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Re: (ET) Chargers (and winch)

Perhaps my concern arises from the fact that my typical applications (snow blowing on a short and angled driveway and tilling) do use the lifts a lot. I have seen the front and rear halves of the pack be out as much as 0.2 volts at the end of a long run. I don't use my ET for mowing as my yard is more garden than lawn. I have burned out a lift motor and a hand cultivator attachment.
The flooded batteries will tolerate this, so long as one ensures the extra charging time required to "equalize" the batteries is provided, or does balance charging (which almost nobody does).
I'm contemplating redoing the rear lift arrangement with a 12-volt winch, so it could be used as both rear lift and a winch. So far, everything I have seen seems overkill; why use a 2500 lb winch on a 600 lb vehicle? Which model of winch are you using? 

Darryl

David Brandt wrote:

I based my opinion on the fact there are several on this list using 3
12V chargers with the original setup, and have reported excellent
results.  Empirical data beats theory any day.

Personally, I won't have to deal with any of that - my lights are LED
and run via CL2 drivers off the full pack voltage (I highly recommend
those inexpensive little CL2 chips!).  The "lift" is now a 12V ATV
winch which will run off the front battery pair.  So everything is in
12V blocks.

With the original setup, I agree the 18V tap is a little weird. Some
have used it with a 24V tap, which would solve the problem.

But even if they did not, the lift is used for only seconds at a
time, and usually only twice per mowing run (lower the deck at the
start, raise it at the end).  Considering ET's use 220 AHr batteries,
and further considering they are flooded, and therefore (relatively)
tolerant of this sort of abuse, that amount of imbalance is easily
tolerated.  One of the center pair will simply be overcharged a bit
(and use more water) while the other one fills up the rest of the
way.  A conscientious ET user will check the batteries to see if they
need water regularly, and fill it up before it gets too low.

Now if there was an application that used the lift a lot, say for an
hour or two, that would cause a problem, but then the original lift
motors would probably burn out before the batteries died.  I imagine
tilling/plowing, and raising it at the end of each row would be the
most extreme realistic application.  I don't know how much current
the lift uses.  If I did, we could figure out exactly how imbalanced
the batteries would be.  I bet it wouldn't be much.  Anyone out there
measured lift current and typical time of use per run?

David Brandt


--- On Sun, 8/9/09, Darryl McMahon <darryl econogics com> wrote:


From: Darryl McMahon <darryl econogics com> Subject: Re: (ET)
Chargers To: "elec-trak cosmos" <elec-trak cosmos phy tufts edu> Date: Sunday, August 9, 2009, 8:14 AM I am a big fan of modular 
charging (one charger per battery). I have 12 chargers in my
current electric car, one per 12-volt battery.

However, the proposed arrangement strikes me as less than optimal.
I am assuming the use of 6 x 6-volt batteries, preserving the
centre tap to power the lifts.

My primary concern is the two electrically centre batteries.  The
front and rear lifts tap at the 18 volt point, which splits the
middle pair if you are charging at 12-volt points.  If your use of
the lifts is unbalanced, this middle pair will likely become
unbalanced as well, and even an intelligent 12-volt charger is not going to actively address that imbalance on the two 6-volt batteries in series. If you are going to let that imbalance slide, 
why not just one 36-volt charger for simplicity (and likely lower
initial cost).

If you choose to use multiple chargers in series, make sure the
chargers are rated for this application (fully isolated).  Any
electrical common points in the chargers will lead to problems.

The Elec-Trak also has a 12-volt tap for the headlights, which
would be addressed by using 3 x 12-volt chargers.

I use the Soneil 3610SRF on my E12 in preference to the original
charger, and have for years. Disclosure:  I am a distributor for
Soneil chargers, because of my experience with this charger.

Darryl McMahon

David Brandt wrote:

I plan to use 3 12V smart chargers in my E15 - they

are only about

$35 each at batteryweb.com or many similar

websites.  Of course if

you desire to spend a lot more by going to a Lester

offboard charger,

or by getting a marine grade multi-bank charger, you

can get

excellent results that way, too, but I have heard from

several on

this list that went this route and would never go

back.

A 3A model is the smallest that you would want to get

- it'll take a

long time to charge, but a typical mowing schedule is

only once a

week anyway, and the smart chargers can be left

plugged in.

David Brandt



-- Darryl McMahon
The Emperor's New Hydrogen Economy (in trade paperback and eBook) http://www.econogics.com/TENHE/ 

Latest review of The Emperor's New Hydrogen Economy in Greenlife
Magazine http://www.econogics.com/TENHE/tenheGLspring2009.htm


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--
Darryl McMahon

The Emperor's New Hydrogen Economy (in trade paperback and eBook)
http://www.econogics.com/TENHE/

Latest review of The Emperor's New Hydrogen Economy in Greenlife Magazine
http://www.econogics.com/TENHE/tenheGLspring2009.htm