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question about Honda 8 HP 12 V power

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JimB517
Past Commodore

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USA
3285 Posts

Initially Posted - 05/05/2003 : 17:19:18

Hi, after 2 or 3 hours figuring out my electrical panel and running wires through the lazerette to the motor area, I fired up my Honda and removed the cap on the starboard external socket for hooking up 12 volt battery charging. This was totally corroded and you couldn't even get the plug in. I shut down the motor and cleaned the socket out, using Wd40 and a tiny screwdriver. It's clean and the plug fits.

Upon starting the engine, I tested the circuit with my voltmeter. There is no juice. With the cover off, I was able to trace a little of the wiring while hanging over the stern wedged between the twin backstays. I found a fuse just inboard of the socket. The fuse was fine and not blown. I pulled out some of the wiring and tested at various points and never found DC voltage (or AC for that matter).

I have a generic Seloc manual that covers all Honda outboards. It sucks for showing any details of the BF8A. From this manual I see that I do have a 12 volt lighting coil and a rectifier/voltage regulator.

Can anyone describe how to test the lighting coil for AC power and how to find and/or replace the rectifier/regulator?

Is it possible that this circuit will not show any DC voltage unless the battery is connected and showing the regulator some voltage?

Indiscipline 1978 FK #398

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/05/2003 : 18:15:17

Jim...there wont be any ouput voltage until hooked to a battery...remember...its an alternator which must have its field energized in order to output.

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

Edited by - arlyn stewart on 05/05/2003 18:18:01

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JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 05/05/2003 : 18:44:28

But it's not an alternator. It's a lighting coil with a voltage regulator/rectifier - similar to what is used on small motorcycles. The manual shows belt driven alternators in the 50 HP and up engines. I understand that an alternator needs a field coil to be energized in order to generate electrical power.

The Seloc manual does say you may have to run the battery down in order to see any significant charging CURRENT. I expected to see VOLTAGE right away.

I'll run my batteries down and give it a try next weekend, especially since I can't see anything wrong with the circuit and wiring. I just expected to measure 12V on the connector with no load attached.

Thankfully the back breaking job of running the wiring and figuring out how to splice it into my custom panel is done.

Indiscipline 1978 FK #398

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Arlyn Stewart
Master Marine Consultant

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Response Posted - 05/05/2003 : 19:21:28

I got into this a few years ago during spring maintenance... the motor was on a block in the shop vice where I had run tested it...nearby was the lawn mower so I pulled the battery from it...set it on the bench and no current flowed from the motor. After checking the diodes, the charging coil for an open... I was confused and posted an almost identicle post as yours.

Someone came back at me to check the battery to see if it was dead... sure enough... the lawn mower battery was completely dead... once I hooked the motor to a good battery...viola.

I think it is an alternator... it uses diodes which must be necessary to rectify an AC wave form. And, I'm not sure if that motor had a regulator. If so, I never found it. The diode package was easy to find and check...think it was a grouping of 4 diodes in a full bridge package. But, that was several years back when I messed with it.

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

Edited by - arlyn stewart on 05/05/2003 19:26:52

Edited by - arlyn stewart on 05/05/2003 19:31:46

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Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 05/05/2003 : 19:32:12

JimB517 Not to be an ass or anything but your the one with the questions. Most of us here with close to 1000 post or over have been there done that and have the shirt. Give it a try. It might save you some money and labor. If it doesn't work ask Leon. Gota love the edit feature hahaha.

Doug&Ruth
Triska (Alberg 29)
Tacoma Wa.

