Re: (ET) Solar charging, part 2

["Jeremy" <nagidog starband net>]

I have a feeling that those considering charging their elec traks via solar
panels do not currently have a solar system.  I charge my e-12 exclusively
via solar power.  Solar panels, as they are very expensive, are better
served if charging a large battery bank.  I would not consider pulling off
three panels so I can directly charge my e-12, that would waste quite a bit
of power as the e-12 got closer to charged and the e-12 batteries were
sucking a very small amount of the amperage produced by the solar panels.  
I
have 12 80 watt panels charging 8- L-16 batteries, I just plug my electrak
in to the 120 outlet from the inverter, the amount wasted by going through
the batteries is not as much as would be wasted by removing 3 panels, or if
I got 3 new panels they would definelty go on the big rack.

Jeremy
----- Original Message -----
From: "Herb Crary" <jhcrary earthlink net>
To: "Elec-trak Mail List" <elec-trak cosmos phy tufts edu>
Sent: Tuesday, April 22, 2003 7:47 PM
Subject: Fw: (ET) Solar charging, part 2


>
> Seems to me that a simple solution might be to put a delay circuit in to
set
> a delay between the times the charger is disconnected and can be
> reconnecteed.
>
> Herb
>
> ----- Original Message -----
> From: "harry landis" <hlandis hotmail com>
> To: <elec-trak cosmos phy tufts edu>
> Sent: Tuesday, April 22, 2003 7:22 PM
> Subject: Re: (ET) Solar charging, part 2
>
>
> >
> >
> >
> > That was the assumption. I just picked the number as an illustration. 
> > My
> > controller won't work if there is a significant load on the battery
while
> it
> > is trying to charge it.
> >
> > Harry Landis
> >
> > From: "Christopher Zach" <czach computer org>
> > To: "harry landis" <hlandis hotmail com>,
<elec-trak cosmos phy tufts edu>
> > Subject: Re: (ET) Solar charging, part 2
> > Date: Tue, 22 Apr 2003 22:02:59 -0400
> >
> > Why is there a 1 amp load on the pack constantly?
> >
> > Chris
> >
> > ----- Original Message -----
> > From: "harry landis" <hlandis hotmail com>
> > To: <elec-trak cosmos phy tufts edu>
> > Sent: Tuesday, April 22, 2003 9:52 PM
> > Subject: RE: (ET) Solar charging, part 2
> >
> >
> >  >
> >  >
> >  >
> >  > Say there is a constant 1 amp load on the battery pack while the
panels
> > are
> >  > trying to charge it. Say the panels can put out 5 amps. Say the
> batteries
> >  > are fully charged. As soon as the controller turns off the panels,
the
> >  > battery voltage will fall a little below the quiescent voltage of 38
> > volts,
> >  > so the controller reconnects the panels for 5 minutes. Now the
battery
> is
> >  > being charged at 4 amps net. This will repeat as long as the panels
can
> > put
> >  > out power. So the panels will be connected essentially continuously,
> and
> > so
> >  > the batteries will get overcharged.
> >  >
> >  > My controller expects to be looking at the resting voltage of the
pack.
> > If
> >  > it is looking at some other voltage, like the resting voltage minus
> some
> >  > voltage drop due to current being drawn, it will not be able to do
its
> > job
> >  > correctly.
> >  > The current draw is a few milliamps.
> >  >
> >  > Harry Landis
> >  >
> >  >
> >  >
> >  > From: "Humphrey, Timothy" <HumphreyT neads ang af mil>
> >  > To: "'elec-trak cosmos phy tufts edu '"
> <elec-trak cosmos phy tufts edu>
> >  > Subject: RE: (ET) Solar charging, part 2
> >  > Date: Tue, 22 Apr 2003 21:19:57 -0000
> >  >
> >  > I know it's your charger, you built it so you should know how it
works.
> > But,
> >  > I'll have to disagree that it will over charge an in use battery.
> >  >
> >  > If the battery is being drawn from, I agree it's voltage will be low
