VAL Digest V1 #12

VAL Digest        Saturday, September 20 2003        Volume 01 : Number 012




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Topics in Today's Digest:

Re: [VAL] Battery question
Re: [VAL] Battery question
Re: [VAL] Battery question
[VAL] Outlet problem
[VAL] Re:waste tank valves-lubricate?
Re: [VAL] Battery question
Re: [VAL] Battery question
Re: [VAL] Outlet problem
Re: [VAL] Battery question

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Date: Fri, 19 Sep 2003 06:25:54 -0600
From: "gshippen" <gshippen@xxxxxxxxxx.com>
Subject: Re: [VAL] Battery question

Dr. G.

How about a solar panel?  Brunton sells one that will recharge a 12 volt
battery completely in 12 hours or a small wind generator as you travel down
the road?

Cheers, GAS
- ----- Original Message -----
From: "Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx.net>
To: <valist@xxxxxxxxxx.com>
Sent: Thursday, September 18, 2003 9:34 AM
Subject: Re: [VAL] Battery question


> You should be running the refrigerator on propane when you don't have
> 120 volts. Carrying energy in propane is far easier than carrying it in
> sulfuric acid.
>
> The charger may not draw current through the full sinewave of the
> generator, but only at the peaks. The generator may not hold up voltage
> well with that kind of a load. I know a generator my dad and I wound
> about 1957 didn't work well with electronic loads for that same reason.
> The Honda has a 12 volt output also that might charge the battery
> directly and maybe better, but then it would be going through the charge
> controller. And while the initial charging from the constant voltage
> source will be fast, the last half the charge, the tapering will be
> slooooow. The Inteli adjusts the voltage to hasten the charge.
>
> A storage battery as commonly used is made up of cells. Each cell
> provides 2 volts. A 6 volt battery has 3 large cells. Two 6 volt
> batteries in series have 6 cell, giving 12 volts. A 12 volt battery has
> 6 cells all wired internally in series. The cells in a 6 volt battery
> are at least twice as large as the cells in a similar sized 12 volt
> battery (size of the box). Current capacity is proportional to the area
> of the plates in each cell. The bigger the cell the more room for
> plates. Because of cell dividers taking up space, the total energy
> (watts = volts times ampere hours) in a given volume of 12 volt
> batteries is a little smaller (few percent) than in a given volume of 6
> volt batteries. Hence the slight advantage for using the 6 volt
> batteries (in pairs for 12 volts) out in the boonies. That is true IF
> and only IF the battery maker actually fills the cells with plates. That
> is not necessarily true. Some sleazy battery makers will put a small
> area set of plates in a big case to make it look big but be cheap.
>
> Gerald J.
> --
> Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
> Reproduction by permission only.
>
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Date: Fri, 19 Sep 2003 10:23:13 -0500
From: "Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx.net>
Subject: Re: [VAL] Battery question

Maybe if you had full noon tropic intensity sun for 12 hours in a day.
So you'd have to be tracking the sun. The ordinary solar panel, say the
$450 panel that puts out 45 watts peak does just under 4 amps. At solar
peak. Say it does that for 8 hours. That's 32 amp hours. My deep cycle
battery is 90 amp hours. Shy by 2/3 a charge. And in the real world it
won't do that well. Brunton is stretching the truth a looooong ways.
There are 25 ampere hour batteries that one panel would charge in a day,
but that's not the deep cycle on my trailer.

Its more efficient to tap into the tow vehicle's charging system to
charge the trailer battery while traveling than to use a wind generator.
A wind generator could work, but its imperfect and would add more
horsepower load from its wind resistance than taking the same power from
the vehicle alternator. And the modern Bargman connector has a pin
reserved for battery charging and does well on my Caravel and F-150.

Gerald J.
- -- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.

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Date: Fri, 19 Sep 2003 10:28:57 -0600
From: "gshippen" <gshippen@xxxxxxxxxx.com>
Subject: Re: [VAL] Battery question

Excellent!  Should one worry about overcharging the deep cells or can one
wire in a protector?
I still like the image of driving down the road charging by wind. GS
- ----- Original Message -----
From: "Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx.net>
To: <valist@xxxxxxxxxx.com>
Sent: Friday, September 19, 2003 9:23 AM
Subject: Re: [VAL] Battery question


> Maybe if you had full noon tropic intensity sun for 12 hours in a day.
> So you'd have to be tracking the sun. The ordinary solar panel, say the
> $450 panel that puts out 45 watts peak does just under 4 amps. At solar
> peak. Say it does that for 8 hours. That's 32 amp hours. My deep cycle
> battery is 90 amp hours. Shy by 2/3 a charge. And in the real world it
> won't do that well. Brunton is stretching the truth a looooong ways.
> There are 25 ampere hour batteries that one panel would charge in a day,
> but that's not the deep cycle on my trailer.
>
> Its more efficient to tap into the tow vehicle's charging system to
> charge the trailer battery while traveling than to use a wind generator.
> A wind generator could work, but its imperfect and would add more
> horsepower load from its wind resistance than taking the same power from
> the vehicle alternator. And the modern Bargman connector has a pin
> reserved for battery charging and does well on my Caravel and F-150.
>
> Gerald J.
> --
> Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
> Reproduction by permission only.
>
> -----------------------------------------------------------------
> When replying to a message. please delete all unnecessary original text
>
> To unsubscribe or change to a digest format, please go to
> http://www.tompatterson.com/VAC/VAList/listoffice.html

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Date: Fri, 19 Sep 2003 13:12:05 -0400
From: "goldens510@xxxxxxxxxx.net" <goldens510@xxxxxxxxxx.net>
Subject: [VAL] Outlet problem

Hi, All,

There is probably a totally obvious answer to this question (Gerald, are
you out there?), but I'm a little vague on electricity. My father has
borrowed my Airstream for the week, and he called last night to tell me
that the electrical outlet on the outside of the trailer "fried" his
battery charger. He's plugged into shore power, and all the other outlets,
lights, etc. are functioning fine. I have never used this particular outlet
before. Any thoughts about what's wrong with the outlet, is it dangerous if
not being used, and what measures should I take when the trailer returns? 

