Re: Battery Chargers, Pulse Units

[roden ald net]

There are lots of things to consider.

If your batteries are just now getting weak after 8 years, I think that's 
pretty good performance.  In an on-road EV, we're lucky to get more 
than 3 years from a pack.

I really think that the existing ET charger is adequate for flooded golf 
car batteries.  That 8-10 year service life is actually quite decent.

That said, it is not a very sophisticated unit, and there are more 
modern types available.

The Italian company Zivan makes a range of modestly priced 3-stage 
chargers in various voltages.  They are based on switchmode power 
supplies, so they are fully transformer isolated, but are much lighter 
than the typical boat-anchor ferroresonant or conventional transformer 
charger.

The Zivan NG1, available in outputs from 12 to 48 volts, is reportedly a 
very well-built unit with the price to match -- $573.  It's a 1000 watt 
charger (about 27 amps at 36 volts).   The older K5 is less robust, 
perhaps not as nicely built, with less capacity (15 amps at 36 volts) -- 
but it's cheaper at $461.

See http://www.mcn.org/a/innEVations/chargers.html for information on 
the Zivan chargers.

Ken Olum points out that three 12v chargers are usually cheaper than 
one 36v charger.  That's true for simple, inexpensive utility chargers, 
but not so true for sophisticated 3-stage chargers.  (Most 12v chargers 
you can buy in a hardware or auto parts dealer for $40 - $75 each are 
simple taper chargers.)

One very interesting charger I've heard of is made by Statpower (see
http://www.statpower.com/tc20.htm for one example).  It's a true 3-
stage charger that delivers 20 amps (they also have 10 and 40 amp 
models).  

Each charger is supposed to be able to charge up to three 12v 
batteries.  It has 3 separate diode-isolated output terminals, though it's 
unclear to me whether the charge control actually senses and controls 
the batteries separately.  Also, all 3 outputs share a common negative, 
so you'd have to disconnect your batteries from the tractor's series 
string before charging -- a real pain.  You would probably want to use 
one separate unit for each 12 volts of the tractor's battery string.

I don't have any personal experience with Statpower chargers, but they 
look pretty sophisticated.

Statpower has an online store where they sell older refurbished units at 
about half price (I suppose one might wonder just what the failure rate 
is if they have lots of warranty returns to refurbish).  A 20 amp dual-
output charger is priced at Can$215 (US$139), pretty reasonable for 
such a unit.  The 10 amp refurbished charger, which does not have the 
dual output feature, is priced at Can$152 (US$98).  

You would probably need three of either unit to charge 36 volts worth of 
batteries.  If these were not refurbs, three of them would cost more 
than a 36 volt Zivan NG1 (but they would do a better job of keeping the 
different batteries at an equal state of charge than a single charger for 
the whole series string).

There are 3-stage chargers made by Guest Corp. which actually have 
three separate chargers in one box.  However, I have heard of reliability 
problems with these chargers.  Too bad.

Sorry that I also have no personal experience with the pulse units. One 
person whose judgement I value points out that nearly *every* charger 
is a pulse charger, because they all rectify AC and put out pulsating 
DC at 120 pulses per second.  However, I have heard reports from 
other people I respect who say they have had good results from units 
like the Canpulse.  I get the impression that these units operate 
independently of the charger.

If you try one, please let us know how it works for you.

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