From: "David Roden" <etpost drmm net>
Reply-To: noaddress drmm net
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) charger voltage
Date: Fri, 28 Jul 2006 17:20:32 -0400
> 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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