On 1/26/2013 11:37 PM, Chuck Hursch wrote:
I have been on the fence regarding buying one of these Elcon chargers. I
would really like to know how they behave regarding aging flooded
lead-acid batteries of the 6V variety. The lack of real answers from the
charger vendors isn't really going to cut it. I've gotten no answer or
answers like:
-----
AFIK, the charger output current should naturally compensate for aging
batteries as a function of the change of internal resistance of the
battery pack (i.e., load to the charger). As the resistance of the
batteries increases with age, current output will change proportionally.
Voltage charging points will remain the same.
-----
Unless there is something going on I don't understand, this is BS. Not
being able to change the constant voltage charging level is going to
result in never getting there as the pack gets to be two to three years
old.
Would someone who has navigated the lifespan of a set of floodies with
one of these Elcons like to share their experience?
I think the set of curves in the charger is set with no input from the
buyer. I'd be surprised at this point if a vendor would load a set of
curves to account for aging.
One of the primary reasons I would buy an Elcon is to make more
efficient use of my 120V/20A line at my apt., plus give me the eventual
flexibility to set up for 240V/J1772 charging. US Battery and Roland,
plus some personal experience have pretty well convinced me that getting
as close as possible to C/10 bulk charging rate (~23A) is worth some
effort for pack life/performance. Well, 13ADC on a 120V line at 11A AC
is a lot better than what I can do with my Zivan K2, charging untended
into the night, safely and repeatedly. However, I've seen varying DC
charging rates for the 2500:
96xx model, pdf manuals are on p1:
13A:
Elcon: (TCCH-96-18):
http://www.elconchargers.com/catalog/item/7344653/7638094.htm
Evolve Electrics: (96XX):
http://evolveelectrics.com/PDF/Elcon/PFC2500%20Manual.pdf
11A:
KTA-EV: (96XX):
http://www.kta-ev.com/v/vspfiles/assets/images/pfc2500.pdf
I suspect it really is 13ADC (since Greg McCrea did write 13A, but, hey,
he's reading a manual too), which is almost too good to be true from 11A
off the line. 11ADC is not worth buying the charger. Anybody have a 96V
pack and what are you seeing?
My current pack is at 4 years and 12K+ miles, including a lot of hill
climbing. I'm juggling low-cycle spares from my 2005-vintage pack into
this pack, and my range is getting to that nasty iffy point to deal with
the hill climb to my apt. I'm probably looking at a new pack within the
next six to nine months (if I can justify it as I ride my bike to work
most of the time now), and I'd like to deal with this charging rate
issue for the new pack.
I can't help you with the Elcon (never seen or tested one). But you are
correct that the proper charge voltage for old lead-acids goes down with
age. A new 6v battery ends its charge at about 7.5v and 5 amps; an old
one is more like 7.2v and 10 amps.
I've had the best luck with chargers that use some form of dv/dt or
di/dt algorithm. These algorithms watch the voltage and current, and
shut off when the voltage stops rising (or the current stops falling).
I think you could *add* something to the charger to produce this
behavior. It could detect the old battery's "full" point, and just shut
off the charger.
--
Humanity is acquiring all the right technology for all the wrong
reasons. -- R. Buckminster Fuller
--
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
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