Battery charging!

Nemo · 03 June 2006, 08:47

I currently have an issue with the engine not charging the battery!

I have recharged the main battery to full power and am currently getting from the battery between 11.4 and 11.9Volts which is OK

When the engine is running, across the battery terminals i still get between 11.4 and 12.2volts at idle and fast idle.

I have also taken voltage readings from the Charge coil (under the fly wheel) and an getting about 8.9 Volts AC- Is this OK?

From the voltage Rectifier/Regulator going in to the main battery leads it is 12.4V max!( I think this should be about 13.0-16.0 volts if im correct)

Can anybody please help me locate where the problem is. Be it the regulator or the charge coil?

The engine is a Yamaha two stroke 50D circa 1988ish

Thanks in advance for any advice

Graham(Nemo)

jwalker · 03 June 2006, 09:30

Quote:

Originally Posted by Nemo

I have recharged the main battery to full power and am currently getting from the battery between 11.4 and 11.9Volts which is OK

No it's not. If the meter you are taking the readings with is definately ok and so is your charger, your battery is fekked. Disconnect the battery, charge it, leave it a day and then read the voltage. You should get about 12.6-12.8v.

If you can put a big load on it and measure the voltage, better still.

One you've confirmed that, then look at the charging system if necessary.

Nemo · 03 June 2006, 09:33

Thank you. I will do that!

Nos4r2 · 03 June 2006, 09:56

One other thing-try using someone else's voltmeter on it to check if it agrees with yours.

BogMonster · 03 June 2006, 10:01

Quote:

Originally Posted by jwalker

No it's not. If the meter you are taking the readings with is definately ok and so is your charger, your battery is fekked. Disconnect the battery, charge it, leave it a day and then read the voltage. You should get about 12.6-12.8v.

If you can put a big load on it and measure the voltage, better still.

One you've confirmed that, then look at the charging system if necessary.

Agree 100%, if it is 11.anything then the battery is either buggered or completely flat, anything less than 12.5 it needs a good charge at the very least. Cheap digital voltmeters can vary by up to about 0.2V in their voltage reading in my experience but not that much.

A discharge tester is the best way to verify the state of a battery though, you could take it to a battery place they ought to have such a thing.

An automotive alternator should give 14.2-14.4V ideally with a few revs on (often a bit less at idle), and anything less than 13.8V probably means there is something wrong. Not sure about the system that outboards use if it is a "charging coil" rather than an alternator, but if they are designed for the same sort of lead acid batteries, I would imagine about the same voltage output should be expected otherwise the battery will get grumpy.

Nemo · 20 June 2006, 10:02

Chaps

The battery charging problem continues,

I have now changed the battery it was nackered! Having changed it the voltage is still down at around 12.5V so the charging system is at fault.

I have also been trying to do some home work as to correct test procedures by phoning my local Yamaha outboard dealer (southsea) I wont name them as the advice or help i didnt get was shocking.

When asked for information on how to test a regulator or lighting coil i was told. "I can sell you a couple of hours of diagnosic time at £35+vat p/h or a workshop manual for about £45"

Now guessing that I could be spending a fair amount of money I dont want to be buying the wrong part and then having to spend more money which is hard enough to find at the moment!

So what have i done!

I phoned the good and helpful people at BHG Marine in Lymington. They could not have been more helpful even to the extent of faxing me the relevent pages from the workshop manuals on how to test the Rectifier, the lighting coil and the pulser coils.

Having tested the items it is the Rectifier the is bad! New one orderd from guess who (Not the place in Southsea)

Nemo

ollyit · 20 June 2006, 10:12

what nice people

hope it sorts for ya mate

Shaggy · 20 June 2006, 10:58

Here's what my service manual says use this information at your peril:

The single phase charging system found on inline engines provides basic battery maintenance. Single Phase, full wave systems like these are found on a variety of products.

The charging system produces electricity by moving a magnet past a fixed coil. Alternating current is produced by this method. Since a battery cannot be charged by AC, the AC current produced by the lighting coil is rectified or changed into DC to charge the battery.

To control the charging rate an additional device called a regulator is used. When the battery voltage reaches 14.6 volts the regulator sends the excess current to ground, this prevents the battery from over charging.

The charging system consists of the following devices:
Flywheel containing magnets
The Lighting coil or alternator coil
The battery, fuse assembly and wiring
A regulator/rectifier

The lighting coil is usually a bright exposed copper wire with lacquer type coating, Lighting coils are built in with the ignition coils on some models and the whole assembly must be replaced.

In the charging system the rectifier/regulator is the most difficult item to trouble shoot. You can avoid troubleshooting the regulator/rectifier by checking around it.

Cheek the AC voltage output of the lighting coil, if the AC voltage is low check the charge coil for the correct resistance and insulation to ground.

If these check ok measure the resistance of the Black wire from the rectifier/regulator to ground for and for proper voltage output on the red wire coming from the rectifier/regulator to the battery. If all the above check with in specification replace the rectifier/regulator and verify the repair by performing a charge rate test.

A thorough, systematic approach to troubleshooting will pay big rewards; build your troubleshooting check list with the most likely offenders at the top.

Do not be tempted to throw parts at a problem with out systematically troubleshooting first.

1. Do a visual check of the wiring and fuses; Are there any new additions to the wiring? A good clue might be "Everything was working OK until I added that well Pump".

2. Test battery.. Well you have a new one..

3. Perform a fuse and red wire check with the voltmeter. Verify the ground at the rectifier. Do you have 12 volts and a good fuse? While you are at the Red wire, check the alternator output with an ammeter. Be sure the battery is down around 12 volts (not sure why)

4. Put a test lamp or ammeter inline with everything turned off and look for a draw.

5. The electrical system cannot keep up with demand. Do a consumption survey.

6. Go to the Source. Check the lighting coil for resistance and shorts to ground

7. If all these tests fail to pin point the problem and you have verified low or no output to the battery then replace the rectifier.

Don’t blame me if you replace the rectifier and it’s still not charging

Shaggy

Paul Beaurain · 09 July 2006, 07:18

Hi
I to am questioning my battery condition.
JW says better still measure the volatge under load.
This is what I get. (quality fluke multimeter)
volatage immediatly after chaging 12.5V
voltage next day(no draw in between) 12.2V
cranking volts 9.8(suzuki 115)

What sort of voltage (under load) is acceptable?

The battery is 3.5 years old.

Thoughts please
many thanks Paul

Nos4r2 · 09 July 2006, 08:29

If the battery is 3.5 years old it probably needs replacing anyway (I would as a matter of course simply for safety).

Is it a sealed battery or can you check the specific gravity of the acid with a hydrometer?