Alternator Replacement (1 Viewer)

[TrickyT]

So I'm feeling better about voltage in the 13s after I called Denso and Odyssey today. Just sharing/documenting my experience with this upgrade here for others.

The tech guy at Denso says that it's not uncommon for their alternators to run in the 13s if they're sensing fully-charged batteries on the other end of the S wire. Many are designed to run at only 13.7v, however most will fluctuate between 13.0 and 14.8v at times given varying conditions. Basically, as long as I'm in that window at all times, he told me not to worry.

According to the tech guys at Odyssey, a PC1200 tested at 77° after a good night's rest is fully-charged at 12.8v. I passed that test on all three batteries as of this morning. They also said that almost no alternator on the market will maintain 100% state-of-charge on their batteries, which is why they recommend buying (of course) their 25 amp Ultimizer Charger and using it every few months to desulfate, bulk, and trickle their batteries back to 100%. (Good thing I already own one and have made that a practice for several years now.)

So long story short, after about 650 miles of driving in the three days since installing the alternator, and after confirming my batteries are still at 100%, I am confident that everything is working well.

I will continue to monitor and if anything changes I'll post in here again.

So far, so good, though, and I'm happy with the upgrade. (Knock on wood.)

Wes

Where/how are you measuring the alternator voltage? I'm a little surprised by the 13.5v output at cruise speed and agree that 14.1 or 14.2 is usually considered normal. What happens when you switch on a bunch of loads (e.g., seat heaters, A/C with blower on high, wipers, transmit with your 2m radio on high output, etc.) If the voltage drops significantly I'd say you have a problem, but if the alternator senses the increased load and keeps the voltage at 13.5 or even higher, then all is probably well. How are your 3 PC1200's tied together for charging? The alternator senses it's output voltage via the "S" terminal which is typically connected to the main fuse distribution block. This ensures adequate voltage to the vehicle electronics. One check would be to disconnect the S/IG/L connector at the alternator and verify low resistance between the S terminal on the wiring harness side of the connector and B+ in the engine compartment fuse block.

Sounds like a nice installation job to me. I like that you used 2 AWG for both B+ and ground from battery negative to block.

 

[CentralOverland]

Where/how are you measuring the alternator voltage? I'm a little surprised by the 13.5v output at cruise speed and agree that 14.1 or 14.2 is usually considered normal. What happens when you switch on a bunch of loads (e.g., seat heaters, A/C with blower on high, wipers, transmit with your 2m radio on high output, etc.) If the voltage drops significantly I'd say you have a problem, but if the alternator senses the increased load and keeps the voltage at 13.5 or even higher, then all is probably well. How are your 3 PC1200's tied together for charging? The alternator senses it's output voltage via the "S" terminal which is typically connected to the main fuse distribution block. This ensures adequate voltage to the vehicle electronics. One check would be to disconnect the S/IG/L connector at the alternator and verify low resistance between the S terminal on the wiring harness side of the connector and B+ in the engine compartment fuse block.

Sounds like a nice installation job to me. I like that you used 2 AWG for both B+ and ground from battery negative to block.

Tom,

Thanks for coming by.

When I measure the voltage at the alternator B, I can get up to 14.0v. At the battery, it's about 0.05v less than that. At my interior gauge, it drops about 0.1v further. So when I say that I'm running 60mph at 13.5v, really it's likely more like 13.65v at the alternator.

Yesterday, I gave her hell. Warm midday, brights and aux lights lit, fridge on, 2M and CB in RX, A/C and stereo on full blast, and even the wipers running. At that point the battery was giving me 13.2v. Then I would hit the 30a compressor and the voltage at the battery would drop to as low as 12.9v for a moment before rising back to 13.2v. I was afraid to try the winch.

My PC1200s are installed such that one replaced the factory battery and the other two are in parallel supporting all non-factory systems through an aux fuse panel powered and grounded with 4 AWG. They are controlled using a Wrangler solenoid or manually with a Blue Sea 4-way switch.

