Skymaster Forum  

Go Back   Skymaster Forum > Messages
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
Thread Tools Rate Thread Display Modes
  #1  
Unread 09-26-17, 12:57 AM
CO_Skymaster CO_Skymaster is offline
Registered User
 
Join Date: Aug 2008
Location: Colorado Springs, CO
Posts: 150
CO_Skymaster is on a distinguished road
Auxiliary Power Units (APU)

I'm looking at purchasing an APU for my Skymaster, but I can't find specific information on the type to buy. For those who have one, can they be used for Avionics only, or can they start the engine if the battery has run down. I'm looking at 24V types with capacities of 20amps, 25amps, and 50amps. Does anyone know the amps needed to turn over an IO-360?

Thanks for any help.

Karl
Reply With Quote
  #2  
Unread 09-26-17, 02:37 PM
JimC's Avatar
JimC JimC is offline
Registered User
 
Join Date: Aug 2012
Location: United States
Posts: 301
JimC is on a distinguished road
From the Owner's Manual for a 1971 F model:

"When an external power source is connected, a split bus contactor automatically removes power from the electronic section of the split bus to protect against damage to the transistors in the electronic equipment by transient voltage from the power source. Therefore, the external power source can not be used when checking electronic components."

Last edited by JimC : 09-26-17 at 03:10 PM.
Reply With Quote
  #3  
Unread 09-26-17, 11:44 PM
CO_Skymaster CO_Skymaster is offline
Registered User
 
Join Date: Aug 2008
Location: Colorado Springs, CO
Posts: 150
CO_Skymaster is on a distinguished road
Thanks Jim,

I am starting to discover the power requirements to start an aircraft piston engine. It's 28V, but it looks like the large APUs that the FBO on my field use have a capacity of 400amp. It seems to start the engine does require about 250 to 300 amp. It looks like none of the APU's I was looking at would work. I can use it to power the avionics for maintenance. I have a 337-A, and I looked at my owners manual. That year does allow connected to a external power source, but I have to use different procedures if I'm using a Generator APU, or series of batteries APU. Thanks for the help,

Karl
Reply With Quote
  #4  
Unread 09-29-17, 08:43 PM
hharney's Avatar
hharney hharney is offline
Forum Administrator
 
Join Date: Jul 2002
Location: Michigan (8D4)
Posts: 2,253
hharney is on a distinguished road
https://www.barnstormers.com/ad_mana...php?id=1301882
__________________
Herb R Harney
1968 337C

Flying the same Skymaster for 47 years
Reply With Quote
  #5  
Unread 09-29-17, 09:48 PM
JimC's Avatar
JimC JimC is offline
Registered User
 
Join Date: Aug 2012
Location: United States
Posts: 301
JimC is on a distinguished road
Another question: do you think your battery will be run down so often that you need to have your own APU?

I think starting APUs make sense for FBOs - for individual owners, not so much. What am I missing?
Reply With Quote
  #6  
Unread 10-01-17, 03:04 PM
hharney's Avatar
hharney hharney is offline
Forum Administrator
 
Join Date: Jul 2002
Location: Michigan (8D4)
Posts: 2,253
hharney is on a distinguished road
Quote:
Originally Posted by JimC View Post
Another question: do you think your battery will be run down so often that you need to have your own APU?

I think starting APUs make sense for FBOs - for individual owners, not so much. What am I missing?
If you need an APU to start your Skymaster you probably have a bad battery or somebody left the master on. Once the battery is down beyond starting it will need to be charged before it's going to work properly if at all. Keep a battery conditioner on the battery at all times when it's not in use and the battery will provide good results for the time period expected. I change mine every 3 years even though it will still start the engine. These batteries only have an intended life of 3 to 4 years and that's if it is properly maintained. The maintenance between using is most important. Think about how long the battery is going to last when you loose alternators in IMC. I want the most I can get. Change the battery before it goes dead and maintain the battery between flights.
__________________
Herb R Harney
1968 337C

Flying the same Skymaster for 47 years
Reply With Quote
Reply


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 05:18 PM.


Powered by vBulletin® Version 3.6.9
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.