Adding Second Alternator to Merc 350 Mag

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-23-2006, 8:06 PM

I am looking to add a second alternator to my 2004 Merc 350 Mag. I have heard there is a kit available that places second alternator on opposite side of existing unit and uses a longer serpentine belt. If any one has any exp. with such an arrangement please let me know.

Also if any one has added a second alternator to this engine package using a different belt arrangement please feel free to share that info as well.

My plan is to add a second 100 amp alternator to charge my house battery bank which powers the stereo system.

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 08-24-2006, 6:54 AM

IMO there are better alternatives than adding a second alt.

1)how big of stereo do you have?
2)what size battery bank do you currently have?
3)Do you ride alot then beach or beach alot ride a little?
4) Are you haveing low voltage issues?

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-24-2006, 11:00 AM

I am planning on the second alternator for several reasons the biggest being both Fineline industries and Merc have recommended against adding a bigger alternator to the stock 350 mag engine management system. Too large of an alternator to their existing system will cause problems to the computer, is what I have been told. So I would like to leave the stock 68 amp alternator and its charging system as is to run the engine and maintain the starting battery.

My house bank which will operate the stereo system and ballast pumps along with a few other accessories will be completely independent of the other system. I have set up several ocean boats and a few small house boats this way in the past.

My house bank will consist of 3 group 24 deep cell batteries these batteries are rated at 70AH each for a total of 210AH. I will also be adding a BAtt Cap to the system which is equal to a 100uf capacitor.

The Stereo system is around 3000 WTT RMS with 4 amps and a lot of speakers, LOL.

when we ride we ride a lot all day some times. Other times on the water it kick it listen to tunes so a lot of both.

As for voltage issues not really because of the large battery bank but what dose happen is; As the Bank starts to draw down the Merc Engine Management system is seeing the heavy load on the alternator and Will set off the warning tone. Even though I have an Isolator the computer is still seeing the heavy load and thinks the battery is going dead and set of the warning. According to Merc tech support common problem because the Computer can not distinguish between the battery banks it just see's load. this is why I would like to set up the second alternator with wet group 24 batteries. ( the wet batteries are a lot more durable to over charging)

As for the size of the alternator 105 amps should be about right. The stereo system should have a load between 50 amps to 75 amps. That is a good load on the alternator and leave some rating to help maintain battery charge.

The Electrical side of the system I do understand pretty well. I have never added a second alternator to an engine with serpentine belt before.

So with all that info in mind I am open to hear other ideas and solutions there’s always 10 Dif ways to get the job done each with pluses and each has it minuses.

(oaf) · (oaf) **Join Date: Jul 2002** 08-24-2006, 11:16 AM

Do you pull your boat out of the water each night? If so why not run a good on board charger like the ProMariner as an example. I have been going around and around about this same issue. My plan of attack for now is going to be 3 Odyssey 2150's at 300 Hh or 4 Trojan 6V AGM at 400 Ah and put the bank to run the stereo only with a perko switch to isolate the 2 banks. The perko should say on 1 99% of the time. Then at night I can pull the boat and hook it up to the on board charger and get the batteries back up. My guess is I should be able to get a weekend out of the batteries without pulling the boat out of the water. I am planning on running a about 2200 RMS on my stereo. I did look at running a second alt and many seem to feel it is not as good of an option. If my initial plan fails then I will be doing a second alt with a Balmar regulator.

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-24-2006, 11:38 AM

Coach,

Your plan is not bad at all. Same way the bass boat guys run and charge the batts for their trolling motors. My only problem with that is what do I do on house boat and camp trips when we are in the water for 1 to 2 weeks? I was hoping to come up with a system that is self sufficient.

(oaf) · (oaf) **Join Date: Jul 2002** 08-24-2006, 11:49 AM

Tom,
That what I was looking at as well. I don't like to take my boat out of the water (all thought I can) for 2-5 days when I go out. I was also thinking of adding a second 100 amp alt with the Balmar regulator (BTW have you used any of the Balmar products?) to charge the batteries. One thing you can do if you are going to do the house boat thing is to plug into the generator at night using an on board charger and charge your batteries that way. Either way you will be using gas to charge the batteries, but using the boat kill 2 birds with one stone. If you put the 2nd Alt on the opposite side will you have to change any of the pullies so it can run one more item or is there an empty area for the belt? My idea was to run 2 alt next to each other and put a longer belt on.

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 08-24-2006, 12:13 PM

My system is roughly 2200 RMS and I run it the way Coach has described with the perko. IMO after various cost/benifit analysis this is the best way to run a large system. IF you have the cash...the balamar charging is probably the way to go.

My alt goes straight to my battery, no boat electronics to "mess up" this way.

(ss1234) · (ss1234) **Join Date: Jul 2005** 08-24-2006, 12:26 PM

I realize you guys have newer boats, but here's a pic of an add-on alt that was done on my 96 Sanger by the previous owner. The original alt was moved below the original bracket. There was one additional bracket that was fab'd and added to support the bottom mounting point of the lower alt. That new bracket mounts to the block using some existing holes. A longer belt was added. I've had the boat for 6 years with no issues.......for what it's worth.

