[VHFcontesting] Managing power in a temporary rover

[James Duffey]

I thought that I might post what I do for power in my rover. I use the  
family automobile for roving, so installations need to be temporary  
rather than permanent.

I use a separate 75 AH deep cycle battery in a battery case for power.  
This will run the rigs for a a full day of operating, but the voltage  
will droop at the end. Depending on the rig, this can be a problem. I  
used to carry a battery charger and recharge the battery when I  
stopped for the evening. This works fine, as long as your rig and the  
operator at the other end can take the low voltage at the end of the  
day. The dedicated battery does not require any mods to the car and  
insures that the car battery can start the car when the stop is done.  
I rove with my wife and I would hate to have to push the car to start  
it.

This time around I added an N8XJK voltage booster, which keeps the  
voltage at 13.8V, or whatever you set it at up to 15V. This worked out  
super and the rigs all behaved themselves when the battery voltage  
drooped.

< http://stores.tgelectronics.org/StoreFront.bok >

They make and sell a 25 Amp model and a 40 Amp model at $150 and $200  
respectively. These are easy to install and use. THere is an RF sense  
input avaialble, so that the boost is only active when transmitting,  
but I have not tried that. There was no trace of RF noise from the  
N8XJK converter. If you rove from a fixed battery consider one of  
these. It will make your life easier.

I also added a DC to DC converter to charge the battery from the power  
outlet (these used to be called cigar or cigarette lighters) when the  
car is running. Powerstream sells a 4.4 Amp job that works fine. When  
I purchased it a week before the contest it was a bargain at $35, I  
bought 2, but I see now that they have raised the price to $80. It is  
an 11V model, but the voltage can be adjusted up to 14V, so I set it  
at 13.8V to charge the battery. It has current overload, overvoltage,  
and over temperature protection built in. It was a great deal at $35,  
but I am not sure it is worth $80, particularly as Powerstream also  
sells DC to DC supplies designed for charging laptops for $50 that can  
be easily adapted to charging batteries from the power outlet. They  
also sell DC powered chargers with higher capacity at higher prices.  
There was no RF noise from this DC-DC converter. Just plug it into the  
outlet and go.

This converter charges at about the rate that the rigs discharge the  
battery, so I get roughly an hour of operation for each hour of  
charge. It keeps one even with the drain and tops off the battery on  
your way out to rove. Plus if you discharge the battery fully, you can  
run the engine and get back on the air reasonably quickly.

Everything that requires power is fused.

The next step is to put Anderson Powerpoles on everything.

It all sounds kind of Rube Goldberg, but it works and leaves no trace  
after the weekend is over. - Duffey

--
KK6MC
James Duffey
Cedar Crest NM