Boats For Sale:
Chasing Loss of Voltage |
Post Reply 
|
| Author | |
cboland 
Senior Member 
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
 Post Options
 Thanks(0)
 Quote Reply
 Topic: Chasing Loss of VoltagePosted: August-10-2020 at 2:53pm |
|
'99 Sport Nautique w/ GT40:
Can anyone provide a wiring diagram or point me in the right direction regarding a voltage drop I'm trying to figure out. I've been troubleshooting a slight rough idle issue, but in the meantime I stumbled across the fact that with the boat running, either at idle or higher (2,200 RPM) I'm only measuring 12.5 volts on the battery. I put the voltmeter on the alternator post and it reads 14.5 volts, so the alternator is good. I'm losing voltage somewhere between the alternator and the battery. I can only see the red cable coming off the alternator post and running up towards the front, but I have no idea where it's going, so not sure where to go next to try and measure. I figure before I start trying to troubleshoot any other issues I need to make sure the electrical system is functioning properly. Thanks.
|
|
|
Bud
1999 Sport Nautique |
|
 |
|
|
Gary S
Grand Poobah 
Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
Post Options
Thanks(0)
Quote Reply
Posted: August-10-2020 at 4:01pm |
|
About 3 feet down that harness that connects to the alternator is the 8 pin plug that connects the engine harness to the boats harness start there.....
|
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 7:30am |
|
Thanks. Turns out I’m not dealing with a stock configuration. A second battery and dual amp stereo system were added at some point, so instead of the wire running from the alternator to the 8 pin plug, it runs all the way up to the bow where there’s been a battery isolator installed behind the driver kick panel. Then it comes back to the engine harness.
|
|
|
Bud
1999 Sport Nautique |
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 2:52pm |
|
I think I may have found my issue, but I could use some input from the electrical gurus.
As I mentioned earlier, a battery isolator was installed under the helm to facilitate a two battery system. Consequently, instead of the positive wire coming off the alternator and running straight to the 60 amp breaker, it comes off the alternator and runs up to the isolator and then a new wire runs back to the engine and connects to the orange wire via butt connector which goes to the 60 amp breaker. The new wire runs are using a heavier gauge wire (8 I think) whereas the original orange wire is smaller. As you can see in the pics, the butt connector has gotten very hot at some point such that the black you see is melted plastic wire loom that it was touching. I assume possibly the step down in wire gauge created enough resistance to heat this up. Should I be looking at fixing this by running the larger gauge wire all the way back to the 60 amp breaker and eliminating the original orange wire in the harness?
   |
|
|
Bud
1999 Sport Nautique |
|
|
|
|
Hysteria
Groupie 
Joined: May-31-2020 Location: Indiana Status: Offline Points: 70 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 3:14pm |
|
Is the upgraded stereo wired to the auxiliary battery or is it fed through that orange factory wire? Any signs of a loose crimp or corrosion in that splice?
|
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 3:21pm |
|
The two amplifiers are powered through direct connections to the auxiliary battery, so that's good at least.
The connector has very clear indentations from the tooth of the crimper, so it seems like it was a pretty solid connection. I did measure voltage again with the engine running after I fooled around with the wire for a bit yesterday and I did get about about 13 volts whereas I had been getting about 12.5v. I have new connectors so I can replace the burned up one now, but if this is likely to happen again or pose a potential fire hazard I want to go ahead and get it done right.
|
|
|
Bud
1999 Sport Nautique |
|
|
|
|
8122pbrainard
Grand Poobah
Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 3:30pm |
|
For large wire gauges that carry higher amps, I suggest solder filled crimp ons.
Who ever did the work on your wiring is on the verge of being a backyard hack. He didn't even use adhesive lined heat shrink crimp on connections!!
 |
|
|
|
|
Hysteria
Groupie
Joined: May-31-2020 Location: Indiana Status: Offline Points: 70 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 3:45pm |
If nothing else, replace the connector to rule it out as the source of your voltage loss. Voltage drop depends on current flow, so without a large load on it the wire size isn't much of a factor. Unless the previous owner made other modifications, you could base your wire sizing off that factory 60a breaker and use one of the handy DC wiring charts to find what gauge you need for the length of that run to the isolator and back.
|
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 3:56pm |
|
Thanks, I agree - for simplicity's sake I'd like to just replace the connector to confirm that's the voltage drop issue and get past that.
