biscuit
new user
Reged: 25/08/2007
Posts: 9
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Each time I start the engine it crashes the plotter, which I then have to reboot (as well as the separately wired GPS). As you can imagine this can occour at moments of maximum akwardness, so any solution (especially one which doesnt involve a major rewire) would be most welcome.
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Stoaty
regular
Reged: 07/10/2004
Posts: 465
Loc: Medway
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Run your chartplotter off your domestic batteries. Not the engine starting battery.
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Stoaty
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Wiggo
regular
Reged: 10/09/2003
Posts: 3410
Loc: (State, Country, etc.)
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Decent batteries, separate batteries? It will always happen if your cranking battery drops too low when staring and the plotter is attached to the same supply.
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The nicest thing about not planning is that failure comes as a complete surprise, and is not preceded by a period of worry and doubt.
Nereid Charter
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William_H
regular
Reged: 28/07/2003
Posts: 3613
Loc: West Australia
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As suggested run the electronics off a battery that is not used for engine start. This may require a wiring change if you have a 1,2,both switch and 2 batteries.
If you have only one battery or rewire is difficult. You could try fitting a silicon diode in series with the +ve supply to the plotter and also one for the GPS. Or move the supply to both so they both go through the diode. You then fit a large electrolytic capacitor rated at more than 15 volts and preferably in the 10000 microfarad range. Bigger is better. Or add several capacitors in paralell.
The capacitor is wired +ve to -ve on the side of the diode towards the GPS/ plotter. The capcitor charges a bit like a small capacity battery to the battery voltage but when the engine is started and the voltage falls the capacitor will provide power to the GPS/ plotter. The diode stops the capacitor voltage from running back to the engine starter.
A small SLA battery would do the same job but would need switching to disconnect when you power off to avoid discharge. Tyhe voltage drop of the diode hopefuilly will be enough to avoid over chage of the battery. But really the capacitor is much less concern. It is happy to be completely discharged on power off and wiull last forever. (almost) But it might need a larger capacitor if your engine is cranked for a long time. The time the capacitor will support your GPS /plotter depends on how much current your plotter and GPS draw.
Capacitors are fairly cheap from Maplin and can be paralelled to increase capacity. Diode should be rated for several amps and are also cheap from Maplin RS etc. good luck olewill
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Trundlebug
regular
Reged: 04/01/2007
Posts: 95
Loc: River Trent
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I have the same problem with my Garmin 120.
When I start the engines (from a separate battery) the Garmin goes blank, yet the Furuno next to it, fed from the same supply, continues to work fine.
Although I can't explain it, the only remedy I could find was to isolate the power to the GPS's when starting the engines. Since I have begun to do this everything has been fine.
I have put the cause down to some kind of spike affecting the Garmin but not the Furuno. Someone mentioned the Furuno is good for 9-24v and the Garmin only up to 15 or something, don't know if that's right.
Although it's a bit of a pain switching off the power to the GPS's it doesn't cancel or wipe anything, so it's not a problem.
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