db electrical alternator

I was running a 110 amp alt with small factory wires on my c1500 . I was pushing 600 watts at 2 ohms & I was ok. I upgraded my sound system to a 2000 watt wired at 1 ohm & the 110 alt was fine with a red top battery. After a few friends fried there alts in competitions I upgraded to a 200 amp DB alt before I ran into problems.Now I only upgraded the wires to zero gauge when I got the 200 amp alt . The reason for the fused (200 fuse)power o gauge to the battery is obvious.The zero gauge wire for the battery post negative to chassis & the zero gauge ground wire from motor to chassis is to eliminate ground loop noise.Hence "the big three upgrade".This is really for big systems with big amps, but if you have lots of noise coming in the speakers on pause or an alternator whine while the motor is reving this ground wire upgrade will fix it.On a boat the 4 gauge fused power wire can't hurt for the 100amp alt.The 4 gauge ground wire upgrade for the alt can't hurt either.It will eliminate ground loop noise & prevent a fire at best.

79nautique wrote: now leave the blower on for a couple hours to draing the battery. Start the boat and watch the amp meter and record the highist reading. bet it's not over 20 amps. Now replace the alt with a 100A unit and do the same thing and 100 bucks say's you will see the same amp reading on the gauge around 20A's So if I listen to Tim a 100A alt is going to charge a battery faster but how is that possible when they both have the same amount of current going into the battery yet the one alt has almost double the amp rating?

I didnt say that.

I can come up with a reasonable scenario where its true, though. Take that same situation and add the draw of a second battery thats been run down by a stereo system with the engine off, plus the load of the stereo that continues to play after starting the boat. Will the alt still put out a maximum of 20A, or will it be greater than that? If a 55A alt was struggling to power all of the accessories with the boat running, wouldnt a 100A alt charge the batteries more quickly? People who use their boats like this are the ones who are upgrading their electrical systems with multiple batteries and high output alternators. (...not usually by people who forget to turn off their blowers.)

All of this is neither here nor there. My statement above holds true. If upgrading the alt, the wiring to the dash needs to be upgraded or fused, and the engine breaker needs to be sized appropriately to take advantage of the alternator output current.

I don't care what any of you say, I can piss farther than all of you.

I'm not arguing anyones point here,but just curious.If you are running the amp directly off the battery,and not thru the ignition switch wiring,why would it be affected?I can see the point about trying to pull too many amps thru a small gauge wire and starting a fire before the breaker trips,but isn't the amount of amperage travelling thru a wire based on the demand from the electrical loads on that particular circuit? I must be missing something and it's probably right in front of me,I'm certainly no electrical guru. Tim,did you modify the schematic on the last page?

    Mike

79nautique wrote: besides the 10si and 12si units where never design to be repairable that's why the stator leads are welded to the bridge assembly and why there is a plastic cover on the side slip ring end or SRE as it was called on the drawings and was made up of the SRE housing, bridge asm, diode trio, regulator, stator, brush holder asm and the DE or drive end contand the De housing, rotor asm and pulley.

Chris, I think you have your alternators crossed somewhere. Every 10 or 12SI alternator I've torn apart (and that's quite a few of them) have all had ring terminals on the stator windings which are secured to the rectifier posts (3 of them) with nuts. The bearings, brushes, rectifier, regulator, diode trio and stator were all replaceable. There's even a screen kit available to convert this alternator to a marine unit.

I'm there for ya BD!

Wow...a J_I_H sighting.....you must be only lurking now-a-days.
We need ya posting more Jim....your special brand of humor.

john

this is what I'm refering to

now if thats the CS so be it I have it backwards after not working there for 15 yrs.

what gauge wire is used between the alternator and start relay? your schematic states 4 awg or has that been changed from the factory.

Chris , I would assume this is as close as we will get to:
For once in my life I was wrong,you guys were correct.There is a major difference between a 10SI and the the unit pictured.
We accept and we will move on.........
           Boat Dr

79nautique wrote: are they on the same post of the starter relay?

IIRC, yes. With the stock wiring the dash lead is not fused between the alt and the dash, which is why Tim has put the stock 55A breaker on the 10awg.


