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Re: (ET) charger voltage
So perfection being in neither the batteries or the chargers, we have to
make do with what we got. What I got is batteries that normally thrown
away and I have found out how to use them when the average person would
shell out big bux for a new pack. When I lose one of these 'oldies'
(won't mow the full 3/4 acre or so any more because of one bad batt) I
bring it down the town battery recycle area, and look for a couple more
same size 6V. Individual charge with a 6V charger and test with my
discharge type tester. Sometimes both of em are better than the one I
threw out. I keep 'one ahead' on this so I can continue the lawn the
same day.
Seems that a lotta stuff runs good even if it don't run by engineering
book rules. Example; The conversion PEV's we drive run by intentionally
overloading both motor and batteries, even cables. We get by this by
doing only intermittent overloads at traffic lights. We should, by the
books, burn out motors fast by this and batteries too. We don't. My
120 VDC PEV pulls 400A at a traffic light with a full charge into about a
23HP plate rating motor. It delivers bout twice that, keeps up with
traffic. This is a rig sold in 1982 with an antique 'commutating SCR'
controller and hasn't busted anything major yet. Although a lot of stuff
including the pack gets awfully hot.
At a non-EAA (a local enviro org) electric and hybrid vehicle event bout
50 miles from here, I saw the best condition GE I've ever seen. Not a
repaint. Decals and seat perfect. Looked like she was indoor stored all
her life and kept clean, used very little. Even had the top battery
covers on. A 12M. Took pix. We displayed a Honda Civic hybrid and had
a small version (whatever would fit in a Civic) of the big NEEAA show
display. Busy at the display all day, great show and lotta people
inquired about the photos of my Solar powered 16, among other things.
Dave
Weymouth MA
On Fri, 28 Jul 2006 10:40:07 -0400 "Elie, Larry \(L.D.\)"
<lelie ford com> writes:
> Than you don't understand how charging flooded series connected
> batteries work. There are a number of web pages that explain it,
> but
> those that design chargers are not a bunch of dummies. Your car
> charging circuit regulates at 14.2 to 14.4 V, and charges a battery
> that
> when new and fully charged at room temperature shows 13.8 V. Those
> 'extra' .6V on the 6 cells helps the battery reach equilibrium. No
> two
> of the cells are identical; internal resistances are different. If
> you
> tried to charge at 13.8 (all you 'need') and if one cell is 'weak',
> it
> will prevent all of the other cells from reaching 'full' charge.
> The
> more cells, the bigger the potential problem. Add to that battery
> and
> cell age, temperature differences and so on, and it's easy to see
> why
> the extra potential is used. Remember, the charger is only a
> constant
> voltage circuit when it isn't dumping lots of current; for most of
> the
> charge cycle it's very much current limited. If you have infinite
> money
> you could do better with a constant current charger dumping perhaps
> 100A
> with an automatic cross-over and detecting 'full' charge off of the
> density of the electrolyte, and charging each cell individually in
> parallel and then only going in series when you are running the
> batteries for output. But no one is going to pay for that. The
> charger
> circuit I did years ago equalized based on seeing each cell as an
> integrator and using op-amps to equalized the cell voltage. It
> worked
> well but added wiring and complexity. Even it cost too much to be
> implemented in our electric cars.
>
> Larry Elie
> Ford Research
>
>
>
> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Michael
> S
> Briggs
> Sent: Friday, July 28, 2006 8:54 AM
> To: David C Robie
> Cc: elec-trak cosmos phy tufts edu
> Subject: Re: (ET) charger voltage
>
>
> Dave,
> Thanks for the feedback, that's essentially what I wanted
> to
> know
> - what the voltage is these 6 volt batteries will hold. As far as I
> see
> it, if they'll typically hold 6.3 V each (so just under 38V
> combined),
> there's no reason the charger NEEDS to put out 42-45V. That high of
> a
> voltage will charge it quicker, but won't give a more complete
> charge,
> since the pack itself can't stay above 38-39V or so, depending on
> the
> batteries. My charger is putting out around 39.5V roughly, which to
> me
> means it should be able to fully charge the pack - it will just take
>
> longer than it would if the charger was putting out a higher
> voltage.
> Since the Landis controller stops charging once the pack
> reaches
>
> 38V, it wasn't making any sense to me why people were saying the
> charger
>
> needs to put out 42+ V to fully charge the pack, since presumably
> fully
> charged is only around 38V. 42V+ will charge quicker (greater
> potential
> difference between the charger and battery pack, so more current
> will
> flow
> into the pack), but quicker isn't necessarily better, especially
> when
> dealing with charging batteries.
