Sun, 27 Jun 1999 18:01:22 +0200 - Message No. 5876
From: "Freddy Van Geit"

Subject: problems with maintenance free battery


You're right to be skeptical about my approach how to charge these batteries
Michael, but believe me, it is the only way to revive dead Yuasa YTX11-BS
batteries.
As an electronic engineer, I had a lot of experience with normal lead
batteries but for once I had to agree with my Honda dealer who showed me his
special Honda battery charger designed to revive Yuasa maintenance free
batteries.
It all has to do with the Gas Recombination Technology principle Yuasa uses,
instead of lead/antimony plates it uses specially designed gas absorbing
lead/calcium plates where the electrolytic is soaked by the plates instead
of floating around them.
Once these batteries haven't been charged for a long time they show an
increased internal resistance due to a solidified electrolytic. If you hook
them up to a stabilized power supply at 14V they will draw only a few
milliamps and they will never charge, just a case of a dead battery you'll
think.
A few years ago Honda had a lot of claims about these 'dead' batteries and
they informed their dealers about this phenomenon and gave them after a
brief seminar the opportunity to buy an expensive charger based on a fixed
current stabilized power supply with a maximum output voltage of 30 Volts!
With a 'normal' battery the charge current will increase very rapidly when
the charge voltage exceeds the battery voltage.
When GRT batteries haven't been used for a while they show the same reaction
but at a much higher charge voltage.
Once you pass the threshold of a few hundred milliamps (could be at 24V!)
the chemical processes in the battery will get the H2SO4 out of the plates
and the internal resistance will decrease (this can take a few minutes)
When keeping a fixed charge current of about 1 Amp, the charging voltage
will drop to about 15 Volts in a matter of hours. When the battery feels
somewhat warm, you know that it is completely charged.

BTW1: due to the GRT technology, all O2 and H is kept inside the sealed
battery.
BTW2: from Yuasa's site: "Note that permanently sealed batteries - Yuasa's
Maintenance-Free battery, for example - generally can be tested only with a
voltmeter or multimeter. These batteries are fully charged when the voltage
peaks and then begins to fall - as high as 17v, for example, on the
Maintenance-Free battery"

Greetings,
Freddy







www@atic.org