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Old 07-08-2013, 05:55 AM   #1
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Default DIYPNP Voltage problem, what to investigate?

I start to wonder if the problem described in my build thread would be better served by a dedicated thread.
I'm guessing that my DIYPNP have a flawed view of the reality when the revs gets a bit higher

The VVTuner reports 16.5V as max voltage and I assume that's max what the alt will give when the DIYPNP asks it for all it can get.

So are there anyone who can spoon feed me (at least a little) how to verify the voltage references and regulators in the DIYPNP to see if there is anything easy to fix this problem. It's worth an attempt before ordering a MS3 from MSLabs.
It can be as simple as poor building by me and would explain why it's eating alternators.
In short, what parts on the DIYPNP board (1.5) would influence the view of the voltage (19V instead of the more probably 16.5). No external independent voltage meter, sorry.

At one time i fried the ground lead to the DB15, when shorting the VVTuner output, so there can be other things affected by that, maybe.
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Old 07-08-2013, 08:18 AM   #2
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what are you using for a voltage regulator?
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Old 07-08-2013, 09:08 AM   #3
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The VVTuner has a clamp to 16.5V IIRC, it can't measure more than 16.5V, so don't take that reading as authoritative.
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Old 07-08-2013, 09:43 AM   #4
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what are you using for a voltage regulator?
The JC design cobbled together by myself, verified to regulate to 14.2V on the bench, as installed (tested at the ECU connector).
It would be interesting to measure the field out while running (if the Alt needs more pulldown power (less resistance to ground) on the field out).

I need a couple external Volt meters then, I thought 19V was impossible from an Alternator. Cheap digital LED ones would be best.

The engine have one extra grounding strap to the chassis and the ECU and MTX-L are individually grounded at the TB so I hope it's not due to floating grounds there.

No chance that there is any reference voltage component /circuit on the DIYPNP board that i could have messed up? Damaged Microsquirt unit?
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Old 07-08-2013, 09:54 AM   #5
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has this always been the case on your install? I have a feeling it's not working correctly. the circuit simply sends a signal to the alt or not, either charge or not. so if you're seeing over ~14.2v, then your circuit is constantly charging and the VVTuner like Rev said, is clamping down when it gets to 16.5v, otherwise it will keep going until the MOV in the DIYPNP clamps at around 22v.
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Old 07-08-2013, 10:34 AM   #6
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Quote:
Originally Posted by Braineack View Post
has this always been the case on your install? I have a feeling it's not working correctly. the circuit simply sends a signal to the alt or not, either charge or not. so if you're seeing over ~14.2v, then your circuit is constantly charging and the VVTuner like Rev said, is clamping down when it gets to 16.5v, otherwise it will keep going until the MOV in the DIYPNP clamps at around 22v.
It has burned one Alternator last year so it's very possible it have been the same way all the time.
Noobishly I don't have saved logs of the early years so it's now I have have some focused data on this.

Field Out is either signal (Vin) or not (4kOhm to GND if I have understood anything), I get that.

My question is if the Alternator would need less resistance to GND or if I just have to retest with some load on Field out (to verify that the circuit actually work as intended on the bench and not just unloaded).
I have no pride at all regarding my soldering skills, so it can be anything (shorts or crappy connections).
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Old 07-08-2013, 10:36 AM   #7
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there's no load on field out... so i don't see how/why you should add it.
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Old 07-08-2013, 10:57 AM   #8
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there's no load on field out... so i don't see how/why you should add it.
I was thinking around the lines of impedance etc in the Alternator, but if it's more of a direct function of Field Out actually being the Magnetic field current then its another story.

Besides testing it on the bench by ramping up "12V" and seeing Field-Out follow it up to 14.2 and then go to zero, what other test can i perform?
Maybe verify that the Field-Out isn't touching anything else and that it really is connected to the right pin on the Alternator (1O, GY/R).

BTW; Really dumb question, should 1T be left open, 12V or GND?
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Old 07-10-2013, 03:01 PM   #9
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Added a small digital voltmeter to the Field Out and tested it out.
Ignition on: 9.2V huh
Getting it running at 2krpm: 4.1V WTF

Disconnecting the Alternator (the 2Pin connector)
Ignition on: 12.2V
Running at idle: 12.1V and slowly going down (since no charging).

And without the Alternator charging like mad the idle was much smoother.

Since this Altenator have behaved like this from brand spanking new, I'm wondering if there is something different in my harness/connection.
Again; should 1T be left open/floating?

The previous Alternator with this behavior behaved as shorted when tested at the shop, so there is a chance that this one was shorted from new. I just want to make sure i have done the best I can I can before getting a new one.

The low voltage on the Field Out suggest to me that the Transistors in the circuit are doing their best with a really high load.

......

With main switch pulled the two pins have 17kOhm and 10kOhm to 12V but infinte and 0.4kOhm to ground.

A spare Alternator (new diode bridge but needs new 12V connection parts) have no connection to ground and 18kOhm and 0.9kOhm to 12V.

All measured grey before grey/red (1T and 1O).

Very crude tests but the 0.4kOhm to ground does not sound nice.

Back to the alternator service shop tomorrow morning then...
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Old 07-10-2013, 04:18 PM   #10
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Make sure your shop knows that this alt is NOT internally regulated (they should know already).

1T can be left floating with no issues.
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Old 07-10-2013, 04:34 PM   #11
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Quote:
Originally Posted by Reverant View Post
Make sure your shop knows that this alt is NOT internally regulated (they should know already).

1T can be left floating with no issues.
They checked the type "LR170-758" but my hope is to get the stock one fixed (replacing the cracked insulation of the 12V output). The next one should be tested before I leave the shop.

Thanks for the verification on the 1T.
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Old 07-18-2013, 10:58 AM   #12
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Same thing happened to me last year, done circuit twice, both time bench testing was alright... after burning the battery, I bought NA autoregulated alt and ask Reverant to build me a copy of his digital alternator control who also bench test at 14.4V. Never had time to install the board before bombing the engine at race track and buying a MS3 from reverant.
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Old 07-19-2013, 04:01 AM   #13
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After testing 3 different alternators the JC style binary control might just happen to work with the Hitachi LR170-758 with the VR-H2000-51 regulator (the part that fries when an alt shop tries to test it as an old-style alt).
Getting the regulator and fix my Hitachi alt seems to be my best option (but the Rev basic MS3 on order might be able to control more alternators).

OEM ECU seems to control the regulator through PWM and I suspect that different alternators have different expectations about the pulldown (for me one alt continued to give 15.5V at idle with 3v on the field out).
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