Well last time I ran down one battery. Now i ran down both.

F

Fasterblaster

New Member
Jun 14, 2007
43
Vancouver, B.C. CANADA
I stuck a charger on the battery #2 that I thought was the one that I had run down. Its a small 4 amp charger and I left it on for about 3-4 hours.

When we went out today, I put the switch to the #2 battery i had charged, but after a couple of minutes, I started getting that awful audible alarm. It went away when i switched the battery switch to "both".

About 30 minutes of running later, the alarm started again. It stopped when i slowed right down, which i did as I headed for the dock but eventually the alarm wouldn't stop regardless of engine speed.

It was a good thing i headed for the dock, because the batteries where too dead to start the motor after I got to the dock. Whew, that was close.

So, the way i see it:
1. either the alternator is not charging or the regulator is not letting it charge; so one of them is cooked.

2. both batteries are fried? seems unlikely, but they may be the exact same age, and I don't know how the previous owner managed the battery switch

3. I killed something when i tried charging the #2 battery without disconecting the battery clamps, eventhough the battery switch was set to "off".

but there are a couple of other points that may be relevant:
1. the #2 battery was run down previously
2. i've been messing with the stereo and may have caused something to short out although the stereo still works fine.
3. I noticed the volt meter registering really low when trouble started. Probably about 8-9 volts.
4. I just installed a new blower fan. But its pretty simple stuff; i thought i better mention it.

Any ideas, advice, suggestions????

FB
-then i got home and backed into the garage door :[- Yeah Baby!!
 
Re: Well last time I ran down one battery. Now i ran down b

Fasterblaster said:
I stuck a charger on the battery #2 that I thought was the one that I had run down. Its a small 4 amp charger and I left it on for about 3-4 hours.

When we went out today, I put the switch to the #2 battery i had charged, but after a couple of minutes, I started getting that awful audible alarm. It went away when i switched the battery switch to "both".

About 30 minutes of running later, the alarm started again. It stopped when i slowed right down, which i did as I headed for the dock but eventually the alarm wouldn't stop regardless of engine speed.

It was a good thing i headed for the dock, because the batteries where too dead to start the motor after I got to the dock. Whew, that was close.

So, the way i see it:
1. either the alternator is not charging or the regulator is not letting it charge; so one of them is cooked.

2. both batteries are fried? seems unlikely, but they may be the exact same age, and I don't know how the previous owner managed the battery switch

3. I killed something when i tried charging the #2 battery without disconecting the battery clamps, eventhough the battery switch was set to "off".

but there are a couple of other points that may be relevant:
1. the #2 battery was run down previously
2. i've been messing with the stereo and may have caused something to short out although the stereo still works fine.
3. I noticed the volt meter registering really low when trouble started. Probably about 8-9 volts.
4. I just installed a new blower fan. But its pretty simple stuff; i thought i better mention it.

Any ideas, advice, suggestions????

FB
-then i got home and backed into the garage door :[- Yeah Baby!!
Click to expand...



First - fully charge your batteries and test them with load tester before you start looking for other problems - they may be none

To check if alternator is working - if boat is in water start your engine and after few minutes, there should be 13-14 volts on volt meter, if not alternator could be broken (assuming batteries are ok)


fyi most batteries once fully discharged have tendency not to hold voltage very good
 
Re: Well last time I ran down one battery. Now i ran down b

Fasterblaster said:
I stuck a charger on the battery #2 that I thought was the one that I had run down. Its a small 4 amp charger and I left it on for about 3-4 hours.
Click to expand...

I don't know the exact size of your batteries. But each probably has a capacity of 70-80 amp-hrs. You don't say what current the 4 amp charger was putting out, but it may not have put out 4 amps for the full time. Even if it did, and you charged for 3 hours, that is 12 amp-hours. So if your battery holds 80 amp-hours, you did not fill it up. You charged it maybe 1/6th of its capacity. You need at least 24 hours with that charger.

Experience tells me there are numerous things out there that a boat can hit. It is also my experience that normally the boat wins, and the thing it hit loses. :grin:

Actually, I am given to understand that not only is the boat stronger than your garage door, it may be stronger than the beams in even a larger garage.
 