> and
> > as
> >  > such your control will either stay on or keep turning on. But, if
that
> is
> >  > happening, then it is not charging the battery. It is merely causing
> the
> >  > charger or solar panels to share the load with the battery. As soon
as
> > the
> >  > load is removed the controller will start to function as required.
You
> > can't
> >  > charge a discharging battery.
> >  >
> >  > One question I have about using it on solar panels though, is how
much
> > power
> >  > does the controller consume itself? If it turns on at night, what
kind
> of
> >  > drain will it present to the battery. It gets it's operating power
from
> > the
> >  > battery, right? I know it could probably run itself for a decade or
two
> > on
> >  > the ET's pack, but should those using solar panels consider a
dimlight
> >  > disconnect, in order to keep what they just put in?
> >  >
> >  > Oh, and by the way, you'll be receiving my order for one soon.
> >  >
> >  > Stay Charged!
> >  >
> >  > Hump
> >  >
> >  >
> >  >
> >  > -----Original Message-----
> >  > From: harry landis
> >  > To: elec-trak cosmos phy tufts edu
> >  > Sent: 4/22/03 4:29 PM
> >  > Subject: Re: (ET) Solar charging, part 2
> >  >
> >  >
> >  > I think my controller would work fine with a DC solid state relay
> >  > instead of
> >  > the AC one. As it happens, I have some DC SSRs available. So if
anyone
> >  > wants
> >  > a controller with a DC SSR (30 amps, I think) just ask. Same price
($40
> >  > including shipping). Note: this control scheme won't work on a 
> > normal
> >  > solar
> >  > installation. It only works in applications like the ET where there
is
> >  > essentially no power drain on the batteries while charging. If there
is
> >  > significant current being taken from the batteries, the battery
voltage
> >  > is
> >  > no longer the rest voltage, but is lower due to the drain. So the
> >  > controller
> >  > thinks the battery is always low, and ends up overcharging it.
> >  >
> >  > Harry Landis
> >  >
> >  >
> >  >
> >  >
> >  >
> >  > From: Jeremy Gagliardi com
> >  > To: elec-trak cosmos phy tufts edu
> >  > Subject: Re: (ET) Solar charging, part 2
> >  > Date: Tue, 22 Apr 2003 16:04:28 -0400 (EDT)
> >  >
> >  > On Tue, 22 Apr 2003 16:00:07 -0400, "SteveS" wrote:
> >  >   > Yes, at the relatively low currents that we are talking about 
> > (5A
> or
> >  > so),
> >  >   > there are inexpensive controllers one could make or buy. Now,
where
> >  > do we
> >  >   > buy cheap (err, inexpensive) solar panels?
> >  >   > SteveS
> >  >   > E12Ss
> >  >   > E20
> >  >
> >  > Okay, now the next question is who can build one (Harry Landis, are
you
> >  > up
> >  > to
> >  > the task)?  I haven't dabbled in electronics since I took a required
> >  > course
> >  > in
> >  > college for my CompSci degree.  That was 11 years ago, and I don't
> >  > remember
> >  > a
> >  > lick of it.  Although, if someone drew up a schematic, I might be
able
> >  > to
> >  > follow
> >  > it.
> >  >
> >  > --
> >  > Jeremy
> >  > E20
> >  >
> >  >   > > This makes me wonder if it would be simpler to build a simple
DC
> >  >   > controller,
> >  >   > > similar to the Landis model.  The Landis Controller is a solid
> >  > state AC
> >  >   > relay
> >  >   > > with a simple DC monitor (when batteries go below 38V it turns
on
> >  > the
> >  > AC
> >  >   > relay
> >  >   > > to the charger).  Can't a similar controller be built that
> monitors
> >  > the
> >  >   > > batteries in the same exact way, but opens up a DC relay from
the
> >  > solar
> >  >   > panels?
> >  >   > > The Landis Controller is only about $40.
> >  >
> >  >
> >  >
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