Association Forum - Starting outboard without battery connected

Assn Members Area · Join

Home.

Association Forum

Ships Store

Cruising

Racing

Technical Tips

Photo Gallery - New

Boat Search - Updated

Manuals & Brochures

Swap Meet

Links

Officer Flag Line & Staff

Bylaws & Constitution

Members Area

Join the Association

Notice:
The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.

Association Forum

Username:	Password:
Save Password
Forgot your Password?

All Forums

Catalina/Capri 25/250 Sailor's Forums

General Sailing Forum

Starting outboard without battery connected

New Topic

Topic Locked

Printer Friendly

Author

Topic

mrapkins
Navigator

Member Avatar

USA
124 Posts

Initially Posted - 06/29/2011 : 06:33:10

On a recent cruise with some colleagues, one boat complained that their outboard was not charging their battery. One of the crew stated that he had started the outboard by hand (no battery attached) and was immediately told by several folks that this would "ruin their diode".

I assumed this was a diode in a rectifier to convert ac from the generator to dc.

I was skeptical that this would happen and helped them in their fault finding, whereupon we discovered that the fuse from the outboard to the battery was blown. I was even more skeptical with the theory that starting the outboard without a battery could cause a fuse to blow when it should have been an open circuit. My conclusion was that the wires that should have connected the outboard to the battery were touching and that this was the cause of the fuse blow.

That said, does starting an outboard without a battery connected (assuming it does have the capability to charge a battery) cause any problems? I can see no reason why it would (except if, as in this case, the wires were shorted).

I read my Honda manual from cover to cover and can find no warnings that the outboard should not be started without a battery connected.

Edited by - on

Joe Diver
Master Marine Consultant

Members Avatar

USA
1218 Posts

Response Posted - 06/29/2011 : 07:06:34

No idea, but I have read somewhere that if you have an engine connected to your bank for charging, you're not supposed to move the A/B switch through the off position while the motor is running.

Edited by - on

Stinkpotter
Master Marine Consultant

Members Avatar

Djibouti
9081 Posts

Response Posted - 06/29/2011 : 07:32:53

You're both right. Disconnecting the battery (by switch or whatever) while the alternator is charging it can do some damage. Starting and running without a battery should not. 2-battery switches are designed so you can switch batteries while running by going through a "Both" position so the connection is never broken.

Another mistake that could have both blown the fuse and damaged the alternator is hooking the battery up backwards. You can only hope the fuse goes quickly enough to save the alternator.

Edited by - on

Stu Jackson C34
Admiral

Members Avatar

844 Posts

Response Posted - 06/30/2011 : 15:40:08

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Joe Diver
 No idea, but I have read somewhere that if you have an engine connected to your bank for charging, you're not supposed to move the A/B switch through the off position while the motor is running.
<hr height="1" noshade id="quote"></blockquote id="quote">

It All Depends on How It's Wired

If I had a $ for every time I've typed this phrase...

IF, I say if, the AO (alternator output) goes to the C post of the 1-2-B switch, yes, you're right, 'cuz you NEVER want to interrupt the AO, it could (not always, but could) fry your alternator diodes.

If, however, the AO goes to the house bank, you could even turn your switch to the off position 'cuz the AO is always connected.

In that case, you'd use either an echo charger, combiner or ACR (or other relay) or actually the B position of the switch, to combine the batteries and charge both banks.

For more fun reading, try this: http://c34.org/bbs/index.php/topic,5977.0.html

While written for "bigger" boats, the electrical concepts are all the same when dealing with AO.

Edited by - on

islander
Master Marine Consultant

Members Avatar

USA
4024 Posts

Response Posted - 06/30/2011 : 16:55:35

<blockquote id="quote">quote:<hr height="1" noshade id="quote">That said, does starting an outboard without a battery connected (assuming it does have the capability to charge a battery) cause any problems? I can see no reason why it would (except if, as in this case, the wires were shorted).
<hr height="1" noshade id="quote"></blockquote id="quote">
It won't hurt it at all. That is what the rectifier is for. The rectifier senses that there isn't a battery so nothing happens. Put a battery into the circuit and it then sends out the power to charge the battery. You can test this by unplugging the charge cable from your outboard and putting a test light on the two terminals on the side of your Honda. The test light will not light. Connect a battery to the charge cable and it will start charging the battery.

Edited by - on

Stinkpotter
Master Marine Consultant

Members Avatar

Djibouti
9081 Posts

Response Posted - 06/30/2011 : 19:24:04

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by islander
 ...You can test this by unplugging the charge cable from your outboard and putting a test light on the two terminals on the side of your Honda. The test light will not light. Connect a battery to the charge cable and it will start charging the battery.<hr height="1" noshade id="quote"></blockquote id="quote">Then disconnect it while the engine is running, and...

The rectifier is likely to not handle that event. But in general, operating without a battery is fine.

