Charging System Woes

**Administrator** · 08-26-2007, 09:13 AM

Mal:

Any chance that the engine was run (even momentarily) with the battery selection switch in the OFF position?

Bill

**lhbradley** · 08-26-2007, 10:07 AM

When the alternator is charging, there should be more than 12 volts on the batteries. How much more depends on the state of the batteries. The original Motorola 35 amp alternator is set for about 13.8 volts, as I recall, so that is what you should see when the batteries are pretty well charged, and the alternator is working OK.

The cable from the alternator does not have to be very large - it only handles about 35 amps or so.

First thing I would do is check the connections. If still no go, try putting another battery in place of one of the boat batteries - even the battery from your car - you can use jumper cables instead of actually trying to connect the car battery up to the boat wiring - and see if you get charging voltage. If not, it certainly sounds like the alternator. You can take it to an auto electric shop to get it tested and repaired.

As another poster suggested, if you somehow put the battery switch to OFF when running the engine, you can zap the diodes in the alternator.

**Mal Leichter** · 08-26-2007, 07:28 PM

Bill, it hasn't been run with the switch off that I know off. I have read a few things about moving the battery selection switch through the off position. Is that NOT supposed to be done??? We usually set it for both and leave it there. Then turn it of when the engine is stopped and we are closing up for the day.

Larry I was at the boat today and looked at a few more thingsI measured the voltage from the output terminal on the alternator to ground (a head bolt) It measured between 13.1 and 13.3 volts from idle to crusing speed. I took this measurement where the orange wire attaches). At the battery, with the engine running it was reading 12.8 volts. I put new batteries in this morning. I checked the alternator more closely today. The label says it is a Motorola 12V negative ground wit a 37 amp output (see the attached picture). It has an orange wire attached to the main output an a 2nd thinner wire that comes out of a box on the back of the alternator and goes to the coil.

The last thing I noticed was that the ammeter that is located back in the cockpit stays right in the middle. NOTE: I've owned the boat for 7 years and the ammeter has Never moved much.

Is there anything else I need to look at or measure????

Mal Leichter

Attached Files

**Don Moyer** · 08-27-2007, 08:25 AM

Mal,

The fact that you're reading 13.2 volts (or so) close to the alternator output is strong evidence that it (the alternator) is operating OK and that you have some serious line loss somewhere downstream between the alternator output and the batteries.

You might consider running the output from your alternator directly down to the big battery cable on your starter solenoid and then checking for voltage at the batteries. A piece of 8 gauge wire should be enough for this short run. In fact, if you could spare a short piece of the orange wire currently connected to the output of the alternator, that would be ideal.

By the way, the thinner wire leading to the coil from the regulator is your field exciting wire.

Don

**David Masury** · 08-27-2007, 09:30 AM

I am going to offer one additional thing to look for when you have charging or any other electrical problem on a boat.... the engine sits in a terrible environment that is very condusive to corrosion. Clean all you contacts and terminals and lightly coat them with dielectric silicon grease...especially the battery ground lugs.

I check my charging and batteries several times a season with a volt meter, having clean and coated contacts I get a good charge on the batteries.

DHM

**bayareadave** · 08-27-2007, 10:54 AM

make sure the batteries aren't fried

The alternator typically won't charge if the engine RPM is around idle speed - unlikely but thought I'd mention it.

After you check your alternator like the other posts say, make sure the batteries aren't fried. If your trickle charger doesn't work correctly, it could cook the batteries. Make sure there is water in them covering the plates (preferably about 1.5" down from the top). You can check their load carrying ability by performing an isolated test on each one: a) check the voltage with an ammeter b) running the blower or other demand for a while, and c) re-check the voltage.

If you have to get another one I recommend a deep-cycle to complement the starting battery. I do everything on my deep cycle, keeping battery #1 charged for backup. Starting batteries aren't designed to handle a prolonged load very well unless they are constantly recharged.

**baileyem** · 08-27-2007, 03:14 PM

battery woes

You may find that never operating your battery switch on "BOTH" will help keep you out of a repeat of your recent predicament in the future. Treat one of your batteries as a starting battery only, and only use it for starting the engine. Use the other, generally a deep cycle battery, as the 'house' battery and run all of yor electronics off that unit.
I ditched my " both-1-2 " switch and wired 3 separate switches into the system: one for the starting battery, one for the house battery and one to combine them both if I have to. The system is set up to charge either/or both bateries, as need be. It works well for me and has been no problem.
I also haul my batteries to my local battery shop every spring and have them load-tested before I installthem in the boat. That way I don't have to guess about wheteher or not they are still good.

Investing in a "Zap-Stop" unit for your alternator will protect your alternator diodes from turning your switch to 'off' while your engine is running.

Good luck Mike

**Mal Leichter** · 08-27-2007, 09:58 PM

Sounds like the consensus is bad wire or connections or bad wire somewhere between the Alternator and the batteries.

