alternator problem, 24ssv

[mpiller]

Hey guys, just took the boat out yesterday (2007 24ssv) and both of the batteries were dead. I replaced one with a new battery, but had my buddy hook it up and he said the first time he had the wires wrong, but fixed it. Boat ran fine for a while and I left it running most of the time in order to charge the dead battery. Well about 3 hours in I noticed The voltage was at about 10 volts, and the motor began to skip/miss a little bit and then died. Now the battery only had enough power to operate the bilge pump, but couldn't start the motor. I had to get it towed back after that. I'm guessing the battery got drained because the alternator wasn't working. The radio didn't work so I figured it was just connected to the dead battery and would work once it got charged back up. We did use the auxiliary 12v plugs for air pumps and ballast pumps quite a bit. My question now is that is there a fuse or breaker before the alternator? Or do I need to just check the alternator's output and replace it if it needs it? The boat had not been having any problems before hand, so Im wondering if my buddy tripped a fuse or breaker by hooking up the battery wrong.
Thanks

[Zim]

Before you do anything else, pull the batteries out of the boat and stick them on a battery charger to see if you can get a full charge. If you left the batteries in your boat throughout the winter, you very well could have ruined them due to cold weather and not being on a trickle charge over the winter.

Once you've charged the batteries up, put a voltometer on the terminals and see if you're getting 12v. Now put the batteries back in the boat, and if you have a perk switch, switch that to the "all" option or "both" whatever it says. Start your boat up, preferably on the trailer if you have a fake a lake. Use the voltometer to check the voltage at the battery terminals while the boats running. While running, you should see around 13.3 volts. If that checks out, now give the boat a little throttle and watch what happens to the voltage at the battery terminals. It should raise up to a max of about 14.4V. Any higher than that (15-16V range) and your voltage regulator on your alternator is shot. If you see no increase with more throttle, your alternator may be shot.

First things first though, confirm your batteries are charged, and in good working order.

[mpiller]

Awesome I appreciate it, I'll try to do that today. As soon as we got off the lake I put the batteries on the charger, the first one (new one) charged up fine but I haven't checked it with a voltmeter, but the battery charger said it was charged up fully. Stuck the other on the charger last night and haven't had a chance to check it yet. If the voltage regulator on the alternator is shot will the alternator still be ok or can I just replace the voltage regulator? And if I don't see an increase in voltage with more throttle does that automatically mean the alternator is shot or is there a fuse before the alternator that could blow?
Thankyou

[Zim]

Awesome I appreciate it, I'll try to do that today. As soon as we got off the lake I put the batteries on the charger, the first one (new one) charged up fine but I haven't checked it with a voltmeter, but the battery charger said it was charged up fully. Stuck the other on the charger last night and haven't had a chance to check it yet. If the voltage regulator on the alternator is shot will the alternator still be ok or can I just replace the voltage regulator? And if I don't see an increase in voltage with more throttle does that automatically mean the alternator is shot or is there a fuse before the alternator that could blow?
Thankyou

If there's a fuse between the alternator and your battery, then I don't know about it. I just had to replace my alternator this year due to a bad voltage regulator. The regulators are not separate from the alternators, so you'll need a new one if that's the case. Also, don't have it rebuilt, because once you crack the case it's no longer sealed for marine applications. My new alternator ran about 180 bucks from a local alternator shop. Yours is a 90amp as opposed to my 70 amp, but that shouldn't matter much.

Check the voltage with the boat running, that'll give you a good idea what to check next.

[michael hunter]

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[mpiller]

Just checked everything out, both batteries had 12 volts before hooking them up to the boat and also once they were hooked up. Once the motor was started the new battery stayed at 13.14 and the old battery stayed around 12.24. Under about quarter throttle the newer battery never increased above 13.5 and the other battery never got above 13 volts. Guessing I need a new alternator? Thanks for the help and the eBay link. How hard was it to replace the alternator? I've done a few trucks before, just never a boat alternator.

[Zim]

Just checked everything out, both batteries had 12 volts before hooking them up to the boat and also once they were hooked up. Once the motor was started the new battery stayed at 13.14 and the old battery stayed around 12.24. Under about quarter throttle the newer battery never increased above 13.5 and the other battery never got above 13 volts. Guessing I need a new alternator? Thanks for the help and the eBay link. How hard was it to replace the alternator? I've done a few trucks before, just never a boat alternator.

Doesn't seem like you need a new alternator with those voltages. If it wasn't charging, you wouldn't see anything above 12 volts. When you see the voltage in the 13's that means you're getting a charge. Try going for a water test and take a jump box with you if you have one (or just hook up 1 of your batteries and bring a pair of jumper cables). You may have just had 2 completely dead batteries before. If that's the case, the alternator won't help them, as alternators aren't designed to charge a battery from "no charge" to a full charge.

[michael hunter]

Remove the battery's trickle charge them over night and have them tested.

[CJD]

The alt sounds good to me.

I bet the problem was you hooked a dead battery to a fully charged one. That drew down both batteries, and then they never had the chance to fully charge. A fully charged battery will show at least 12.6 volts...using a real voltmeter...not the "that's about right" meter in the boat instrument panel.

Your new battery sounds good. The old battery, with 12.24 volts following a full charge, is on its death rattle. I would not count on it, and would separate it from the good battery when not charging.

[mpiller]

Okay that could make sense, since the good battery was bought new this past saturday. I just hooked it up so I could start the motor and figured while out riding the dead one would charge up but y'all are saying that could have drained the new battery causing both to die? I'd rather spend $90 on a new battery vs $90 on an alternator considering the battery is a 2 minute switch. So to test, y'all think I should take it on the lake and then test the batteries out once it's under more throttle? Luckily I'm in a housing community with a small lake I can put the boat in for shorter periods of time.
Thanks guys

[CJD]

That would be my bet.

To put it in perspective...a typical battery will have about 130 amp hours. Lets say the new battery was charged, but the old was down by a full 130 amp hour drain. Now, with a 90 amp alternator, you would still have to charge over an hour (130/90 hours), with no other load, for the dead battery to charge fully. Add to that the extra time needed for the loads you put on it. And, when the batteries were hooked up reversed, you also ate quite a few of the amp hours on the new battery.

So, it could be something else...but I would bet it was just low batteries and not enough time to charge them.

[Swamplandkarl]

If you un hook the battery while the motor is running and it dies you prolly need a new alt...if it stays running you prolly have a bad battery...

[mpiller]

Ok so I was in a hurry earlier and believe I may have had the digital multimeter on the wrong setting. Just rechecked the batteries again and the older one put out 12.75 volts without the motor running or anything drawing on it. The new battery put out 13.14 volts again so it looks like my older battery should be fine? Gonna try to put the boat in the lake in a bit and start the motor and see what results I get this time. Basically from my understanding the alternator should be fine if the batteries jump to a little over 14 volts once the motor is running? Really hoping this could have just been from the other battery being dead last Saturday.
Thanks guys

[Zim]

Ok so I was in a hurry earlier and believe I may have had the digital multimeter on the wrong setting. Just rechecked the batteries again and the older one put out 12.75 volts without the motor running or anything drawing on it. The new battery put out 13.14 volts again so it looks like my older battery should be fine? Gonna try to put the boat in the lake in a bit and start the motor and see what results I get this time. Basically from my understanding the alternator should be fine if the batteries jump to a little over 14 volts once the motor is running? Really hoping this could have just been from the other battery being dead last Saturday.
Thanks guys


You can always take the battery to an auto parts store and have them load test it. That will tell you if your batteries are good, and it's free.

[mpiller]

I'll give that a shot tomorrow with the older battery. Unfortunately we had some tornado warnings and bad weather come through so I didn't get the boat out tonight but should be able to tomorrow morning and hopefully get some better readings on the volt meter.

[CJD]

The batteries are not capable of 13.14 volts on their own without being on a charger...or within a handful of seconds after removing a charger. Your voltmeter is off. You can interpulate the high battery from 13.14 down to the max it could be of 12.69v...and that would still put your old battery at an actual 12.3v. That's still on a death rattle for a charged battery. But, if you separate it when not being charged and use it as a secondary battery for the stereo, you could still get a season out of it...maybe.

[mpiller]

Just took it out today, before start up I got the same 13.14 and 12.75 volts on the batteries. Before ever contacting either terminal the volt meter read about .60-.80 volts so I'm guessing it's off. Upon starting the engine the batteries stayed exactly the same, never above 13.14 or 12.75, also under throttle the batteries never moved up at all. Thinking I'll go ahead and order that new alternator and get a new battery too.
Thanks for the help guys

[mpiller]

Quick question about my perko switch, both batteries are the same neither are a deep cycle. When selecting which battery to use on the perko switch, each battery should be able to do everything right? Say I choose battery 2, it should be able to play the stereo along with start the motor, but battery number one should be able to do the same also? Today when starting the boat nothing would work on battery 2 as if it were completely dead even though it showed 12.75 volts, flipped the switch to all and everything worked fine. Completely forgot to check if it would work on battery 1. But if I understand correctly the common on the perko switch sends power to the starter and everything else, both batteries had a charge and each battery had a positive cable running to the perko. The ground is run to one battery and sends a jumper to the other. What could be causing number 2 on the perko not to work and could this be related to my problem? I'm really just learning to use the perko correctly, luckily last summer I never had any troubles.