Outboard Charge Regulator

[wicked]

I've got a new Tohatsu 9.8 4 stroke outboard with a battery charging circuit. With the engine running fast, I measure up to 16.5V across the battery terminals (I haven't yet measured the current). I'm concerned that this seems a bit high and may wreck the battery / instruments.

Is it recommended to fit a charge regulator of some sort or is this fairly typical for an outboard ?.

I have a solar charge regulator on my solar panel - could I use one of these regulators for the outboard charging or do I need a different gizmo ?

Thanks.

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[oldharry]

Yes, too high for both the battery and electronics. A regulator for a solar panel would be OK provided it is able to handle the amperage which will be considerably more than most Solar cell arrays. Not sure where you can source stand alone voltage regulators. Adverc?

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[William_H]

Disagree with old harry. The voltage you measured would be with no battery connected. With a battery connected the voltage would be that of the battery as raised by the charger depending on the battery charge level. If you measure the current into the battery you would find it not a great deal. I would guess maybe 3 amps.
The voltage at 16.5 with no battery and no load means that theoretically as the battery became fully charged the charger would continue to pump current into the battery until the voltage got to 16.5 volts yes far too much however you would find in practice that the voltage of the charger would be reduced by the battery load anyway. i would suggest that assuming you have a reasonable sized battery ie 40AH or more and assuming you only run the engine for an hour less every few days that you will never overcharge the battery hence never get the system vokltage about 13.5 volts.
If you have any concerns fit a voltmeter or use a multimeter to monitor battery voltage. An ampmeter will tell you how much is going in and I think you will find it not so much as to be as concern and it will reduce with the battery being charged anyway. The current you get into the battery on test will indicat the size of the regulator you will need if you decide to go that way. I suspect you will find the current is in the range of the existing solar regulator (which you probably don't need anyway) which may be used as regulator for the O/B. The trick is to try it without regulator while monitoring voltage of the battery and the current from the O/B. All will become obvious regards will

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[wicked]

No - I am measuring 16.5V with the battery in circuit - i.e. connected to the outboard charging cables. In fact I have 2 identical batteries, both quite new and approx 65ah, with an off-1-both-2 switch. I get about 16.5v or thereabouts whichever battery I have switched in to circuit, so I don't suspect the batteries.

The engine is mostly used to chug out of the harbour, but is sometimes used for longer periods (10+ hours) to motor home when there's no wind. I don't want to mess around disconnecting the charging manually, and I'm a bit concerned that I may fry something at these voltages for a sustained period.

I can buy from Maplin (part no N54AJ) a 7A solar charge controller for about £20, but I'm not sure if these would be suitable for use with an outboard lighting coil/rectifier setup.

Dave

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[Guest]

OBD electric feed normally AC

The electric feed from an outboard is normally AC and has to be sorted to DC to charge a battery.
All my outboards have had to have little black boxs wired in to convert AC to DC ..... without this box, which included the regulator as well ... the electric supply from the Obd is only for lights and items that can live with AC

I assume that the original postee has a box converting the supply from the Obd - possibly fitted inside the cowling - if not external ????

For example - most older Johnsons had a electrical flash sign and AC Lighting written next to it at the socket in cowling ..... good reason for this !


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[Guest]

Regulator etc

When I sorted my Merc 7.5 with electric - the Merc regulator was a AC to DC convertor and Regulator in one.
The dealer - Merc service agents - advised that the charge rate from the supply was not so high to warrant worrying about - fit the box and enjoy. (In fact he even advised that a diode wired in correctly would do the job - but not to quote him ...... I only pass that on as a comment and do not expect flak for it .....)


<hr width=100% size=1>Nigel ... and of course Yahoo groups :
http://groups.yahoo.com/group/gps-navigator/

 

[oldharry]

Could well find the open circuit voltage from this type of set up to be in excess of 40 volts. !6+ volts <at the battery terminals> is quite enough to blow every bulb in the boat and to fry any electronic gear

And yes Nigel, agreed AC wont do the battery any good, but Wicked says he is using a< lighting coil rectifier set up>, so unless the rectifier is duff, he only needs a voltage controller of sufficient current carrying capacity for the set up. Divide the stated wattage of the coil by 12 to establish what the maximum current is likely to be in amps at the correct charge voltage. ( and yes I know batteries charge at 14 volts, but as alternator voltage output increases the amperage drops, so the 12 volt figure will give the highest likely amperage at the battery terminals.)

