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Re: (ET) charger voltage
Why not just open the cell caps with the charger running to see if all
the cells are gassing. Use a flashlight to look inside underwater. If
they are gassing they are full charged. If they are not they are not.
Gas only comes when the plates can't accept any more chemical changes, so
the electrictity not used in the plates does electrolysis of water
instead. (very simple WW1 era trade school explanation of full battery
determination which needs no accurate metering. I believe it came from
Audel's when I was in Jr hi school using a Buick big spkr pushpull audio
output AM radio and a tungar 6V battery charger as an extremely good
sounding early hi fi made from trash. The big bopper etc sounded real
good on it. So did such as Stravinsky's firebird and Rite of Spring and
that Russian one, 'age of gold')
Mike; You missed a fantastic electric and hybrid vehicle show in Ipswich
MA yesterday run by 'I care', the local enviro org. As one display, the
best condition GE I've ever seen, a 12M. I ran the EAA exhibit.
Dave
Weymouth MA
On Sun, 30 Jul 2006 09:21:52 -0400 (EDT) Michael S Briggs
<msbriggs alberti unh edu> writes:
>
> Harry,
> What I've been wondering is if the 38V set point (yes, I
> know it's
> not a cutoff point) will allow "full" charging, based on my not
> knowing
> exactly what the voltage of a fully charged pack is (which is what I
> was
> initially trying to find out). If a pack is almost, but not quite
> fully
> charged, does that mean that the voltage will drop below 38V? Or,
> should
> a fully charged pack be able to maintain something higher, like
> 38.2V? (in
> which case I might want to bump up the set point voltage some)
> I'm quite happy with the design of your charger, just
> trying to
> learn more about what voltage a fully charged pack should maintain,
> and if
> I should therefore adjust the set point a little.
>
> Mike
>
> --
>
> --------------------------------------------------------------
> Michael S. Briggs
> UNH Physics Department
> (603) 862-2828
> ---------------------------------------------------------------
>
> On Sat, 29 Jul 2006, harry landis wrote:
>
> > I guess there's nothing like a battery charging question to get
> the list
> > active. My charger controller (it's a charger controller, not a
> charger)
> > does exactly what the stock timer does, except it measures battery
> resting
> > voltage, not time. The timer turns the stock charger on and keeps
> it on for
> > a set time, then turns it off. My controller turns on the same
> stock charger
> > for a set time (about 4.5 minutes) and then turns it off. During
> the on
> > time, the voltage is not controlled or measured by my controller.
> So the
> > voltage will rise to 40 or 45 volts just like it would have with
> the stock
> > timer. After the set time elapses, my controller measures the
> battery
> > voltage. If the battery rest voltage drifts down to 38V, it turns
> the
> > charger on again for another 4.5 min. Therefore, the 38V setpoint
> is not a
> > cutoff voltage, but a start voltage.
> > Full details are on the elec-trak.com website in the Classifieds
> section
> > here:
> >
> >
>
http://www.elec-trak.com/bin/classifieds/classifieds.cgi?search_and_displ
ay_db_button=on&db_id=15&query=retrieval
> >
> > It's a great site. Thanks, Don!
> >
> > Harry Landis
> >
> >
> >
> > From: Michael S Briggs <msbriggs alberti unh edu>
> > To: "Elie, Larry (L.D.)" <lelie ford com>
> > CC: elec-trak cosmos phy tufts edu
> > Subject: Re: (ET) charger voltage
> > Date: Fri, 28 Jul 2006 19:28:14 -0400 (EDT)
> >
> >
> > On Fri, 28 Jul 2006, Elie, Larry (L.D.) wrote:
> >
> > > Actually, the more cells, the greater the likelihood of one bad
> actor.
> > > I've seen them actually reverse charge. Let's see how well you
> can
> > > bring the pack up when one cell is at -2.3V.... You are lucky
> to get
> > > the others to 60% charge.
> >
> > I'd think though that if that happens, you should just replace the
> > battery. :)
> >
> > > Mr. Landis and I have disagreed on this in the past. His
> charger works.
> > > The ET charger works. They don't work in exactly the same way.
> If the
> > > ET charger stopped at even 40V you will not get a full charge.
> Harry's
> > > charger will pump it up again a number of times after the
> battery cools
> > > which gets the job done. It won't be as fast, but if you want
> to just
> > > leave it on for months it's superior. There are other
> techniques
> >
> > That's sort of what I'm saying - that a higher voltage will let
> you charge
> > faster, but you *could* get a complete charge with a lower voltage
> > (as long as it's still a good bit above the voltage of a fully
> charged
> > pack). But, that may not be convenient for most people.
> > That said - I checked the capacitance of the cap on my
> charger
> > about a half hour ago, and it is indeed toast (read no capacitance
> at all
> > - which now has me wondering how the charger is putting out a
> fairly
> > stable 39.5V with an apparently dead cap). So, I'll be replacing
> it.
> > But, I still am looking to find out exactly what the
> voltage of a
> > fully charged pack should be, so I can decide whether to up the
> set point
> > voltage on the Landis controller, and if so, to what. I don't want
> to
> > leave it plugged in permanently when not in use - so I'd rather
> not have
> > it shut the charger off *right* when the pack first hits 38V, if
> it can
> > charge up higher than that.
> >
> > > available as well. Remember, the ET charger can put out lots of
> current
> > > when the batteries are low because it is a simple constant
> voltage
> > > design; you dropped the peak voltage the current it would put
> out at
> > > lower voltages is also reduced.
> >
> > Yup, thus slower charging.
> >
> > > Another factor you are leaving out is that 38.2V is the room
> temperature
> > > voltage 90 minutes or more after charging. The voltage at the
> pack at
> >
> > I'm not leaving that factor out - I don't know that factor. :) My
> initial
> > question on this was asking what the voltage of a fully charged
> pack
> > should be. If it only drops to 38.2V 90 minutes after charging,
> then
> > apparently a fully charged pack just after charging should be
> higher - and
> > that's what I want to know. I figure I could bump the set point on
> the
> > Landis up to a smidgen under that fully charged voltage, at least
> for
> > during the summer, and if I don't use the Elec-Trak in the winter,
> I could
> > move the set point back down to 38V.
> >
> > > the end of the cycle on an ET charger will be over 42V, with the
> > > batteries well above room temperature. If you really want to
> see where
> > > to cut off, measure each battery with a DVM and see if they are
> all at
> > > least 6.4+V. Frequently, you have one still at 5.9V with others
> at 6.5V
> > > at the 38V level. By the time you are at 42+V, the worst
> battery is
> > > usually near 6.4V. Try it yourself and see.
> >
> > Can't try it right now, since my charger is only putting out
> 39.5V. :) And
> > of course the Landis is shutting off the charger when the pack is
> at 38V.
> > So, what should I bump it up to? 39V? 40V? 42V? Of course, I'll
> need to
> > replace that capacitor first....
> >
> > Mike
> >
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