Question 2017 60 HP 4Stroke. No crank/blown fuse. Not sure what cause.

[AJ B]

Yesterday on the water fishing for 6 hours motor started fine about 4 times in between fishing spots (about one hour total run time). Got to the dock to back my trailer in and when I got back to the boat the merc wouldn't start. Got the beep, and it tried to start but I don't think even one cylinder compressed/turned over before the starter stopped. I turned the key about 5-6 times (spaced apart by a few minutes) with same results. I disconnected and reconnected/tightened the battery, same result. I used jumper cables off a trolling motor battery. It took a minute or so before it would turn, but it did and I got it started to load onto my trailer.
It sure seemed like a low battery but I got it home and the battery was showing 12.48 volts on a digital voltmeter which seems well within the envelope for starting. (Note I was getting low volt alarm on Fishfinder set at 11.5 volts, but that's happened before when the finders are turned on and pulsing...) The batts are about 6 months old and all fluids are good. This morning I went to troubleshoot and checked all the fuses and found a 25 amp fuse blown on the engine (its in the picture--fuse bank on the right, the white 25A fuse with black ink marks I put on it).

My setup: 24v trolling system (Ulterra) separate from starting/house battery.
House batt used for starting and powering electronics (helix 10 mega, helix 7 g2n, network switch).
On board 3 bank charger always plugged in when stored.
Tracker 175 TF stock except for electronics/TM.
I know the finders draw about 4 amps combined but never had the problem before.

Of course I will replace the fuse, but does anyone know what circuit this fuse protects? I'm trying to determine what caused it to blow, and how to keep it from doing so again. Any troubleshooting help is much appreciated.

[gatorglenn]

Not sure what it's for. My 06 is different. Post this over on the merc 4 stoke board. And ask Don, he'll know. But post the ser# with your tread.

[mrc.in.wi]

My guess is your battery is to small. A 60 hp will take a while to recharge a depleted battery (30-45 minutes?). Modern engines will blow fuse to protect the computer from low voltage then a spike, possibly when you jumped it.
I would think you need a minimum of a 27M to run engine, live well and electronics.

[Bill Reynolds]

I too think it is a bad battery. I had a starting battery failure last year and it had the same symptoms. A digital voltmeter does not impress a load so it could show proper voltage and still fail under a load. Suggest you take it to a battery shop or automotive parts store and have them do a load test.

[berudd]

I too think it is a bad battery. I had a starting battery failure last year and it had the same symptoms. A digital voltmeter does not impress a load so it could show proper voltage and still fail under a load. Suggest you take it to a battery shop or automotive parts store and have them do a load test.

I agree but will add that I took my PM-1 to Sear for them to test and they said it was fine. They were wrong and I wasted a couple of trips chasing ghosts until I figured that out.

[AJ B]

Thanks fellas I posted over at the Merc 4s with serial number. My batt tray has two type 27s and won't fit a third that size (dimension wise) unfortunately. I was thinking about getting an AGM for the house batt that is the same size as the one I have--my charger will take it. I wonder if that will help. In the meantime I'll chase the fuse wires when I get back to see what that fuse goes to. I am curious because when my Fishfinder are firing the Helix 10 mega routinely shows 11.7-11.9 on its voltage display when running, so I can understand about loaded volts vs. resting volts. When I turn off the sonar on the unit, the volts jump back north of 12.

[Kodiak16]

Whats the voltage when the motor is running? Should be between 13.2 and 14.1. If not your alternator might be bad.

[Basskisser]

Are you charging the cranking battery with a separate charger than the deep cycles? A portable type? I blew a fuse in my 2013 60hp Mercury and the dealer said it happens sometimes when you hook up a separate charger. Not sure how true that is, just what I was told. I started using the 2 bank charger in the boat, only and never had a problem again.

[AJ B]

Kodiak, you're right the finder never shows anything above 12 even when the motor is running which always concerned me, but it also doesn't show anything high like that in my garage with the charger hooked up. Baffling. The symptom sure looked like a low battery, and it was the one time that day that I had to leave the charger disconnected overnight before fishing (there was construction on my road so I had to park it on a side street). I have a feeling the battery was not getting a charge from the motor, and/or the motor wasn't providing juice to the spark plugs. Maybe the fuse is related to that. I know the alt if fried can blow a fuse too. I'll start it in my driveway, check volts at the batt with a voltmeter, then again with a new fuse I guess. If it's that simple (not likely of course) I sure would like to know what caused the fuse to blow in the first place.

