RE: (ET) Re: Soneil charger experiences & advantages

["David Roden (Akron OH USA)" <etpost drmm net>]

On 19 Apr 2005 at 11:21, Markus Lorch wrote:

> The 1212 will not float
> the batteries at a constant voltage but rather wait until they
> drop below a set point due to self discharge and then charge with
> a full power pulse until they are full again. This pulsing to maintain 
> the
> battery at full state will help to break down remaining lead sulfate
> crystals.

Correct me if I'm wrong, but the "pulsing" algorithm you describe sounds 
like 
that of a simple cycle-dropping charger.  They typically cycle several 
times a 
minute.  They turn on again not because of self discharge, but rather 
because the surface voltage from the charge dissipates quickly.

The $50 ones you can buy at K-Mart and NAPA (with blinking LEDs) work 
that way.  Even in the absorption stage, they apply a rather high 
instantaneous charging current, and depend on the duty cycle to limit 
average current and keep the battery from overcharging.  I worry about 
this, 
especially for gel batteries.  I'd be concerned that the high 
instantaneous 
current would cause abrupt gassing.  Gas gels too much, and they start to 
suffer from electrolyte cavitation.

That said, I've used them with reasonable success (cheap cycle dropping 
chargers, I mean).  But I'd still much prefer a true constant voltage 
float stage.

As for "pulse charging," there's some religion involved, IMO.  One fairly 
savvy 
EV professional I know of is a believer, and so are some of the Home Power 
crowd.  This surprises me because so far the only real "proof" I've seen 
that 
they work has been anecdotes and "lab results" provided by the folks 
selling 
the gadgets.  I've never seen independently verified evidence that pulse 
charging has any measurable effect on hard-crystalline lead sulfate.  More 
to 
the point, no one has yet shown me that it reverses sulfation any better 
than 
a long, slow, constant current equalization charge.  

The claims for pulse "desulfators" usually involve some kind of fuzzy ad-
speak about "resonance with the lattice structure of the crystals," but as 
far 
as I can tell they are essentially just slow ("trickle") chargers.  Soneil 
seem 
to have a pretty good reputation, so I'd be rather surprised if they made 
such 
claims for any of their chargers.