electrical quandry

[billyt]

I have a 1991 Prowler Bass Boat by Sunbird. Leaving Michigan for Texas everything worked. Got to Texas and nothing works--it's as if the battery isn't hooked up. Checked the fuses, replaced 2. Had a mechanic friend check it out and he said there was power on every toggle switch, but still nothing works. When I direct line the aerator, it works--same with the bilge pump. Am replacing the four toggle switches, but is there anything else I can check before I have to take it to an electrical guy? I'm leaving for vacation in 3 weeks and sure need to find out what's going on.<br />thanks<br />blt

 

[cuzner]

Re: electrical quandry

Loose or shorting ground from fuse pannel.<br /><br /> Jim

 

[cp]

Re: electrical quandry

Bad connection (high resistance) at the battery. You get voltage at the toggle switches, but the high resistance prevents any meaningful current flow so nothing will work. Clean and remake the battery terminal connections. Good luck.

 

[jlinder]

Re: electrical quandry

Can't beat a cheap meter. (A lot less money than hiring a mechanic).<br /><br />Check the voltage the 2 wires to the item in question (aerator). Probably very low or zip.<br /><br />Now look at the voltage from the aerator negative wire to the negative wire of the battery. If zero or close to it ground is OK. If not, trace the ground back till you find where it goes from a high voltage to zero (or close to zero).<br /><br />If still not working, do the same with the positive wire. From it to the negative terminal of the battery do you get 12v or something much lower? Trace the line back to the switch, fuse, etc. until you find where it jumps up to 12v. Then you have found your problem.

 

[billyt]

Re: electrical quandry

Hey Thanks. That makes sense. The terminals were pretty gray so I brushed them a bit, but not thoroughly. Also, they guy I bought the boat from had replaced the bilge pump and has some pretty wimpy connectors that go onto the positive terminal. I don't know a lot about electrical, but I know when a job is sloppy. That and I'm real obsessive-compulsive about neatness and details! Thanks for the tip. I'll try that when I get home, and see what happens.<br />blt

 

[crab bait]

Re: electrical quandry

it's always bad connections an or bad ground..always..

 

[billyt]

Re: electrical quandry

What OLMPILOT described in the last reply to his question is what happened to me. Because everything seems to be wired together, when whatever it was shorted, it took all of them out. I don't know much about electrical, but I'm not seeing a fuse panel, or at least what I think everyone is describing. My mechanic friend did remove 2 fuses this morning, but, I've crawled under the dash many times and never saw them up there. I haven't had this boat long, and I don't have any wiring diagrams to go by. All your help is appreciated.

 

[swist]

Re: electrical quandry

Meters are your friends in general but they can also be false friends. pchonda alluded to this. Meters draw close to zero current! (If they didn't they would load the circuit and the voltage would be wrong). Put a 1000 ohm resistor in series with a meter and a battery and it will still read the battery voltage, or very close to it, but any real device won't work at all!

 

[jlinder]

Re: electrical quandry

swist --<br />Correct. You cannot just put a meter on something that has no load and see if there is a problem.<br /><br />The only valid way I know of is to have someone try to run the gear and see what the voltage actually is under real world conditions.<br /><br />Makes it a 2 man job a lot of times, but it is the best and in the end the easiest way to go.<br /><br />Also, not a bad idea to have a long lead on one of the probes. For example, you can measure the voltage difference between the negative terminal of what you are checking and the battery negative terminal. That will tell you if you have a bad ground.

 

[billyt]

Re: electrical quandry

Upon further poking, prodding and pulling, I also discovered when the previous owner installed his new bilge pump, he linked everything together (with wire nuts no less). Also, as far as I can see, the only ground wire I find is on the fuse panel. I've never done this before and I have a good friend who is an electrical master, so he is going to re-wire everything -- correctly. Doesn't seem like it should be that difficult, but I know enough to know I don't know anything. thanks for the help.

