tgell001

This weekend something I've never stumbled across happened to my 2004 VP 8.1Gxi-D w/ Duo Prop.

Towed the boat to the lake with the intent to camp onboard. So I hooked up an inverter to run a blender, a TV and charge phones. Nothing complicated. That was the only thing new this weekend from the previous 10-12 weekends. Have not charged the batteries since flushing them last Saturday.

Started strong at the ramp. Ran out and did some hot laps and went sightseeing (approx 20 miles). Ran back and posted up at a sand bar and hung out all day. I ran the blender off the inverter, and played music all day. Started it in the evening to go to dinner and it started weak but no big deal, it's to be expected after running all the accessories.

Went to dinner running 40mph and 3200rpms for 15 or so miles. Went up to dinner for like 2 hours and left the batteries both on. I say this because I have an amp always on and the Capt choice requires power to stay open. But, started similar as before (weak).

Switched over to one battery to run back to the harbor (figuring I can charge 1 faster then both) and ran WOT for 30 or so mins. Was trying to top the boat out and while bumping the trim noticed once that the motor lost power for an instant and picked right back up gettin' it. I honestly thought I lost a tooth or something on the drive gear but figured that would have made a noise and repeated it self. Backed down to 3/4 throttle and trimmed down and it never repeated itself.

Pulled up to a nice spot to camp and only ran a few LEDs and the radio for a few hours, then isolated the batteries, started the generator and went to bed.

Woke up at dawn and thought maybe I should run the battery charger off the generator for a few hours to charge the batteries (knowing something is fishy at this point). They charged for maybe 2-3 hours and the tender readout said they were not fully charged but doesn't have a number. Boat started weak but still started up on both batteries. On the way to breakfast 3-5 miles at 30mph I adjusted the trim right out the gate with no stalling. Go up towards the no wake/dock and adjusted the trim and BAM, momentary stalling. Adjusted again, nothing, adjusted again, stalling. It was about 50% of the time I moved the trim it would miss. And when I did the voltmeter bottomed out. Scratching my head we pulled it and got breakfast, went to leave and...... Click....

I don't have a voltmeter on my boat but the gauge did look good (only has a number 13). Sea tow to the rescue!

Got home and plugged it in. Both batteries charged to 12.98 and held to 12.8 after an hour or so. Put it on the muffs and the alternator is putting out 13.8-14V (bouncing around) at the alternator output and matching at the batteries terminals.

My original conclusion I jumped to was the alternator is going bad. But is it possible I just ran the batteries too low and never gave them chance enough to charge? I would think the runs I did would have maintained.

Can an alternator loose it ability to output amps w/o losing volts? Because my voltmeter over loads at 10A.

Sorry for the the essay but I've been burned on forums for leaving stuff out before haha

SB

iTrader: (1)

Yes, a weak (in charge or actual condition) battery but okay alternator can still be overpowered by a running engine and the use of trim and/or tabs. ignition cut out will happen.

It's up to you to figure out if your batteries are okay and need more charging or if they just won't hold as much as of a charge as they need to.

Edit in: Merc Marine alternators only put out 45-55 amps depending on engine model, so can take a long time to fully charge 2 batteries. Home chager could take a day or so to charge 2 batteries also. Maybe two days. LOL.

With the amt of battery use you use, make sure to fully charge them when you get home so you start off fully charged for next adventure. And you may want to look into using a ACR along with a 'House' big deep cycle for your needs when docked/camping/etc. Something like this: https://www.bluesea.com/resources/53...-Battery_Video

Also see here: https://www.bluesea.com/products/cat...-A-Battery_Kit
This will keep a starting battery on hand and fresh for starting because it will only be used for such.

Do some studyin on the ACR system and starting vs deep cycle batteries and you'll see what's up quickly.

ALL_IN!

iTrader: (1)

Agree.

tgell001

Thanks a bunch, I'm so quick to jump off the deep end and replace things out of prevention. But today, I was just scratching my head when everything seemed fine. I've already looked at running an accessory battery system but it's never really been an issue as this was out first camping excursion w/o shore power.

Sometimes you just need reassurance you're not crazy, thank again

apollard

I agree. Especially if it's a stock alternator, you never charged the batteries back to good voltage. I changed to a GM 10si type alternator to avoid such issues - you also have to increase the power AND ground from the alt if you do this. Also have the ACR as shown above. Never had a problem since.

tgell001

Help me understand the ACR. It basically senses current load and isolates batteries as starting and accessory? Or does it require me to rewire? I get the charging aspect of it, that's makes sense.

apollard

The ACR is nothing more than a voltage sensing relay. When voltage is above a certain value (usually 13.6 volts), it connect the two batteries - the same as the "Both" position on a battery switch. When voltage falls below a setting (usually 12.6 volts), it disconnects the batteries.

I have both the 1-2-Both battery switch and an acr. I have 2 batteries. The stereo and inverter are connected to battery 2.

The alternator charges whichever battery is connected according to the switch (I leave it on battery 1). When the voltage rises above 13.6, the ACR connects the batteries and both charge. When I stop and crank up the tunes, the ACR disconnects the batteries when the voltage gets to 12.6. This allows me to drain battery 2 much more than I could with them connected and still have a basically full battery for cranking. I never have to touch the switch.

So why have the switch? If I leave the nav lights on or battery 1 just goes dead, I can still switch to battery 2 and crank the boat. So, the swich becomes and emergency thing - or if I want to disconnect power completely. The ACR does all the work.

I've run one of these on all my boats for over 10 years and it works fantastic.

Wally

iTrader: (1)

I would take the batteries out of the boat and charge them over night and take them to a local garage or pep boys etc to have them load tested to make sure the batts are ok.
Then i would check all my main connections for good grounds...make sure the cables are not corroded inside....you can have a good looking cable but corroded so badly inside it will act like a huge resistor when trying to transfer power.