D-100 resets on engine start

[Alfio]

My D-100 resets on engine start. It is paired with a D-120, which does not do a reset under the same condition (powered by same battery bus). They both do not have internal batteries. Have noticed the battery voltage dip down to 10V during engine cranking as measured by the D-120.

This is somewhat of an annoyance, since I wish to monitor the engine parameters as I start it (the D-120 is facing the passenger).

I have now found the D-100 to exhibit other symptoms. Once, when masters were powered, the D-100 came up no problem, but the D-100 did not start until about 1 minute or so. I though it had died. This symptom has not surfaced again.

Yesterday, I turned on the master power, and subsequently turned off the D100 and D120 since I was doing some configuration work on the transponder (saving battery power). The D100 powered up on its own after about a minute. I turned it off again, and after a couple of minutes, same thing, it powered up on its own.

 

[dynonsupport]

Do you have keep alive connected to the D100? If so, try disconnecting it. Also, if you're not on firmware version 5.0, try updating to it, as it helps with some power issues.

 

[Alfio]

Had KA disconnected, and software is at 5.0.

 

[dynonsupport]

The D100 will turn off at 10V if it doesn't have a battery (the D120 works down to lower voltages). So that by itself is not alarming.

As far as the D100 not turning on... You want to make sure it is getting good voltage. If you get it to not turn on again, you will want to check and see what the EMS says the voltage is during that time.

As far as the unit turning on after you turned it off with the button, while master power was present. That can happen while the unit is turned off and then sees the voltage go below 9.75V and then to above 10.25V, it interprets that as a fresh power cycle and says: "power just came up, so I better turn on". If you were doing something with power at that time it may have simply saw the power go down and then back up. This is an expected behavior.

So all this make me wonder if you are getting good power to your D100.

1. Do you have diodes in line with the power to it?  (while these can have advantages to prevent back-power and such, they also cause voltage drops)

2. How does the voltmeter on the D100 for "MS" compare with what the battery actually is?

A few things for you to check, let us know.

 

[Alfio]

1. Do you have diodes in line with the power to it?  (while these can have advantages to prevent back-power and such, they also cause voltage drops)

No diodes.  Battery, 6awg cable to fuse block, fuse, then D100. D120 has its own fuse.


2. How does the voltmeter on the D100 for "MS" compare with what the battery actually is?

More testing yesterday evening .... The D120 was showing 12.5V, and D100 showing 12.4/12.5V. I shut down the D100, and it powers back up a few seconds later. Performed this test 3 times, with same results.

Started the engine. D120 showing 14.4V, and D100 about the same. Shut down D100, and it stays off. Performed this test over a couple of minutes.

 

[dynonsupport]

hmmm, not exactly sure what to make of it. It could be that everything is working correctly and the couple times you saw "weird" behavior it was because of the voltage dipping for some reason and the unit deciding to turn on once the voltage came back. But there certainly could be more to it. Let's keep an eye on it, the key is to figure out if anything is repeatable, or if those symptoms were caused by something else.

Now, with respect to the D100 staying on when you crank the engine. The only way to ensure that the unit stays on is to install a battery. So I'm not sure if that is worth it to you or not (not trying to be a salesman here). There are other reasons to install a battery that I'm sure you are aware of.