Audible alarm????? Do you know what that was for? Not a low battery.

Since it sounds like the #2 battery never did get fully charged, if you put the battery switch on "both", you invited the bad battery to suck the good battery down (assuming #1 was fully charged but we don't know that and instead of using it, you used both)

I'm still not a fan of using "both" unless it's for "house use" or because you have to, to start the boat because both batteries are weak. I'd always charge each battery one on one so that means the switch on either #1 or #2 when running.

I agree, 1st fully charge each battery. You can't test anything with dead batteries.
 
I put battery #1 on the charger last night. Battery switch is off.

The more i think about it, my guess is the alternator is not charging. If it was, i think the volt meter would have been reading well higher than 12 volts as it struggled to charge up the battery(s). In this case, it was reading 10 volts or less.

The motor at higher rpm was drawing down the battery(s) quicker than at low rpm assuming electronic ignition likely consumes more power at higher RPM than at low.

So the storage system is being drawn down and the charging system is not replenishing it or it is trying to and can't replenish it fast enough.

A boater buddy of mine says its unlikely that a marine alternator on a 2003 unit would go out. He figures i must have accidently disconnected something when i was leaning into the engine compartment while installing my new blower fan.
 
I'm not sure what you're looking for now. You fully charged one battery? Have you been out running with that battery?

In the previous post it sounds like you said you put 1 battery on the charger, but then are assuming another scenerio without making sure each battery is fully charged and/or tested.

Yes, MPI uses more juice, but if the charging system and batteries are good it's not a problem.

I'm sticking with starting with the basics and eliminate the obvious first. Fully charge and test each battery for starters (I made a funny) :grin:
 
All tested up now by BCAA. The results are:

Battery(s) are pretty good. I had them on a 4 am charger for about 20 hours each but they needed a little more.

Alt was not charging.

Closer inspection revealled that the original Alt had been swapped out for a heavy duty truck 120 amp truck unit. Hmmm. This unit has been over-heating. The alt repair man is looking into it, but says it has been over-worked.

In order to get the truck alt mounted, the original install brackets were "altered". A OEM replacement will no longer fit without installing a new bracket. Arrgh.

I'm thinking a new Marine unit. I don't know if the original alt was not big enough to support the big stereo. I'm more interested in a reliable electrical system than a kick but stereo, so i may be tearing out some electrical equipment. The Alt repairman says there may be a short somewhere that is draining the batteries and causes the alt to have to work too hard when the boat is running. He can also set me up with a 160 amp marine unit, but it will require some bracket mods.

My question of the day is this: Just how big of an alt should I need?

thanks again for the advice.

fb
 
First off, get rid of the truck alternator. Unless your alternator guy is experienced in rebuilding to marine specs. It's really just protection, but it needs to be there.

It sounds odd unless you've got 99000 watt amps in the boat. I've NEVER heard of anyone having to replace an alternator in a boat because a system was too much. That's what a battery bank is for.

Did you previously run with the battery switch to Both? If so, if you have a bad battery, that would explain it "over working" the alternator, fighting a losing battle trying to charge 2 batteries, 1 of which was killing the other.

If not, well, I'm out of ideas. :grin:
 
Fasterblaster said:
The regulator in the Alt was fried. Unit is back in the boat and working fine. I'll replace it with a marine alt when i figure out what size of unit i should have.
Click to expand...

You didn't ever run with the switch on OFF did you?
 
I don't know that i ran it with battery switch off. I don't know how to start it with the switch off. I may have charged battery #1 with the switch on though. Maybe thats what did it.

I've been out three times now and the voltmeter is consistently at or slightly above 14 volts. No sign of weakness yet, but i don't know how to check the battery charge without calling BCAA.

Motor off with the battery switch on #1 i get 12.25 volts - but i accidently left it on last night. Battery switch on #2 i get 12.33 volts.

What is the best all around tool for checking the electrical system and the battery(s)?

btw, i would add a picture, if i could figure out how to re-size the pic. Its 1.5 mb and that is too big. Finally, something is too big...
 
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