Electrical issues

I just purchased an 81 Clipper Trawler but due to a sudden illness of the seller , he was not able to show me the working fundamentals of the vessel. I powered the boat back to my mooring, a three hour trip, but the ignition/starting batteries did not charge. I took them out had them checked and they took a charge fine so the problems I do not think are the batteries. I had the battery selector on "both" when making the trip back, is this the correct positio? How do I best determine why they are not charging? i ran the engine for about a half hour after putting bCk the charged batteries and they went from 13.6 volts to 13.1 in that time

Sorry to be the first jerk.....

But if you can't trace wires and deduce charging and running circuits...time get someone who can give a hand.

There are a zillion ways to rig electrical systems..best to have someone that can quickly identify stuff so you aren't frustrated and damaging things.

Without a detailed diagram or a bazillion questions...all internet responses are just a guess....well maybe it can be slowly pieced together...but no one can be sure a suggestion is correct without several exchanges of possibilities for each wire involved.

Don't be mean. He sounds like me.

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I would love to help but I don't know s@$t.

No worries;,I figured as much. I am trying to get an marine electrician in but did not want to miss something obvious or simple. I know I have an incredible learning curve ahead!

Can you at least have a conversation with the seller? It may be something simple, easily explained. Or if there was a broker,if there is something peculiar, just maybe he explained the system to the broker.
Batts going from 13.6 to 13.1 may be just losing surface charge after the recharge you did, apart from initial starting demands diesels don`t use electrical power to run. Batts holding at 13.1 after a start are likely ok, though there are better tests for batt condition, like load testing, and hydrometer tests for specific gravity for flooded unsealed batts.

And I was JUST KIDDING about Psneed. That dude is incredibly helpful.

It's the end of the day. I'm drinking rum.

Thanks, I have a call into the broker as well as the surveyor trying to see if I can talk to the past owner.

cardude01 said:

And I was JUST KIDDING about Psneed. That dude is incredibly helpful.

It's the end of the day. I'm drinking rum.

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Don't wait to the end of the day...rum makes you schmarter if you schtart at luunch.....just read annie of mysh posshts...hic....

Twell said:

Thanks, I have a call into the broker as well as the surveyor trying to see if I can talk to the past owner.

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Actually..thank you for the kind compliment cardude!

For the OP.....I was serious as can be.

There are auto switching devices in charging systems that may be working, maybe not. My auto charging relay didn't work so I replaced it with a battery switch.

A pretty savy guy could figure out my whole ele trick system in an hour or two..,but an inexperienced person may never figure it out.

It is 100 better than the way the boat was set up to begin with...but as more batteries and systems were added...the system became a tad more compicated.

For the most part it meets all ABYC recomnendations, and is pretty bullet proof and simp,e once explained. Even better..it is easy to troubleshoot which many systems aren't because they are automatic and hard to isolate each component.

So again..not to be mean..but unless familiar with new and old tech...and a rapid learner of what can do what...figuring out multip,e charging sources, multiple loads and multiple battery banks is for someone quite advanced....not a newbie.

You CAN do it...but why struggle when there are tons of guys way smarter than me floating around all over the place that for a cold beer or two will help you figure out.

Without disagreeing with any of the suggestions about getting a marine electrician to review your setup I suggest you add a multimeter with a clamp on ammeter to your tool kit. It will be invaluable in solving problems like this. The first question is whether the alternator is outputting any charge to the batteries. Could be a blown diode.

Bay Pelican said:

Without disagreeing with any of the suggestions about getting a marine electrician to review your setup I suggest you add a multimeter with a clamp on ammeter to your tool kit. It will be invaluable in solving problems like this. The first question is whether the alternator is outputting any charge to the batteries. Could be a blown diode.

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...and here's a great manual for understanding marine electrical systems.

Boatowners Mechanical and Electrical Manual by Nigel Calder

Thanks again!

FlyWright's right. Read the book, even if you have somebody help, you will want to know what he or she is talking about

You will save yourself a lot of time and agravation if you take the time to diagram your electrical sys. As a minimum understand how the batt are comnected together, how the eng alt charge the batts and how your batt charger is plumbed into the system. Also very important to know what the batt sel switch does.

Daveo said:

FlyWright's right. Read the book, even if you have somebody help, you will want to know what he or she is talking about

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Absolutely

Twell said:

No worries;,I figured as much. I am trying to get an marine electrician in but did not want to miss something obvious or simple. I know I have an incredible learning curve ahead!

Click to expand...

T
In addition to getting some knowledgeable help you will want to get up the learning curve ASAP even if it's not to fix / rewire things but to diagnose and be able to ask the right questions and/or provide helpful info.

HERE IS A POST with several useful Electrical / Electronic references & links

Agree w/ FlyWright about Nigel Calder's Boatowners Mechanical & Electrical Manual and BayPelican's recommendation for a digital / clamp-on ammeter - careful not all of these can handle DC Amps - I found an inexpensive Sears one that does DC Amps and has served me well

I spent 2 seasons chasing down my charging system turned out to be an incorrectly wired alternator I believe, from the factory. Finally found the culprit and traced it back to fix the mistake.

Good luck

I powered the boat back to my mooring, a three hour trip, but the ignition/starting batteries did not charge.

How did you determine that the batteries did not charge?

I had the battery selector on "both" when making the trip back, is this the correct position?

It would rarely hurt to be in BOTH while the engine is running

i ran the engine for about a half hour after putting bCk the charged batteries and they went from 13.6 volts to 13.1 in that time.

If the voltage went DOWN with the engine running, the alternator or its voltage regulator is usually not working correctly. A fully charged lead acid battery's rest voltage is 12.78 volts DC. When you start the engine, the voltage will dip down due to the starter load then recover to greater than 12.78 volts once the alternator begins to charge the batteries. On some boats, the engine RPM needs to be above idle speed to see this effect. The alternator voltage regulator should try to drive DC volts up to around 14.5 volts. Something as simple as loose or improper belts will cause the alt to not charge. An easy test would be to measure the battery volts with the engine off, start the engine and raise RPM to fast idle for 2 or 3 minutes then take another measurement. The volts should now be higher than 12.78 and slowly rising. If it is, then the alt and VR are at least working. How well its working needs a tool called a Clamp On Ammeter that can read at least 40A DC. There are lots of clamp on ammeters on the market, with the vast majority reading AC Amps and a tiny (less than 10) DC Amp scale. You have to look for one that reads DC Amps of 40+ amps.

I have a battery selector switch. 1,2, both, and off. Came with the boat. It doesn't have a damn thing to do with battery charging. Wouldn't know today what it does if I hadn't drawn a diagram. My selector switch is used to connect or disconnect my DC load center to the different batteries.

Usually, the common terminal on that rotary switch is connected to all DC loads: starting and house and is also connected (maybe through the engine) to the alternator output. The 1 terminal is connected to the start battery and the 2 is connected to the house battery (or visa versa). So that selector switch does determine which batteries are charged by the alternator.


And as others have said, if the switch is set to both, all batteries get charged from the alternator.


The shore power charger often has two or more outputs. One gets connected directly to the start battery independent of the rotary switch and the other output gets connected to the house battery.


But as others have also said, there are a million ways to wire a boat's DC system. The foregoing is typical though but not certain.


David