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Isolation Diodes???

Old 10-27-2003, 12:15 PM
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Default Isolation Diodes???

Does any one know if Yamaha HPDI's have these? I don't even know what they are but I need to know to figure out which Guest Isolator to use with three batteries. I think it is #2403. Here is where I am getting my info.

http://www.brokenlegdave.com/Manufac...e_Scanners.htm

Thanks for your help.

Kirk

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Old 10-27-2003, 01:05 PM
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Default Isolation Diodes???

I think you will find that the HPDI already have a two battery isolator built-in.
http://www.yamaha-motor.com/products..._hpdi_2004.htm
So, two motors and you've got built-in ability to keep 3 batteries isolated and charged.
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Old 10-27-2003, 02:10 PM
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Default Isolation Diodes???

Yes, you need the 2403 model, two alt's and three batteries.

And here is how ya hook it up:


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Old 10-28-2003, 05:18 AM
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Default Isolation Diodes???

Dang, even a picture! thanks

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Old 10-28-2003, 08:03 AM
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Default Isolation Diodes???

Kirk, I'm not sure why you need an isolator if I understand your setup. I have a pair of 250 HPDIs with three batteries. Each engine has two "hot" leads from the built-in voltage regulator/isolator, a primary and secondary. I have each primary hooked up to one of the batteries, which are switched through a Guest three-way selector switch that allows each engine to be started by either engine battery (or both at once).

Both secondary leads are connected directly to the third battery, which is then connected to the main "house" circuit breaker panel through an "on/off" switch. The three batteries and two engines are connected to a common ground.

This setup allows either or both engines to charge the house battery, which is isolated from the two engine batteries. So if I troll on one engine, the house battery is still being charged.

You should be able to exactly the same thing with your two HPDIs without need for an external isolator.

The second lead from the HPDI voltage regulators is something that the installer of the engines has to have connected (it's "optional") -- maybe yours didn't do it? But fixing that is very very simple and that would be lots cheaper and than getting the external isolator.
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Old 10-28-2003, 08:27 AM
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Default Isolation Diodes???

Saltdog;
I agree with you 100%. The HPDI circuitry is self-isolating and no external isolator is required.
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Old 10-28-2003, 08:40 AM
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Default Isolation Diodes???

Well it might just be my ignorance when it comes to batteries and electrical wiring. Here is where I am coming from. In my current boat, I have two batteries and two motors. If I try to run off just one motor, the alternator does not generate enough juice to keep the batteries up. By the time I am done trolling, the yamaha gauge is blinking at me because the charge has dropped to 12.0 volts. The run in at higher rpms recharges the battery and I have never had a problem with one but ideally I would like to put the two battery switches to BOTH as this eliminates the problem (volts don't drop as quickly with two batteries involved. So I my current boat, the solution (I think) is to get an isolator and run with the switches on BOTH.

Now applying the above, I have a new boat coming that will have three batteries. If the HPDI alternators work like the OX66, I am concerned that I will have the same isuue. Maybe just having a third battery driving the electronics eliminates the problem, I don't know. But if one motor charges the house battery and one engine battery, what prevents a bad battery from dragging the other down with it? Thats what I am trying to solve. I really appreciate your thoughts as I am no electical guru by any means.

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Old 10-28-2003, 09:11 AM
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Default Isolation Diodes???

You should be just fine. The 250 HPDIs have a bigger alternator than the OX66s that puts out its maximum charging current at much lower rpms. I run my radar and sounder and GPS and the fishbox pumps all day without drawing down the batteries at all.

Perhaps the most important thing you can do since it is a new boat is to make sure that it has good (and big) batteries. I have three Group 31 "Lifeline" AGM deep-cycle batteries. They are plenty big to meet the Yamaha specs and will last much longer than "starting" batteries. Get the manufacturer/dealer to install batteries like that andyou will never run low on juice again.

The built-in isolator will prevent a bad battery from dragging down a good one. Do not put the battery switches to both!! It will defeat the entire purpose of having isolators and risk damaging the alternators. That switch position is for starting in an emergency.
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Old 10-28-2003, 01:31 PM
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Default Isolation Diodes???

