RE: (ET) DC-DC Converters - Lot of 6

["Phil Trice" <pctrice purdue edu>]

David,
        (At the risk of lowering the signal/noise ratio :-), You raise 
some very
good points. I looked at the spec sheets for these yesterday, and came to
the same conclusions.
The point remains, though; are there any DC-DC convertors out there that 
are
usable (ie, reasonable current capacity, size, etc) and affordable? Barring
that, are there known, stable designs that could be turned into usable
products?

        -Phil Trice
        1976 Sears Electric tractor



-----Original Message-----
From: owner-elec-trak cosmos phy tufts edu
[mailto:owner-elec-trak cosmos phy tufts edu]On Behalf Of David Roden
(Akron OH USA)
Sent: Tuesday, March 26, 2002 2:32 PM
To: 'elec-trak cosmos5 phy tufts edu'
Subject: Re: (ET) DC-DC Converters - Lot of 6


On 26 Mar 2002 at 12:57, Chapin, Tim wrote:

> 6 dc-dc converters on ebay..

Careful!  These are for 24 and 48 volt nominal input, so unless you've
upgraded your ET to 48 volts, they wouldn't help much (you'd still have to
tap the pack).  The specs say "18 to 36 volts" for the 24 volt units, but
that's intended to leave "headroom" for higher voltage during charging, not
for routine operation.

If you tried to use the 48 volt units instead, you'd have problems. They
probably won't put out full current, and are more likely to overheat, when
run below nominal voltage.  Also, when you loaded the tractor and the pack
voltage sagged, they'd probably drop out.

Finally, each is capable of delivering only 20 watts.  That's about 2 amps
at 12 volts -- barely enough to run the headlights, if even that.  You 
might
be able to parallel all six and get 8-10 amps (DC:DC converters don't share
loads perfectly, so you probably wouldn't get 12 amps), but you'd still 
have
the input voltage problem.

These DC:DCs probably have some uses, but I wouldn't buy them for an ET's
lights and/or lift.


David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea 36vdc
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Thou shalt not send me any thing which says unto thee, "send this to all
thou knowest."  Neither shalt thou send me any spam, lest I smite thee.
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Est. yearly US cost to safeguard Persian Gulf oil supply: $50 billion
Est. 2001 value of US crude oil imports from Persian Gulf: $19 billion
                                                          -- Harper's 
Index,
April 2002
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =