Alternator Upgrade Situation

[Jeff T]

I have the 315 Merc in my 22v, which has a 65 amp alternator. I am adding a kicker 750.1 to push a 12in solo, kicker 650.4 bridged to push a pair of wetsounds pro80s, and a second battery to my setup. I already have the stock Clarion 200.2 amp. I feel as though I need a bigger alternator to supply enough power when I'm running the boat.

I spoke with Tige about what options I have. They told me that whenever they have a Merc that comes through that needs a bigger alternator, they bolt up the 95 amp that comes with the MP engines (Part # 475752). They bolt up to the same mounting brackets. I then confirmed with Ray (Parts) at Marine Power. Affordably this is my only option as high output alts are pretty pricey. I think the MP alt runs somewhere around $200.

My question is, has anyone ever done this swap out before and if so, did it create any issues?

Does anyone have any concerns with this?

As always, thanks for the help!

[Domsz06]

I'm interested to hear about this. In my 21IR I was told I don't have any options to upgrade an alternator. I fryed my first one, had it rebuilt and then ran a 2 gauge charging wire as well as a 2 gauge ground and it has helped, but still when I'm running some serious tunes it hardly keeps it above 13 Volts. I have to idle the boat at 2500-3000 rpms to charge the batteries every half hour. I think a 95 amp alt would be great. IS there really an alt we could all get.

Back to the point in hand, if I were you I would for sure upgrade your alt. Nothing worse then frying yours when your at the lake. Plus it's a serioius fire hazard.

On mine I'm running the stock amp, and then a PPI 1000x2 and rockford 1000x4 and i really want to get a bigger one. Like I said if I were you I would.

Anyone know if there is a alt for my 03 21IR with the 350 315 merc that I could ad? I mean it cost me 100 just to rebuild it.

Thanks.

[Jeff T]

Domslude, there is an option for a high output alternator for the MP. Since the stock MP alt will mount up to the Merc, I have to believe the high output would do the same. I DON'T KNOW THIS FOR SURE. I can remember what the output was, but I want to say it was around 120 or so, and the price was upwards of $600 (not exact). That is why I didn't pursue it any further because I can't swing that much.

If the 95 doesn't cut it, I wonder if you could have the 95 amp rebuilt for a higher output putting you up over the 100 mark and you would be into it for $300 or so. Just a thought.

[Domsz06]

yeah I did find an option for one that was over 600, but for that price I'll just make my little one work a bit harder. Like I said it does just fine when i don't listen to any really hard bass. If i don't turn the PPI up all the way either it does fine. Just sometimes I really like to hear the NVS's Scream, that's when I do get into trouble.

Maybe Andrew will chime in, or Matt and let us know.

[Moki]

I am in the same boat (pun intended ). I need to upgrade my alternator. I have the 2000 330 HP Mercury Black Scorpion, I am guessing that the 90 will fit on mine? Lee, Andrew, Tony the Tige....are you out there?

[Coach]

The 95 Amp Alt will be fine for your application. Depending upon how hard and how long you run the stereo you will more than likely need to run a good charge on the battery.

[Domsz06]

if it will fit the 95 would be fine, but can anyone else confirm if it will fit in other boats? Iknow I'd like one.

[spharis]

Mounting the alternator is a given. It should use standard Delco mounting tangs, as all GM style alts do. Mando style, etc. The tangs should come off the alt in two locations and have a bolt hole in the center of each one. It would be very uncommon for you NOT to be able to use a standard Delco style alt.

The only issue when choosing an alt is 3-wire or 1-wire, and if your tach uses the alt tach signal, and if you have a dash warning light that is used. All of that can be accomodated for.

95A alt is a high RPM rating. It should do 45-65 at idle. The stock 65A is running 35-40 at idle. The most knowledgable person I know regarding alternators is a guy named Ron who rebuilds for a company that sells on ebay under the name DB Electrical. They also build/rebuild for many of the name branders you see for $300+ (stinger, delco, etc). I have been speaking with him regarding a custom 100A for my electrical system. I will be going with one similar to one of these.

http://cgi.ebay.com/ebaymotors/Delco...mZ130051707529

Regardless, there is no reason to purchase an alternator for 100A for more than $100. I have an alt Ron built for my SPL tahoe setup and it is still running strong. It puts out 80A at idle, and ~150-175 max. I paid waaaayyyy less than what the big boys charge for China assembled electronics.

Jeff, do you have pics of your alt, or can you take photos of the lugs, and I or Ron can confirm which alt you can buy and save some cash.

[Jeff T]

I will try to get a picture tonight and post it up.

[spharis]

I just called Ron and he told me he also has the Stinger battery isolators. The price they sell them at is under what you see them on ebay for, so if you need one of those too, he said I can shoot him a message and he can get in touch with you.

[Jeff T]

The only issue when choosing an alt is 3-wire or 1-wire, and if your tach uses the alt tach signal, and if you have a dash warning light that is used. All of that can be accomodated for.

I just spoke with Harvey at Tige. The 65amp on the Merc is a 3 wire. My tach comes directly off the ECM, and I do not have a warning light.

[Domsz06]

spharis,

so you can get us a connection with this guy? I'd love to have a beefier alternator. What information do you need so that I could get this done. I'm pretty sure mine is a one wire, but would have to confirm this. I'm driving to get my boat over the x-mas break, and would love to beef up the charging.

Thanks again.

Dom

[Domsz06]

wow that one from ebay is 70 bones? If I can find one that fits mine I'm doing it!!!

[Moki]

Spharis,
Nice tip again! I am definitely going to upgrade when I get my boat back.

[Razzman]

spharis,

so you can get us a connection with this guy? I'd love to have a beefier alternator. What information do you need so that I could get this done. I'm pretty sure mine is a one wire, but would have to confirm this. I'm driving to get my boat over the x-mas break, and would love to beef up the charging.

Thanks again.

Dom

Well here it is! http://cgi.ebay.com/ebaymotors/NEW-100-Amp-Delco-Marine-Alternator-Mercruiser-1-Wire_W0QQcmdZViewItemQQcategoryZ31284QQhashZitem13 0051908212QQihZ003QQitemZ130051908212