[VHFcontesting] Roving: Battery vs Generator

Jack Isenberg ihi at frontiernet.net
Tue Nov 17 13:45:01 PST 2009


Hi John,

Lots of great questions there.  It is not just an "either/or" batteries and 
generators.
Let me describe what I am doing and hope it helps you a little bit.
First, I am running LOTS lower power than you and that is indeed a big 
factor in making your tradeoffs.

My setup is the following:

I have two deep cycle (100 AH Marine.RV) batteries.
I also have two 1000 Watt Honda generators.  There is a cable where they can 
be hooked together and provide 2kw out of one outlet.
I have two for 2 reasons.  1 is backup. The other is that most of the time I 
only need 1KW or less (unless I am running the heater there is no
engine heat in the trailer)
the Hondas are very quiet both acoustically and electrically.
I run a single heavy duty power cord on a reel out about 50 feet to keep the 
generators a bit far away.
plugged into the generators is a MFJ 4245 (45 amp) variable switching 
supply.  It is floating on the batteries (through individual switches and 
fuses of course)
this keeps the batteries charged and the batteries provide the output for 
transients above 45 amp.
I was a bit leery of floating a switcher on the batteries, but it has been 
working very well for several years now.

the output of the 2 batteries (again through in line fuses) goes to a 100 
amp rotary switch (used primarily on boats to switch their DC) and
can select either battery or both in parallel.
The output of the switch goes to an Accuvolt which provides a steady 14 
volts even if running off batteries that are getting low.
The accuvolt has a remote on/of switch so I can shut it down if I don't need 
it, but I don't often so that.  It does have a tiny bit of noise (radiated)
so I sometimes shut it off to receive a very weak signal.  The Accuvolt can 
provide 100 amps.

The output of the accuvolt goes to three powerpole strips (rigrunners) with 
three separate heavy cables.

In terms of operation:

If I am going to be at a site for a somewhat limited time and/or it is 
inconvenient to set up the generator (too public of a location), I simply 
run off the batteries.
If I am running off the batteries for longer than the laptop batteries will 
last, I have a sine wave invertor to power them.
I also use the invertor to supply the 20V and 24V supplies.
If I am going to be at a site longer, I run the power cord, set out one of 
the generators (I alternate which one) pull the rope (usually once)
and am off and running.
One of us usually sets up the generators, computers, powers upp the 
equipment, etc while the other pushes up the masts.  so setup isn't really 
too long (always
would like to have it shorter)

When I turn on the switching supply, I start with the voltage control low 
and increase it keeping the output below 40 amps (Usually no
problem unless I have been running off batteries for a while).  In a matter 
of seconds to minutes I am usually at full output from the supply.
A tiny bit cumbersome, but no real problem.

I usually run off One generator, the switching supply on both batteries, and 
the battery outputs paralleled.

There are some things I run directly off the A/C like the computers, 
frequency meter, 432A power meters, 24v supply for relays, 20v supply for
the 5760 brick osc and oven, one fluorescent light (the other one is 12v), 
and any power tools I need like soldering gun, soldering Iron, etc.

.Overall I would say my experience with this operation is very positive.

Fuel is a tiny bit of an inconvenience, but not much.  By alternating the 
use of the two generators I can always be refueling a cold generator.
Usually when I am setting up, I refuel the other generator. I have 2 one 
gallon cans and a 2.5 gallon can, however I almost always only take one 1 
gallon
can with me.
I usually only have to fill the can and generators up when I have to stop 
for gas anyway.
The good side is I am probably using a lot less gas than you for power
A full generator (0.6 gallon) will easily run the rover for several hours.

Feel free to ask any other questions.  If you want any pictures, let me 
know.

73
Jack
WA2IID


----- Original Message ----- 
From: "John D'Ausilio" <jdausilio at gmail.com>
To: "(Radio) VHF Contesting" <VHFcontesting at contesting.com>
Sent: Monday, November 16, 2009 2:40 PM
Subject: [VHFcontesting] Roving: Battery vs Generator


> After the most excellent NEWS group meeting on Saturday, I drove home
> with some new ideas churning around in my brain .. mostly as a result
> of seeing an LDMOS based FM broadcast pallet amp about the size of a
> postcard that would do 750W on 48V.
>
> I'm going to need to replace my battery bank this year .. it's seen
> hard use and is ready to go the the great battery recycler in the sky.
> Question is, should I consider "going generator"?
>
> I'm interested in direct rover experience with small portable
> generators .. good and bad experiences, recommendations pro or con,
> etc. One thing that's nice about the self-contained rover is the
> (relative) inconspicuousness .. it I have to pull out a generator and
> start it up and run a cable back to the rover that's much more
> obnoxious in public places than an idling van. Fuel might be another
> inconvenience .. or maybe not if a tank lasts as long as the driving
> tank does. I'm sure other things will occur to me .. change = fear :(
>
> de w1rt/john
>
> 



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