Re: (ET) charger voltage

["David Roden" <etpost drmm net>]

> New batts are about 6.5 ea.  
> Average batteries chg to about 6.25 6.3

Open-circuit, maybe; but if you expect a full charge in a reasonable 
amount 
of time, the charger needs to push them to around 7.4 - 7.5 volts 
(on-charge 
voltage) with current down around C/50 (4-6 amps for a golf car battery).  
At lower voltages you essentially have a float charger.  Yes, it can 
charge 
the battery, but it could take >weeks< to achieve full charge.

> Landis controller ...

I've posted here about this before and I'm not going to get into it in 
detail yet again.  If you're interested, check the archives.  

Briefly, as I see it, Harry Landis's device is a battery maintainer, not a 
charge controller.  If you can use it with any kind of success as a charge 
controller, it's purely by luck and accident.  I imagine that Mr Landis 
disagrees with me though. ;-)  

In any case you won't find one on my batteries.  I don't need a maintainer.

> Occasionally. people 'equalize' batteries by intentionally overcharging. 
>  This ain't good for them.

There's no other way to equalize batteries, unless you have access to the 
individual cells (I don't know of any golf car battery on which that's 
still 
possible, as all intercell connectors are now internal).  If equalization 
is 
performed at reasonably low currents, the battery gains more life by 
avoiding sulfation (proper charging), than it loses from grid corrosion 
(overcharging).

> ... gotta build a desulfater ...

I know this will annoy the "true believers," but I have yet to see any 
concrete evidence that a "desulfator" does anything significant other than 
applying a long, slow equalizing charge.  The pulsing nonsense has no real 
effect ("crystal resonance"???!) and is just an excuse to charge you more 
money. ;-)

> Charge em to the point that every cell is gassing.  Then leave em
> overnite to remove 'surface charge'.  Test em in the morning.   That 
> will tell you where your batts are at agewise.  

This will work; but IMO, it's more accurate to measure voltage while on 
charge.  Charge until the on-charge voltage stops rising, and note what 
that 
voltage is.  It will fall as the battery ages.  (DV/DT is also a fine 
strategy for charge control, btw.)


David Roden - Akron, Ohio, USA

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