D180 blacks during engine start

[SammyQ2]

I can't keep the screen lit up during engine start and the clock resets.  I have tried hooking up my ships large back-up battery to the Keep Alive line to pin 2 on the EFIS DB25 connector but it doesn't help. I can't hook up the DB25 pin 15 External backup power, since that is an always hot bus.

Since I already have a ship back-up battery I opted not to install the internal battery.  

Any other suggestions?

 

[rvator51]

Can you hook up pin 15 through a switch so you only turn it on for startup?

Regards,
Tom Velvick

 

[dynonsupport]

Keep-alive will not fully power the unit in any circumstance. It only pulls enough current to keep the clock running. Tom's suggestion or some variation on it could work, as would installing the optional internal backup battery.

 

[dynonsupport]

If you have a backup battery in the plane, this should be hooked to the emergency bus input on the EFIS, not the keep alive wire. The EB bus will keep the unit running.

 

[SammyQ2]

I don't want to add any more switches. I guess I will just live with it. I understand the clock will reset once the GPS is turned on. Just as long as I don't lose anything else, I guess I'll be fine with it.

 

[16FW]

Do you have an avionics bus? That is where I connect mine. It comes on when I switch on the radios, after the engines are running.

 

[SammyQ2]

No avionics bus, per se. My D180 is wired directly to the endurance bus, thus it comes on whenever the master or endurance bus switch is ON. The manual says several times that this is okay. I just didn't know that the D180 would black out at engine start.

 

[PhantomPholly]

I have my D180 hooked to the Master, not the Avionics bus, because I use it for engine instruments during start.

IMHO, if you use the EMS as primary you should have the battery backup - period. There is no guarantee that bus voltage won't drop below minimum for the unit causing re-boot otherwise, and even if it doesn't it isn't good for electronics to have to deal with "brownout" while the starter is turning.

With the backup battery, as soon as bus voltage drops it will automatically switch to battery. You'll get the nasty message saying it will shut down in 30 seconds unless you respond. Well, you shouldn't be cranking for over 30 seconds, and once bus voltage comes back up it will go away.