Upload

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 08-24-2006, 1:44 PM

ON other thing to consider, you own a v-drive Tom. Tryign to remove/replace the alternator is hard enough for me on an 04SSV, I don't knwo if you'd have enough room to work with to add another alternator???

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-24-2006, 3:43 PM

Hey everybody, thanks for all the input so far I have seen a kit on a MC that had two Alternators one on each side of the motor. As for enough room to work on it ya you are right adam not a lot of room but for other reasons the motor has to come out of the boat this fall so I will be making the upgrade then.

(bob) · (bob) **Join Date: Feb 2001** 08-24-2006, 6:30 PM

Steve you dont eat belts running 2 alternators off one small belt??

(big_ed_x2) · (big_ed_x2) **Join Date: Jul 2004** 08-24-2006, 6:46 PM

What about those times where you can't recharge at home???

If it is wired right,2 alts,relay and 3-4 bluetops work best......no maintenance and bump as long as you want with no getting stranded.Going on 2 years with 0 problems and 0 dead batteries.

(oaf) · (oaf) **Join Date: Jul 2002** 08-24-2006, 8:00 PM

Big Ed-
Can you post some pics of your set up if you have them? I would like to see some more pics of the set ups. Also Tom do you have any pics of the MC that had the dual set up? Thanks

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-25-2006, 12:39 AM

Coach, Funny you ask for pics of the MC system I was talking about because it was Big Eds system actualy. Problem Is his dealer put it in for him and I don't know where they got the kit from. But I do like his set up a lot.

(oaf) · (oaf) **Join Date: Jul 2002** 08-25-2006, 5:38 AM

Tom or Ed-
With the 2nd Alt on the opposite side of the Main Alt was there another pulley slot to run the Alt (in place of a water pump) or was a new pulley installed? That sound like a very easy and more reliable way to run a second alt (vs piggy backed) if there is another pulley slot avalible. I am very in this set up.

ilovetrains 08-25-2006, 9:20 AM

A couple of ideas:
if you wanted to run one altenator, the computer can be fried if it get's more than 68 amps or current (if I understand you). Why couldn't you run a larger altenator, run the power through the battery bank first, then put an in line resistor back to the engine?

On the two alternator idea, since an alternator is always draing power (unlike an A/C compressor for example) you are increasing load on the motor. You will probably loose 10-15 hp adding a 100 amp altenator. I think you are btter off adding a second pulley and belt than trying to run a single belt. Less tension on each belt and if one fails, you would theoretcially be able to still make power. Both circuits must be kept seperate or you have ,ade a 24 volt system.

(ss1234) · (ss1234) **Join Date: Jul 2005** 08-25-2006, 9:44 AM

Bob-
Thanks, it will probably go out this weekend since you mentioned it......(JK, I hope). I think I've replaced them twice since I've had the boat, but just as preventitive maintenance. They really didn't look that bad.

(oaf) · (oaf) **Join Date: Jul 2002** 08-25-2006, 12:57 PM

If you go with a large alt you need to get something like the Balmar Duo Charge. It seperates the bank and the starting battery and only trickles off a small charge to the starting battery. Once you start having pulley made or buying new ones the complexity of the project.

The price break down is something like this

2 alt- $300 for 2nd alt $300 for Balmar Max Charge $50 for a new belt

1 HO Alt $1000 for the alt, $300 Balmar Max Charge, $200 for Duo Charge, $300 for new pulleys

So the HO Alt system will run you more

(norcalmalibu) · (norcalmalibu) **Join Date: Jun 2004** 08-25-2006, 5:30 PM

woah where do you get 1000 bucks for high output alt! dam thats highway robbery!

(oaf) · (oaf) **Join Date: Jul 2002** 08-26-2006, 12:34 AM

Go check West Marine or anyone else for a 200 Amp Alt. I am not talking about some 100 Amp small dog.

I am only talking about the big dog the realy players will be using.

(oaf) · (oaf) **Join Date: Jul 2002** 08-26-2006, 12:38 AM

Here is an example of a 165 Amp Alt

http://www.go2marine.com/product.do?no=116026F

Here are some more prices

http://ecatalog.westmarine.com/t514.asp

(grant_west) · (grant_west) **Join Date: Jun 2005** 08-26-2006, 6:45 AM

2 alternators and 1 belt "No bueno"
1 alternator and 2 belts "bueno"

please explaine what or why Merc tec support says you cant run a large single alternator.
BTW Im sure if I asked Nautique if it was ok for me to add "insert your faverote accessory" to my boat they would say no. It seems that the factory is pretty against adding anything that they didnt put there Upload

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-26-2006, 9:04 AM

Grant,

It has to do with the Engine management system on the 350mag (mine is an 04) I had heard of guys burning up computers so I called before changing my alternator and they were against it and recommended a separate 12v system for the stereo and accessories. It has to do with the fact that the Computer monitors Amperage and Voltage and the engine management system can not handle an HO alternator. I'm sure there is a work around but at talking with Merc. I was going to go the 2 alternator set up and leave the stock set up alone. BTW I like your set up really simple and reliable.