Edited by - Douglas on 05/05/2003 22:15:51

Edited by - on

Leon Sisson
Master Marine Consultant

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1893 Posts

Response Posted - 05/05/2003 : 20:40:47

'JimB517',

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I found a fuse just inboard of the socket. The fuse was fine and not blown. I pulled out some of the wiring and tested at various points and never found DC voltage (or AC for that matter).<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>Try working forward from the AC windings under the flywheel. That's the two blue wires in the male/female 2-pin connector.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>... details of the BF8A. From this manual I see that I do have a 12 volt lighting coil and a rectifier/voltage regulator. ... it's not an alternator. It's a lighting coil with a voltage regulator/rectifier - similar to what is used on small motorcycles.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>I believe that is correct. As a permanent magnet dynamo, there is no need for a field winding. Output regulation is accomplished either by boiling off electrolyte, or by shunting excess current to ground.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Can anyone describe how to test the lighting coil for AC power and how to find and/or replace the rectifier/regulator?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>There are a couple of ways to test the AC coil. The resistance, measured between the two blue leads, disconnected, without the engine running, should be about 0.13 ohms give or take 10%. Another test would be to measure for AC voltage or current at that same connector with the engine running, or try to light up a spare headlight bulb with the AC.

The rectifier assembly is a black finned brick about 1-1/2"x1-1/2"x1". It is located just behind the shift lever shaft in front of the engine block. It is attached by a single 6mm bolt and a few wires. It is a single phase full wave bridge rectifier. The test method is the standard polarized continuity go/no-go test for a single phase 4-lead bridge rectifier circuit. The manual does not specify forward voltage drops for the diodes.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Is it possible that this circuit will not show any DC voltage unless the battery is connected and showing the regulator some voltage?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>This type of charging system does not require a battery to operate. When I bought the low compression Honda [url="http://www.catalina25-250.org/forum/topic.asp?TOPIC_ID=3392"]described here[/url], I tested the charging system using a 100w spotlight, but no battery. At first, the engine wouldn't light up the light. After scratching our heads, the seller and I started cleaning corroded wiring connectors, as you did. After we cleaned the last ones, the blue AC coil leads, the spotlight came on. Without a battery.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>The Seloc manual does say you may have to run the battery down in order to see any significant charging CURRENT. I expected to see VOLTAGE right away.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>Yes, I agree with you here. By the way, the max current is only about 5A.

-- Leon Sisson

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Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/05/2003 : 21:14:49

Leon...

The BF8A that I referred to is a 1983, maybe we need to talk some year models here to get things straight. It will not output without being connected to a battery...

Sometimes its necessary to get into the head of the Japanese writers who document this stuff.... On page 23 of the manual after it talks about connecting the positve battery terminal to the positive charging cord and warning of damage if reversing...it says, "The outboard motor's 12 volt output is intended for battery charging only. Electrical accessories should be connected to the battery as shown."

I doubt if a tech writer in the western culture would have combined the words "intended and only".

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

Edited by - on

Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 05/05/2003 : 22:10:10

Arlyn,

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>The BF8A that I referred to is a 1983, maybe we need to talk some year models here to get things straight.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>I'm referencing the Honda factory service manual, "SHOP MANUAL, OUTBOARD MOTOR, BF75-BF100-BF8A", Honda Motor Co., Ltd., copyright 1984.

The five Honda outboards I have span several models and years, and all appear as described in that manual. The only differences I've found are points vs. CDI ignition, 7.5HP vs. 10.HP carb, maybe a coresponding difference in camshaft grind, long shaft vs. short shaft, and cowl decals.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>It will not output without being connected to a battery.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>All I can tell you is I see no reason why it wouldn't. In the shop manual there's even a schematic of what's inside the rectifier unit, and it's just a four silicon diode bridge. There is no formal regulator, as I described above. The entire charging system, what little there is of it, is stone axe simple.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>"The outboard motor's 12 volt output is intended for battery charging only. Electrical accessories should be connected to the battery as shown."<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>That's because there's no voltage regulator other than the battery. If you wire say, a VHF or stereo directly to the Honda's 12VDC output, the voltage will more or less follow the engine RPM, probably frying the radio, and certainly not allowing it to operate correctly. If you were to run a high power spotlight directly off the engine, it would dim to nothing at idle. The battery serves to stabilize the 12VDC power. It accumulates and averages the output of the alternator.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Sometimes its necessary to get into the head of the Japanese writers who document this stuff.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>Yes, English first not language of effectiveness birth.<img src=icon_smile.gif border=0 align=middle> I'm sure we've all sometimes wondered how some of those Japanese technical translators got, let alone kept, their jobs. Honda eventually wised up, and later year technical documentation is much improved over the earlier translations. When Honda first attempted to penetrate the American market, there was quite a cultural disconnect...

