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New Alternator - still not charging battery

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  • #16
    Take a look at his page - lower diagram. You may need a wire connected to the "B" terminal of the four plug connector. Just a shot in the dark wihtoug a schematic of your boat but for some reason the alternator is not being excited. Back in the day I used to make my own self exciting alternators by installing a jumper wire to this terminal (although there were only tow terminals then) https://paceperformance.com/p-3980-s...nnections.html

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    • #17
      Morning folks, thanks for the responses, I will try to answer some the questions posed...
      waterlogged882 - the battery was purchased new in May, so a bit more than 2mo old. It is in good shape, holds charge well - I charge it Friday night and it holds charge for multiple trips over the weekend without alternator...

      mikeg205 - I did not replace the main battery cables but they appear in good condition. I have checked the connection points, all bolted solid. Ground is good. The engine starts at a flip of the key every time - the only issue I have is that the alternator is not charging. I agree with you that it does not look like the alternator is being excited... even thought it should self excite at 1400 rpm. When alternator is connected to the boat wiring, the voltage at the alternator post equals the battery voltage - last measurement was 12.4V. One thing I did not measure (and should have) is whether there is any voltage at the alternator if engine is running and alternator wire is disconnected - I thought about that as soon as I left the boat last night. I will try calling DB Electrical again today - I have still not gotten a call back after 5 calls last week...

      CapeH20Skier - the original alternator has two wires - hot and excite. I capped the excite as the new alternator is self exciting at 1400 rpm. DB Electrical confirmed that #ADR0424 would work on the LT-1 before the first purchase and i have seen reports on this forum that folks used that alternator successfully. I was thinking of SkiDIM as well - I will call them to see if they have anything to say on the topic.

      flyski - thanks for sending that link, I was researching the same thing as well. The new alternator does have that 4 pin connector - from what I can gather it is not needed for the alternator to run. The 4 pins are labeled P L I S - phase/relay, light, field monitor, remote sense. I know on the 10si and 12si alternators you need to connect terminal B to 12V to excite those alternators and I wonder if same thing needs to happen in my case. However, there is no excite/terminal B on my connector. The connector in the link you posted does seem like the one on the DB alternator and pin B from the link corresponds to the L (light) pin on the alternator. From what I researched, the P and L pins simply output 12V when alternator is working P I think is rated at 4A for relay and L is rated at 1A for light.

      Thank you all for taking time to look at this issue!

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      • #18
        Ok, a bit of a development - managed to get a hold of DB Electrical and while they told me that they cannot answer technical questions("we just sell them"), they got me a schematic of the plug.
        The I in P L I S appears to be ignition - I interpret this to be the excite wire... what do you think? If this is excite/ignition wire than the alternator is not self-exciting, which makes me feel quite embarrassed

        Now I need to figure out where to buy the connector for that 4 pin plug and try it out.
        Attached Files

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        • #19
          Your local auto parts store will sell that plug.......

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          • #20
            thanks, I found the plug.
            Now researching whether I need to add a diode or resistor on the ignition wire - any feedback on that topic? I remember reading a post on this forum where someone added a diode to prevent a potential problem with turning off the engine if the I terminal on the alternator remains energized...

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            • #21
              did some more research and I *think* I have my plan ready...
              From what I saw it appears only the older carbuarated systems need a resistor on the ignition wire. My 94 LT-1 has EFI and supposedly the excite wire does not supply high enough amperage to require resistor. Does anyone know more about the current the excite wire supplies?

              My earlier comment regarding the diode was based on this post: https://teamtalk.mastercraft.com/sho...2&postcount=15
              I am not sure a diode is necessary on these new alternators but i guess I will find out if the engine does not stop when I turn off the ignition key...

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              • #22
                I think you are on track about the diode. It won't hurt anything. According to the information at the bottom of the page on the link I sent you earlier, you may need a resistor on the I wire if your charging voltage is regulated too high. I would turn off everything that isn't necessary to start the engine and have a voltage meter attached to read as soon as it starts - if voltage gets above 15 shut it down and add the resistor. I'm looking forward to seeing this resolved!

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                • #23
                  Thank you flyski - I really appreciate your help. I ordered a resistor and am looking for the diode now... I will work on this over the weekend and will report back.

