Re: (ET) Ccccold Batteries

["Christopher Zach" <czach computer org>]

I think you're finding the problem in the Landis charge controller that I
mentioned in earlier posts. It's simply not equalizing the pack. And with
the pack out of whack your hack will be in the sack, jack.

(You have to admit that was a nifty bit of alliteration)

Seriously, the problem simply is that the Landis can not compensate for
either temperature or equalization voltages. I have this discussion on the
EV list, as I own a 95 Geo Prizm electric with a 300 volt pack (two strings
of *25* batteries). I'm quite familiar at this point with charge voltages
(charge to 15 volts per battery) and equailization voltages (15.6 volts per
battery) for 50 minutes. On the Elec-trak this works out to a charge 
voltage
of 45 volts with a top-end equalize of 46.8 volts.

Now, on the Elec-trak you probably don't need that last little bit. But you
should be taking your pack above 42 volts. And to be honest you should take
it up to 45. And *hold it there* For a length of time. That's what the 
timer
is for.

Temp compensation: You should add an additional 3mv per cell (Elec-trak has
18 cells in six batteries) per degree centigrade below 20 degrees
centigrade. At 0 degrees C (freezing) you're looking at adding an 
additional
volt to the above numbers. Note this is the temp of the battery, NOT the
outside temp.

I'm sorry if this comes down a bit on the Landis concept: It's a neat idea
and seems like it should work. The problem is if you use only the Landis,
your batteries will never get fully charged; some will charge more than
others. Then range is determined by the weakest battery. If you turn the
Landis up too high, your batteries will simply overcharge, and boil the
water away. Too low and you don't get the equalize.

The dial charger on the Elec-Trak and that big honking transformer is as
dumb a solution as there can be. It's really stupid. And it results in the
batteries being somewhat overcharged and boiling off a bit of water. But
these are flooded batteries; you can add water with no problem. And the
timer will cut off before you cook the batteries anyway.

It's a simple solution. And I hate to say it, but unless you want to build 
a
really complicated charge system it's the best way to go. Use the timer.

As for the foot switch, take it all apart and lube the plates with a *bit*
of grease. Makes it happier.

Chris



----- Original Message ----- 
From: "T Humphrey" <thumphrey mynra com>
To: <elec-trak cosmos phy tufts edu>
Sent: Tuesday, January 20, 2004 2:43 PM
Subject: (ET) Ccccold Batteries


> OK Where do I start.....
>
> It's cold and so are my batteries. So obviously I have reduced
> range.
>
> I have noticed two things and have some questions also so if my
> thoughts seem distracted it's because they are, please bear with
> me.
>
>
> I have a Landis controller. I noticed one day when it was a nice
> warm -10 degrees outside (yeah, neg 10, not uncommon in the
> northeast lately) that my range was greatly reduced. I was plowing
> the driveway, then the neighbors driveway, and  STOP, no slowing
> down just STOP. No readings on the gauges, no power to anything.
> Actually I should confess, my wife was doing the plowing, and
> could not tell me what the gauges were doing just before the shut
> down. Anyway after about 6-7 minutes, click, everything came back
> up. I told her to take it back to the garage.
>
> Plugged it in, it immediately started to charge, .....good. I am
> fortunate that I heat my house with a wood boiler, and it is in
> the same garage stall as the ET. So I have a real good reason to
> visit the ET every 4 hours or so. I noticed after about 12 hours
> that the charger had stopped and was now in the "Landis Phase".
> This seemed really bad to me, since when I was using the stock
> timer it would run continuous for what 15-18 hours or so. Has
> anyone timed the timer?
>
> Two days later, she was plowing again. She could not finish our
> own driveway, let alone the neighbors. I figured it was not a full
> charge on the batteries. (Yes David, I will go get a hydrometer).
> So I did two things;
>
> 1. I made a jumper wire that I can clip onto the Landis Controller
> to bypass it, which allows it to run constantly until I remove the
> jumper.
>
> 2. Figuring in the sub-zero cold this time of year, I reset to
> Landis Controller to come on at 41v.  Thats 2.27 vpc, is this too
> high, should I go higher? I will reset it back to 39 when the
> warmer weather comes. I noticed after a 36 hour constant on charge
> (very slight gassing, almost unnoticable) with the controller set
> at 41v, it is still cycling every 20 minutes or so.
>
> After my 36 hour charge, I was able to plow my driveway and have
> lots of power when I got done. Put it on charge, let the Landis
> charge it, It started cycling after less than 8 hours so I
> bypassed it for the overnight, in case I needed it again in the
> AM.  Then let the Landis take over. Like I said I am in the garage
> at leat every 4 hours, so there's no chance that I will forget to
> remove the bypass.
>
> There is one more possibility that could result in my wifes loss
> of power on the tractor. The pedal is very sluggish on the return
> stroke when it's this cold. If she, I, we, were to stop the
> tractor with the brake, and the pedal didn't return all the way
> off, then the tractor will not restart until it gets "reset to
> zero". I noticed many times, when I was plowing, that I had to
> lift the slider with my toe. Any suggestions, I'm thinking heavier
> spring as this one is pretty weak at the top.
>
>
> trying to...
>
> Stay Charged!
> Hump
> I-5 NY
>
>
>
>
>
>
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