On 2005-10-05, (Rubicon) <> wrote:
> I read in a previous post about the induction method of charging an
> electric toothbrush.
> In my wanderings around the net I've seen a series of commercial
> marine fishing devices that report the depth and spread of their nets
> to the ships. These devices have two stainless contacts on their
> exterior for re-charging their batteries in a cradle. It'm wondering
> how these re-charging contacts work, especially when they're in salt
> water and does anyone have a circuit. My reason is that I'm thinking
> of putting together a "Kontiki", a floating battery powered torpedo
> shaped fishing device that takes a line out past the breakers. The
> prop is either at the rear or under its front for better
> self-correction and it's on a timer. As they're battery powered
> (sealed lead acid or ni-cad pack) it'd be good to be able to re-charge
> it without having to be constantly opening and closing it. As I write
> this it occurs to me that an overcharge would possibly cause the
> batteries to vent and build up pressure and fumes inside the
> watertight casing. I understand that sealed lead acid batteries and
> saltwater don't mix (chlorine gas) but it they seem to be in regular
> use as a power source.
> Any help here is greatly appreciated as I'd really like to know just
> how they accomplish this.
I expect there's a diode after the contacts to stop current leaking back
sealed lead acid is probably a bnetter choice unless you intent to put the
charge controller inside the torpedo body.
. . . . . . . . .
charger . ::: 12V
. . . . . . . . . .
The charger would need to be modified to compensate for the extra
voltage drop introduced by the diode.
another option would be to put a relay that's controled by a reed switch
in place of the diode that way a strategically placed magne in the
charging cradle can activate the relay and with the relay contacts there's
no appreciable voltage drop.