Thanks,

Amanda
'68 Safari
Sacramento CA
WBCCI/VAC 7280

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Date: Fri, 19 Sep 2003 10:32:16 -0700
From: Jeffrey & Daile Engle <eMac1@xxxxxxxxxx.US>
Subject: [VAL] Re:waste tank valves-lubricate?

Hello Jim,
	On our 77 Sovereign's black tank valve quit holding water about a week 
ago and I've been doing a lot of "stinky" research in this area. Like 
what kinds of maintenance do the valves need to make them last as long 
as Thetford say's they should? I crawled down under mine here the other 
day and started the real nasty job of replacing both valves and was 
real fortunate to find that the last person to go this way had not put 
any insulation around the valves to make the job worse than it already 
was. (wet, gooey, @#$%infested insulation, you get the general idea). 
Anyway to make a long story short, This whole ordeal has made me very 
interested to know how a person takes extremely good care of them as to 
make them LAST!!.... So I know this email doesn't help you much but I 
am interested to see what you find out... I know that when you use a 
"Valve lubricant" such as "Aqua-Kem" brand, you need to use it with a 
compatible digester/waste deodorant in order for things to work 
properly. Read the bottle or bottles to make sure they work together.  
Jeff
> Date: Thu, 18 Sep 2003 01:52:33 EDT
> From: NuDog@xxxxxxxxxx.com
> Subject: [VAL] Waste tank valves - lubricate?
>
> Noticed valves are getting stiff in pushing them closed - opening is 
> fine -
> some way to lubricate them to prevent problems?
> Thanks Jim

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Date: Fri, 19 Sep 2003 11:36:37 -0500
From: "Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx.net>
Subject: Re: [VAL] Battery question

The voltage regulator that sets the charging voltage for the tow vehicle
battery does a pretty good job of protecting the deep cycle battery in
the trailer. When charging from solar cells, one does need a battery
charging protector.

Its more engine load to pull the wind mill than to turn the alternator.
The will mill would work but its not efficient.

Gerald J.
- -- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.

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Date: Fri, 19 Sep 2003 10:43:12 -0700
From: Joann Wheatley <jwheatle@xxxxxxxxxx.edu>
Subject: Re: [VAL] Battery question

" taking the same power from
the vehicle alternator. And the modern Bargman connector has a pin
reserved for battery charging and does well on my Caravel and F-150."

Is the Bargman connector what I need in order to charge the batteries 
whilst driving? and does it have a disconnect that all by itself (i.e. 
not manual) prevents the trailer batteries from draining the tow 
vehicle battery? If not, could you please recommend such a device?
   And thanks also for the advice on the silicon solvent.
Jo Ann

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Date: Fri, 19 Sep 2003 11:40:43 -0500
From: "Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx.net>
Subject: Re: [VAL] Outlet problem

The outdoor outlet is likely corroded and may have lost spring tension
to overheat the charger's plug. Should have hurt the charger itself as
the plug is replaceable.

The outlet is probably not dangerous if not being used, but should be
replaced, by an electrician if you don't feel ready to do it. The
replacement outlet should last longer if filled with silicone dielectric
grease to keep out moisture. The gasket on the outlet cover should be
renewed to help keep moisture out also.

Gerald J.
- -- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.

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Date: Fri, 19 Sep 2003 12:05:17 -0500
From: "Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx.net>
Subject: Re: [VAL] Battery question

There are two ways to connect the trailer battery charging to keep from
running down the tow vehicle battery. The old way is a big diode
isolator that has a terminal for the alternator output (disconnected
from its normal circuitry under the hood), a terminal for that circuitry
disconnected from the alternator, then a third terminal for trailer
battery charging. There is some voltage drop in the isolator, but so
long as the alternator voltage regulator works on system voltage, not
alternator terminal voltage, it charges both batteries correctly and
prevents use of one of the batteries from running the other down. This
diode isolator is available at good RV stores and good auto parts
stores.

My Ford's factory trailer towing kit has a simpler scheme, under
computer control, there's a relay (an electrically operated switch) that
connects the trailer charging line to the tow vehicle charging line only
when the tow vehicle engine is running. Something like that should be in
all factory towing packages.

You don't want to simply connect the two batteries in parallel. The wire
in the tow vehicle harness and the trailer isn't fat enough to carry the
current for helping start the tow vehicle and will overheat. You want
there to be fuse or circuit breaker protection (part of my towing
package) at both ends of the charging wire to prevent a fire if that
wire gets shorted because the battery can supply a couple thousand amps
(limited with the wire resistance) to such a short and really overheat
the wire and ignite its insulation. That should be a part of the
Airstream wiring also. A master fuse on the battery for charging and
loads.

The 7 pin Bargman connector is standard these days when there are brakes
involved on an RV. And are standard with the factory trailer towing
options on the tow vehicle.

Gerald J.
- -- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.

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End of VAL Digest V1 #12
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