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

["Markus Lorch" <mlorch vt edu>]

Hi David,

thanks for your feedback ... this is probably valuable advice.
I always intended to automate a process where I would use the
built in charger for a bulk charging phase and then let the 
Soneil chargers finish up but to date its mainly manual.:

If I need a fast recharge, then I turn on both the main charger 
and the Soneil chargers in parallel and set the main charger, 
to a relatively short time (I made marks for 1 hour and 2 hours
on my timer), when the main charger shuts off the small chargers
will continue and finish the job without overcharging.

One thing to note: I cannot reliably turn on the main charger 
and then, right when I shut it off turn on the soneil charger.
I have to wait until the batteries drop to a resting voltage that
indicates that they are not yet fully charged otherwise the 
soneil charger will go into charge sustaining mode (float) right
away and the batteries will never be brought up to an equalizing
voltage. Simple fix is to either connect the soneil chargers in
parallel right away or to spin the main motor for a few seconds
which brings the battery voltage down enough for the smart chargers
to detect that there is work to do :)

On another note, the lead engineer from Soneil, Sach Jain, tells
me that the charging curve of the 1212 charger (5A) is in his 
oppinion better than that of the 1206 (3A). 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. Many people and customers however prefer the 
constant float voltage method of the 1206 and from battery manufacturers
I got conflicting answers as to which is the better method depending
on who I asked within the same company.

Markus

> -----Original Message-----
> From: elec-trak-bounces cosmos phy tufts edu 
> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of 
> David Roden
> Sent: Sunday, April 17, 2005 2:06 AM
> To: elec-trak cosmos phy tufts edu
> Subject: (ET) Re: Soneil charger experiences & advantages
> 
> 
> It may not be too big a deal in our application, which is a 
> relatively low 
> stress one for batteries, but golf car batteries are usually 
> happier when 
> they're hit with a more muscular initial charge than 3 amps.  
> A lead battery 
> really should have a charge that starts in the range of C/10 
> to C/5 (that 
> is, amp-hour capacity expressed as amps divided by 5 to 10).  
> Thus a 250 amp-
> hour battery should be charged at 25 amps or more.
> 
> I'm not an electrochemist, and my understanding of the reason 
> for this is 
> rather dim.  I get the impression that the higher current 
> somehow penetrates 
> the lead sulfate on the plates (this lead sulfate is NOT a 
> pathological 
> condition, as some gadget marketers would have you believe, 
> but rather a 
> natural consequence of discharging a battery).  From what I 
> understand, it's 
> NOT necessary to have that high a current during the entire 
> charge period, 
> just for the first few minutes or so.
> 
> Some batteries need this more than others.  In particular, 
> Hawker Genesis 
> batteries are notorious for developing severely reduced 
> capacity if they 
> don't have high current charging at least on some cycles.
> 
> A set of low current modular chargers is probably fine for 
> performing the 
> finish charge on your battery pack, but it may be a good idea 
> to use the GE 
> charger for at least the first few minutes when you recharge.
> 
> 
> David Roden - Akron, Ohio, USA
> 
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