I can confirm that my S wire terminates in the factory distro block.

What level of resistance should I be concerned about in the S wire? And should I consider replacing that entire wire if it's too high?

Thanks for the help.

Wes

 

[spressomon]

Dan, where did you hear that the Sequoia alternator uses avalanche diodes for rectification? Rectifying the inherent AC voltage produced by a alternator to produce high-current DC output is typically done with silicon power diodes. Avalanche diodes, which are also made of silicon but operate in reverse bias mode, are most often used as a voltage reference in electronic circuits or sometimes to suppress voltage transients in circuits. You can't use them as rectifiers because they cannot handle large currents. So there must be some misunderstanding here.

Tom, when I was in the process of installing my Mobi-Arc welder, I was told alternators with avalanche style diodes were incompatible including the Sequoia alternator (for the same reason). Additionally when I was considering an HO alternator from DC Power Systems I was told by them they would need to build me a non-avalanche diode rectifier for use with the Mobi-Arc welder...as their HO alternators utilized avalanche style diodes...

 

[TrickyT]

The "S" sense wire carries little current, so no need for a larger wire. My main concern was something got messed up when you changed the alternator connector. Like some wire strands got broken or damaged or the connector terminal is not making good contact with the alternator side of junction. There's a voltage regulator inside the alternator and the S wire tells the regulator what voltage the alternator should output.

It's clear that the alternator is working, since you're getting more than just battery voltage. (A fully charged AGM battery puts out 12.8 - 13.0v.) I say run it and see how it behaves during your trip.

 

[TrickyT]

Tom, when I was in the process of installing my Mobi-Arc welder, I was told alternators with avalanche style diodes were incompatible including the Sequoia alternator (for the same reason). Additionally when I was considering an HO alternator from DC Power Systems I was told by them they would need to build me a non-avalanche diode rectifier for use with the Mobi-Arc welder...as their HO alternators utilized avalanche style diodes...

OK, I see now. But you've got some apples mixed in with the oranges. Welders like the Mobi-Arc (are they still selling those?) "trick" the alternator into putting out something like 30 or 40 volts during welding. They do this by either fooling the alternator's voltage regulator to make it think it's generating less voltage then it really is, or by bypassing the regulator altogether and having a module in the welder act as the alternator's regulator. But it's the regulator that has the avalanche diode in it, not the diode rectifier pack. The avalanche diode is not recitfying the alternator's AC current. You need silicon power diodes for that. So you threw me off in your post when you said "the rectifier difference between the two alternator models." At any rate, the comment about avalanche diodes only applies to welders like the Mobi-Arc that need the alternator to output a much higher voltage then it was designed for. For Wes' use it is not relevant.

 

[spressomon]

Thanks Tom for setting me straight! However I'm still a little cornfuzed: For the Mobi-Arc welder, whether it utilizes my OEM alternator or the HO from DC Power, it would use an external voltage regulator (Ford style; provided). I need to talk to Scott but I was fairly certain it was the rectifier, containing avalanche style diodes, that was the offending culprit (since the OEM regulator got replaced with an external regulator anyway...).


Please indulge me: For education/curiosity why do you think Toyota changed from non-avalanche style diodes to avalanche style diodes?

 

[TrickyT]

Thanks Tom for setting me straight! However I'm still a little cornfuzed: For the Mobi-Arc welder, whether it utilizes my OEM alternator or the HO from DC Power, it would use an external voltage regulator (Ford style; provided). I need to talk to Scott but I was fairly certain it was the rectifier, containing avalanche style diodes, that was the offending culprit (since the OEM regulator got replaced with an external regulator anyway...).


Please indulge me: For education/curiosity why do you think Toyota changed from non-avalanche style diodes to avalanche style diodes?