Not to beat a dead horse but this is exactly the point everyone is trying to make:

79nautique wrote: the number of accesories in use at one time is what creates the load on the alternator

I think we're all assuming that anyone looking at purchasing a 100A alternator is doing so b/c they have, or plan on, increasing the current draw with stereo amplifiers, ballast pumps, etc. You wouldn't need a 100A alt simply to replace an aging/faulty one.

Ok I'll take that as correct Tim and Doc,

So since we have multiple batteries that need this extra current to charge then and they are creating this huge load on the electrical system aka Alternator. So we need double the current that was there before because we have two batteries now. Explain to me have all of this current is going through the dash and wiring harness and causing this fire hazzard because the wire gauge is too small from the factory for a 100A alternator.

So is it true that electricity takes the path of least resistance?

what has less resistance 0 awg or 6 awg wire. The 0 awg wire does right? so then since the path of least resistance is the 0 awg wire and the alternator wire is connected directly to this wire how can the load created from these draing batteries/high power amp connected to the batteries going to flow through the dash panel wiring and burn down the boat when it doesn't travel though the dash wiring harness? So if it doesn't travel though the dash why do I need to increase the size of the wire going to it when all of the current is going through the battery cable connected to the alternator wire at the starter relay? (path of least resistance basic electricity) I'm missing how the boat is going to short and melt down and cause a fire because the dash wiring harness has failed?

with the logic you are trying to peddle it would imply that all wires within the electrical system could see the full amperage output from the alternator and that's just not the case. And with your logic the battery is not going to be charged until the current passes throught the ignition switch and the dash panel before it ever reaches the battery. Again this is just not true or how the electrical system works. The current going to the dash is not going to change just because you increase the output of the alternator, you haven't changed any of the loads in the wiring curcuit so the load is the same as it was before the upgrade. Oh so now we are going to add a stereo that wasn't there before ok fine now we have increased the load because now we have to power the head unit so maybe now the load increase by about 10 amps maybe well within the capacity of the current wire, but hey what a minute we have amps too, well ok that's fine, what are the wired to? the battery directly not the dash or ignition switch so that current passes through the battery cable right.

So if I am not creating more load at the dash than what all ready is there why do I have to increase the wire size, I don't.

TRBenj wrote: The dash is fed directly by the alt. It does not go through the breaker. Only the charging circuit (alt-->batt) goes through the breaker.

wrong

I suggest you refer to the wiring diagram in the PCM manual and not an edited diagram that is not completely correct and you will see the batter cable, alternator pos lead, and the pos lead for the ignition switch all go to the same post on the solenoid/relay.

I don't see any circuit breaker in the PCM diagram either. I guess that means I should just remove it.

I know that on my boat, the main POS lead off the alternator and the main dash lead were located on the same terminal on the circuit breaker. The battery and starter were the only protected ciruits. I don't believe it had ever been touched.

79nautique wrote: I can't see the picture now, RR filters it out, put I don't understand whats hard to read in the diagram to figure out where everything is connected looks pretty clear to me and I didn't see any posting by me on your wiring diagram topic link you posted.

Like I said, thanks for the help putting my diagram together.

In the PCM manual, the electrical connections are correct, but the physical connections depicted are misleading. For example, the alternator does not connect to the ballast resistor like the diagram shows (though it is electrically equivalent). Its also difficult to tell which wires connect to which posts on the starter solenoid. The second diagram is much clearer.

When youre able to see the pics, be sure to tell us if you still think the alt goes through the breaker on the way to the dash. Reference connections #22 and #23.

Hollywood wrote: Bremsen wrote: I know that on my boat, the main POS lead off the alternator and the main dash lead were located on the same terminal on the circuit breaker. The battery and starter were the only protected ciruits. I don't believe it had ever been touched. So you're basically combining Tim and Chris's arguments here. Tim says dash needs to be protected from the battery by the breaker, which it is. Chris says it does not need to be protected from the alternator. So basically Tim's diagram needs the orange alt output on the other side of the 50A engine breaker.

No, he's confirming what I said. He just misused the term "protected." Only the starter and battery are on the UNprotected side. Everything else is on the protected side, that is, protected from the battery which is the greatest current source in the boat.