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-   -   Today's Novel: Is an upgraded alternator a good idea? (http://www.wakeworld.com/forum/showthread.php?t=793890)

Houstonshark 06-12-2012 10:40 AM

Today's Novel: Is an upgraded alternator a good idea?
I'm adding a 3rd Trojan T-1275 battery to my system and will have a total of 450Ah for the stereo bank. Here is the current charging system wiring:


Basically, with the way the system is wired now, I can just leave the battery switch in Position 1 all the time and let the ACR separate the starting battery from the stereo batteries when the motor is off or when the voltage gets low. I have switches installed in the glove box where I can turn off each 'Zone' of the system while parked and will usually only have the tower speakers and sub on if we want it really loud or just the bow speakers and sub for a moderate to low volume. This should help with the power consumption.

I have 6 JL HD amps running a total of 4500W RMS. We rarely stop for long periods and play the stereo real loud but we did on Memorial Day weekend. We took the boat out on Saturday and rode a little, parked and played the stereo a little and did the same on Sunday. I noticed that after the stereo played on Sunday for about 20min with the boat off, the sound started to distort and I had to turn the volume down.

We took the boat out on Monday afternoon for a little while but never really played the stereo loud. I brought the boat into the dealer on Tuesday where it stayed for a week and a half until I picked it up this past Friday.

I launched the boat Saturday morning and cruised for about 20min before stopping to meet up with some friends. I played the stereo at a very low volume for maybe an hour and again noticed the sub cutting out and distortion. The stereo battery bank was reading 11.6V.

Even with the boat running, the ACR would not close the loop to allow the stereo to play (via the power coming from the alternator). Will a bigger alternator ever actually keep up with charging the starting battery and 3 stereo batteries (450Ah)?

Granted, this all could have been avoided if I had ran an extension cord from the dock to my on board Xantrex 40A TrueCharge2 each night. Once I did that this past Sat night, all was well on Sunday. I always keep it on the charger in the 3 mode setting (Bulk, Absorption and Float) when the boat is in the garage. I guess I thought for as much as the boat was running Memorial Day weekend, I wouldn't need to charge the batteries overnight. Lesson learned!

In the past with the car I used to compete with, we had a hell of a time with upgraded alternators. I actually had Stinger alternator (if I remember correctly) spin a blade off and nearly penetrate the hood. We also had a lot of problems with regulators where the idle or low RPM voltage of the alternator would be 11.5 or 12V but at higher RPM's would output as much as 16V or more if I remember (this was in '97 so my memory fails me some). My car actually died at the end of a parade once where I played the stereo at a moderate volume because I was only going a couple miles an hour and the alternator was putting out so little voltage.

Is that the case with Marine alternators too or can you get one with good output at low RPM's? Is it a waste to even try to charge with the alternator?

Sorry for the novel. I just wanted to get it all out there.

Thread Notes
Chatt, I approve the use of cows in this thread.
I approve the use of MS Paint for picture editing at an elementary level.
I approve any non or off topic comments or hijacks as long as they are funny.
I do not approve the mention of MB unless it is funny in nature.

jeff_mn 06-12-2012 12:25 PM

3 Attachment(s)
Whoa whoa whoa..

Have you considered just selling your boat all together and getting an MB? Their stock alternator is uranium enriched.

Houstonshark 06-12-2012 2:37 PM

^^^ I like your style.

shawndoggy 06-12-2012 3:03 PM

Doesn't your boat have the same alternator as an MB (PCM ex343)?

This is the thread you are (to lazy to be) searching for: http://www.wakeworld.com/forum/showthread.php?t=320581

chpthril 06-12-2012 3:42 PM


I think the size of your system has exceeded the designed capabilities of the ACR. Once you restart the engine on batt-1, switch over to batt-2. This overrides the ACR and diverts the alt's output to batt-2 through the switch rather then the ACR. Even with a higher output alt, the ACR may still "bounce" due to the level of the house bank, until it comes up some.

Houstonshark 06-12-2012 6:03 PM


Originally Posted by shawndoggy (Post 1759425)
Doesn't your boat have the same alternator as an MB (PCM ex343)?

This is the thread you are (to lazy to be) searching for: http://www.wakeworld.com/forum/showthread.php?t=320581

OK, so I did search but apparently didn't search long or hard enough. Grant's charging system install looks killer and is probably ideal for my system but I'm not ready to go there yet.

I looked it up and the PCM EX343 alternator is a 100A 'High Amp Alternator' according to PCM:


As Mike pointed out, I think the ACR is the issue, although I think the ultimate issue was me not connecting the charger at the end of the day, no matter what.

Thanks Mike! I didn't think to switch the battery selector to 2 after the engine was running.

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