Alternator Question

[CODY_YARBER07]

So, I bought a 140 amp Delco Marine alternator to run my stereo and the place that I bought it from (DB Electrical) explained to me which wires went where and I proceeded to install it. Once I got it installed I tested it and it is not charging. Not wanting to ruin my weekend on the lake I hook my old 30 amp alternator back up. It ran my stereo fine with no problems at all. I have two batteries isolated by a dual battery relay. The stereo includes 4 Polk Momo Speakers and a Polk Momo sub powered by a Sony Amp (250 watts RMS) AND 2 Wetsounds Pro 80's powered by a Cadence TXA3004 which sends about 300 watts to each Pro 80. Now I have no clue how much amperage this setup draws but like I said it has been working fine with the stock alternator. DB Electrical has offered me a replacement alternator or a full refund and I am leaning towards the refund if I can get by with my old alternator. Like I said, I ran it all weekend and it had no problem keeping charged. Just wondering what you all thought about it. Thanks so much, Cody.

[Patrick Hardy]

Cody wish I could help you, I am in the same position, I have to upgrade my 55 amp alternator. I have read all of the past threads and have more questions now than answers. It seem like it is a bad alternator that they sent you. DB Electrical gets a lot of references on these type of web sites, so i would think that unfortunately you got a bad unit. If they are willing to pay for your shipping cost both ways, I would give them another try. My 2 cents worth.

[JimN]

Originally Posted by CODY_YARBER07

So, I bought a 140 amp Delco Marine alternator to run my stereo and the place that I bought it from (DB Electrical) explained to me which wires went where and I proceeded to install it. Once I got it installed I tested it and it is not charging. Not wanting to ruin my weekend on the lake I hook my old 30 amp alternator back up. It ran my stereo fine with no problems at all. I have two batteries isolated by a dual battery relay. The stereo includes 4 Polk Momo Speakers and a Polk Momo sub powered by a Sony Amp (250 watts RMS) AND 2 Wetsounds Pro 80's powered by a Cadence TXA3004 which sends about 300 watts to each Pro 80. Now I have no clue how much amperage this setup draws but like I said it has been working fine with the stock alternator. DB Electrical has offered me a replacement alternator or a full refund and I am leaning towards the refund if I can get by with my old alternator. Like I said, I ran it all weekend and it had no problem keeping charged. Just wondering what you all thought about it. Thanks so much, Cody.

If the OEM alternator has only one wire and the new one needs an excite lead, which can be verified by looking at the diagram or calling the source, not having the excite lead connected will keep it from charging. This is needed because the old one (one wire) would have a permanent magnetic field and in the new ones, the magnetic field isn't created until the excite lead triggers energizing of the field coil.

[JimN]

Originally Posted by Patrick Hardy

Cody wish I could help you, I am in the same position, I have to upgrade my 55 amp alternator. I have read all of the past threads and have more questions now than answers. It seem like it is a bad alternator that they sent you. DB Electrical gets a lot of references on these type of web sites, so i would think that unfortunately you got a bad unit. If they are willing to pay for your shipping cost both ways, I would give them another try. My 2 cents worth.

ANY decent shop that does auto electrical repairs should be able to tell you what you need.

[Patrick Hardy]

Originally Posted by JimN

ANY decent shop that does auto electrical repairs should be able to tell you what you need.

JimN, I was told by two local Marine rebuild shops that my alternator could not be rebuilt to a higher amperage. I thought that was weird, but i just got off of the phone with SKIDIM, they said the same thing.
Actually they said that for my 1996 190 w/ LT1 there are no after market alternator amperage upgrades or kits available to them. He said that they get a lot of calls about this problem w/ the early years LT1. I am waiting for a call back from Indmar about this. This has been a real interesting DIY job.

[TX.X-30 fan]

Originally Posted by JimN

If the OEM alternator has only one wire and the new one needs an excite lead, which can be verified by looking at the diagram or calling the source, not having the excite lead connected will keep it from charging. This is needed because the old one (one wire) would have a permanent magnetic field and in the new ones, the magnetic field isn't created until the excite lead triggers energizing of the field coil.

Good stuff JimN.

[JimN]

Originally Posted by Patrick Hardy

JimN, I was told by two local Marine rebuild shops that my alternator could not be rebuilt to a higher amperage. I thought that was weird, but i just got off of the phone with SKIDIM, they said the same thing.
Actually they said that for my 1996 190 w/ LT1 there are no after market alternator amperage upgrades or kits available to them. He said that they get a lot of calls about this problem w/ the early years LT1. I am waiting for a call back from Indmar about this. This has been a real interesting DIY job.

They're partially correct. That case can be rebuilt to about 75A and that's about it. Then, it needs to go up to the next size, which is easily available to them and that's what I just got for BriEOD- a 105A version. The next size up needs different brackets but if you want, I'll call the guy and ask what it will take to get up to 140A. He does them all the time and stocks most sizes, ready for rebuilding. Beyond stock parts, it becomes a bit of a custom job but really, anything can be made to work properly.

[CODY_YARBER07]

I guess what my main question is, can I get by with the old alternator?

[Patrick Hardy]

Originally Posted by JimN

They're partially correct. That case can be rebuilt to about 75A and that's about it. Then, it needs to go up to the next size, which is easily available to them and that's what I just got for BriEOD- a 105A version. The next size up needs different brackets but if you want, I'll call the guy and ask what it will take to get up to 140A. He does them all the time and stocks most sizes, ready for rebuilding. Beyond stock parts, it becomes a bit of a custom job but really, anything can be made to work properly.

JimN, that would be great if you could hook me up with pricing / info about 105A version and the 140A version. Send me a PM about it,Thanks Patrick.

[proporjet]

Im not an alternator but an engineer with an opinion. You know what they say about opinions...
A 30A alternator sounds weak in this application. Keep in mind the maximum power specs that your speakers can handle, amps can supply....are just that Max RMS specs. Running at a lower volume is lower than that maximum power your system will use plus the wasted power that is giv4en off in the form of heat...
Running around for the day at some low or moderate volume is going to appear and possibly be OK. The only way to really see what is going on with the charging system is to take some measurements. This is not really easy but you can measure the charging current (and check the voltage)to the battery(ies) and measure the current and voltage out of the battery. Normal rectifier (thing that turns AC to DC) voltage is ~13.3-13.6V but with a large current drain the voltage will be on the low end if not closer to 13V. Make the measurements with the stereo system off, on at low volumes and on at high volumes. See what you get. I dont think you need a 140A alt but think you should have more margin than what I'm guessing a 30A alternator provides during Sandman cranking at full volume...