VAF Forums

VAF Forums (https://vansairforce.net/community/index.php)
-   Electrical Systems (https://vansairforce.net/community/forumdisplay.php?f=43)
-   -   Battery backup versus standby alternator (https://vansairforce.net/community/showthread.php?t=149176)

rapid_ascent 05-02-2017 08:05 PM

Lots of stories on VAF about failed alternators. Batteries are a maintanence item that can have a low probability of failure if properly maintained. I plan a dual alternator system. I may have a small secondary battery too but my first line of defense is the backup alternator.

Bevan 05-02-2017 08:43 PM

Batteries degrade (fail) slowly over time in that they store less useable energy, and yet we still fly with them never really knowing their capacity at that particular time.

AlexPeterson 05-02-2017 09:34 PM

two alternators vs two batteries
 
It also depends also on the type of ignition one has. I have dual lightspeed ignitions, so I prefer two batteries. I have a setup to test the backup battery (whose only function is to feed the second ignition) using a 12v lamp. This draws a known current, so I can calculate the effective amp-hrs available until it drops to some specific voltage. I test it annually.

DanH 05-03-2017 05:26 AM

There is no one answer.

I entirely agree with the dual alternator strategy for an IFR bird, and lean toward dual alt/dual battery for EFI/EI.

That said, the KIS approach to VFR with a low-draw (<1 amp) electronic ignition is a small secondary battery. KIS is good.

vic syracuse 05-03-2017 05:37 AM

Quote:

Originally Posted by AlexPeterson (Post 1170341)
It also depends also on the type of ignition one has. I have dual lightspeed ignitions, so I prefer two batteries. I have a setup to test the backup battery (whose only function is to feed the second ignition) using a 12v lamp. This draws a known current, so I can calculate the effective amp-hrs available until it drops to some specific voltage. I test it annually.

For those with dual electronic ignitions I would encourage you to check the backup battery as often as possible, certainly more than once per year. I have seen more than one airplane come through my shop with the backup battery reading 5 volts! Sometimes it was due to a charging system failure and sometimes it was a corroded connector on the battery. Klaus has a schematic that allows you to test the backup battery prior to takeoff.

Vic

AlexPeterson 05-03-2017 07:10 AM

Quote:

Originally Posted by vic syracuse (Post 1170371)
For those with dual electronic ignitions I would encourage you to check the backup battery as often as possible, certainly more than once per year. I have seen more than one airplane come through my shop with the backup battery reading 5 volts! Sometimes it was due to a charging system failure and sometimes it was a corroded connector on the battery. Klaus has a schematic that allows you to test the backup battery prior to takeoff.

Vic

Good point - I do check the voltage of this battery prior to startup before every flight. I also full time monitor its voltage during flight to be sure the proper charging voltage is being applied. The test I do annually is a capacity check, where I run it down to perhaps 10 volts, to determine amp-hr capacity.

Veetail88 05-03-2017 07:16 AM

You should check with Rosie about this, but read his Carribean trip thread first! :)

JHartline 05-03-2017 10:19 AM

Thank you all for the replies
 
I feel like the available backup-battery solutions are getting better but maybe not the ideal situation for me just yet. And the points about how to avoid getting stranded somewhere are well made. While my mission won't take me into austere locations we have all seen how deserted ramps are late on a weekend evening when we're trying to get home.

I will be talking with Stein very soon and I'm sure he will provide some great options to consider. Thanks for the input - it is always valuable and always appreciated.

vic syracuse 05-03-2017 11:43 AM

Well done
 
Quote:

Originally Posted by AlexPeterson (Post 1170393)
Good point - I do check the voltage of this battery prior to startup before every flight. I also full time monitor its voltage during flight to be sure the proper charging voltage is being applied. The test I do annually is a capacity check, where I run it down to perhaps 10 volts, to determine amp-hr capacity.

Well done!

Vic

DanH 05-03-2017 02:44 PM

Quote:

Originally Posted by vic syracuse (Post 1170371)
Klaus has a schematic that allows you to test the backup battery prior to takeoff.

Vic, got a link? Found these two (both appear to be voltage monitoring)...

http://lightspeed-aero.com/Manuals/PS_Diagram.htm

http://lightspeed-aero.com/Images/du...ator-LSEr4.pdf

...but nothing to test battery capacity.

Re voltage monitoring, these are less than $5 delivered, and can be configured to alarm:

http://www.vansairforce.com/communit...&postcount=166


All times are GMT -6. The time now is 01:54 AM.