Frans,
I understand what you are saying about the +B & C connections... good
points, but keep in mind my bird has been flying perfectly in it's
current wiring form for over 200 hours. Just recent has this trouble
come out.
I will be changing the C wire direct to the battery.
Thanks,
Jeff R. N128LJ Gold Rush
On Apr 9, 2010, at 3:06 AM, Frans Veldman wrote:
> >
>
> On 04/09/2010 02:21 AM, JEFF ROBERTS wrote:
>
>> Tonight before it got too dark I managed to check the following
>> with the
>> engine at 2200 rpm's. At first after charging Battery, the voltage
>> check
>> direct on the terminals was 12.5. The GG alternator inputs on the
>> regulator we're 15.7 AC so I'm assuming the engine is producing
>> correct
>> voltage. I checked the +B out of the regulator and it read only .55
>> volts DC. Moved the engine up to 3000 RPM's and the +G only went
>> to .55
>
> All right. Alternator is good. Battery is good. Regulator doesn't
> work.
> But wait! This doesn't necessarily mean that the regulator is faulty.
>
> Based on your tests I strongly suspect you have a wiring problem.
> Without digging into the documentation: the +B should be connected to
> your battery, so it should read AT LEAST the battery voltage, i.e.
> 11.5
> Volts.
>
> Furthermore, the regulator has a connector labeled C, and this is its
> reference input. This is where it measures the battery voltage, and
> uses
> this as a decision point how much of the juice of the alternator it
> should go "let through".
> So, in order for the regulator to work correctly, the C lead should be
> definitily be connected to the battery somehow. Ideally, it runs
> with a
> separate wire to the battery, but most folks simply tie it up to the
> +B
> lead, which is supposed to be connected to the battery anyway. (This
> is
> ok, but ignores the voltage drop over the battery cable, which is
> minimal in most setups, so for sake of simplicity, just ty it all
> together at the output of the regulator).
>
> So, my next suspect is that the C connector is not carrying battery
> voltage as well. Which is very bad:
>
> In this condition, the regulator "thinks" that the battery voltage is
> way too low, and cranks up the output. But regardless how much it
> tries,
> the C connector will never read the correct voltage since it is not
> connected properly. So, even if it outputs 20 Volts, it still thinks
> that it should try harder because it measures "a far too low
> voltage" on
> the C connector. You won't notice this, as the output of the regulator
> is not connected to the battery.
> I hate to tell you this, but in this condition it is well possible to
> silently kill the regulator. After that point it will cease outputting
> anything at all. And if you replace your regulator, you will kill the
> new one as well instantly. Alas, this may be your current situation...
>
> So. What you need to do to get out of this mess:
> 1) Double check that the minus of the battery is connected to the
> metal
> case of the regulator. Also check that the minus of the capacitor is
> connected to the metal case of the regulator.
> 2) Don't replace the regulator yet. Make sure that, without the engine
> running, but the main (battery and alternator) switches to ON, you
> measure on the output of the regulator the battery voltage (anything
> above 11 Volt is ok). If this is not the case, the regulator is simply
> not connected to the battery. It doesn't matter whether the
> regulator is
> defect or not, the output should read battery voltage if it is
> connected
> correctly to the battery. Correct your wiring, switches, relais,
> fuses,
> CB's until you read battery voltage at the output of the regulator.
> Yes,
> all this with the engine OFF, but with the switches in flight
> condition.
> Proceed only to the next step if you have fixed this problem.
> 3) Run the engine. Measure again. Voltage should increase above 13
> Volts. If it does, you most likely have solved the problem. If it
> doesn't, you have killed your new regulator and should get a new one.
> Most likely you have killed your previous regulator in the same way,
> but
> it doesn't hurt to test it again now you have fixed your wiring. Maybe
> you are lucky and it has still some life in it, otherwise you have to
> buy a new regulator again.
> Oh, and while you are at it, replace the big capacitor as well. If
> it is
> has been destroyed (which is likely in the overvoltage condition it
> may
> have experienced) it will kill a new regulator in a short time.
>
> Note to readers: Yes, you CAN disconnect the regulator from the
> battery,
> but ONLY if you make sure that the capacitor stays connected to the
> regulator at all times, and that the C connector is connected to the
> capacitor as well, so the regulator "sees" what it is doing. The
> capacitor acts as a dummy battery in this case.
>
> Jeff, the best way to avoid this kind of troubles again, is to connect
> the C tab to the B tab on the alternator, and run from there a
> dedicated
> wire to the capacitor (without fuses, switches, etc). Keep that wire
> as
> short as possible, and make sure it is a fat wire. Run a dedicated
> wire
> from the minus from the capacitor to the metal case of the
> regulator, to
> make sure the loop stays always closed. Do not connect anything else
> to
> the capacitor.
>
> Let me know how this works out.
>
> Frans
>
>
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