More Yamaha outboard nonsense

Topcat47

Topcat47

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Up to my eyes in bits from my own 4hp, a pal turned up this morning with a Malta (3.5). He wants an outboard to charge a battery. I'm happy to swap the motors, if his cannot be modified and mine can.

Does anyone know?
 
It depends on whether they have lighting coils fitted, if not then it'll cost an arm and a leg to fit them even if they can be. If they are fitted then all you need is a rectifier but again it'll cost a stupid amount to fit the official part but it is almost certainly possible to do something cheaply with a Maplins part or parts. (Just a bridge rectifier probably)

The electrical output from many small outboards can be pretty minimal though.
 
I don't know about the lighting coils, how would I recognise them? I don't have a workshop manual for either engine.

And another, is it possible to get fine pitch props for either engine?
 
If it has a lighting coil there will be a 2-pin output socket somewhere. If so, you will probably need a rectifier to charge a battery as the outputs are usually AC rather than DC.

As Vic says, the output is pretty meagre and you will need a lot of engine hours to put more than a few amperehours back.

I set up one on an Evinrude 9.9 many years ago & was very disappointed in the output produced. It just about kept the battery going for a week's summer cruising with no electronic stuff beside the occasional use of an echo sounder, VHF on receive, a small tiller pilot & a fluorescent light.
 
Funnily enough, that's why they don't call it a charging coil or alternator. You can wind one on an old transformer core, as I did years ago, but you only get one (electrical)cycle per flywheel rev, lose through the bridge rectifier, and end up with not-a-lot, unless the engine is screaming. Best just to connect a bulb on top of th motor, then folks will see you at night. (Unless there is room under the flywheel for multiple coils in parallel, each rectified, like a proper alternator))
 
Here's one for the more mathematically/electrically inclined.

I have a Yamaha 9.9hp 4-stroke electric start as our main engine. I want to be able to continue to charge the starter battery as needed and then via an A/B switch, trickle charge the house batteries.

The Yamaha ignition system is AC with a rectifier, not an alternator. There is no regulator. The battery leads from then engine outputs 13 amps DC at 13.5 volts, thus producing 175 watts. This being the case, I want to make sure I don't over-cook the house battery bank with 13a when only a 2a float charge is required.

As silly as it may sound, I'm toying with the idea of simply connecting a 150 watt, 240v inverter to the 13 amp 13.5v engine output to run my 240v shore-power battery trickle charger. In essence, I would be using the 240v inverter as a regulator between the engine and the batteries.

My shore power charger 240v mains supply specs:
Charging at:
2a draws 0.16a off the mains,
4a draws 0.26a
8a draws 0.51a
16a draws 1.04a

As long as I set it to only a 2a charge, a 150w inverter should be more than enough. Indeed, an 8a charge would only require 122 watts.

My question is; while motoring, would I be able to do a 2a trickle charge from the 240v mains charger (which requires 38.4 watts) using a 150w 12v inverter which supplies the 240v?

I'm sure I'm missing something obvious here, or my math is wrong, but if it works, it would enable a more stable charging environment for the house batteries.

The mains charger automatically adjusts its output to maintain the proper charge and gives a nice digital readout of amps, volts and percentage of charge. Also it would be nice to leave everything connected when we simply want to re-plug into shore power again.
 
The Yamaha has an alternator - thats the gadget that produces alternating current. If the said alternator is controlled to produce no more than 13.5 volts you wont fry your battery bank - the alternator on a conventional diesel is usually regulated to float at 13.7 volts or thereabouts once the batteries are charged. The battery voltage by that timne has risen to 13.7 otr just below so no current flows.

If there really is no control on the output of the Yamaha alternator, then the voltage could simply continue to rise above 13.5 and you would have a problem. Check with Yamaha.

If you have any doubts about what I say above, take your voltmeter and put it across the battery terminals of your car with the engine running and after the battery has become fully charged. Lights etc off. You will see a voltage in the 13s
 
The "alternator" on the Yamaha 9.9 is actually made up of a couple of coils under the flywheel that generate AC into a rectifier assembly when a magnet in the flywheel passes by. A pretty blunt instrument indeed. You would have to get into the motor's guts to find a way to reduce the charge voltage.