I did manage to find the literature on the isolator that has recommended wire sizing. I don't know exactly how long the run is from the alternator, under the floor, and up to the helm, but probably around 10 ft or slightly longer. Consequently, this says it should be 6 gauge. I'm pretty darn sure that's not what's there right now. |
|
|
Bud
1999 Sport Nautique |
|
|
|
|
8122pbrainard
Grand Poobah
Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 4:09pm |
You need to figure up and back so that's 20 feet. So, per the chart, you'll need heavier than 6.
|
|
|
|
|
Hysteria
Groupie
Joined: May-31-2020 Location: Indiana Status: Offline Points: 70 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 4:10pm |
|
What size is your alternator? I'm assuming it's under that 60a fuse size, but you should double check that to be safe. The wiring requirements for the whole run to the isolator and back should exceed the size required for the isolator only (being twice the length) which is why I suggested basing it off that.
|
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-11-2020 at 4:18pm |
|
It's the stock alternator for the GT40, which I believe is a 51 amp alternator.
|
|
|
Bud
1999 Sport Nautique |
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-12-2020 at 1:40pm |
|
Because I hate threads that never follow-up on the issue, I will pass along that simply replacing the butt connector got me up to 13.1 volts as measured on the battery at idle, so that was clearly an issue.
I'll clean the connections on the isolator and I won't be surprised if i can pick up a little more, but it looks like rewiring that run with heavier gauge wire is really the answer.
|
|
|
Bud
1999 Sport Nautique |
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-18-2020 at 9:13pm |
|
So I have ordered new 4 gauge wires which are en route. These will get the wiring appropriately sized for the long runs they are making. However, in looking at what I’m replacing I’ve found an issue I’m not sure of how to appropriately handle.
Recall that in my setup the positive wire comes off the alternator, runs up to the helm to a battery isolator, and then one cable runs to an aux. battery, the other runs back to the engine to plug into the existing orange wire of the boat harness. The issue that I’m running into is I’m planning to run 4 gauge wire back to the engine from the isolator and using a butt connector to connect it to the 10 gauge existing orange wire defeats the purpose as that is so much smaller. The orange wire branches off with one end running up to the 60 amp breaker, the other end going to the 8 pin plug of the boat. I’m not sure how to handle this with the new 4 gauge wire since I can’t get that into the 8 pin plug. Could I run my 4 gauge wire directly to the 60 amp breaker and then have the existing orange wire run down to the 8 pin plug from the 60 amp breaker?   |
|
|
Bud
1999 Sport Nautique |
|
|
|
|
8122pbrainard
Grand Poobah
Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
Post Options
Thanks(0)
Quote Reply
Posted: August-18-2020 at 9:23pm |
|
Bud,
I wouldn't worry about the actual 8 pin plug. Bypass it and make your 4 ga. connection directly at the breaker.
|
|
|
|
|
cboland
Senior Member
Joined: July-15-2004 Location: Atlanta, GA Status: Offline Points: 185 |
Post Options
Thanks(0)
Quote Reply
Posted: August-18-2020 at 9:40pm |
|
Thanks, Pete. It seemed like that would be OK, just wanted another set of eyes on this since electrical is not my forte’.
In the interest of keeping it clean, not disrupting the existing splice/Tee of the orange wire, and not having a live orange wire (the old “to alternator” wire) just hanging loose, do you see anything wrong with running that old “to alternator” wire up to the breaker as well? In effect, having two orange wires coming off the breaker, then consolidating into the one which runs to the 8 pin plug.
|
|
|
Bud
1999 Sport Nautique |
|
|
|
|
8122pbrainard
Grand Poobah
Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
Post Options
Thanks(0)
Quote Reply
Posted: August-18-2020 at 9:46pm |
|
Terminating all the orange wires at the breaker would be my choice. The only reason for the 8 pin harness plug is to make the install quick.
|
|
|
|
|
Post Reply
|
|
Tweet
|
| Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |
Topic Options
cboland wrote: