Electrical Problem

[fxdl]

I have a '99 Lund Tyee with a 4.3L EFI. My problem is my accessories seem to rob power from each other. For example, if I have my navigation lights on and plug my spotlight into the cig lighter, the spotlight is very dim and my navigation lights also go dim. My stereo won't play with lights on. My horn won't blow with other accessories on. If my blower is on, everything else goes dim or simply won't work. My battery seems to hold a charge and the meter shows about 14 volts. Where should I start?

 

[Silvertip]

Re: Electrical Problem

You need to check the battery cables (both ends) and make sure they are squeaky clean and tight. Then you need to follow the +12V and ground leads to the circuit breaker or fuse panel. One or the other or both have a high resistance connection (corrosion or loose). All the current for accessories passes through that +12V and ground lead. A bad connection on either end means it cannot pass the current required for the accessories. Turning one on robs the other.

 

[bruceb58]

Re: Electrical Problem

Get your digital volt meter out, get a long lead and tie one end to you negative battery post and start measuring voltages at various points with your acessories on, This includes measuring grounds.

 

[fxdl]

Re: Electrical Problem

Thanks for the advise. I won't get to it until this weekend, but it sounds like something I can handle.

 

[eurolarva]

Re: Electrical Problem

If you dont have a digital volt meter use a 10 amp battery charger instead . Disconnect the battery and use the battery charger in its place. All of the components you mentioned are low current devises and should not draw off the battery that bad. Turn each devise on and watch the current meter on your battery charger. When you get a jump with any devise that is probably your problem area. Also if your battery is reading 14 Volts something is wrong. Fully charged battery will not read more then 12.75VDC. If you can get the battery load tested that will give you piece of mind as well.

 

[fxdl]

Re: Electrical Problem

The volt meter on my boat is not exactly precision equipment. It's just a needle type gauge and the needle is somewhere between 12 & 14 volts. It appears to favor the 14, but who knows.

 

[tommays]

Re: Electrical Problem

All the power on a standard boat goes through the plug between the motor and boat

Its and easy place to over look and many times all it takes is unpluging it pluging it back in again

The hose clamp that holds it toghter has a way of pushing it apart and then you start to get voltage drops that are strange


Tommays

 

[jtexas]

Re: Electrical Problem

tommays, just FYI, not all boats power all their accessories through the engine harness; many use a fuse panel wired directly to the battery. Or, if your boat's previous owner was anything like mine, a bunch of individual wires of random color and size, connected directly to the battery, some with inline fuses.

 

[bruceb58]

Re: Electrical Problem

The problem is not that something is drawing too much current...the problem is that there is a voltage drop somewhere. Do the test with a digital volt meter.

The test with the charger is uneccessary.

These meters are very inexpensive these days. I always keep one in my boat.

If you dont have a digital volt meter use a 10 amp battery charger instead . Disconnect the battery and use the battery charger in its place. All of the components you mentioned are low current devises and should not draw off the battery that bad. Turn each devise on and watch the current meter on your battery charger. When you get a jump with any devise that is probably your problem area. Also if your battery is reading 14 Volts something is wrong. Fully charged battery will not read more then 12.75VDC. If you can get the battery load tested that will give you piece of mind as well.

 

[eurolarva]

Re: Electrical Problem

When you draw too much current from a 12 volt battery you loose voltage. If you are testing for shorts a battery charger is a better option then testing with a battery because they are regulated where a battery is not. You put a short across a fully charged marine battery you could get hurt. The problem with people using volt meters is they have to know how to use them. Testing DC voltages while on AC or worse testing voltage while on ohms will end the life of a volt meter real quick. A volt meter is a great tool to have as long as you know how to use them.

Look for loose and corroded wires. They tend to be the biggest problem. Also make sure your lights are all 12 volt bulbs and not 24 volt bulbs. Pull the bulbs and verify the connectors are not full of rust as well.

 

[tommays]

Re: Electrical Problem

Well not all boats BUT pretty much every MERC I/O powered boat has a 50 amp breaker and cables that run up to a fuse pannel under the dash to run the ACC circuts as part of the standard wireing harness and checking the plug is a fast and easy place to start

There are some different ways BUT it will be close to this and the ACC circut is from 1 and 6 unless somebody went to a lot of trouble from standard


Tommays

 

[bruceb58]

Re: Electrical Problem

eurolarva,

You need to read his first post.