Don Can you confirm the connections of the orange wire

1. From Alternator outout into one side of the ammeter.
2. from the other side of the ammeter to the battery side of the ignitionswitch
3. from the battery side of the ignition switch to the input side of the battery switch
4. from the individual output terminals on the battery switch to the positive terminal on the battery

If this is not right can you please fill me in.

ALSO what is the idea of connecting the output of the alternator to the positive connection on the starter??? Does that simply bypass all the wiring in between and just give you a direct path back to the battery or battery switch??

Thanks to everyone for the input. I know what I will be doing this weekend!!!

Thanks Mal

**Don Moyer** · 08-29-2007, 10:05 AM

The answers to your questions are basically all yes. The attached schematic and instructions should help. Connecting the alternator directly to the big battery cable on the starter solenoid is shown on the schematic as an optional connection to shorten the charging circuit which will frequently increase the efficiency of the alternator in cases where the distance from the engine to the cockpit control panel is quite long (as in the case of many center cabin engine installations).

Don

Attached Files

wiringkit.pdf (220.5 KB, 1089 views)

**Mal Leichter** · 09-03-2007, 07:48 AM

OK Don

I went down yesterday with tools and supplies to try to address this problem.

One thing I notised right away was that the existing orade wire is #10 wire. You specified #8.

I Checked the 2 batteries for voltage. One was 12.3 and the other was 12.6. The 12. 3 one had been used for instruments on Saturday and not charged very long. I then turned on the battrey switch to both and started the engine. I then measured the voltage as the engine ran and it was 12.5 and 12 .7. I shut rhe engin off and remove the nuts from the output lug on the alternator and the large positive lug on the starter solenoid. I cleaned all terminals and connectors well. Then I installed a wire from the alternator output to the starter solenoid. I put the large battery cable back on the starter and tightened the nut and washer. I reconnected the orange wire to the alternator along with the new wire I had connected and tightened up the connection on the alternator.

Should I have put the ORANGE Wire back on???

At any rate I started the engine and took voltage readings. The readings were now up to about 13 volts with the switch on BOTH. WHen I turn the switch to either 1 or 2 (going through BOTH not off) I would read between 13.1 and 13.3. That is the same reading I get reading from the alternator output lug to ground

What should the alternator to ground reading be on a new motorola 35 amp alternator??? Just seems to me that 13.3 Volts is a little low as compared to other alternators.

Looks like I do need to replace the existing wiring but I want to make sure I wave a good alternator too.

ONCE AGAIN THANKS for all your help and guidance.

Mal Leichter

**Don Moyer** · 09-03-2007, 06:08 PM

Mal,

Good for you! Your voltage readings now are quite normal for the original 35 amp Motorola alternators.

Don

**Mal Leichter** · 09-26-2007, 08:55 PM

Problems AGAIN Don!

We were sailing Sunday for about 7 hours when I noticed my Chartplotter Radar was off. To make a long story short I had dead batteries again. I had my battery pack so I started the engine and ran it for about an hour fast enough to charge as we continued to sail.

Today I went sailing again and the batteries were both dead. I started the engine with my battery pack then took it off and the engine continued to run. After about 5 minutes the engine stalled. I put the battery pack back on the batteries restared the engin again and removed the pack. The engine ran long enough for me to get out and under sail then I turned it off.

Later I had toi restart the engine to get in because the wind was poor. Started it with the battery pack and removed it. After a few miniutes it died again (sounded like somebody turned off the key). Once again I restarted it and took the pack off. THIS TIME I got out my volt meter and measured 6.2 volts from the output terminal on the alternator to ground. I checked it a 2nd time just to make sure the connetions were good. Still the reading was 6.2 volts. I turned the engine off and measured the batteries. They were way low 6.1 Volts.

I put the pack back on one of the batteries with the battery switch on BOTH (The switch is three years old)and re started the engine. This time I left the battery pack connected. I ran the boat back to my mooring (about 3 miles) in about 30 minutes. It ran fine with no stalling as long as the battery pack remained attached.

Before I turned the engine off I re checked the alternator output. Now I was getting 10.1 Volts.

QUESTIONS!
Could the stalling have been because of the low battery voltage?
Could the Change in outputs be a result of the battery pack being connected for the trip back

I have ordered a new alternator from MM because I assume the alternator is shot. What else could it be??

Thanks in advance
Mal Leichter

**jhwelch** · 09-27-2007, 06:07 AM

No matter what is going on with your alternator you need to
put your batteries on an external charger; leaving them totally discharged
will ruin them in the long run (and perhaps this has already happened).

-jonathan

**Mal Leichter** · 09-27-2007, 06:12 AM

Thanks Jonathan. Brought them home yesterday and they are on the charger now

Charging System Woes

Charging System Woes

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