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Re: (ET) Chargers
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?
--- 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
> > 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
> Latest review of The Emperor's New Hydrogen Economy in
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> Elec-trak cosmos phy tufts edu