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                  • #24
                    Hi folks, happy Friday (or at least what is left of it). Here is the latest update on my alternator - it is finally working (sort of) after I hooked up the excite wire to the newly purchased 4 pin connector. The verdict is that I wrongly assumed that the alternator is self exciting until I finally connected with DB Electrical and found out the alternator needs to be connected to ignition switch. Embarrassing but I will suck up my pride and admit I was wrong

                    The "sort of" situation is that I am now getting over 15 volts from the alternator. First I hooked it up without a resistor and measured 14.2V at the excite wire connection. However, at the positive terminal of the alternator the voltage was 15.4V (at battery is about 15.4V as well).

                    I hooked up a 82ohm resistor at the excite wire and voltage dropped very little to 15.3V. the voltage at the excite wire remains about 1.2V lower... I had not charged the battery after last weekend so I wonder if drained battery is causing the regulator to provide over 15V. I started soldering the resistor, planning go out on a boat trip to see if the voltage will drop after the battery gets charged a bit, but then a summer storm made me abandon my plans until tomorrow morning.

                    So here are my two questions for the day... 15.3V seems a bit too high, is it not? My boat is 94 with LT-1 and EFI - I don't believe it has external regulator (I did not see one) and old alternator had only excite and hot wires, am I wrong about not having an external regulator?

                    Thanks again for any help and feedback!

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                    • #25
                      Spent some time in the water - alternator output is 15.4V at all RPM, which a little high... Battery was charged to over 13V after we were done riding.
                      The voltage remains steady at 15.4V when I turn on pumps, blower, lights, etc. That would indicate to me the regulator is working, it is just set at 15.4V?

                      See the pic below of the printout that came with the alternator - can you help me decipher the two red items - does that indicate the regulator is set at 14.6V or 15.6V?
                      Attached Files

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                      • #26
                        Originally posted by zzpich View Post
                        - can you help me decipher the two red items - does that indicate the regulator is set at 14.6V or 15.6V?
                        from this article:
                        https://www.knowyourparts.com/techni...or%20is%20good.


                        "today’s computer controlled vehicles. If 50 to 60 volts were to be applied to the circuit, the circuits in newer vehicles would also likely be fried. Fortunately, most newer vehicles (but not all) are redundantly protected by secondary regulation and Zener blocking technology. Zener blocking technology is basically just a way to block high voltages from damaging the vehicle’s electronics. Secondary regulation is a second voltage set point used by the regulator to shut the alternator down if it detects high voltage output. Once the voltage rises above this set point, it is possible that the vehicle will quit running, even though the alternator is good. If the vehicle is not protected, the likely result will be damage to very expensive computers and other components."

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                        • #27
                          Thanks flyski, this makes sense. It appears that my voltage of 15.4V is below the second regulation point and hence it does no cut off. I will call around tomorrow to see if I can find any feedback on what is causing the 15.4 voltage.

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                          • #28
                            Originally posted by zzpich View Post
                            Thanks flyski, this makes sense. It appears that my voltage of 15.4V is below the second regulation point and hence it does no cut off. I will call around tomorrow to see if I can find any feedback on what is causing the 15.4 voltage.
                            You've come a long way - almost there - you'll get it. Then we'll all be the wiser for your experience!

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                            • #29
                              Hey folks, a quick update on my alternator - spoiler alert, I got it dialed in

                              When I finally got the schematic and looked up the 4 pins in the plug, the one wire that was listed as required was the ignition/excite wire. As I did some more research, I read in one alternator thread on a different forum someone saying that a power supply he was using was kicking into max output if the sense wire was not hooked. I finally got to the boat this weekend and connected the sense wire to the starter post and voila - 14.6V at starter, 14.5V at battery. It turned out that the sense wire was listed as optional in the literature I found but it is actually required for proper operation of this alternator. Based on prior alternator experience I though that the remote sense's function to increase output when you turn on a lot of accessories but its function in this particular alternator is a bit different. In my final setup I did not have to use diodes or resistors. I just wish that DB Electrical had provided the schematic and some basic description/installation guideline with the alternator but I guess that is too much to ask for these days...
                              On a somewhat separate note, during my research I found the online alternator bible - I thought I will post it here as it may be helpful for others in the future: https://www.pirate4x4.com/threads/12...#post-44988321

                              Thank you everyone for your help on this project, I greatly appreciate it!

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                              • #30
                                Great news! I'm glad you got it sorted and shared your experience for posterity ;-)

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