Lake St. Clair Fishing Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
531 Posts
You'll need a Voltage meter, set to measure DC (direct Current) voltage. A alternator typicaly produces 14 volts or more. Your battery is around 13 volts.

If the alternator is working properly, while the engine is running, the output should be around 14 volts at the battery. Idle speed is OK. There is a possibility the belt may be slipping when the engine is under load, so you may want to investigate that. WHILE THE ENGINE IS OFF!

Keep your fingers and anything else which you value away from the moving parts of the motor.


Typicaly the red lead will go to the + (positive) side, while the Black (negative ) lead will go to the - side.

It is possible for a battery to have 12-13 volts and still be bad. If your trying to check for a bad battery you'll want to test the battery as well. That can be done at any local auto parts store for free.

Naturaly you realy should leave this to the pro's, but with as much as they charge this will get you a good idea. I'll be lurking here in case you have any questions.
 

·
Registered
Joined
·
2,550 Posts
Discussion Starter · #3 ·
ED,

Here's what voltages I read:

battery 12.84 volts when I got to the boat

Before each time that I turned of the engine through out the day I would take a reading, and it varied from 12.8 to 14.1 I did notice that once I reved the engine the reading would go up. Being suspicious, I only ran one battery and left the other as a reserve. The boat took on some water last year and the alternator did get a little wet. So it's my first suspect. (The boats got a 454, and the alternator is mounted pretty low) I do have a volt meter on the dash, it's readings vary. Sometimes is 12 - 13 volts, others 14+ volts.

I was a bit suspicious about the gage, but, last week I was at Metro and when I turned the key the radio died , engine barely turned over and started. The batteries are 1 year old, both 800 amp. Over the winter I had them on a trickle charger.
And I always turn the battery switch to off when I leave the boat. Not even the stereo memory has power.

So, if the alternator is OK, it must be the battery? I'll try the other one next time out, and monitor it the same. I'm also gonna take a reading everytime I get to the boat, to see if there is any current drain.
 

·
Registered
Joined
·
531 Posts
Ok,

When you rev'd the engine the voltage went up, this tells me that the alternator is producing. The meter on the dash is OK for an idea, however it's not graduated fine enough to give you an accurate reading. The multimeter really is the way to go.

QUOTEbattery 12.84 volts when I got to the boat

The battery may read that but it does seem a bit low. Remember that it's not the voltage that starts the engine it's the "AMPS". You mention you have 800 amps, when those are fully charged they should be more than adequate for turning your engine over. If it appears they are struggling it could be a couple of things.

If your starter "bendix" is going it'll draw more amps. This eventualy will drag down the battery's. You'd need to run your engines awhile to "re-charge". If you just go out for a bit, then stop, that'll cause them not to "re-chrage" all the way. Do this a few times and now your battery's aren't fully charged and there you are.

Water and alternators aren't a good mix, however I'd be a little suspicious of the battery's first. Can you switch between them? I.E. use a different tone to start, then switch the next time out? If one seems to be OK, then your culprit is the other.

You can buy a battery tester pretty cheap. It will have a squeeze bulb which you draw up the acid from the battery's cell with. Yes I said ACID! So don't be using your finger to check the level with and then use it as a swizzle stick in your cocktails.
They typicaly have a few different colored balls in them, if they are up to par a number of the balls will float, not too many indicates a battery going bad. You'll have to test each cell, there'll be six in all, 2 volts per=12 volts. The alternator charges at about 14 volts, therefore my concern about the 12.84 volts.

I don't know if the two are connected in series or parrallel, it does make a differenece. I suspect te are parralel, you may want to find out.

I hope this helps, I'll be standing by if I can help anymore.
 

·
Registered
Joined
·
2,550 Posts
Discussion Starter · #5 ·
Thanks for the help. The boat's got 2 batteries, hooked in parallel with a battery switch that allows me to use #1,#2, 0r both. The other battery read 13.4

Never thought that I don't run the boat enough, and it does take a bit before it starts. A typical boating day for me is to put 1 - 3 hours running time on the boat, stop 2 - 3 times. Usually 3000 rpm or more. I could be at anchor/ tied up 3 hours with the marine radio and stereo on. I'm assuming that 1 battery could deal with that, maybe I'm wrong?
 

·
Registered
Joined
·
531 Posts
Marine battery's really need a deep cycle charge. the 454 is a BB, and has a relatively compression. That's make it a little tough to crank. I suspect your a bit retarded in the timing to give you a little more low end out of the hole. that makes it a little tougher. So when you start adding these all up you can see why it's tough on a battery. if you think about how long a battery charger takes to charge a battery, then think of how long your alternator has to charge you kind of see what's happening. There;s different dynamics involved, but that's a pretty good rule of thumb.

I'd try switching between the two and see if one's better than the other, assuming you don't buy/have a tester.
 

·
Registered
Joined
·
3,691 Posts
QUOTE(EDBDBOAT @ Jun 30 2003, 07:38 PM)Marine battery's really need a deep cycle charge. the 454 is a BB, and has a relatively compression. That's make it a little tough to crank. I suspect your a bit retarded in the timing to give you a little more low end out of the hole. that makes it a little tougher. So when you start adding these all up you can see why it's tough on a battery. if you think about how long a battery charger takes to charge a battery, then think of how long your alternator has to charge you kind of see what's happening. There;s different dynamics involved, but that's a pretty good rule of thumb.

I'd try switching between the two and see if one's better than the other, assuming you don't buy/have a tester.
Minor correction:

If the timing is too far ADVANCED it will be hard to crank. Sparks too soon, before piston is close enough to the top of the stroke. The early ignition slows the up stroke. Too far retarded the spark ignites the fuel when the piston is near or past the top of the stroke and make it easy to crank but run poorly.

We snapped many a starter nose cone in our high compresstion drag big blocks from running alot of timing advance. in this race application we had to start carnking then add power to the ignition to prevent this.
 
G

·
RUN THE BOAT ON A TRIP TO SAY MIDDLE DETROIT RIVER FROM METRO BEACH, THEN TURN OFF THE BOAT.
TRY TO RESTART IT, IF IT DOESN'T RESTART, YOU MOST LIKELY KILLED THE BATTERY, AND HENCE YOUR ALTERNATOR IS BAD, AND YOU NEED TO REPLACE IT.

I HOPE THIS HELPS
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top