The built in Isolator's on the motors are reallly just ther to protect the altanator, not to direct traffic(power). The external battery isolators, actually direct traffic(power).

The problem with Saltdogs method, is you can never charge the port battery with the Starbd motor and vice versa. And, you have to really understand what your battery switch is doing (where it's directing traffic and NOT directing traffic at each setting).

With the setup above, it is the simplest to use, and safest. Both motors charge all three batteries, which ever battery is the least charged, will get the most charging current, until it is brought up to a good charge, then the charging current is switched to the next lowest battery, and so on. The isolator does this for you, regardless of what your battery switches are set to. And as for the switches, you have three. Two are on/off type switches, the third is a 1,2 or both type switch and is only used for emergencies. When you use your boat, turn the port and stbd on/off swithes to ON. When done with the boat, turn them OFF. That's it!!

If you have an emergency offshore, then you can use the third switch (parrallel switch), to parallel any or all or any combo of the batteries to get a motor started. Once a motor is started, the isolator will start charging all the batteries and allow you to start the second motor.

I personally think they should outlaw installing 1,2, both battery switches the way they do, it just causes to much confusion and problems because most folks don't understand them or how they are connected. Do a search here for "Battery Switches" and you will find about 30 different guys here asking about how to use there 1,2,both type switches, that should tell ya something.

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Old 10-28-2003, 02:12 PM
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Default Isolation Diodes???

Birdman, I think your setup is fine and has lots of advantages as you describe. If someone wants to spend the extra money for those capabilities, that's obviously their choice. But it is not corrct that the built-in regulator on the Yamaha HPDIs does not manage the charging voltage to each battery based on its condition. I have a voltmeter on the engine battery circuits for the port engine and also can show voltage on my plotter running offthe house battery. After starting the engines, the voltage one the engine battery circuit is noticeably higher for a few minutes until it recharges from the starting drain. Then it drops about 0.8V and the voltage on the house circuit goes up a similar amount until the house battery is charged. If I increase the load on the house circuit by turning on the radar, the voltage actually goes up as the isolator compensates by directing more of the charging outut to that circuit.
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Old 10-28-2003, 03:16 PM
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Default Isolation Diodes???

Yes, but it won't direct traffic between the two motor batteries which is what I was referring to. I should have stated that a bit more clearly.

By the way, your not talking much more money for this setup. the on/off battery switches are allot cheaper than the selector type switches, and a batt isolator is only 100-200 bucks.

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Old 10-29-2003, 06:30 AM
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Default Isolation Diodes???

Thanks for all the help. Seems Birdman's ideas make the most sense. It allows for all batteries to be charged without having to worry about a bad one killing the whole set.

Kirk

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Old 10-29-2003, 08:10 AM
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Default Isolation Diodes???

Saltdog;
I personally like your approach as the best of the two. Birdman's system is good, but definitely over-kill for the application. I also think your decision to go with type 31 batteries is execllent. I don't think users are aware of the enormous amount of current that those high-pressure injectors take at high RPM's. This does not mean that the battery is supplying current to run the injectors, but all the available charge current is used for the injectors, and little or nothing for battery charging. That is where the secondary charge circuit really shines.
Since you seem very savy about the HPDI charge system, perhaps you know whether the secondary charge circuit has its' own stator winding or does it use the same stator winding as the primary? If it has its own winding, that makes the system a real homerun.
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Old 10-29-2003, 09:06 AM
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Default Isolation Diodes???

Birdman, what software did you use to make your wiring diagram? I have a different setup using a battery combiner with simple on/off switches(one engine and two batteries) that I would like to document for future reference. thanks



_____



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Old 10-29-2003, 09:55 AM
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Default Isolation Diodes???

marinerman,
MS Visio, pretty easy to use.

Gil,
I'm pretty sure both leads on the HPDI uses the same stator, it all comes from the same place. And further, the HPDI doesn't use anywhere even close to to the full ouput current of the alt. They have 60 amp alts, the motor does not use anything near that. The injectors use a belt system from flywheel, it is not an electronic pump.

In fact, the Yami HPDI motors put out more charging current than any outboard motor on market.