I've pretty much got nothing more I can add, but if Scott or someone else can provide additional details I'm all ears. When I learned about semiconductors (many years ago now so things may have changed), avalanche and zener diodes were used in a way opposite to most diodes in that you reverse biased them and used the voltage that they "broke down" at to act as an accurate reference voltage in a regulator design. But the rectifier packs in alternators don't require a material property like that. They need to be able to pass a lot of current in the forward bias direction. So I just don't see why you'd use an avalanche diode in a rectifier pack if it wasn't part of the internal voltage regulator.

 

[TrickyT]

Can a Mobi-Arc be used with any kind of Toyota alternator? Maybe you can't separate the voltage regulator in a Toy alternator from the rectifier pack? It looks like in a Ford-style alternator that the regulator is a separate but still internal unit.

 

[spressomon]

No the Mobi-Arc welder can not be used with any Toyota alternator IIRCC. The early 100-Series model years (I believe through 2002 but maybe later), for instance, comply. But per Scott the Sequoia alternator definitely does not comply. This came up because I wanted, like the OP, to use the 150A Sequoia alternator but was advised not to...because of the avalanche style diode issue/incompatibility.

I'll see if I can reach out to Scott to have him comment here.

 

[OregonLC]

Subscribed for pure geek tech fetish.

 

[TrickyT]

Subscribed for pure geek tech fetish.

OK, but note that Dan and I have pretty much temporarily hijacked the original thread and right now it's about Mobi-Arc and Toyota alternators. Poor Wes, he just wanted to know about his alternator output voltage!

 

[spressomon]

Hijack's my middle name

 

[OregonLC]

Don't kill my buzz. Mo sparky tech, less chatter.

 

[mobi-arc]

OK, I see now. But you've got some apples mixed in with the oranges. Welders like the Mobi-Arc (are they still selling those?) "trick" the alternator into putting out something like 30 or 40 volts during welding. They do this by either fooling the alternator's voltage regulator to make it think it's generating less voltage then it really is, or by bypassing the regulator altogether and having a module in the welder act as the alternator's regulator. But it's the regulator that has the avalanche diode in it, not the diode rectifier pack. The avalanche diode is not recitfying the alternator's AC current. You need silicon power diodes for that. So you threw me off in your post when you said "the rectifier difference between the two alternator models." At any rate, the comment about avalanche diodes only applies to welders like the Mobi-Arc that need the alternator to output a much higher voltage then it was designed for. For Wes' use it is not relevant.

Hello all, will add some comments. Correct, we're no longer selling the MOBI-ARC unit....we developed a new line of products which have broader applications so although we still service and support MOBI devices, we're not placing new units in the field.

TrickT, your description of the way an alternator is used for welding is pretty accurate. In the case of the MOBI, the alternator's voltage regulator is either removed or incapacitated so it doesn't conflict with the regulator built into the MOBI control unit. So when welding in required, the MOBI regulator pulse-width modulates the alternator to create about 55 volts which makes it feasible to strike an arc. We don't de-regulate or fool the regulator into full-fielding the alternator, although that is the procedure home-grown,Premier/Link-arc/Thunderbolt....whatever it's called these days ....on-board welders use which is arguably dangerous as the voltage can get quite high when de-regulated.

The elevated voltage created during this process will conflict with the avalanche diodes which have become a common choice of diode/rectifier pressing to rectifier plates in many alternator. Avalanche diodes rectify the AC to DC and are used for a couple reasons: 1) they're slightly more efficient that standard high voltage silicon rectifier having a lower forward voltage drop, and 2) they start to avalanche or conduct at approximately 25 volts so if the regulation system were to go open circuit, the alternator's voltage won't go sky-high...it will be throttled to about 25 volts which is voltage level where the ECU and electronics won't be damaged. So from a high voltage electrical protection standpoint, avalanche diodes are good, but it's a deal-killer for welding as you need to achieve higher voltage to strike the arc so we would either not use those alternators that have avalanche diode rectifier plates, or swap them with rectifier plates we would spec with non-avalanche rectifier plates.