> I'll measure the capacitance of the charger capacitor
> anyway
> (have
> a multimeter that can measure capacitance) to see if it's ok or not
> though.
>
> Thanks,
> Mike
>
> --
>
> --------------------------------------------------------------
> Michael S. Briggs
> UNH Physics Department
> (603) 862-2828
> ---------------------------------------------------------------
>
> On Thu, 27 Jul 2006, David C Robie wrote:
>
> > Depends on the age of your batteries. New batts are about 6.5
> ea.
> > Average batteries chg to about 6.25 6.3 (where do you think vacuum
> tube
> > heater voltage std 6.3 came from? 2.2V/cell). Older ones (like
> some
> I
> > got) chg to maybe 6.15. No matter how long or what rate you charge
> a
> lead
> > acid battery like we use, it will not go over this 'age and abuse
> > related' voltage.
> > If you find one in the string that's consistantly low, swap it
> outa
> > there. Your tractor will thank you.
> >
> > Occasionally. people 'equalize' batteries by intentionally
> overcharging.
> > This ain't good for them. If I find a low one. I put it on a
> separate
> > 6V charger to bring it up as far as, by experience, I know it will
> go.
> > My packs were not bought new, they are recycles and inherently
> some
> are
> > better than others. I make sure each fall that the best ones go
> in
> the
> > tractor that has the snowblower.
> >
> > Charge em to the point that every cell is gassing. Then leave em
> > overnite to remove 'surface charge'. Test em in the morning.
> That
> will
> > tell you where your batts are at agewise. Of course, to charge
> them
> the
> > voltage of the charger must be a little over this.
> > So, depending on battery condition, anything from half a volt
> over
> > about 36.5 to 39
> > will trickle charge em, and a volt or two above will hi rate
> charge
> em.
> > (the charge voltage automatically tapers down because of the
> capacitor
> -
> > it and it's winding is called a ferro resonant circuit which is a
> form
> of
> > regulator) (therefore, open circuit voltage means little except
> too
> low =
> > bad capacitor.
> >
> > Dave
> > Weymouth MA
> >
> >
> >
> > On Wed, 26 Jul 2006 18:50:03 -0400 (EDT) Michael S Briggs
> > <msbriggs alberti unh edu> writes:
> >>
> >> I've been scanning through the archives, and also the Service
> >> Manual, and
> >> am seeing some mixed messages on this - what voltage should the
> >> charger be
> >> putting out to the batteries? Mine's putting out a shade under 40
> V
> >> (39.5V or so), and they seem to not be holding as much energy as
> I'd
> >> like
> >> (T-105s that are a few years old, bought used). According to the
> >> Service
> >> manual, 40-45 V is ok (well, not on exactly the same wires as I'm
> >> measuring the voltage, I'm measuring across the battery pack,
> rather
> >> than
> >> at S3 and S1 directly on the charger, so there's presumably a
> small
> >> amount
> >> of voltage lost between the points the manual says and the points
> >> I'm
> >> measuring at, especially if some weak connections, such as at the
> >> Diode
> >> heat sink). According to the archives online, I've seen people
> >> saying that
> >> if the voltage isn't 42-45V, the charger won't fully charge the
> >> batteries
> >> enough (some people who replaced the capacitor when the charger
> was
> >> only
> >> putting out 39V or so, for example).
> >> With mine charging, the charge meter goes slightly into
> the
> >> white
> >> section - whereas in the archives, I've seen statements that if
> the
> >> meter
> >> doesn't go all the way to the high end of the white section, the
> >> batteries
> >> won't get a full charge.
> >> On the other hand, the Landis controller only has the
> >> charger on
> >> when the pack voltage falls below 38V, by default, unless you
> adjust
> >> it
> >> up. So, if charging to 38V will give you a full pack, then
> there's
> >> no need
> >> to have the charger putting out more than 39V or so (other than
> that
> >> the
> >> higher the voltage it puts out, the quicker the pack will
> charge).
> >> So, which is it? Is 39-40V from the charger ok, or
> should
> >> it be
> >> 42-45?
> >> Essentially it comes down to - what should be the
> voltage
> >> of a
> >> fully charged battery pack (I know it's higher than 36V, but how
> >> much?)?
> >>
> >> Thanks,
> >> Mike
> >>
> >> --
> >>
> >> --------------------------------------------------------------
> >> Michael S. Briggs
> >> UNH Physics Department
> >> (603) 862-2828
> >> ---------------------------------------------------------------
> >>
> >> _______________________________________________
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> >> Elec-trak cosmos phy tufts edu
> >> https://cosmos.phy.tufts.edu/mailman/listinfo/elec-trak
> >>
> >
>
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