They don't make 2 hours on 100 watts though back it down to 30 or 50 and
they do alright on SSB.
----- Original Message -----
From: "Colin McDonald" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 05, 2005 9:44 AM
Subject: Re: battery packs


good points...however, i have seen those portable charging units that claim
about 7 amp hours plus about 1500 cold cranking amps to be able to jump
start a vehicle....these type of packs should provide enough current to
operate at a relatively heavy current draw for several hours given the
intermittent nature of SSB operation...if FM was going to be operated then i
think one of those packs would certainly go dead quickly but SSB only draws
that current when modulating and one is only really modulating for brief
periods of time throughout that one  hour.  Its not like you will be rag
chewing when you are trying to make contacts...lets say maximum 15 seconds
of modulation at 12 amps or so with 50 watts.
You take that and you times that 15 seconds over and over until you get
about 35 minutes, using the 7 amp hour pack and you are looking at an aweful
lot of contacts and several hours.
I dont know how to actually calculate that, but the math is sound and you
can figure out the number of hours you could get out of a relatively low
current supply, assuming it will provide the higher current for short
periods of time...which most of these portable packs will do.

These portable packs are smaller then a regular sized car battery and much
lighter...easy enough to attach to a back pack or be even hand carried if
necessary.
I still want that website that gives all this info regarding battery
packs...allot of this idea of using lesser current supplies and figuring out
how long you can run a higher current draw on SSB is all on this website.

73
Colin, V A6BKX
----- Original Message -----
From: <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, August 05, 2005 1:26 PM
Subject: Re: battery packs


> Message-Id:
<20050805132709.LBGM3503.ibm70aec.bellsouth.net@[68.212.116.131]>
>
> Fred wrote,
>    >Well, if you're going to use battery power, you'd better think of
>    >qrp, 50 to 100 watts will drain them in a hurry, or you'd better
>    >take the world's longest extension chord for the charger.
> Even then, better be two stout dudes if you're gonna pack enough
> battery power to do this.  gel cell packs that would handle that kind
> of power and give you a few hours of operation are quite heavy.
> Definitely be thinking qrp in this application.
> I had a bunch of those 7 amp/hour gel clels that came from burglary
> and fire alarm systems and they can be heavy even.  Up at Charity
> Hospital here in NEw oRleans we've got a couple of 100 amp/hour
> batteries and they're heavy dudes.  I brought them up there on a two
> wheeled handtruck.  NOt something I'd want to be packing up a mountain
> along with food tents etc.
> THough everything else in our hobby has miniaturized except antennas
> batteries haven't downsized that much. AS one fellow said, when they
> get there we'll actually see efficient electric vehicles.
> wEre I going on such an expedition I'd consider qrp cw.  YEs Virginia,
> leave the laptop at home too.
> Speaking of such activities I'd probably use the National RAdio
> emergency net as a point of contact with the outside world.  These
> folks use the guard frequencies 7068 10122 and 14050 khz.  tHey're
> there for just this purpose.
>
>
>
>
> Richard Webb
>
> Electric Spider Productions
>                                             "They that can give up
essential liberty to obtain a little temporary
> safety deserve neither liberty nor safety."
> --- Benjamin Franklin, NOvember 1755 from the
> Historical review of Pennsylvania
>