Thanks Tom for setting me straight! However I'm still a little cornfuzed: For the Mobi-Arc welder, whether it utilizes my OEM alternator or the HO from DC Power, it would use an external voltage regulator (Ford style; provided). I need to talk to Scott but I was fairly certain it was the rectifier, containing avalanche style diodes, that was the offending culprit (since the OEM regulator got replaced with an external regulator anyway...).



Please indulge me: For education/curiosity why do you think Toyota changed from non-avalanche style diodes to avalanche style diodes?

The alternator either had to be regulated by the connected MOBI, or if not connected, regulated by either and external regulator or sometimes internal regulator where we could disable the internal regulator when the MOBI was attached. The change to avalanche was due to slight efficiency benefit, along with a single point of high voltage protection.

I've pretty much got nothing more I can add, but if Scott or someone else can provide additional details I'm all ears. When I learned about semiconductors (many years ago now so things may have changed), avalanche and zener diodes were used in a way opposite to most diodes in that you reverse biased them and used the voltage that they "broke down" at to act as an accurate reference voltage in a regulator design. But the rectifier packs in alternators don't require a material property like that. They need to be able to pass a lot of current in the forward bias direction. So I just don't see why you'd use an avalanche diode in a rectifier pack if it wasn't part of the internal voltage regulator.

In this case the avalanche cause the diode to conduct at +/- 25 volts which then loads the alternator which then get hotter than s*** very quickly and then fails....all very dramatic.

No the Mobi-Arc welder can not be used with any Toyota alternator IIRCC. The early 100-Series model years (I believe through 2002 but maybe later), for instance, comply. But per Scott the Sequoia alternator definitely does not comply. This came up because I wanted, like the OP, to use the 150A Sequoia alternator but was advised not to...because of the avalanche style diode issue/incompatibility.

I'll see if I can reach out to Scott to have him comment here.

I can't remember which Denso alternator did or didn't use avalanche diodes...we used to check the BOM for a given alternator, drill down the rectifier plate, and description of the rectifier plate would detail if avalanche diodes were used, as it was common for GM after about 1985 to go that route, but Nippon-Denso, Hitachi, etc...used them on some alternators and not on others....it's kind of a pain which is why some providers of alternator-actuated welder require that they provide the alternator in order to insure the correct configuration of rectifier plate, regulator, etc... is used in order to achieve a positive installation.

 

[TrickyT]

...
In this case the avalanche cause the diode to conduct at +/- 25 volts which then loads the alternator which then get hotter than **** very quickly and then fails....all very dramatic...

Good info, Scott! Protecting expensive vehicle electronics like the ECU at the expense of self-destruction of the alternator makes good sense. I hadn't considered something like the voltage regulator failing and the alternator voltage running wild and now understand how avalanche diodes would protect against that. Also found this Q&A on the topic in an engineering forum: http://www.eng-tips.com/viewthread.cfm?qid=237708. According to it, the avalanche diodes also protect the electronics against voltage spikes by dissipating the spike into the alternator windings.

As to the original topic of this thread, using avalanche diodes in the alternator has nothing to do with the possibly low alternator output voltage that Wes was concerned about.

 

[Odyseuss]

Its probably another hijack for this multi-directional thread, but-

Does anyone have a picture of a Sequoia Alternator that has been modified to fit in a 100 series?

I am considering going this route and as per info in this thread, it sounds like one of the tabs needs to be removed.

 

[CentralOverland]

After two weeks of voltage ranging in the 13s, today my voltage spiked high enough to set off numerous warning lights, beepers on the National Luna monitor, and send the A/C into hurricane mode. Thankfully, I was near home and able to shut it down within a minute or two.

I spent 30 minutes on the phone with the Denso tech, and together we came to the conclusion that my "S" and "IG" wires must be mixed up. I ran downstairs, metered and snipped and twisted, and sure enough, that was the problem. This 130a Sequoia alternator is now pumping a smooth 14.2 volts.

