Honda 9.9 RPM drop when Running Scotty---Normal?????

[Sharphooks]

Hello Gents,

Just purchased a brand new Honda 9.9 HI-Thrust. First time I ever bought out of the box---was hoping for better results.

A bit touchy on the cold-start: I'm not used to auto-chokes so when it refuses to start on the first few cranks, I guess there's not much one can do except keep cranking it over until it fires up. Never had that problem with all the Yammies I've owned over the years unless I had a dirty carb. You wouldn't expect that in a new motor!!?.

But here's the real concern: once it warms up it runs fine. Until I put it under load when operating a Scotty electric. There's an immediate and very noticeable drop in RPM's when I'm lifting the downrigger ball. Once I shut off the Scotty, the RPM's increase back to normal.

The dealership I purchased it from said the alternator is very sensitive to a power draw and a drop in RPM's is "normal". What say you? Should I be bringinging it in to get it looked at?

 

[Mi Chica]

Doesn't sound right. It should not be that sensitive. Possible wiring issue?

 

[JDR]

Just out of curiosity how is your battery, a weak batt could cause the motor to drop under load. Do you have a volt meter if so see what the volt is when this happens. 2 batts. try running both to see if it makes a difference. also check all wiring and connections. JDR

 

[Sharphooks]

Hello gents

Thanks for the quick response. Battery's are 100%. I had the same RPM drop when running on No. 1 and No. 2 batteries and while running on the main. Wires were all reattached to batteries (connections cleaned and tightened) but there could possibly be corrosion in the Scotty plugs (newer twist-in models). I'll check those also.
Thanks again.

 

[TenMile]

That does seem odd. Could be that you've used too small wiring between your batteries and downriggers? Each rigger will draw about 8 amps pulling a 12lb ball. You should be using roughly an 11 gauge wire (12V, 8Amps ~ 20ft) for a 3% loss of power. If the gauge is too small, the battery/alternator may have to send more power to your riggers to compensate for the loss?

I did find this little write-up:

The Honda BF9.9 provides 2 Amps at 1000 RPM and an amazing 12 amps at 3000 RPM. This helps to maintain the battery charge or keep electronics going - even at trolling speeds.

What that suggests is that when you're using your DR's, the engine senses it needs to supply more juice from the alternator so the RPM's fall back.

 

[Island Fish Lifter]

I disagree with all of you. Thats normal. It makes sense. If you had a larger battery or more than one battery you may not notice it at all.

 

[Sharphooks]

Hello, again, Gents

Rechecked all the wiring. Wire gauge is correct (burly Scotty rated). Zero corrosion on Scotty plugs (twist-ins, probably not the corrosion issues as I used to have with the older plug-ins). I did notice the Scotty ground wire shared a battery connection with a ground from the hydraulic trim tab actuator---just for grins, I separated the two grounds, re-connected with their own neg post attachment points, and buttoned everything back down. All wires and wire connectors squeaky clean and re-connected. Can't draw conclusions in my driveway--need to run the Scotty under a load with a 10 lb ball to see if I've side-stepped the RPM bog-down issue.


hey, Island Fish Lifter-- I have two large marine batteries that tested fully charged. The RPM's bog down whether I'm running off one or two.
I've never had that issue with a Yamaha T-8 before---the Honda supposedly has a big burly alternator that kicks out more juice then the Yamaha which is why I'm paying attention to this situation.

I'd like to buy into your take on the RPM issue. But I also want to go into the summer with the confidence that my Honda 9.9 alternator is at 100%

I'll post after I get everything wet and test the Scotty again under load.

Thanks for all your comments in the meantime

 

[Kisinana]

It sounds like your alternator is working correctly. Increase in load creates a stronger magnetic field between rotor and stator hence the drop in rpm. In a water wheel generator the wickets on the water wheel open more as the load increases and speed is kept constant. Because you cannot have the rpms immediately increase automatically as the alternator magnetic load increases its only alternative is pull down on the output of your motor and pull down the rpms.
You may however still have a problem but not with the kicker but more likely the batteries or a downrigger motor, are they deep cycle?
I would be inclined to put a meter on the lead off your downrigger and take a load reading.