The problem is that I can't merely reduce the maximum output voltage, as that will also cut output at lower RPM's. What happens is that when the batteries are getting near full charge, the voltage starts creeping upwards, and can reach 16 or 17 volts, which is hard on the house battery.

I have to constantly monitor charging voltage and when it gets above 14.7 volts, I have to turn on the cabin lights, etc. to get the voltage lower. That's really not satisfactory. As I mentioned, my owners manual recommends buying an optional regulator from my Yamaha dealer for just this situation, but no dealer globally seems to be aware of it's existence.

The cables from the engine to the battery are used for both supplying power to the starter, and then to provide charging to the batteries. I need to limit the charge voltage to 14.7 volts, and whatever rectifier/regulator is built into the motor doesn't do that.

I tried asking Yamaha, since they vaguely mention the existence of such an animal in the literature that came with the motor. After going in circles between the company, and the numerous dealers they referred me to, nobody has a clue. I have found some regulators designed for solar panels, but they don't take into account supplying heavy (100 amps!) current back to the starter motor.

Thus is my predicament when it comes to safely charging the house (other than using a separate on-deck generator, or going totally solar).
 
What little I know about outboards is really confined to Johnnyrudes .

Larger engines from OMC especially those with power operated tilt and trim are fitted with higher output stators and rectifiers combined with regulators. I don't know how they work though. But I might try and find out.

Generally the the small ones have a max output of 5 or 6 amps and only achieve this at max revs.

For all practical purposes I disregard the battery charging capability of my Evinrude Yachtwin. I do not normally run the engine fast enough or for long enough for it to do much in the the way of charging, and certainly overcharging is no concern whatsoever at least not with a decent sized flooded lead acid battery. Perhaps If I had a gel battery I might be more concerned.
 
The regulator/rectifier referred to HERE might be of interest.

So far all I have been able to discover about regulators fitted to outboards is that they are probably shunt regulators and utilise the engine's water cooling to dissipate the heat
 
I have a 5HP Yamaha 2-stroke - the 5CS - and using a 25 watt silicon bridge rectifier I am getting 12.8 volts at idle and around 22 volts at mid throttle. Bearing in mind the 25 watt bit of the rectifier spec, surely I cannot put too much juice into the battery, as at 12v I'll max out the rectifier at 2A?

I am still pondering whether the 22V bit is a problem, but since the heating of the battery is the enemy, I reckon this should be safe, as the minute any current flows the voltage will drop accordingly.

Can anyone spot the flaw in Baldrick's cunning plan? If so please let me know before I fry my battery.... /forums/images/graemlins/laugh.gif
 
[ QUOTE ]
I am still pondering whether the 22V bit is a problem

[/ QUOTE ] What you are seeing is normal for the rectified but unregulated output from the charging system of a small outboard.

Without looking it up I'd guess that the maximum output from your charging system will be 5 or 6 amps at 12volts, but that will be at full revs. Larger outboards have more powerful stator coils and a combined rectifier/ regulator which, being a shunt regulator, has to be water cooled (at least that's how Johnsons and Evinrudes do it)

Curious then why you only have a 25watt rectifier, or is it a DIY job not the proper Yammie part.

I assume the 22 volts you measured is with no battery connected and no other load.

In practice with a battery connected you will not see such a high voltage and you will only see anything like the 5 or 6 amps when charging a battery that has been discharged a bit.

Also if this is an outboard on a sailing vessel you will probably seldom run it as full speed for any length of time.

However you should look at a more suitable rectifier, one that will comfortably handle the max rated current of the charging coil. The owners manual should tell you what that is. You stand a real chance of blowing the rectifier if I am right about the max current being 5 - 6 amps

My outboard has a charging system with a max output of 5amps and a built in unregulated rectifier. Over charging is not the problem, very much the opposite, which is why I also have a solar panel. My nav lights total 40 watts so those alone would exceed the rating of a 25 watt rectifier.
 
[ QUOTE ]
I just spotted this at Maplin...

[/ QUOTE ] It appears that its max current rating is only 1.5 amps.

Even if rated at a higher current I would be a bit concerned about it used in conjunction with an outboard charging system because it simply switches off once the battery is charged. If it is sudden it might cause a surge that would harm the rectifier. We know that proper alternators are susceptible to that and they say the same for outboard charging systems.

It would be just the ticket for a smallish solar panel charging a very small battery.
 