The problem seems to lie in the fact that the previous owner, Christo Slee, had already done some mods to the alternator wiring which created some color changes, and the 2004 FSM wiring diagram I use differs from what I actually own, a 1998, which created even more confusion.

Short story long, for those of you with a 1998, the factory colors from the factory distro block to the alternator itself are as follows:

"L" wire is red with a blue trace.

"IG" wire is black with an orange trace.

"S" wire is white with a blue trace.

No guarantees on any year other than a 1998.

Finally, knock on wood, I think I've fixed it. Another 700 miles to go tomorrow. Will monitor.

Hope this helps,

Wes

 

[CentralOverland]

Its probably another hijack for this multi-directional thread, but-

Does anyone have a picture of a Sequoia Alternator that has been modified to fit in a 100 series?

I am considering going this route and as per info in this thread, it sounds like one of the tabs needs to be removed.

I did not shoot a pic of mine sans the third metal mounting tab. It's an easy slice. Used a Dremel.

The tech at Denso, who had once modified an alternator to support a dual battery setup on his Chevy, assured me that one bolt was enough for a good ground. He didn't seem put-off by the fact I'd modified mine.

Again, though, I'm not convinced that it's necessary. From my perspective, I think it *might* actually fit without cutting it off.

 

[Odyseuss]

That is good hear @CentralOverland . I will test fit it before I cut it, and I will post pictures either way.

I am working towards this upgrade. I already have the connector. I ordered a 150A alternator and should have it soon. I should also have a few ANL fuses for this alternator upgrade and my dual battery.

I would have liked to be able to use the factory fusible links in the OE housing. My 01 LX has a 140A fusible link for its 100A alternator. I spoke with my local dealer parts dept. and was told that the Sequoia had a 150A fusible link for that 150A alternator and that it is the largest fusible link that Toyota offers of that style that he is aware of. I have not been able to find a fusible link of that design with a higher amperage rating.

I question whether it is accurate that the Sequoia actually uses a 150A fuse for that 150A alternator, as that doesn't seem like a high enough rating for a fuse in that capacity. It seems like a higher amperage fuse would be necessary. something closer to 175-180A seems more appropriate. I am interested to know what fuses are being run by users with the higher amperage alternators and if anyone is aware of a source for them that will fit in the factory fusible link housing attached to the positive battery cable.

I am prepared to go with the ANL style but if I could use the OE housing, it would be nice. I wonder if the OE fusible link design might not be capable or appropriate for amperage higher than 150A.

Here is a picture of the fuse design that I am referring to. The blue 100A fuse is shown because that was the largest one that I had on hand as a spare.

 

[TrickyT]

After two weeks of voltage ranging in the 13s, today my voltage spiked high enough to set off numerous warning lights, beepers on the National Luna monitor, and send the A/C into hurricane mode. Thankfully, I was near home and able to shut it down within a minute or two.

I spent 30 minutes on the phone with the Denso tech, and together we came to the conclusion that my "S" and "IG" wires must be mixed up. I ran downstairs, metered and sniped and twisted, and sure enough, that was the problem. This 130a Sequoia alternator is now pumping a smooth 14.2 volts.

The problem seems to lie in the fact that the previous owner, Christo Slee, had already done some mods to the alternator wiring which created some color changes, and the 2004 FSM wiring diagram I use differs from what I actually own, a 1998, which created even more confusion.

Short story long, for those of you with a 1998, the factory colors from the factory distro block to the alternator itself are as follows:

"L" wire is red with a blue trace.

"IG" wire is black with an orange trace.

"S" wire is white with a blue trace.

No guarantees on any year other than a 1998.

Finally, knock on wood, I think I've fixed it. Another 700 miles to go tomorrow. Will monitor.

Hope this helps,

Wes

Glad you nailed this one, Wes. I knew something was up, but without being able to put my hands on it directly it was hard to diagnose. Not sure how you got to the right Denso tech guys, but I'm impressed.