Wiring question

[Steve Krzesinski]

I bought this mark three over the winter. The wiring and other things have obviously been changed over the years. Therefore my concern. This is an electrical issue.With the main switches in the off position, I connect the two power cables to the battery. I connect the 12 gage wire to the negative wing nut battery post. As I get the positive 12 gage wire near the positive wing nut post I get a small spark. Touch it a second time ....no spark. A volt meter shows 12 volts between the post and wire, which is zero after discharging the wire (spark). However, the charge can be seen to slowly build up again. Seems there is a capacitor in the circuit. I have yet to trace wires, but apart from that and since this is the first "big" boat I have experienced, do you have any ideas? Is this normal (for some reason) or has the previous owner miswired something that I have to locate and correct?

 

[jim stevens]

Hmmm-It does sound like the wire your hooking up has a path back to negative and some capacitance. Maybe an automatic bilge pump float? Some times these aren't straight dry contact open/close switches, but some kinda silicon PFM technology. (pure 'ahem magic)Jim

 

[Rich Lemieux]

Battery Charger?

Do you have a Battery Charger connected to the battery? My charger will do the samething (Truecharge 40+)

 

[Ray Bowles]

Normally the positive terminal is hooked up first

and the negitive last. This helps protect equipment.Ray

 

[Don Alexander]

Ammeter

Steve,May I suggest you try connecting up using an ammeter in series. This will kick when the connection is first made then settle down to nothing if everything is off. If this is what happens then, as you suspect, there probably is a capacitor in circuit. It could be in the input filter of any electronic device such as radio, autopilot instruments etc, or it could have been added as a suppressor.On my own boat I have a hulking great 20,000 mfd across the radio input because my Autohelm bites great chunks out of the supply and it only affects things when I transmit. This is why set makers suggest connecting the radio directly to the battery - I prefer to be able to isolate it though.

 

[Derek Rowell]

For Ray - How and why?

You've got me scratching my head on this one! If you are charging a capacitor you are going to get the same in-rush current and spark regardless of the order of connection. How does it protect equipment?Derek