new problem with '04 70 yamaha

[bhs91]

I am out on the big pond last night and everything is going great with the motor, no alarms, no limping, catching fish, etc...Then about 3 hours into the trip I turn the key and a quick fire, then nothing, turn the key again, nothing!!!???? A mild panic sets in, but then I take stock to narrow things down when I bring the boat in AGAIN!!! Depth finder on, aerator on auto for 2 hours, numerous runs up to start a drift, lights on cause of the rain, all of which I have done before...I fire it again and it fires, reluctantly, but starts. We make another drift , with the motor on and then head in. We get in fine, while I am waiting for my buddy to back up the van, I start checking stuff out...when i use the tilt and trim, all the lights dim, I let it run for a couple minutes, run the trim and it is fine for about 30 seconds and then starts to die, the trim that is, not the motor. Now what could it be? The battery is about a year old, got it from the dealer last spring. COuld it be the alternator, do boats have an alternator?

Any thoughts would be great.

Thanks,

BHS

[Jim Almquist]

Sound like all of the electronics are running off 1 battery and it is also your starting battery.The charging system on a boat motor is a wheatstone bridge or a rectifier but that just means that when your motor is idling it puts out maybe 1 amp and when you are going wide open it will put out 6 amps but that is all dependant on your motor.So if you are not traveling great distances you will not charge the battery enough to compinsate the loss when you start your motor up.I made the same mistake trolling at nite running the livewell and have the lites on stopped to take a break and the motor would not start and had to swap batteries with the electric trolling motor.I will not connect anything to my starting battery anymore.

[bhs91]

OK that sounds about right. Should I connect stuff to my trolling motor battery then? Or should I buy a 3rd battery?

Thanks for the info.

BHS

[iffwalleyes]

You could connect stuff to your trolling motor batter but I wouldn't as if you only have one trolling motor battery it is getting run down fast enough the way it is. Also electronics will get alot of interference from trolling motor when hooked up to the same electrical source. I guess I would just watch what you have on also you might want to get a larger battery or at least make sure it is a combination Deep Cycle/Starting battery if it is just a starting battery it will run down faster. Also you could have your battery load tested it might just be worn out already. After all dealerships aren't putting optima batteries in the boat they are most likely using a smaller battery than you should have to help keep there costs down.

[PerchJerker]

Yep, get it load tested at an auto parts store, my guess is it's a bad battery. If nothing else you can rule out the simple and easy thing first by getting the battery checked.

[marine_man]

I'd also have the battery checked... seems like it's a little weak... although it sounds like you had a lot of things running, and as someone else said, your motor only charges efficiently at a higher engine speed, so you may have just run your battery down.

marine_man