Hoppecke fiber nicads [RE-wrenches]

Wed Nov 21 07:01:38 PST 2001

Jeff,
Rob Wills would have the most info on these, but I do have some experience
(also Pete Talmage). We put in several systems using the FNC's in 1990/91.
All but one system was changed to lead acid battery's within four years. The
manufacturer finally owned up to the fact that these batteries were,
largely, unsuitable for home power systems. Hoppecke replaced the FNC (fiber
nicads) with Hoppecke OPzS lead acid cells (which have been very good).
The problem with the FNC's was that you could never get close to their rated
(20 hr) amp hour capacity out of these cells.
Worst case capacities were documented showing the actual usable amp hours
were 20% of the factory 20 hr rate. And this was after months and months of
tweaking the system (per the Hoppecke Engineers instructions) to get the max
out of the FNC's.
We even tried running 24 volt systems with 19 cells (so we could still use
the Trace inverters) so that the per cell voltage could get up to 1.75v for
an EQ charge and regularly charge to 1.675v. Upon discharge there would
always be one cell that would drop out and go to 0.00v while other cells
were still at 1.2v. The next discharge cycle, after a complete recharge,
would yield a different cell going to 0.00v first! This test was done on
four different battery banks and it was always random as to which cell would
drop out. When the one cell would go to zero the battery bank voltage would
go to 23v and then drop from there rendering the bank pretty much useless at
well below expected amp hour capacity.
The best case FNC system is the one I am still using in my small rental
house. I can get 275 to 300 amp hours out of a rated
630 amp hour bank (20AH rate; they are rated 600AH's at the 10AH rate). We
have never gotten over 50% of rated capacity with the FNC's. This is not
ideal as Hoppecke sold these FNC's as batteries which could be used to 90%
of their rated capacity. In this system I am using an Exeltech XP1100 12v
inverter and I regularly charge the batteries to 16.75v. With a
Trace/Zantrax inverter we would not be able to get the voltage so high and
we would get considerably less amp hours out of the bank.
I still have inventory on the FNC's which we replaced in 1994 if you are
interested in a good deal on these interesting cells. I recently sold (40)
407L's for $38 each, these sell for $440 each when new! They are a good
battery when you can afford to derate them by at least 50% and can charge
them to 16.75v regularly and EQ to 17.5v occasionally. They are good in
cool, or cold places (as long as they are well charged) because they do not
lose capacity with temp drops as much as lead acids.
In a word, Beware.
Dave

-----Original Message-----
From: Jeffrey Wolfe, Global Resources [mailto:global at sover.net]
Sent: Tuesday, November 20, 2001 10:52 PM
To: 'RE- wrenches at topica.com'
Subject: Hoppecke fiber nicads [RE-wrenches]

Hi all,

Well, so far we've avoided them, but it looks like we *may* get into a
system design using some Hoppecke Fiber nicads. (20 cells FNC 306 L). While
I've asked the manufacturer for info and application recommendations, what
is everyone's experience with using these with Trace SW and RV Power
Products equipment? Everything I've seen connected to these (and it's
admittedly not much) is working poorly because the charge controller does
not charge the batteries high enough, and the inverter shuts down on over
voltage when the batteries get close to a correct voltage.

Are there easy and good solutions for these? Does anyone have long-term
systems out there with these that they are happy with?

Thanks,

Jeff

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