Edited by - on

mrapkins
Navigator

Members Avatar

USA
124 Posts

Response Posted - 07/01/2011 : 04:38:15

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by islander
 ...You can test this by unplugging the charge cable from your outboard and putting a test light on the two terminals on the side of your Honda. The test light will not light. Connect a battery to the charge cable and it will start charging the battery.<hr height="1" noshade id="quote"></blockquote id="quote">Then disconnect it while the engine is running, and...

The rectifier is likely to not handle that event. But in general, operating without a battery is fine.
<hr height="1" noshade id="quote"></blockquote id="quote">

I cannot understand how a rectifier "knows" what is connected and alters its behavior accordingly!

I cannot understand how an open circuit will cause a diode to fail. If it's open circuit, no current flows so how can there be a problem?

Edited by - on

Stinkpotter
Master Marine Consultant

Members Avatar

Djibouti
9081 Posts

Response Posted - 07/01/2011 : 06:29:26

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by mrapkins
 I cannot understand how an open circuit will cause a diode to fail. If it's open circuit, no current flows so how can there be a problem?
<hr height="1" noshade id="quote"></blockquote id="quote">Based on what I've read, tt's the opening of the circuit that's the problem. If the alternator is pumping to the battery and suddenly the circuit opens, something bad can happen. My preference is not to test the assertion, given that a few people apparently already have.

Edited by - on

Joe Diver
Master Marine Consultant

Members Avatar

USA
1218 Posts

Response Posted - 07/01/2011 : 08:13:28

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stu Jackson C34
 
If I had a $ for every time I've typed this phrase...
<hr height="1" noshade id="quote"></blockquote id="quote">

Thanks for taking the time to type it out yet again though!

Edited by - on

Sloop Smitten
Master Marine Consultant

Members Avatar

USA
1181 Posts

Response Posted - 07/01/2011 : 08:24:11

The output of the alternator goes to a diode rectifier which both turns the AC into DC and also electrically isolates the outboard from the battery when the outboard is not running. The rectifier has a small leakage current but it is completely insignificant compared to for example battery self discharge.

When the battery is charging,and you disconnect the battery, the coils in the alternator are all "charged up" with no place for the energy to go and it creates a big voltage spike which can easily damage the outboard rectifier. Once the rectifier is damaged, it no longer turns the AC into DC and the leakage current can go WAY UP so now the rectifier can drain your battery when its connected.

Bottom line, if you disconnect the battery while it is charging there is a lot of energy with no where to go and diodes in the rectifier are fragile electronic components. They will act like a fuse (the weak link in a circuit) and blow.

Edited by - on

islander
Master Marine Consultant

Members Avatar

USA
4024 Posts

Response Posted - 07/01/2011 : 14:38:08

I don't consider myself an electrical wizard but Nowhere in the Honda manual or any other outboard that I know of that has battery charging capabilities is there a warning or big yellow caution sticker stating not to start engine unless charge cable and battery are hooked up. I ran many small outboards on dingy,s through the years without any battery hook up including my 9.9 Honda that I have now. The P.O never had it hooked up in the 6yrs he owned the boat and for the first year nether did I. I hooked it up on the second year and it charges without a problem.

Edited by - islander on 07/01/2011 14:40:19

GaryB
Master Marine Consultant

Members Avatar

USA
4304 Posts

Response Posted - 07/02/2011 : 06:25:59

As Dave and Joe stated above, it's not a problem to run your motor without a battery hooked up but IS a problem to have it hooked to a battery and disconnect it while it's running.

Edited by - on

britinusa
Web Editor

Members Avatar

USA
5404 Posts

Response Posted - 07/02/2011 : 14:09:09

I called the guys at onlineoutboards.com (we have a link to them in our members area for a discount

'John' confirmed that disconnecting the battery when the engine is running could damage the engines electrical system. He quoted from the manual.

I just read the manual(s) at Nissan.com and they have a notice about this.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">Do not disconnect the battery cords while the engine is operating, the electrical parts could be damaged<hr height="1" noshade id="quote"></blockquote id="quote">

<center>

</center>
Here's a link to a larger version better suited to printing.
http://www.jointdecision.us/_images/spoofs/WarningLabel_2011.png

Paul

Edited by - on

islander
Master Marine Consultant

Members Avatar

USA
4024 Posts

Response Posted - 07/03/2011 : 05:27:26

Thanks for bringing this to my attention, So then everybody is partially right in this discussion. You can start and run the engine as long as the cable is not plugged in. If the cable is plugged in and you start the engine, Don't unplug it. I believe John, But that label???? I don't think an engine manufacturer would say " Really Screw Things Up"

Edited by - on

britinusa
Web Editor

Members Avatar

USA
5404 Posts

Response Posted - 07/03/2011 : 06:42:39

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by islander
 But that label???? I don't think an engine manufacturer would say " Really Screw Things Up"
<hr height="1" noshade id="quote"></blockquote id="quote">

Look at the URL

Paul

Edited by - on

Topic

New Topic

Topic Locked

Printer Friendly

Jump To:

Association Forum

Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.