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[snowleopard]

16.5v is certainly way too much. one quick check is to take the caps off the battery, if the cells are gassing you can be sure long term damage will result.

the 7A solar panel regulator (also available from the Compass catalogue) is designed to be wired in series to limit current flow (as opposed to the likes of Adverc which control the output voltage). you really need to check the maximum current with a flat battery before fitting one of these devices.

an outboard dealer may be able to supply a solid-state regulator suitable for this application. i still have one i bought about 10 years ago which cost £45. i didn't get round to fitting it before the engine was nicked so can't say how well it works!

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[oldharry]

Re: Regulator etc

I had a Yam 6 with a rated 90 watt alternator without a rectifier. Maplins supplied a 10amp capacity full wave rectifier for around £3, which worked perfectly, and the voltage never rose above 14.5.

Unfortunately this guy is getting too high a voltage out of his set up for safety.

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[Guest]

I can't see where he says he's using a rectifier .....

I asume that the obd is fitted with one as he calls it a Battery Charging circuit ......



<hr width=100% size=1>Nigel ... and of course Yahoo groups :
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[William_H]

As Nigel says we assume it has the rectifier fitted to the pick up coils. If you open up the motor and find the wiring to the inside of the plug it should have a box of some sort between the plug and the point where the wires dissapear under the flywheel. Like Nigel my experience is based on Johnson but still it should be similar.
Next check how many volts you read from your batteries with engine stopped? Many cheap digital meters will read hi when the battery gets low. If you read something like 13 volts with motor stopped then meter is OK but if it is still over 14 get a new battery for meter. does the cabin light seem excessively bright? Can you get an ampmeter? or open the circuit and put your multimeter on amps range hopefully at least 5 amp range any less may melt the meter.
If you are getting 16.5 volts at the battery then all my understanding of battery charging goes out the window! ( unless it is a very high current generator ie around 20 amps) I assume here you are reading voltage on the battery post. A high voltage up the line toward the motor (but 13.75 at the battery post) would mean a high resistance in the wiring or even battery terminal. The only other possibility (unlikely) is both batteries fully charged and possibly boiled dry. Please let us know what the outcome is. Yes I reckon the solar regulator would work fine but I still reckon you shouldn't need it especially with battery switch on both batteries. regards will

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[graham]

I had the same problem with a Yamaha 8 .It was connected to charge the battery through a rectifier but during charging the voltage would go to high.

2 wrecked VHF sets later I learned to switch off all electronics during charging.

Not ideal I know but a simple solution at the time.

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[silverseal]

If it is a brand new engine, would it be an idea to speak to the warranty department, to find out what is going on, and perhaps to see if they have any recommended kit to sort the problem?

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[jkim1]

Have read all the others. and have some questions.
1 what is the stated output of your alternator.
2 Is it ac or dc. or rather does it have a built in rectifier
3 What sort of rectifier do you have as Mercury normally fit a single diode( which they charge a fortune for).
4 If its a single diode throw it away and buy a 35 amp bridge rectifier from Maplins.
5 Get hold of a couple of car headlight bulbs and see what amperage you can get out of it. The alternator that is.The reason for this is that a solar regulator unless you are very wealthy and have loads of solar cells will be too small.
6 If the current is above 6 amps you will have to get hold of a regulator to handle whatever current you are producing, it would probably have to be a wind generator regulator.
7 If you have lights, pumps on the boat does the voltage drop when you turn them on ( with the batteries in circuit that is).
8 Pray

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[wicked]

Thanks to everyone who took the trouble to respond. Some people missed the point so here's a few facts:

The outboard has a battery charging circuit - i.e. it produces DC via coils under the flywheel and a rectifier. The rectifier is factory fitted (with heat sink type fins - says on it SB6-13 3.D 9.1 whatever that means!)