Actually I posted the wrong link like a muppet...

http://www.maplin.co.uk/Module.aspx?ModuleNo=97384

Thanks for the info Vics. The regulator was on the engine when I bought the boat, so I don't know whether it is an add-on, although since it was not connected to the engine AC circuit I guess you are right.

I have very small current demands - single LED bulb in a tri-colour, chartplotter, and little-used radio. I will be fitting LED cabin lights, but at the moment, even monitoring the VHF leaves a total draw of about 2-4A. However, I do have a tiller pilot, which I don't use much - just single-handed tacking - because of the annoying clicking of the stepper motor. I haven't yet checked the draw for this.

The handbook for the Yamaha 5CS doesn't give any indication of the max output of the coil.... is there a way of discovering this without any risk of damage to the circuit?

The boat also has a small solar panel, but I haven't yet found out what power it is ... the battery monitor arrives today, so in any case it will be possible to monitor it all and switch stuff off accordingly.... or get a bigger rectifier if necessary - at less than four quid a pop I could afford to go up to 50W and see if all is well, and so on until the output is suitable. My instinct tells me that a small (5HP) outboard is not going to throw out more than a couple of amps at mid throttle, so the 25W rectifier fitted may well be fine.

I would appreciate your, clearly informed, thoughts on the item linked above.... sorry for the earlier error!
 
[ QUOTE ]
like a muppet...

[/ QUOTE ]
That's more like what's needed but they are charge controllers, not regulators, intended for use with solar panels where necessary. I would not like to comment on their suitability to control the charging from the outboard. The Maplin site gives no really useful technical info although I think I have seen more elsewhere. If you can identify the make maybe you can find the manufacturers website. Note it has connections for the input, the battery, and the load.

Electrical systems and demands on small boats have a tendency to grow. The technical bumph on the auto pilot should tell you typical current draws for that.
Surprised about the noise you get. From a stepper motor?. Mine, which I use almost continuously doesn't make that much noise and is not operated by a stepper motor. (Check your power supply to it while it is operating to make sure you do not have a poor connection somewhere) If its a Raymarine/Raytheon/Nautec or a Navico/Simrad one you should be able to down load an operating manual if you don't have one.

Very surprised that the manual for the outboard does not state the electrical output but based on what I already know and what I can find out on line I will stick my neck out and say that it is 6 amps. You could determine it by loading it with progressively with an ammeter and voltmeter connected to see what the maximum current is that you can draw before the volts fall below 12. BUT are you absolutely sure its not in the techincal data. Thats where I found it for other models. Unless you have a very small battery or are motoring flat out for hours and hours at a time you really do not need to worry about the outboard overcharging the battery.

No problem finding a suitable bridge rectifier from Maplin. they have them rated from 1.5 amps to 35 amps and prices all below £2. I dont understand their case description though so would suggest a visit to your nearest shop to be sure of getting one with spade terminals.

You should be able to get some idea of the power of your solar panel by comparing its size (area) with others on the market. My 5watt panel is a bit more than a foot square overall.
A controller is advised for panels over 10watts but below that 10 watts into a 90 or 110 Ah battery is OK without a controller and 5 watts into anything over about 45 Ah is also OK.

BTW dont operate your autopilot dierctly from the outboard without the battery connected. I did accidentally once and it burnt out the voltage regulator circuit in the autopilot!
 
Many thanks for the lengthy & helpful reply!

I am setting my outboard up to plug into a deck socket, and there is already a deck socket for the TP10 - and I see from the handbook that it's a screwjack, not a stepper motor - but I don't like the noise, although to be fair it isn't very loud.

I have read the entire Yamaha Manual from front to back, and still no mention of electrical output. Based on your advice, and my own initial thoughts, I can't see that a 100AH battery is going to be over-charged by a 5HP motor being used for 20 minutes at a time.

Thanks for all the advice - I have ordered the regulator from Maplin, and will experiment with the bridge rectifiers once the system is all in place and the battery monitor is giving me the relevant info.
 
Why not get a charge controller that drops a relay when batterys are up to charge.

Maybe even use an old rectifier box that drops out from an old inboard dynamo engine - My old Vire had a regulator on the engine-bay bulkhead that did the job.

Sure Maplins or Lucas shops would have something to do the job ??
 
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