possible broken 300 amp single circuit switch

[KindOfBlue]

I had my chartplotter directly connected to a BlueSea 300 amp single circuit switch and last week the plotter stopped turning on. Also connected to this switch is my link 2000 battery monitor.

I tested volts supplied to the plotter. This turned out to be just fine (12.3-12.6 depending upon battery charge state). I figured that my chartplotter was broken. To confirm, I re-wired the chartplotter directly to the battey (it's fused) and it works.

So I am thinking that the 300 amp switch is broken and the plotter couldn't pull the current needed to fire up although the volts were there. Any other ideas before I test my theory with an expensive switch replacement?

[mitiempo]

Switches rated for 300 amps have a large contact area when connecting. Even if this was reduced to the size of 18ga wire the plotter should still power up. I would suspect something else like the wiring either to or from the switch. How is your link connected to the switch?

[KindOfBlue]

There are only two studs on the switch. The plotter and monitor are on one side. On the other side has 3 cables. 1 from the charger, 1 cable to the pos battery post and 1 cable to my SSB. I was advised to run my SSB directly to the battery and I used this post.

[btrayfors]

Check the connections on the chartplotter terminal end; also, could be an intermittent caused by a stressed or broken wire....when you moved it to the battery it worked.

I agree it's unlikely the switch but, hey, stuff happens on a boat :-)

Before you replace the switch, hook up a real load to the post the chartplotter and battery monitor are on. A big 12V lightbulb or other 12V load. Or, move the SSB terminal to the other side of the switch and transmit. If that works OK, then it's not likely the switch at fault.

BTW, connecting your SSB to this switch is not the same as a direct connection the battery. There are other loads on this wire. Best practice is to use AWG6 cable directly from the house battery terminals to a post or small terminal strip located near the radio. Use a 30A fuse in BOTH the positive and negative cables.

Bill

[KindOfBlue]

Originally Posted by btrayfors

BTW, connecting your SSB to this switch is not the same as a direct connection the battery. There are other loads on this wire. Best practice is to use AWG6 cable directly from the house battery terminals to a post or small terminal strip located near the radio. Use a 30A fuse in BOTH the positive and negative cables.

Yeah you got me there. I do use 6awg wire with 30 amp fuses for my SSB. I did this on your recemmendation on ssca. Thank you again.

From the post on the switch to the battery is a 1/0 cable about a foot long so I figured close enough, but. I can move it. I was trying to keep the battery post from being stacked up with wires.

I'll continue to test the switch, but the plotter doesn't work on the switch post.