Re: Charging telemetry data--take 1

["Christopher Zach" <czach@computer.org>]

Mmm.... Interesting data points, thank you.

I took a detailed look at the telemetry. At full blast the system was
dropping to 290 at 60amps (full throttle reverse), and 275 at 120 amps (max
full throttle fwd up max grade).

As for the date, I haven't dropped the pack yet. However I am willing to
guess that they are the ones that came with the car, and are thus 1994
vintage (ie: *old*).

The verdict might just be that the pack is a hopeless little basket case.
Still, 30 miles of range is enough to meet the orig objectives (drive to
parent's house with the kids, 22 mile trip). I might just want to consider
this to be my "training pack" and concentrate on babying it as I learn to
drive an EV. Then in the fall I can drop the pack and replace it with a
shiny new something (with knowledge about what makes a "good" pack and how
to drive it).

Any other comments are totally welcome and appreciated.
Chris



----- Original Message -----
From: "Seth" <vze3v25q@verizon.net>
To: <ev@listproc.sjsu.edu>
Sent: Friday, June 28, 2002 10:34 PM
Subject: Re: Charging telemetry data--take 1


> A couple things:
>
> 12.8 is pretty full, especially for worn out Hawkers. For fresh gel
> batteries, I would expect 13.00-13.03 per 12V module. But I am not as
> familiar with Hawkers. My 1996 vintage GP38EV10 are full at
> 12.78-12.85V. Full being defined as a day of 13.6V then a day of rest.
>
> 400V float seems a bit high. 250ma/ string seems high for 26 Ah
> batteries. I might suggest closer to 100 milliamps max.
>
> Mid 290V sounds fine for full power. That's ~11.8V which is good for a
> low current, higher voltage AC traction system that trades modest power
> for reasonable battery life. On fresh batteries I would expect the
> voltage to be more like 305ish at max power.
>
> The gauge reads 1/2 full because the old batteries only have ~60% of
> original capacity. So 50% discharged is really 85% or thereabouts.
>
> Did you mention the date code on the Hawkers? I suspect they are at the
> end of their calendar life, ignoring battery neglect.
>
> Seth
>
>
> Christopher Zach wrote:
> >
> > Ok, I came home, and plugged the PC into the Dolphin. Then I powered up.
> >
> > The Dolphin has a counter that controls the fuel gauge. Currently it
reads
> > 100%. The battery pack voltage at rest was 320 volts (25 12 volt
batteries
> > per string, 2 strings.)
> >
> > Works out to an average of 12.8 volts per cell. Hm.
> >
> > I then plugged in the charger. When at 100%, the controller brought the
pack
> > voltage to 400 volts at about .5 amps. This appears to be the "trickle
> > charge" mode designed to equalize the batteries (high voltage, low
current)
> >
> > I then fired up the car and drove up and down the steep driveway hill.
> > Voltage at full power was in the high 290's (I have to check) with a
power
> > output of about 35kw (120-130 amp draw). From a 52amp/hr pack how is
that
> > for sag?
> >
> > At the end of a few ups and downs, the pack was down to 97.5% by the
> > counter, and still at about 320 volts at rest (ok, 319).
> >
> > I then plugged in the charger. After a few minutes to let it get up to
steam
> > (normal) it was reading a pack voltage of 331 volts with a charge
current of
> > 3.3 amps for a 1.1kw charge. Line voltage was 111 volts (down from 121
idle)
> > at 12.8 amps (the max the controller will take, I can adjust this)
> >
> > The batteries are now 97.8% full. Here is what I am wondering:
> >
> > What if the problem is this: The system has this neat counter that
watches
> > current go in and out of the batteries. When the *counter* reaches 100%,
it
> > declares the batteries "full" and does 8 hours of trickle charging at
400
> > volts/.5 amps. Then it shuts down. This will keep the controller from
> > overcharging the batteries.
> >
> > But over time, the counter becomes out of whack with the "truth" of the
> > batteries. The counter thinks "full", but the batteries will still want
a
> > bit more charge. But they don't get it. Time passes, and the max charge
of
> > the batteries becomes less and less.... This sort of bears up in my
test;
> > after 30 miles the gauge read half full but the batteries were tired.
> >
> > Now, being the guy I am, I apparently can reset this number to anything
I
> > want. The question is should I reset it to something like 90% when it
thinks
> > it's full to give it another 10% of "overcharge"? Will I run the risk of
> > damaging the batteries? At what voltage should this pack read "full"?
> >
> > To be honest, the pack might be only 60% full. And the fact that it's
> > happily sucking max power right now (3.3amps) makes me wonder about
that.
> > I'll watch it and see if it goes to trickle simply because the counter
hits
> > 100%.
> >
> > Thoughts and comments from the battery crowd? The biggest thing I may
have
> > going for me right now is that this pack only has 1,800 miles on it; it
> > might be saved...
> >
> > Chris
>
> --
> vze3v25q@verizondotnet
>
>
>