Lastly, I don't get why it's overkill. It cost's about the same amount. Let do the math, you spend $500 for three good batteries, $100 for two 1,2,both selector switchs, $100 for 1 gauge wiring... So how does adding a $100 device, make it overkill? I spend $100 on Sat. night drinking beer.

I call that doing it right, the safest way.

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Old 10-29-2003, 11:00 AM
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Default Isolation Diodes???

Gil -- I am pretty certain that there is only one set of windings on the HPDI alternator. As for the current draw from the engine, I'm not sure what causes it, but it sure does go up significantly at high rpms as evidenced by a noticeable voltage drop as you go from 4000 rpms to WOT. Since the alternator output peaks below 4000 and stays level above that speed, the engine's own power draw must be causing the drop. It's not going negative by any means -- the voltage is still well above the battery voltage.

As for using Birdman's layout, I think he's right that the incremental cost is pretty minor. I don't know enough about electrical systems to understand what happens when you have three isolators/ two voltage regulators in the circuit and whether that might have long-term negative consequences for the alternators. My point was that it is needless complexity when you already hgave two isolators available. With the basic setup I described as the way Regulator set up my boat, you can still charge either engine battery with either engine in an emergency by using the three way selector switches.

*
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Old 10-29-2003, 11:51 AM
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Default Isolation Diodes???

Birdy;
I guess I am the victim of mis-information. I was under the impression that the HPDI injectors where electrically driven with a peak current pulse of up to 50 Amps. Don't know where I got that. In fact, I thought that was one of the reasons Yamaha specified larger batteries for all of their fuel injected engines. If that is not the case, then they must be cam-driven from the fly-wheel belt, as you suggested. Anyway, thanks for the update.
If the Secondary charge circuit has its' own stator coil, its' charge voltage and current output will be completely independent of the Primary output. If it uses the same coil, then loading affects on the Primary will effect the Secondary output. Big difference.
I know that you love your isolator and have had good results with it. Nothing wrong with that! However, I think Saltdog's system of both engine Secondary charge circuits connected to the single house battery is simple, does the job, and with far less components to go wrong.
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Old 10-29-2003, 12:43 PM
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Default Isolation Diodes???

Gil -- at least on the 250 HPDI, the injectors are electronically driven. I have no idea how much current it takes to operate them, however, though I suspect it is a fair amount given the pressures involved. The high pressure fuel pumps are run off the flywheel through a belt.

I have never seen a satisfactory, logical explanation for why the big HPDI engines require a large amp/hour battery for operation given that the alternator is clearly producing more power than the engine is using at all rpms basd on the voltages I see. Usually a big battery is specified because of a high load at starting, for example turning ove a Diesel with high compression.
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Old 10-29-2003, 01:04 PM
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Saltdog

My 3 battery sys is exactly like you explained, I did replace the house group 24 with a 31 because after hours of low speed trolling it couldn't keep up with power demands.

I've been told the O2 heater element amp draw is a big current user, and one reason for the battery spec change.
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Old 10-29-2003, 01:26 PM
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Default Isolation Diodes???

You guys are looking at the battery spec change backwards.

The larger batteries are speced not because of drain on them, the motor powers itself, you don't even need batteries in that respect. the larger capacity is because of the high OUPUT of the alternator on the HPDI's. The output current is so high it was/is frying batterires. Just another reason to install a good battery isolator. Again, the isolator on the motor is not sufficient to protect anything and will not direct traffic. It only allows you to keep two batteries connected to one alt, without one draining into the other.

Lastly, Saltdog, in my system, you do not use the motors built in isolators at all, they are not connected to anything (the second lead is not connected), so there is no negative or long term effect.


quote:With the basic setup I described as the way Regulator set up my boat, you can still charge either engine battery with either engine in an emergency by using the three way selector switches.
The "using the three way selector switches" is what scares me, that's the problem. Cause there are more wrong settings on those switches, then right ones.

Oh, and as for "far fewer parts to fail". Let count parts, my system, three bats, two alt's, one isolator. Your system: three bats, two alts, TWO isolators. Which one uses less parts?

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