He has a voltage drop when he is has a higher load. This indicates a voltage drop due to a resistive connection. He is not testing for a short.

You are coorect that he needs to look for loose or corroded wires. That will be what he needs to find by using a meter.

Regarding voltmeters, it will never hurt a meter to measure dc voltages while in AC mode. In fact, that is a valid way to measure AC ripple on a DC signal. Almost every meter can survive measuring a dc signal in ohms mode.

By the way, I have a BS and MS in electrical engineering with 20 years experience. This stuff is basic electrical 101 stuff.

 

[bruceb58]

Re: Electrical Problem

Tommays,

I don't think that drawing is going to help him much. However, the wire that you see at "note 2" is the one that feeds the fuse panel near the dash. That is the wire that could have the voltage drop in it and is noted by you at connection #6. The ground is on connection #1.

 

[tommays]

Re: Electrical Problem

The plug back at the motor is out of sight out of mind BUT I have seen enough issues with the plug and voltage drops at the pannel to say that its 2 minutes well spent before before you go crazy with wires that are much harder to get to


Tommays

 

[eurolarva]

Re: Electrical Problem

Bruce. My statement about measuring DC volts on the AC setting only means that the reading will be inaccurate. I have seen meters fry testing DC with ohms and 9 out of 10 fluke meters are going to have a blown fuse from people testing voltage using the current feature on a meter. You have more education then I do considering I have a two year associates degree in electronics and spent 7 years with Honeywell and Alient building and testing equipment for defense. Most of my seven years has been testing and troubleshooting to the component level. I do not dispute that a DVM is a powerful tool however if a person does not know how to use one it is not very helpful. The equipment mentioned in this post should run fine on a battery charger with less chance of doing serious damage. Most boat owners own a charger considering they have batteries that need charging which would reduce the need to buy extra equipment. My post was a suggestion which was a valid one. I saw your post and though I did not agree with it I did not quote it and make a comment that it was not necessary to do it.

If all equipment is in parallel to the battery and say one of the parallel circuits is engaged that is shorted while the other equipment is on excessive amounts of current will be required to handle the short which will in turn rob the battery of power bringing the load voltage from 12.6 to say 10 volts. This 10 volts will be present at the blower, stereo now do to the excessive amount of current required for the short. In the reverse say the fog light burns open all the other parallel circuits will still be operating at 12.6 volts. I am not saying there is a short but a circuit that was using say 15 ohms is now using .7 ohms will give the results he is experiencing. A 5 year old marine battery on its last leg will also give the same results.

 

[bruceb58]

Re: Electrical Problem

Ok..let the original poster decide what he is comfortable with.

Not sure how you did your testing when you with the 2 companies you mentioned but I bet you used a DVM or a scope.

If he does not have the wherewithal to use a DVM, he is going to have a tough time tracking down his problem.

 

[bruceb58]

Re: Electrical Problem

I agree.

The plug back at the motor is out of sight out of mind BUT I have seen enough issues with the plug and voltage drops at the pannel to say that its 2 minutes well spent before before you go crazy with wires that are much harder to get to


Tommays

 

[ricksrster]

Re: Electrical Problem

It could also be more than one connection. It is a pain, but all the fuse connections, + connections, and ground connections should be checked, cleaned, and tightened. Also check for any broken insulation.

 

[fxdl]

Re: Electrical Problem

Good discussion. Well, I've corrected the problem. I bought a DVM and began testing. My battery was putting out 12.42 volts and that's roughly what I was reading at most accessories until I turned on more than one at a time. Then the voltage would drop to about 10.6.

My boat is a wiring nightmare and tracing wires is not fun. In the process of unplugging wiring harnesses during my testing, I must have cleaned up some corrosion, because it's working great now. My blower is louder than I've ever heard before and I can now play my stereo full blast with the blower on. Even when I thought everything was working fine, the stereo would cut out when I cranked it up. Life is good. I really appreciate you all taking the time to help me with my problem. This is a great discussion board.

One other question. Is there any product available to prevent this from happening in the future? Like something that can be sprayed into the plugs to prevent corrosion? Thanks

 

[bruceb58]

Re: Electrical Problem

Your battery dropped to 10.6V or the connection at the battery dropped to 10.6V?