help on Nightsun light system

[John Keith]

I know that Nightsun light systems have been discussed in this group before
but I never closely followed the discussions (I know the company has a
terrible customer service attitude, won't supply replacement parts, etc.) But
the info I would like to collect for a friend now is what can be done with
batteries that don't seem to hold a charge for any length of time. Is there a
way to make this system work? My friend has gone through three sets of
batteries and none of them will deliver more than about 20 minutes of useful
light output. Any help, ideas or suggestions would be welcomed.

John Keith

[Joern Yngve Dahl-Stamnes]

Thus spoke the keyboard of ke...@hpfcso.FC.HP.COM (John Keith):

What your friend has done the only wrong thing that also I have done -
discharged the battery too much. When NiCa batteries got to discharged,
they swell (it's volume increase a little bit). This damage the structure
of the battery cells which again cause lower capasity. And there is nothing
one can do to fix this once the cell has been damaged - exept to get a new
battery :-(

So what can your friend do to make this system work? I will do the
following thing with my system:

1. Change the battery with a lead-acid gel battery. A 12V, 6Ah battery will
give more power than the Nightsun NiCa battery pack. I will build a
aluminum box what can be mounted on my MTB just as if it was a waterbattle
cage. I will also try to make the box as waterproof as possible.

2. I will build a battery monitor that will warn me when the voltage drop
belowe a given value. If it continue to drop, it will cut the main light
too protect the battery. This is a rather easy project. The printed circuit
will fit into the battery box (that's why I want the box to be waterproof).

3. Build a new changer for the lead-acid gel battery which automatic cut
the carging when the battery is fully charged. To overcharge a lead-acid
gel battery can damage it.

4. Ride my bike in the dark ;-)

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* I went back to my mother, * Joern Yngve Dahl-Stamnes *
* I said, "I'm crazy ma, help me!" * University of Trondheim *
* She said, "I know how it feels son, * The Norwegian Institute of Tech. *
* 'cause it runs in the family." * Division of Physical Electronics *
* - The Who, Quadrophenia * e-mail: da...@fhydra.dnet.unit.no *
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