With no load connected oldharry is quite correct, you get 40 ish volts. The risk here is that if the engine is run with the instruments switched on and the battery switch accidentally left off, then something is going to pop. I would like to protect against this.

Battery voltage with nothing switched on and given time to settle is about 12.8V
Batteries are fairly new Delphi Marine deep cycle sealed lead-acid.

With the battery connected I can measure up to about 16.5V which everyone seems to agree is too high.

I have measured the charging current and it's about 5A (I assume it's a 60W charging circuit).

I found this shunt regulator rated at 6A on the net which looks like it may do the job:

http://www.galeforce.uk.com/Solar-PV/BR1.pdf

I think I'll buy one and give it a go. Not sure if it will protect the instruments from a high voltage spike if the battery is accidentally switched off while the outboard is running but I guess I could fit a car headlight relay to disconnect the charging circuit if the battery is off.

I'll let you know if it works.

Dave.

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[VicS]

I can confirm that if you have the engine running and the battery disconnected you are very likely to do damage to any electronics that are switched on. i did just that a number of years ago.

You can avoid that particular problem by having a 2 pole switch as a main isolator switch. One pole isolates the system from the battery and the other isolates the charging circuit from the system.

You still need to control the volts coming in from the engine though to protect the battery from overcharging. A shunt regulator must be able to handle the maximum output from the engine though. If 5 amps (or 60 watts) is the maximum then try the 6amp one you have found, but be prepared for it to get pretty hot.

<hr width=100% size=1><font color=purple>Ne te confundant illegitimi.</font color=purple>

 

[Joe_Cole]

David,

I had exactly the same problem when I bought my engine (Mariner). The voltage was similar and it was boiling the battery and it also caused some problems with instrumentation. In the end I spoke to the manufacturers and after a bit of "discussion" (The words "fit for purpose" were used a few times!) they agreed to let me have a regulator. Once fitted the problem was resolved.

I think that some manufacturers are simply fitting rectifiers as its cheaper than a proper regulator. However, to describe this as a "battery charging circuit" is missleading.



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[William_H]

Hello Wicked It seems I was wrong in that it is indeed a gutsy charger fitted to the outboard. I am still surprised at the voltage of 16.5 volts at 5 amps. I would have expected more current especially for 2 65AH batteries anyway I must be wrong.
As for the shunt regulator this now worries me. Shunt regulators are made for solar panels so that there is no semiconductor (transistor) in series which drops .7 volt minimum) hence full voltage is available from the panel. The power is reduced by wasting it to ground ie when the battery is up to voltage all the solar current goes through the regulator transistor.
Now with your charger if the batteries are full you need to shunt at least the 5 amps you currently have going in to the battery but in fact more because you have only pulled the charging voltage down to 16.5 volts. You need to dissipate more currenmt to get it down to 13.75. Probably that will be more than the 6 amp rating. Of course the battery will always take a little at 13.75 volts but I still think 6amps is not enough rating. What you need is a series reulator ie it puts a transistor in series to reduce the current and voltage from the O/b. I suspect the wind charger regulators may be series regulator. If all else fails you could fit a resistor in series about 1 ohm rated at 20 watts from Maplins would solve the overcharge of the batteries problem btu would limit your charge into a flat battery and would not solve the problem of 40 volts with no battery connected. If you fitted 3 Silicon Power diodes in series this would reduce the voltage on the batteries to 2.1 volts less under all conditions but may still not solve the above problems. Perhaps you need a purpose built regulator from the O/B manufacturer. If all else fails PM me and I will give you a design for a series regulator if you could assemble it from components from Maplin or RS regards will

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[andyball]

shunt regulators quite commonly used on motorcycles for the same problem.

it is usually possible to fit a combined regulator/rectifier from a small bike/scooter...perhaps at less cost if you source a pattern part, not a genuine honda/xxx one .

The voltages you mention sound about right- our old 8hp w/80W coils would take 140AH over 16V unless the nav/cabin lights were on....not if the batteries needed charging of course.

Annoying that outboard manufacturers still offer such unregulated systems.

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[oldharry]

Nigel: See last sentence of Wickeds second post (21/08) he refers to his '...outboard lighting coil/rectifier set up'

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