Alternator Problems.

[redrockerfan]

I have a 2004 21i tige with the 350 mercury motor. It has a 70 amp alternator and the gage is reading 10 volts while running, with 1 batt on with nothing else on but the motor. Does anyone know what alternator is in this boat and if I need to go to a bigger amp alt? The stereo system has 2 amps running speakers. Alpine V12 amp and a punch 45 amp.

[da.bell]

How old is your battery in the boat? Have you had the battery checked out? Not unlikely to have a battery that is bad either.

[redrockerfan]

Brandnew Batt. I tested them and there fine. I talk to the service manager at tige water sports in corona ca and Im just going to take the alternator in to him and have him test it. I gave him the haul #s and it reads the its a marine power motor.

[dogbert]

If you do need to replace it, there's a 90 amp version of it that will fit your boat (standard Mercury Marine part).

[redrockerfan]

Do You have a part # for that alternator ? or a link

[hillboy700]

part number

That would be a nice part numbe rto have :-)

[chpthril]

Brandnew Batt. I tested them and there fine. I talk to the service manager at tige water sports in corona ca and Im just going to take the alternator in to him and have him test it. I gave him the haul #s and it reads the its a marine power motor.

How did you test them? The volt gauge will read the system voltage, that's either the static charge of the batteries (engine off) or the alt's output when the engine is running. If the gauge reads 10V's with engine running, your batteries are run down and are not fine. Remember, you have a 12V system. A fully charged battery will read 12.8, with the engine running and a dead alt, the fuel pump and ignition will put a small load on the battery, so the gauge will still read what the battery's state of charge. In theory, the alt cannot put out a charge that is less then the battery's static charge, so if the battery was fully charged that is what the gauge would read if the alt was NOT chsrging.

Sound like you have a dual battery system. If so, is it separated by a Perko type 1/2/Both/Off switch? Does the gauge change state whent the switch is in 1 or 2 or both?

If you have a volt meter, whats the static charge of each battery and what is the voltage output of the alt with engine running.

Could be a shorted battery or a bad alt, or a ground cable that got forgotten during summerization. Easy to test with everthing in place before you start pulling parts.

[chpthril]

Brandnew Batt. I tested them and there fine. I talk to the service manager at tige water sports in corona ca and Im just going to take the alternator in to him and have him test it. I gave him the haul #s and it reads the its a marine power motor.

If you do need to replace it, there's a 90 amp version of it that will fit your boat (standard Mercury Marine part).

Do you have a Merc or Marine Power? They could be entirely different alt's as well as even wired differently but the same case. Could be Denso or Delco.

[dogbert]

I have a 2004 21i tige with the 350 mercury motor. It has a 70 amp alternator and the gage is reading 10 volts while running, with 1 batt on with nothing else on but the motor. Does anyone know what alternator is in this boat and if I need to go to a bigger amp alt? The stereo system has 2 amps running speakers. Alpine V12 amp and a punch 45 amp.

Do you have a Merc or Marine Power? They could be entirely different alt's as well as even wired differently but the same case. Could be Denso or Delco.

I think he said Merc...hey, is that a squirrel?

As for the part number, check here.

[redrockerfan]

Marine Power. I charged the Batts the night before. The batts are brand new.The boat running at 3500 rpms the volt gage reads 10-10.5 volts with nothing eles on.The gage states 10 volts with just one batt on in position 1- all or 2.

[dogbert]

Sounds like your alternator is shot. It sits so low in the back of the engine on our V-Drives that if you have any amount of water in your bilge, the fan belt and alternator will spray it around. Eventually your alternator dies. I ended up moving my bilge pump from underneath the V-Drive to the back by the transom. Hopefully it will last longer this time. We're always taking on water while surfing.

[redrockerfan]

My boat is a direct drive, I have 2 bilge pumps in the boat. Thanks for the info. I will have to take it off and bring it home with me and have it checked.

[chpthril]

Marine Power. I charged the Batts the night before. The batts are brand new.The boat running at 3500 rpms the volt gage reads 10-10.5 volts with nothing eles on.The gage states 10 volts with just one batt on in position 1- all or 2.

Not trying to get in yur chit here, but somethings not right and I cant figure it out Regardless of whether or not the alternator is charging, the gauge should read at least the battery voltage level, and if they are good and charged, should be 12+ volts. If the alt is charging, the gauge will read that voltage output. In other words, the gauge cant read less then what the system voltage is. So, if the gauge reads 10V's, then there is a bad connection (probably a ground) and bad battery, or the alt is shorted and has become a load on the battery instead of a supply and pulling down the batteries.

What is the voltage level of each battery with the engine off?

What is the voltage reading at the battery(s) with the engine running? and also at the large wire on the back of the alt (should be same as at the battery)

What is the reading at the back of the gauge with and without the engine running?

Just curious. Hate to see you spend the time pulling/replacing parts cause something just smells fishy.

[dogbert]

chpthril's right...when my alternator went out, the batteries read 12+ for a while until the batteries ran down. Any chance you have a short somewhere?

[redrockerfan]

Im going down to the rive this weekend and I will check all these points out. I put a meter on the batt and they read 13 volts but the gaga is reading 10. Thanks for the info. I will keep you guys posted.