-- Leon Sisson

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 05/06/2003 : 01:10:07

Thank you Arlyn, Leon, and Douglas. I am not sure the model year of my Honda BF8A. It was bought used by the PO in about 2001. It is fairly new. I would guess 1998 or so. I will take the serial number over to our local Honda shop and find out (and get the actual shop manual) someday.

I will first attempt to find and clean the blue AC wires coming off the coil, check for resistance and see if I am getting any AC when it's running. I'll find and check the wires that plug into the rectifier. The Seloc manual says if there's AC but no DC then, by process of elimination, it must be the rectifier.

Since it's simple and direct, I will run my main batteries down (easy to do with a 12 V spotlight) and hook up the circuit, just to see if the motor puts out anything at all under a load, as Arlyn suggests.

I got some cool new flexible solar panels today. There's a shop here in San Diego that has the United Solar USF-11 for $99 and a regulator for $35. That's about $25 less than Sailnet. I bought two flexible 11 watt, 0.7 amp panels. Combined with the 5A from the motor and careful use at night I should be independant of AC shore power - for a 3 day weekend at least. So I'll hook them up and see if my batteries come back up!

http://www.solarelectricinc.com/

These are seconds with slight cosmetic blemishes. The panels are great, you can mount them on the deck, forward hatch, hang them from the lifelines or tie them to the sailcover.

Indiscipline 1978 FK #398

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 05/07/2003 : 23:40:05

hmmm.. my 1997 Honda 8hp behaved like that from day one... (brand new). Putting a voltmeter across the plug yields zero. I always thought it was by design and it needed a battery to produce voltage.
Now I'll have to check that out.

I do know that my older generation 7.5 HP Honda has voltage at the plug without a battery.

Currently maintaining two holes in the water...'77 Venture 23 and new to the family,
'78 Catalina 25

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Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/08/2003 : 07:48:54

It would be interesting to substitute a standard full wave bridge for the Honda rectifier... it might be that the diodes in their bridge are switching diodes needing reverse bias to open.

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

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lcharlot
Master Marine Consultant

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Antigua and Barbuda
1301 Posts

Response Posted - 05/08/2003 : 08:44:46

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
I got some cool new flexible solar panels today. There's a shop here in San Diego that has the United Solar USF-11 for $99 and a <hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Jim - are these panels coated with a material than can be walked on, for deck mounting? I saw some solar panels at Sail Expo that were coated with a super-tough plastic and are designed to be walked on with no problem, but I don't remember what brand they were. I need to get a new panel for "Quiet Time"; there is no shore power at Folsom Lake Marina, solar panel is the only way to charge batteries unless I want to drag tham out of the boat and take them home every weekend. The 64 watt panel looks good, if it is not too large to mount.

Larry Charlot
Catalina 25 #1205 "Quiet Time"
Sacramento, CA

Edited by - on

JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 05/08/2003 : 13:09:13

Yes, the USF-11 solar panels can be walked on! The manual says bare feet or soft soled shoes only. Actually feels like fairly good non-slip.

I love these panels. They sewn into a tough vinyl backing and covered with a real tough plastic lamination. They have grommets for hanging. They are quite flexible - but stiff enough so that you can't roll them up. The manual says don't fold them or cause a crease. I'm just going to bungee mine over the sail cover or toss them on the cockpit seats when I'm not aboard.

We have not had one single sunny day since I bought them!

