I am discovering that the stock Alternator on my boat is not sufficient for my after market stereo and dual batteries. <BR>What have you all done to solve this problem? <BR>I am running 2 amps, total of 950 watts and my fues' total 80amps with dual blue top optima batts.... <BR>Thanks in advance.... <BR> <BR>E$<img src="http://www.wakeworld.com/MB/Discus/clipart/smile.gif" border=0>

With 950 total watts your stock alternator and two blue tops should be plenty. It sounds like you are not starting out with a full charge on your batteries. <BR> <BR>I am running a 140 amp alternator with 8 blue tops and a built in charger on my 01 SAN.

I'm running, <BR>1-500 watt 1 channel <BR>1-300 watt 2 channel <BR>1-200 watt four channel <BR> <BR>It's all stock but two batteries and it's working fine so far.<img src="http://www.wakeworld.com/MB/Discus/clipart/happy.gif" border=0>

how many amps is your stock alternator??? <BR>JJ

That system should not be killing your batteries unless your playing for really long periods with the boat off. Buy a 3 stage charger and top off the batteries at night.

Thank you all for the replies. <BR>I believe the stock ALt is only 40 maybe 60amps, I have an 01 SAN with the GT-40 by PCM. <BR>I put a volt meter on my batt cables and its only hitting 12.95 with a good amount of throttle. SO I think its just slowly fading out cause it can not keep up even with the motor on with the amount of amps my stereo is pulling. <BR>I am looking to see what my options are in getting closer to 100amps in a marine application for a ford motor, I think that should be sufficient for my set up dont you all think???

Oh, and I had to ask what CAR is running off of 8 BLUE TOPS!!! That also must help to throw a FATTY WAKE behind your Super!!!

I am having a similar problem but its more related to ballast pumps. Running 4-5 pumps at a time results in a significant drop on the voltmeter. Can anyone give me a link and estimate on a high output alternator for a 2000 malibu wakesetter with the monsoon motor? <BR> <BR>Thanks.

KG, <BR>Thanks for the reply, <BR>I have a 3 stage but as i mentioned above my actual alt is only throwing 12.95v out with a load on the motor, so even if I top mine off before I head out I have the possibility of not being able to keep them charged. <BR>Prob sounds like I am answering my own question, but I am really curious as to the options out there with after market alt for my GT-40 motor...

I took my stock 70amp alternator and had it rebuilt to 130amp for about $200. I have six blue tops (five for stereo and one for ignition) and it will bring the batteries up from 11.0 to the high 12's while wakeboarding in between drinking sessions. <img src="http://www.wakeworld.com/MB/Discus/clipart/proud.gif" border=0>

My system is just south of 2500 watts, no lights (except LEDs), 100 amp alternator, two golf cart batteries, works for me. <BR> <BR>Here is a little Excel spreadsheet that can calculate your needs, it calcs pretty close to reality for my boat: <BR> <BR><!--attachment: Alternator_calcs-347874.xls*mime_msexcel.gif*application/vnd.ms-excel*17.4*Upload*Alternator+calcs%2exls --><center><table border=1><tr><td><img src="http://www.wakeworld.com/MB/Discus/icons/mime_msexcel.gif" align=left alt="application/vnd.ms-excel">Upload<br><a href="http://www.wakeworld.com/MB/Discus/messages/65921/Alternator_calcs-347874.xls" target="_blank"><b>Alternator calcs.xls</b></a> (17.4 k)</td></tr></table></center><!--/attachment--> <BR> <BR>Download it and open it in Excel then just fill in the blanks as shown.

my system is close to the size of mikeski, but with the addition of 3 towre lights, same battereis, same size alt. The key for me is keeping my battereies fully charged when not in use. When I run my stereo (high volume) and lights my alt cannot keep up. But that is for short durations only.

E Money- I am running 5200 watts of orion amps,2-12w7's,10 speakers on the tower and four in the hull. Seven batteries are for the stereo and one for the engine.

Does anyone think 12.95 Volts from the alternator is a bit low?? <BR> <BR>I am thinking you should be seeing 14 volts +/- 0.5 volts from your alternator.

yes, it's a little on the low side, but unless your seeing that on a voltmeter, it's proabbly not accurate. My dash voltmeter will read 13.3 or so and with the instrument it's reading 14.2-14.5. Also, as the amp draw increases the voltage will drop. typical 100 amps alternators under full load will throw around 13.3-13.5 volts, usually only at full charge will you see the full 14.2-14.5

So how do you calculate wattage for saying how big your stereo is? <BR> <BR>Example. I have two 10 subs rated at 375W max. I have two wetsound pro 80s at 225W RMS. I have four cabin speakers at 45W. <BR> <BR>Ampwise, I have a 600x2 and 450x4 Rockford Fosgates. <BR> <BR>I'm just trying to figure out how much wattage I have <IMG SRC="http://www.wakeworld.com/MB/Discus/clipart/happy.gif" ALT=":-)" BORDER=0>

the total RMS wattage that your amplifiers produce.