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Old 14-03-2018, 08:42   #1
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Maximum voltage Yamaha 9.9 alternator

Hi,

I own two Yamaha 9.9 High Thrust engines. 2014 & 2015 model.

The documentation states that each has an unregulated 80Watt (6.67A@12V) alternator (=2*80Watt).
I'd like to add those in a regulated charging circuit which can handle 50Volts at most.

Still, I was told that the maximum voltage can be much higher than the 12Volt at different load situations.

Does anyone know the maximum voltage which can occur?

Thanks,

Franziska
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Old 18-03-2018, 15:33   #2
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Re: Maximum voltage Yamaha 9.9 alternator

Franziska,

This is similar to a motorcycle engine electrics. So there is a rectifier which converts the AC to DC and then a regulator. I had a Suzuki that took out the regulator which trashed the battery in short order.

Your other problem is that the 80 watts will be at 5000 revs or something, how fast do you normally run those engines.

Most of the bike shops in the UK will bring in an electrician to solve electrical or electronic ignition. If a local yamaha dealer can't help then an independent vehicle electrician ought to be able to solve it quite cheaply. The regulators are available from the manufacturers and generic types so not expensive.
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Old 18-03-2018, 15:59   #3
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Re: Maximum voltage Yamaha 9.9 alternator

Franziska-
Many of the "unregulated alternators" are what we usually called generators in the US. There's a lot of argument about how the terms should be applied.
Really, battery charging is all in the numbers. You need reliable numbers and the best way to get them for your engine is to spend $20 on an inexpensive digital multimeter (at least, that's US market price). Set it on the DC 20V range and hook it up with a couple of alligator clips to the motor, see if the motor puts out more than 20VDC when it is revved up all the way. If it does...repeat on the 200VDC scale.
Now in theory if they are only 80W alternators, then a 10-amp regulator which is rated for an input voltage some 15% higher than your alternators put out, would be plenty sufficient. Personally, I'd make it a 20A rated regulator at twice the measured voltage, because I like conservative ratings. Things tend to work a lot longer that way. And note that those regulators MUST be adequately cooled, usually by mounting to a substantial metal part.
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Old 18-03-2018, 16:11   #4
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Re: Maximum voltage Yamaha 9.9 alternator

Quote:
Originally Posted by Franziska View Post
Hi,

I own two Yamaha 9.9 High Thrust engines. 2014 & 2015 model.

The documentation states that each has an unregulated 80Watt (6.67A@12V) alternator (=2*80Watt).
I'd like to add those in a regulated charging circuit which can handle 50Volts at most.

Still, I was told that the maximum voltage can be much higher than the 12Volt at different load situations.

Does anyone know the maximum voltage which can occur?

Thanks,

Franziska
12 volts, unless you can figure out how to put the engines in series.....
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Old 18-03-2018, 16:53   #5
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Re: Maximum voltage Yamaha 9.9 alternator

Thanks guys,

got a direct reply from Yamaha today.

As I had been told, and contrary to what I personally expected as well, peak
Voltage values to be expected are briefly much higher than 12V.

So 12V is, unfortunately, not the 100% correct answer.

See attached screenshot.

Now I will have to check if I have a single or double charging coil attached.

I am not on board at the moment but am pretty sure Yamaha can tell me that based on the engine built numers I have forwarded to them.

Apart from that Hellosailor is right, taking a multimeter and measuring is probably best.

More soon, thanks, Fran

More soon.
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Old 19-03-2018, 02:15   #6
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Re: Maximum voltage Yamaha 9.9 alternator

The voltages quoted by Yamaha are open circuit voltages. When we had ours we just connected to the batteries which was via the starter cables. Never had a problem with overcharging which I guess is OPs fear, even after 60nm crossing in flat calm motoring.
If you think about it, there are thousands of these and similar engines wired up like that on yachts and power boats. In practice, not a problem.
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Old 19-03-2018, 02:42   #7
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Re: Maximum voltage Yamaha 9.9 alternator

Hi Rapanui,

yes overcharging is the issue I am wondering about.
Maybe you are right, I might see an issue which does not exist?!

But then again all my other charge sources go to the housebank and are regulated.
If the engines charge to much, all others should therefore regulate down.

My engines are at the moment also direct attached, the thought of adding the regulator came up as I am revamping part of the charge system.
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Old 19-03-2018, 03:13   #8
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Re: Maximum voltage Yamaha 9.9 alternator

The price of a regulator isn't huge, so worth considering if you can identify the right one.

Be interesting to see what Yamaha charge for an outboard regulator compared to their motorcycle parts.

Pete
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Old 20-03-2018, 02:00   #9
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Re: Maximum voltage Yamaha 9.9 alternator

You could add s shunt regulator which would clamp the voltage at around 14.4v. If you use a PWM or MPPT reg, it would have to cope with the full open circuit output of the Yamaha or fry the input electronics. As I said, had ours directly connected to a 110ahr battery without problems, Yamaha 9.9 high thrust electric start
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Old 20-03-2018, 03:48   #10
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Re: Maximum voltage Yamaha 9.9 alternator

Quote:
Originally Posted by Franziska View Post
Thanks guys,

got a direct reply from Yamaha today.

As I had been told, and contrary to what I personally expected as well, peak
Voltage values to be expected are briefly much higher than 12V.

So 12V is, unfortunately, not the 100% correct answer.
Right, it's a normal 12 volt system which means the circuit described to handle 50 volts will easily handle it

When the manual says a 12 volt system or 12 volt alternator, the charging voltage will be much like that of your average automobile alternator (or solar controller) which puts out anywhere from 13.2 -14.4 volts. (but we still say it's 12 volts)

Example, my 12 volt solar controller holds the voltage at similar levels (13.3 to 14.4 volts) for days (or weeks) on end to my two 12 volt batteries that are in parallel

When it's advertised as a 12 volt system or alternator, that's for the average person so as not to confuse with too many details

Mainly the only time a meter is used is if you think your alternator or battery has a problem although some of us like to know the exact voltages (like you) whether it be out of an alternator or on the panel side and/or the battery side of our solar controllers

Looks like you wanted the exact voltages rather than just what it's called
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