 

[Bassblaster]

"The Honda BF9.9 provides 2 Amps at 1000 RPM and an amazing 12 amps at 3000 RPM. This helps to maintain the battery charge or keep electronics going - even at trolling speeds.

What that suggests is that when you're using your DR's, the engine senses it needs to supply more juice from the alternator so the RPM's fall back."

Hey Tenmile,

Wouldn't this answer create the opposite effect than stated?

If the motor/alternator were to sense an additional draw of power required, wouldn't it increase the rpm to generate more power based on the info regarding the RPMs and out put? This being the case, the motor should be revving to accommodate the additional power drain, not slowing down. If the motor is designed to automatically compensate for such things, then I would think it's an issue with whatever sensor is supposed to control this function. If it is not working to compensate for the electrical draw by increasing the RPM's, then the result would be a straight drain of power, regardless of how many batteries you had hooked up. I'd also think that for there to be two batteries and for it to still be happening that Kisinana might have a point in there being an additional issue with the downrigger drive motor.

JMO

 

[King_Cod]

I would take a amp clamp with you and check the total amperage draw from your downriggers and also the amperage output of your kicker alternator. My Merc Optimax does the same thing when I'm using my downriggers. It will drop in RPM while trolling and pulling up 15lb balls. I don't have that problem when using my kicker though.

 

[TenMile]

Wouldn't this answer create the opposite effect than stated?

If the motor/alternator were to sense an additional draw of power required, wouldn't it increase the rpm to generate more power based on the info regarding the RPMs and out put?
JMO

I think that would be the case if the motor had some sort of auto-throttle like generators do, however I've not heard of a kicker doing that sort of thing. I suspect that the alternator senses the increased load, outputs more power but because the engine can't increase it's own throttle, the RPMs drop.

We have an older generator that works the same way. When you increase the load, the RPMs will drop somewhat. The new ones with the Eco Throttles can automagically compensate and increase the throttle/RPMs based on load.

 

[ratherbefishing]

I actually OWNED and OPERATED a 2003 Honda 9.9 Powerthrust (electric and pull start) and it did just what you have explained for the 6 years I owned it. It was wired correctly, batteries were of sufficient charge and size. Would always drop a little in RPM when pulling 15lb balls and ramp back up when the load was off. No idea why and no mechanic I ever asked could explain (tho I never asked a Honda tech).

On another note...cold starting was a PITA. I found that best approach was to turn it over for a few seconds then stop, goose the throttle a couple of times and then start it up again. Seemed to get it going most of the time.

 

[Sharphooks]

Hey R.Be.Fishing--

Thanks for your comments. Nice to know I'm not alone on this. hate to keep bringing up silver and blue but I never had that problem with Yamaha kickers before


Anyway, more info: went out on the water today. This time I brought two Scotty's with me to do some testing. Ran the one on the port side (wired to Battery No. 2, shared with the Honda T9.9) Same old drop in RPM's when lifting the ball. Ran the other Scotty on the starboard side (Wired to battery No. 1--same battery that fires up my Honda BF150) No drop in RPM.

Tried switching battery isolator switch to No. 1, No. 2, and both. Each time, the Scotty wired to the same battery as the HondaT9.9 caused the Honda T9.9 RPM's to bog down, each time the Scotty on the starboard side wired to No. 1 battery did not bog the RPM's down

So this is what I think I'm going to do: I'm going to wire the HondaT9.9 directly to the battery isolator switch so it's not directly connected to the same battery as the Honda T9.9.

Anybody else have their kicker wired to the isolator switch???

A Honda dealer recommended this to me today. It's got me curious, though I'm still puzzled why all the Yamaha T8's and T9.9's I've owned over the years never had their RPM's effected in this manner, even when I got lazy and ran Scotty's off run-down batteries!

