Re: (ET) Timer stuff

["Tim Humphrey" <hump evgrin com>]

Chris;

I can't answer your questions with a definate yes or no. I will describe 
what the controller does, and you can make
your own assumptions. I'll also talk about how I use the controller.

I'm sure Harry will post how to get one if he didn't reply to you 
privately. I believe he has an ad up on
elek-trak.org ...
...
...
...
In fact he does.....
Here's his write up..

This controller replaces the stock timer on the ET. Basically, the 
controller checks the rest voltage of the battery
pack, and if it is less than 38 volts, it turns on the charger (via a 
solid state relay) for about five minutes. After
the five minutes is up, the controller turns off the charger and waits 
until the pack voltage again falls below 38
volts, at which time it again turns on the charger for another five 
minutes, and so on. This controller does not
replace the stock charger, it only replaces the timer. You just plug in 
the ET when not in use and forget about it.
The setpont is adjustable via a trimpot on the circuit board.
The setpoint is set to 38 volts, which is equivalent to 2.11 volts per 
cell, which is the resting voltage of a fully
charged flooded lead acid cell at room temperature. Some people like to 
tweak up the setpoint a bit in the winter, but
I have never bothered. I have used these on my E8M and E12S since about 
1992, and have now gone through two sets of
batteries each.
I have sold around 80 of these over the last 5 years or so, with 
essentially no problems. You can see the installation
instructions at:

http://www.gis.net/~hlandis/mowerinst.doc

The price of a controller is $40, including shipping to the US and Canada. 
Send check or MO to
Harry Landis
207 Oak Street
Norton, MA 02766
Or PayPal to:
hlandis hotmail com
Please don?t use the Reply To button on this ad, as Hotmail (evil 
Microsoft) doesn?t like it and frequently sends the
message to my junk mail folder. Contact me directly at:
hlandis hotmail com


Now, having pasted that, I will say that I do turn my controller up during 
the winter, I also use my tractor almost
daily during the winter, sometimes twice daily, I'm sure you understand.

Another trick I sometimes use is.... I have made up a short piece of 12ga. 
wire with alligators one each end. When I
feel the need I just clip the wire across the solid state relay, 
essentially shorting it out and forcing the charger
to run until I remove the shorting wire. If your batteries need 
equalizing, this may do it.

You can have my timer, I'll never re-install it, it functioned well when I 
removed it..




-- 
Stay Charged!
Hump
"Ignorance is treatable, with a good prognosis. However, if left 
untreated, it develops into Arrogance, which is often
fatal. :-)" -- Lee Hart


>
>
> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of Christopher 
> Zach
> Sent: Monday, May 23, 2005 9:14 AM
> To: Elec-trak list
> Subject: (ET) Timer stuff
>
> Ok, everyone seems to recommend the Landis, so I think I'll bite the 
> bullet and give one a shot. It should be
interesting; my big questions are:
>
> 1) Can it bring the batteries up to a "full" state of charge as 
> indicated by my battery monitors (7.35v per battery)
>
> 2) Can it equalize an out-of-balance pack?
>
> Also I wonder if it can be slightly rigged to act as a solar charger. 
> One could use it's on/off control to modulate
a MOSFET in series with the panels. Might be the magic solution for 
everyone who wants to charge solar but can't
find a 36 volt solar charge controller.
>
> Where do I get one?
>
> Chris
>
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