only ONE thing to be careful about ..always make sure one battery
is in the circuit any time the battery is running.
give full redundancy ...
full flexibility, and full manual control.
Why people don't do it like this is beyond me ..not idiot proof I suppose.
but charging two batteries in parallel on a system meant to charge one
battery ?????
and what if one is really weak ?
can't work very well as far as I'm concerned.
perhaps you have a stock 65 amp alt.
if it's related to diesel vanagon , I make an adapter bracket to fit the
common 90 amp waterboxer alternator.
do you have a simple battery hydrometer ?
and nice lead acid batteries with cell caps so you can test each cell ?
a small hydrometer costs like 3 bucks at a FLAPS ..and will tell you easily
the condition of each cell.
You got one bad cell , the battery is basically junk.
and yes..if I have 14 at the alt and loose up to a volt to the battery, I
work on that ...better / cleaner cables....redundant cables if necessary, on
both pos and ground sides.
and the battery switch method for each battery ..
totally completely fool proof ......as long as you keep at least one battery
connected while engine is running.
what's not to like ?
it's simple, robust, low tech, inexpensive ...
and you can start off either battery , and control which single battery gets
charged ????
I mean ..why not ?
you have to think a little..
but having full control is so nice.
ever notice that everything in a basic small aircraft is totally manaul
control ??
that's for simplicity, light weight, and reliability ..
you have to have a brain to remember carb heat on or whatever..
and flaps set right for take off or landing ..
or fuel mixture..
but by golly , you have TOTAL control and it's all low tech and
simple/robust.
Why not do it that way ?
and totally end all this mystery why is my aux batt not getting charged
right ? And simple is good.
I would only have two identical type batteries I think too. ideally about
the same age each too.
and the 90 amp alt is super common ..
heck, I can even get adjustable solid state regulators for those ..or your
65 amp one ,
but I don't normally mess with those anymore.
Make it simple whenever possible for the most versatility ..
heck, in my system if both batteries are a little weak...you can start off
both of them if you need to. Full redundancy, yet simple with FULL control.
Scott
www.turbovans.com
----- Original Message -----
From: "Don Hanson" <dhanson928@GMAIL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Tuesday, January 25, 2011 10:42 AM
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
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