Merc 115CT 6 month 100 hour service so soon

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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 23 Feb 2020 at 8:18am
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Titanium
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Which is why, good practice is to fire up the engine, put into fast idle with fast idle lever .. takes to about 1200+ rpms (automatic if battery measures low on the merc ct)
 This just kicks in the alternator.. with very low out put.
Then use the winch...
If swell and/ or current running, the engine is dropped into gear, to face the swell and run up on the anchor and lift to take a lot of load off the winch and the battery and alternator.

 An alternator can be gear in such a manner it will charge at lower rpms.. putting heat aside...but it loads the engine.. which at idle  a 100 or so rpms above idle . This load will them have the engine with excessive loads on the powerhead due to the power/rpm curve at that point and in practice idle very rough stall very may or just cut out.

An example of this is in pre LED days, idle the car then turn on lights, wipers , fans the engine idle would drop.. if not tuned well would stall... pre alternator day ..

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Post Options Post Options   Likes (0) Likes(0)   Quote Bounty Hunter Quote  Post ReplyReply Direct Link To This Post Posted: 23 Feb 2020 at 1:03pm
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Titanium
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Originally posted by Steps Steps wrote:

Which is why, good practice is to fire up the engine, put into fast idle with fast idle lever .. takes to about 1200+ rpms (automatic if battery measures low on the merc ct)
 This just kicks in the alternator.. with very low out put.
Then use the winch...
If swell and/ or current running, the engine is dropped into gear, to face the swell and run up on the anchor and lift to take a lot of load off the winch and the battery and alternator.

 An alternator can be gear in such a manner it will charge at lower rpms.. putting heat aside...but it loads the engine.. which at idle  a 100 or so rpms above idle . This load will them have the engine with excessive loads on the powerhead due to the power/rpm curve at that point and in practice idle very rough stall very may or just cut out.

An example of this is in pre LED days, idle the car then turn on lights, wipers , fans the engine idle would drop.. if not tuned well would stall... pre alternator day .. 


i think fast idle is more about getting the alternator spinning faster than the engine providing enough hp to drive it.

extra engine loads from an alt are measurable but only a very small drag on the engine in our case.

the calc would be as follows;

35A alt (at full field current) x 14.4V (charging voltage) = ~500w

alt output is maybe 50% efficient? (loss from friction, heat etc) 500w/.5 = 1000w of engine power to turn it.

1kW = ~1.3hp @ full charge. in this case its attached to a 115hp engine.

obviously a lot less drag at low engine rpms where alternator isnt putting out much juice...
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 24 Feb 2020 at 8:51am
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Titanium
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i think fast idle is more about getting the alternator spinning faster than the engine providing enough hp to drive it.

 Yes
Your numbers are ball park correct.. the load is not taken into account is the internal resistance of the battery after a fire up, plus the loading of accessories. the alternator wants to supply but cant.. hence why the heat.

I mentioned the load at engine idle speed if alternator is geared to charge at that speed and the effect it has... very rough idle and stall if load too high.
 Its just another factor as to why alternators are not geared to charge at idle speed..even big 350 ci V8s fitted with smaller 64amp (factory)  single wire ac/delco alternators that even 1200 could not maintain enough current to run lights and wipers at the same time...

Even back then with a few levers and stuff, the engine would automatically go into a fast idle/ semi  rich choke mode
 The merc  electronic concept of increasing engine speed is not some magic new idea at all

 Once upgraded with a single wire 110amp alternator a lot of the 'visible' load on engine and alternator at idle disappeared.


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Post Options Post Options   Likes (0) Likes(0)   Quote Smurfy Quote  Post ReplyReply Direct Link To This Post Posted: 24 Feb 2020 at 3:15pm
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I've got the same motor...and yes it's got heaps of grunt, very happy with it. Picked it up new end of june 2019 and just done 44 hrs so far. 
My only criticism is that the Merc gauges for Tank Level and % Remander do not tally with the Fuel Used amount, which seems correct. The Merc dealer confirmed that the Fuel Used is always correct so i have to manually track that to work out how much i have left in the tank.  Do you have the same issue Joker?
So you're offended...oh dear how sad, never mind.
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2020 at 9:33am
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My only criticism is that the Merc gauges for Tank Level and % Remander do not tally with the Fuel Used amount, which seems correct.

 I think you will find this is the case with most vehicles.
Fuel tanks are not usually a square box, or if they are are not mounted level or the ground not level.
 Even in our boat, with a under floor square tank.. what the needle reads on the water, near flat, and what reads at the pump.. front end of the tank slightly high due to hitch height and slop of forecourt, and what reads parked up are all different on the gauge.
My truck takes ages to drop to 1/4...then from just under 1/2 down drops quicker.
 The volume at the top of the tank is far greater than the bottom section..
At 1/4 full on the gauge it is 29% left before light comes on
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Post Options Post Options   Likes (0) Likes(0)   Quote Joker Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2020 at 9:48am
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Smurfy, I've never worked out how to use the remaining fuel tank guage. I just fill up the tank and zero the fuel used guage. I dont touch it until I fill up again so in my case with a 120L tank if I've used say 80L then there is around 40L left. 
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Post Options Post Options   Likes (0) Likes(0)   Quote Smurfy Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2020 at 12:34pm
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Originally posted by Joker Joker wrote:

Smurfy, I've never worked out how to use the remaining fuel tank guage. I just fill up the tank and zero the fuel used guage. I dont touch it until I fill up again so in my case with a 120L tank if I've used say 80L then there is around 40L left. 

Thats what i have to do as well Joker...i only fill up every 3rd or 4th trip  but have to manually track the fuel-used figure since last fill then take that off the 130L full tank.  It seems to be spot on everytime.  

May i ask what boat have you got that CT mounted on? Mines a Mclay 591 and it goes very well with heaps of grunt with 4 POB.
So you're offended...oh dear how sad, never mind.
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Post Options Post Options   Likes (0) Likes(0)   Quote Bigfishbob Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2020 at 2:53pm
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Are you guys using the Vessel View Gauge? I just have the vessel view set to show the Fuel remaining from the fuel tank sender in one corner, and then the fuel used in another corner. 

reason being, is that I then know how much fuel i have used for the day, because I only have a 80 litre tanks which gets topped up from 20 litre jerrycans. So using the tank sender to give me fuel remaining, lets me know when to top up the tank!
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Post Options Post Options   Likes (0) Likes(0)   Quote Joker Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2020 at 6:09pm
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Smurfy, I have the 115 CT ProXS on an FC560 Centre Console that pushes it really well even when fully loaded with 4 crew, 120l fuel, extra fuel, full live bait tank, extra batteries for the Minn Kota and a crap load of tackle. 
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Post Options Post Options   Likes (0) Likes(0)   Quote Big -Dave Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2020 at 9:11pm
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You may find that the tank level guage needs calibrating. Starting from empty, put measured amounts of fuel in and input the data on the smart guage.
Even then, it's only going to be correct when when the boat is flat and level..

I would trust the fuel used computer.
It's very accurate on my honda, see no reason for the merc to be any different.
you can't fix an idiot with duct tape, but it does muffle them for a while...
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Post Options Post Options   Likes (0) Likes(0)   Quote Big -Dave Quote  Post ReplyReply Direct Link To This Post Posted: 25 Feb 2020 at 9:35pm
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As for the charging issue
If the voltage is above 13 volts, it is charging the battery.
The battery will be accepting current. Unless the battery is stuffed.
If the alternator cant supply enough current, the voltage drops.
It's that simple.
you can't fix an idiot with duct tape, but it does muffle them for a while...
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