 

[Fish-Hunter]

Yes the Kicker (Yamaha 9.9) on our boat is wired to the Bat. switch (as is the main motor alternator). This will allow whichever motor is running to charge the battery or batteries that are selected on the switch. I believe that this is a good idea but not sure however that this will solve the RPM drop on your kicker. When you get amperage draw the motor will drop RPM unless you have an automatic throttle contol to maintain RPM. I haven't seen one on a kicker B4, not to say that they aren't out there, (maybe that is what keeps the Yamaha's at the seemingly constant RPM that we have noticed, i'm not an outboard techie - just know enough to get me into or out of trouble). How many RPM is it dropping? Is it almost stalling out the motor? It does sound as though it is common on these Honda motors, it may be something that you have to end up living with just like the cold starting issues. Did you get to talk to a technician that really knows his stuff at Honda? or did you talk to a repairman/salesman? It would be interesting to hear what a Tech (in Honda Corp.) would have to say about this situation for sure.

 

[Sharphooks]

Hey FH,

No, the RPM drop is subtle--has no effect on outboard performance. It's just noticeable by sound is all--perhaps a few hundred RPM drop max. If I'm running at 2,000 +, you don't hear it.

The suggestion to wire to the isolator was made by a salesman, not a tech. But it makes intuitive sense---any Scotty draw-down would be spread between two batteries if isolator is switched to "both" and maybe wouldn't cause the RPM drop.

But it adds an additional challenge: the power cables of the Honda won't reach the isolator. I either have to splice pigtails or add terminal studs.

 

[Fish-Hunter]

Hey FH,

But it adds an additional challenge: the power cables of the Honda won't reach the isolator. I either have to splice pigtails or add terminal studs.

Damned Murphy!! What are they 6" short.

Did you get a chance to measure the amperage draw when the DR is pulling up? Just to make sure that you don't have a rigger problem drawing too much amperage.

It would still be interesting to hear what a Honda Tech has to say. If he explains that this is normal, then you don't have to chase your tail any more and keep wondering???WTH??? If he says no way, you should not be experiencing that, then hopefully he has some further suggestions, or else, back to the mullberry bush.

 

[TenMile]

You're not alone -- this guy found and fixed his problem:

http://arimaboatownersgroup.yuku.co...ATOR-KICKING---DOWNRIGGER--USED-NORMAL?page=1

As for wiring to battery isolators -- I would strongly advise that instead of using a manual 1, 2, Both switch that you consider getting yourself an Automatic Charge Relay (ACR) like the BlueSea Add-A-Battery system. You wire up battery 1 and 2 to the appropriate terminals. Add in your charging sources (Main, Kicker and Shore Power) to the third terminal. When the ACR senses that it is receiving more Amps than the batteries are supplying, it Combines both your batteries and charges them. Otherwise, it isolates your Starter and House battery and protects all your electronics from the starter surge. Much better system than the manual battery switch and costs about the same.

 

[MGH]

Think he added to thread. Read to the end of that posting at arima... and you find that he didn't solve the problem.

 

[Sharphooks]

Thanks for the comments about the BlueSea ACR, TenMile-- I was just in a marine supply shop yesterday looking at one.

Talked to another Honda tech: he assured me that the drop in RPM's is perfectly "normal' for a Honda if it's wired directly to the same battery as the Scotty. It is, and for the time being, I guess I'll just presume that the RPM thing is due to the sensitivity of the Honda's charging system to power draws rather then some electrical problem.

If it turns out to be an alternator or generator issue on in the future, at least it's a comfort knowing that all the up-front $$ I paid for a late model 9.9 Hi-Thrust helped finance a pretty generous warranty

 

[JDR]

from reading all the inputs, I don't think you have a problem,just normal. As a retired mechnic, if an alternator is loaded as in your case it creates a drag on the motorcausing it to slow down because it needs more rpms to produce more power. If the riggers draw 8 amps and your motor alternator only produces 2 amps at 1000 rpms then you will have an rpm drop because the alternator is trying to produce the amps. Also don't forget all the other electronics on board that are also drawing power. it is amzing how much drag an alternator has on a motor when trying to produce max amps.,..Also just for note; just because batteries test12 volts or better does not mean thay are good; a load test with the cold crank hrs for 10 to 15 seconds is the only way to test a batt. it should not drop below12 volts. Not sure of there state take them in and hva them load tested. Hope this helps JDR