Nate,

As for the cost of HO alternators in the 200 amp rang Coach is correct on their cost. An alternator shop can get 200 plus amps out of just about any alternator the problem is life span at that kind of amperage you are generating a lot of heat and that heat burns stuff up after a while. The marine grade HO are designed for long term continues use. There are big differences in a HO alternator and a cheapy rebuild HO alternator.

(Message edited by tantrum916 on August 26, 2006)

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-26-2006, 9:11 AM

BTW I don't claim to know all about the Merc 350 mag engine management system just going off what I was told and that would be why I'm on here exploring options and to learn and share info.

(grant_west) · (grant_west) **Join Date: Jun 2005** 08-27-2006, 9:03 AM

Tom do you have a pic of the front of the motor.

(bob) · (bob) **Join Date: Feb 2001** 08-27-2006, 10:12 AM

How about this set-up I founnd on I.D.s website Upload

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-27-2006, 4:42 PM

Bob I have been looking for that type of mount used to run the direct drive set up in our race boats but I have not been able to locate one for small block. Is that on a small block or is that a big block. BTW is that in a Hallet day cruiser?

Grant,

I don't have any pic of the front of the motor because to motor is still in the boat. But it's a stock 350 mag.

(Message edited by tantrum916 on August 27, 2006)

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-27-2006, 7:48 PM

I think I may have figured this whole thing out, Merc engine management system has issues when sensing too large amperage/load as I have been told by Merc Tech Support. With that in mind I found a battery combiner that will let your started/engine battery see only 30 amps from the charging system. Here is the link

http://www.balmar.net/PDF/Duo%20Charge%20Manual.pdf

So my thoughts are:

one large alternator (135 amps)w/pulley sized for 2700rpm to 3000rpm range

Quality voltage regulator

Digital Duo Charger.

Alternator and voltage regulator connects directly to the house bank with the Duo Charger connecting the starter/engine battery to the charging system.

With the Duo Charger the Merc. engine management system only sees 30 amps of out put from the charging system.

I need to make some phone calls to confirm my findings but pretty sure this will work.

I think this set up will work quite well for my application.

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 08-27-2006, 7:59 PM

where are you gettign the 135 amp alt? how much?

(tantrum916) · (tantrum916) **Join Date: Mar 2005** 08-27-2006, 8:05 PM

Let me confirm size and fit before I point you in the direction, found on the net a few sourses

(bob) · (bob) **Join Date: Feb 2001** 08-28-2006, 2:48 AM

Tom the picture come off of Image dynamics web, http://www.imagedynamicsusa.com/gallery/main.php

boat on right. Kens Boat page 7

(big_ed_x2) · (big_ed_x2) **Join Date: Jul 2004** 08-28-2006, 7:28 AM

Saturday, August 26, 2006 - 6:45 am:

quote:
2 alternators and 1 belt "No bueno"
1 alternator and 2 belts "bueno"

How do you figure???

Maybe b/c your V-belts can't take it?Do you want to further explain.

(Message edited by big_ed_x2 on August 28, 2006)

(grant_west) · (grant_west) **Join Date: Jun 2005** 08-28-2006, 10:18 AM

Ed: Glad your hear your systyem is bumpin with no problem's. But I wouldnt call your system a real high draw system. I forgot how many batterys you have but you have a pretty efficiant system

Most stock boats with V belts have a single 3/8 V belt. I have found that it pretty hard to get one single V belt to withstand the tourqe that a HO alternator can put on a single belt. Balmar says my 210 alternator can pull as much as 8 HP
I guess thats alot. They suguest 2 1/2 V belts to prevent the belts from slipping and smoking.
Another advantage of the Balmar voltage regulator(max charge) is that it applys voltage and makes the alternator start working slowly. Ill explane
when you start your boat the Blamar system dosent make the alternator start working unitll 5 min's after your motor has been running and then it starts making your alternator working slowly no matter what your battery status is that put lest stress on your belts so as not to smoke a belt. A traditional alternator and regulator will apply full tourqe on your belt right at start up. The sudden jeark or tourqe to the belts is what causes them to slip.

(grant_west) · (grant_west) **Join Date: Jun 2005** 08-28-2006, 10:20 AM

BTW if you have a flat or Serpentean belt this a mute point. Serpentean belts are the bomb and can take the tourqe.

(big_ed_x2) · (big_ed_x2) **Join Date: Jul 2004** 08-28-2006, 6:47 PM

I have 4 total blue tops
1 for the boat
3 for the sound system

As I would agree with you on that my system that is not competition status,I would say it is bigger then average(I sound like I'm in HS with that last statement)

What would you consider high draw 2 belt no bueno?

BTW Serpentine belt baby!