Re: Second Run - Sonnenschein Gels

[Dave Goldstein <goldie.ev1@juno.com>]

On Fri, 28 Jun 2002 08:06:38 -0400 "Dave Harris" <gvanman@cac.net>
writes:
 . . . . 
> Time to step in and clarify a few things regarding the 
> Sonnenscheins:

-[CLIP]-

> The A500C DTB Series (Dryfit Traction Block)
> Now we are getting somewhere!
> These are made specifically for EV and Traction cycling 
> applications.
> Cycle life is rated to 6-800 cycles IEC/3-400 cycles DIN.
> These are designed to be charged/discharged on a regular 
> basis to 80% DoD and back.
> Obviously the price goes up as you move from the A212 
> series to the DTB's but you get what you pay for.
> It is more expensive to use a cheaper battery that is not 
> designed for the application that you are going to use it in.
> I see so many posts to this list where people buy used standby 
> type batteries and hope to get them to work in an EV application! 
> Invest a bit more money and buy appropriate batteries for the job.
-[CLIP]-

[On Thu, 27 Jun 2002 22:25:50, Seth <vze3v25q@verizon.net> writes:]
>> The Sonnenscheins have a poor 1 hr rate (50% of 20 hr) but I don't
>> believe the Hawker rating of 80% of C/20 at 1C. The Sonnenscheins 
>> also appear to be under half the cost of Hawkers.

[Dave Harris replies:] 
> Depends which Sonnenscheins you are talking about and which 
> application they were designed for.
> The EV DTB's are rated at the C5 rate and will deliver 70% of this 
> at C1.  C20 rate is not very appropriate for most EV applications.
> 
>
> >>From: Peter VanDerWal  <ev@l...>
> >>Date: Thu Jun 27, 2002 8:55pm
> >>Subject: Re: Second run
> >>  Um, you're comparing apples to oranges here.  The Sonnenscheins 
> >>  are Gel cells and the Hawkers are AGMs.

[Dave Harris replies:] 
> I agree here, AGM's have a lower internal resistance than the Gel's 
> and are able to sustain higher currents because of this.
> 
> >>Gel cells are not really appropriate for EVs unless you can keep 
> >> the current levels WAY down, say under 250 amps at all times.

[Dave Harris replies:] 
> Tell that to the electric and hybrid bus manufacturers - most of the
> successful programs are using the Sonnenscheins as the power 
> source! Again, it depends on the type that you are using.
> As a rule of thumb, the maximum sustained current acceptable is 2 x 
> C5 rate i.e. C5 rate of 180ah = sustained current of 320 A.(Obviously
not 
> for very long!).
> Which EV's need to sustain currents this high anyway? (John Wayland 
> et al excluded!).
> Even the El & Hybrid buses do not sustain these high currents for 
> very long.
> Cheers,
> 	Dave Harris (and yes, I do have a vested interest!)

---

  Thank you, Dave Harris!!

   I think you did a masterful job clearing up some of 
the misconceptions about Gel Cell Batteries that have 
appeared from time to time on this List.  Sonnenschein 
gels from Germany have an excellent reputation for good 
performance and long life in heavy-duty traction (EV) 
applications, and the Dryfit 6 volt gels tested by Arizona 
Public Service some years ago in its EV fleet, were the 
longest-lived Lead-Acid batteries ever tested, as I recall
(>30K miles!) 

   You also presented some information about the various
classes of Sonnenschein 12v gels that I had not seen before.

   In summary: Yes, gels have higher internal resistance
than AGM (Absorbed Glass Mat) batteries and do not 
deliver the extremely high amps required for drag racing.
But *properly-selected gels* are more than adequate 
for highway applications -- and, with a good charger,
are likely to last a heck of lot longer!.  

   In a car like Chris Zach's US Electricar Geo Prism --
which is how this conversation began -- two strings
of Sonnenscheins, each capable of delivering a 320
amp peak (i.e., - 640 amps total) should be more than
adequate for any demands from the Dolphin controller.

   But Chris will likely need a more suitable charger 
than that offered in the Prism.  Which many not be a
bad idea!  

   I am surprised that it hasn't been mentioned on 
this list previously, but the US Electricars had a 
very bad reputation among fleet managers for *under-
charging* their batteries -- a particular problem with
Hawker Batteries, which all but *demand* a high
initial charging current (~50 amps initial inrush would 
be ideal!).  

   But the weak USE charging system, with its limp
output further split between the parallel battery strings,
simply was not up to the job.  The result:  Continually
undercharged and partially-sulfated Hawker Batteries
that delivered only about half of their rated capacity! :-(

    Therefore, a new $8,000 set of replacement Hawkers
is likely to lead to considerable unhappiness in fairly
short order!  

   A far better approach would be to find the correct
Sonnenschein 12v batteries and to UPGRADE THE
CHARGER -- and to still be able to pocket some 
additional cash.  

   Thanks, again, Dave Harris.   Didn't we meet, 
once upon a time, during the heyday of the G-Van?

   And no, I don't have a vested interest in any of this.

   Regards,

   Dave Goldstein
   President, EVA/DC and
   Program Development Associates
   Gaithersburg, MD

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