 

[cuzner]

Re: electrical quandry

Hey Billy,make sure check out swists post crimp vs solder, there is a hyper link to some info on boat wiring requirnents.. good to know even if someone else is helping you out.<br /><br /><br /> Jim

 

[olmpilot]

Re: electrical quandry

Billy, take some notes from your friend, but also head alot of the advice from this site. I never did this before and with the help of the folks here and resources they provided, wired everything up to a fuse block, put in a battery switch and replaced some of the shotty wiring that the previous owner(s?) had done. I did get a nifty little tool that was suggested for tracing wires and it was a tremendous help. They have it at boatersworld.com for $49.99, but I got it at Lowe's for $32.00+tax. http://www.ancorproducts.com/Products/products_pdf/tools_meters/tools_meters_pag73.pdf <br /><br />All in all it took me about 4 days and several hours of head scratching to figure out where everything went, but sure was easier than working on a car electronic system, and now I have peace of mind knowing where to look should anything go wrong in the future.. particularly if I'm out on the bay or in the middle of the night. So, watch what your friend does, so you will have that same knowledge.

 

[billyt]

Re: electrical quandry

Good points, guys. I do appreciate the advice on this site and have printed everything so I'll have it. I do have another question, though: Since I will only be using my boat in fresh water (and I'm 400 miles from the coast), do I still need to get tinned wire? Also, is 8 guage too big and 10 enough, or better to err in the side of caution? Some of the simpler stuff I will attempt on my own, but with a friend there guiding me. It's become something of a mission to do this myself as much as possible.<br />blt

 

[jlinder]

Re: electrical quandry

Billyt,<br /><br />Take a look at another thread called wire, wiring, and current capacity. A number of people posted some real interesting information there.<br /><br />Basically there are 2 different factors that give you the minimum wire size: capacity and voltage drop.<br /><br />With capacity you are worried about how much current the wire can handle before burning up. There are tables out there (see other thread) but I like the general rule used in building wiring. 14 gauge can carry 15 amps, 12 gauge can carry 20 amps, and you double or half the current every 4 gauge sizes. For example, 14 gauge carries 15 amps, 10 gauge carries 30 amps, 6 gauge carries 60 amps, etc.<br /><br />The other limiting factor is voltage drop. You lose voltage due to the resistance of the wire. You do not want the voltage drop to exceed 3% of the voltage, or about .36 volts. The drop is a combination of the gauge, current draw, and length of the wire. You can calculate it, but much easier to use the tables. Just figure out the length of the wire, the current draw, and the table will give you the minimum wire gauge.<br /><br />The voltage drop problem is usually the limiting factor.

 

[18rabbit]

Re: electrical quandry

Another factor is heat. Conductors routed in or through engine compartments, machine rooms, or anywhere else there is heat do not carry as much current. You may need to take this into account when wiring a boat. There are tables available that indicate the appropriate AWG per the conductor’s insulation rating. Often means bumping up one or two wire sizes.

 

[18rabbit]

Re: electrical quandry

 

[jlinder]

Re: electrical quandry

18rabbit,<br /><br />I saw that. I was looking at a table that said you could put 20 amps through an 18 gauge wire. On land you could never use that for more than 7.5 amps.<br /><br />In small type as a footnote it said this was related to 105 degree centigrade rated wire. There is a lot of wire out there that is not rated for this heat. How many people out there will miss that?<br /><br />Hint: Think of the number of times you have seen someone trying to run some big power draw device with 3 cheap extension cords strung together, or a portable heater off that bargain basement little cord? <br /><br />People get cheap, and it is too easy to just take the first number you see for wire gauge to justify saving some money. Not the place to save a few cents.

 

[KaGee]

Re: electrical quandry

BillyT:<br /><br />Other than the branch feeds, 90% of your 12volt wiring can be handled by 14 guage copper stranded wire. Some even 16 guage. Modern Electronics seldom use anything larger than 16 and that's overkill. (My GPS uses 20!!) It depends on the device you are wiring and it's requirements. <br /><br />As for tinned, that's up to you, but IMO it's generally overkill in freshwater areas. The termination point is the weak link in the wire connection chain. You have equal opportunity to have corrosion build up there... tinned wire or not. Understand that ANCHOR is in the business to sell packaged wire products to the Marine aftermarket. So part of the tinned wire thing in 12 volt applications is marketing propaganda.<br /><br />Technical Clarification: <br /><br />A "SHORT" is when a "positive" voltage source comes into direct contact with a "negative" or "ground" (rest of the world refers to it as "earth")point. "Shorts" cause fuses to blow.<br />Shorts create sparks! Shorts can cause fires, especially in boats!<br /><br />The proper term for a condition where contact or termination is interrupted is called an "OPEN" condition. When an OPEN condition exists, stuff don't work. The circuit is interrupted. Fuses are OK. You loose your mind because things look ok. <br /><br />So, you are looking for an "OPEN", not a short.