Indiscipline 1978 FK #398

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JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 05/08/2003 : 13:17:11

I noticed you mentioned the 64 watt panel. That is a Unisolar rigid panel. The only ones you can walk on are the flexible. The biggest one is the USF-32 (32 watt, 2 amps).

This panel is about 3.5 feet long and 18 inches wide. Solar electric has this for $199.

I would think that one USF-32 plus the $35 regulator would keep your batteries fully charged. You could always get 2 (4 amps). The regulator is OK up to 7 amps and cuts off the voltage at 14.3 (the panels can generate up to 16 V - not good for gel or AGM batteries).

I would just drop them on my cockpit seats or bungee to the sailcover when I am not there and plug into the regulator. When sailing, drop them into the lazerette.

The flex panels are protected with blocking diodes so they will not drain your batteries at night or in shadows.

Indiscipline 1978 FK #398

Edited by - on

Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/09/2003 : 17:49:40

This afternoon with some spare time... the '93 Honda 8 four stroke was fired up and the charging circuit tested. It will not light a test lamp hooked directly to the output. With an ampmeter and battery... it does output.

Still hoping that memory is the first major thing to fail.... <img src=icon_smile_wink.gif border=0 align=middle>

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

Edited by - on

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 05/10/2003 : 22:24:49

"It will not light a test lamp hooked directly to the output. With an ampmeter and battery... it does output. "

Good... that matches what I observed on my Honda 8hp engine and confirms it is by design and not something wrong. One less thing to fiddle with. Since the older 7.5 would produce voltage without the battery, it's obvious they changed something in there.

Currently maintaining two holes in the water...'77 Venture 23 and new to the family,
'78 Catalina 25

Edited by - on

Ben - FL
Admiral

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880 Posts

Response Posted - 05/11/2003 : 08:48:48

I'm still looking for my Dunce Cap<img src=icon_smile_clown.gif border=0 align=middle>

Safe voyages,
Ben, FL s/v Chick-a-pea C250wk
<img src="http://www.members.aol.com:/benraye/pictures/fullsail.jpg" border=0>

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JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 05/12/2003 : 14:09:17

I hooked the motor up to the battery, turned on all the cabin lights, and measured voltage at the battery. The Honda 8 hp put out voltage and current. It does not with no battery attached.

Explaination.

My new solar panels came with a voltage regulator. The panels put out 23 volts in noon sunlight. Hooked up to the regulator, I measured no voltage at the output side. Upon reading the manual, it said that the regulator needs to see 12.5 volts on the output side of the circuit to work. If the batteries are drawn down below this the regulator should be bypassed. When I connect the panels to the system, the on-board voltage jumped up to 13.6 volts (from about 12.9).

According to the Seloc manual, the Honda BF8A has a rectifier and regulator. Must work in the same way.

It makes sense, that way the output plug on the side of the motor is not "hot" if nothing is attached to it.

Indiscipline 1978 FK #398

Edited by - on

dgabel
1st Mate

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USA
75 Posts

Response Posted - 05/12/2003 : 17:04:16

I'd sure like to see a schematic of that charging circuit. If someone could scan it and send to dgabel@optonline.net, then I probably could explain why it outputs no voltage with no battery connected. I have a Nissan 9.9, so I don't think that's any help.

Dave Gabel
Walkure, 79 tall rig, wing keel
Sail # 1484

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Arlyn Stewart
Master Marine Consultant

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USA
2980 Posts

Response Posted - 05/12/2003 : 21:49:46

http://www.stewartfam.net/arlyn/schematic.jpg

<img src="http://www.stewartfam.net/arlyn/schematic.jpg" border=0>

Arlyn C-250 W/B #224
<img src="http://www.stewartfam.net/arlyn/rr.jpg" border=0>
N/E Texas and Great Lakes

[url="http://www.cox-internet.com/arlynstewart/"]Arlyn's C250 Mods n Cruisin Stories[/url]

Edited by - arlyn stewart on 05/12/2003 21:51:25

Edited by - on

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