Basskisser, I have a 3 bank charger. Batts show fully charged at all times when hooked up or disconnected.

[richg99]

Had a 6 month old battery fail on my van. They don't build 'em like they used to.

[turbocoupe]

Try another bat. They can have dead cells in them and still read 12v.

[contium]

The 60 HP Mercs don't have an alternator but rather a stator with a voltage regulator. They really don't put out much current. My starting battery will be discharged to about 50% at the day of fishing even with a lot of running around. It use to keep the battery fairly charged when I ran two Gen2 HDS 7's. When I switched 2 two Gen3 HDS 9's and a Gen2 HDS9, it couldn't keep up. Going to get a larger starting battery soon. Nice thing about the 60HP, if your starting battery dies, they are super easy to rope start lol

[AJ B]

Rope start--Old School! Those were the days. Nice to have the rope for sure. I will be troubleshooting the charging system tomorrow. I replaced the fuse and so far the new one hasn't blown with the ignition set to run (not start). Hose hookup tomorrow. I have disconnected the on board charger. Tomorrow I'll check the voltage and specific gravity of the cells and get it load tested. Either way, after reading lots of posts, I'll look for a higher capacity AGM for the starting.
I'll check voltage at the battery terminals with the motor running with and without the fuse to see if the fuse protects the charging system routed to the battery (just curious). 25 amps is a lot so maybe that's the circuit. If the fuse blows upon ignition/running, I got bigger problems I'm afraid. I'm not sure if an insufficient battery could cause a blow. I certainly appreciate all the contributions.

[AJ B]

Ok so I did some troubleshooting. I tested the main diode and it tested fine. Put a new 25A fuse in, started the motor no problem. Checked the volts at the battery and even at the finder, showed near 14 at 2000 rpm and 13.5 at idle in both places. Pulled the fuse, started motor and volts stayed at 12.5. So I deduce the fuse has much to do with current from the motor to the battery for charging. It may have been that way the whole time I've had the boat (2 months). I am not sure if my motor was pulling from its own system or the battery for a spark without the fuse in but no matter. It's fixed other than not knowing why the fuse blew in the first place. It may very well be a bad battery. My charger gets very warm too. I checked the batt fluids and each cell showed mostly the same specific gravity in the lower part of 'good' bordering on fair (I forgot the number). I'll be looking at higher capacity batteries probably get an AGM since I can't go to a larger one.
I sure appreciate all the advice. You know, of all the forums I posted this on, this is the only one with responses. Cheers.

[Tim Kelly]

Sounds like you've nailed it to me. I bet it was blown when you bought it so the motor was never charging the battery. Go fishing and see whether it lasts a day, if it doesn't, then buy a new battery. At least you know it is charging the battery now. Maybe someone hooked the battery up the wrong way round at some point which blew the fuse?

[AJ B]

Just to close the loop on this topic, I replaced the main battery (stock Interstate cheapo group 24, 70 minute reserve capacity) with a regular wet cell deep cycle Interstate group 27, same as the two TM batts I have (I was mistaken above, my tray fits three gp27s just fine). Ran on the water several hours while fishing. The motor is charging the battery fine with 13.5+ volts all day while running. Volts with motor off and live well/fish finders on was 12-12.5 all day too. The 25 amp fuse stayed intact. I'm not sure why that fuse was blown but I wouldn't be surprised if me or someone before me crossed the wires on the battery for even for an instant like Tim said--I did a lot of wiring work rigging my boat (which is why I tested the diodes as well).
Thanks again for all the help--especially the battery replacement advice from five of you! The old batt tested fine at Autozone but I've had bad car batteries test good at sears and autozone before, don't know why. I preemptively replace my car batteries after two Vegas summers on them.
Lots more confidence in it now especially if I decide to do some night fishing with lights. Cheers.