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DPDT Toggle switch for BAT and 2 Alternators?

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supik

Joined: 22 Aug 2018
Posts: 70

Posted: Thu Aug 23, 2018 8:49 am Post subject: DPDT Toggle switch for BAT and 2 Alternators?

To keep things simple I was thinking about using the Honeywell DPDT on/on/on toggle switch for switching on BAT + Alternator 1 & Alternator 2 (aux alt) at the same time. The design would include one main battery and the IBBS standby bat.



Switch position logic:



1. BAT + ALT 1 & ALT 2

2. BAT

3. OFF



To manually switch of either ALT 1 or ALT 2 I would have to pull either ALT1 or ALT2 field CBs positioned after the main switch. I understand 2 possible design problems:



1. The wire going to the main switch feeding the ALT fields has no protection

2. The switch would be a single point of failure



-any other problems I am missing with this setup?



thanks!

https://www.steinair.com/product/locking-toggle-switch-dpdt-ononon/

_________________
Igor

RV10 in progress

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Thu Aug 23, 2018 9:28 am Post subject: Re: DPDT Toggle switch for BAT and 2 Alternators?

One overlooked problem is the $72 cost of the switch plus shipping.

_________________
Joe Gores

John M Tipton

Joined: 07 Aug 2018
Posts: 45
Location: Devon - England

Posted: Thu Aug 23, 2018 1:52 pm Post subject: DPDT Toggle switch for BAT and 2 Alternators?

Plenty on eBay: £10.00 or so



John



Sent from my iPad



     ----x--O--x----



 	  Quote: 	
		   On 23 Aug 2018, at 6:28 pm, user9253 <fransew(at)gmail.com> wrote:

 

 

 

 One overlooked problem is the $72 cost of the switch plus shipping.  

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=482651#482651

ceengland7(at)gmail.com
Guest

Posted: Sun Aug 26, 2018 5:15 am Post subject: DPDT Toggle switch for BAT and 2 Alternators?

On Sun, Aug 26, 2018 at 1:51 AM, supik <bionicad(at)hotmail.com (bionicad(at)hotmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "supik" <bionicad(at)hotmail.com (bionicad(at)hotmail.com)>

 [quote="nuckolls.bob(at)aeroelect"]At 11:49 AM 8/23/2018, you wrote:

 > --> AeroElectric-List message posted by: "supik" 

 > 

 >    Unless you've been doing this for a long time, there's

 >    significant risk that 'simplifications' move your

 >    risk factors in the wrong direction.

 > 

 >  

 >  

 >    Bob . . .

 Bob, that's the reason why I am asking here. I was looking at the Z figures, but haven't found a combo I was looking for:

 1 Main bat

 1 IBBS backup bat

 2 Alternators

 .and the option that none of the Alts can be selected ON unless the Bat is ON. With BAT ON, separate selection of Alternators shall be possible.

 thanks,

 --------

 Igor

 RV10 in progress

If that's a big deal to you, how about using a double pole single throw master switch. One side supplies the ground path to energize the battery contactor, as shown in the Z drawings. The other side feeds DC power from the main bus to the two alternator control switches. Wit master on, either alt can be selected; with master off, neither can be powered.

Charlie

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Sun Aug 26, 2018 9:21 am Post subject: Re: DPDT Toggle switch for BAT and 2 Alternators?

The battery should be connected whenever an alternator is operating because the battery stabilizes electrical system voltage.  Without the battery, system voltage could vary plus or minus 1 volt or so.  That voltage instability might cause the over-voltage protection device to activate.

  It is OK to mix and match features from several of the Z wiring diagrams.  If you draw your own schematic with the features that you want, post it on this forum for peer review.  An easy free program for drawing schematics is ExpressSCH.

https://www.expresspcb.com/free-cad-software/

_________________
Joe Gores

donvansanten(at)gmail.com
Guest

Posted: Tue Aug 28, 2018 8:30 pm Post subject: DPDT Toggle switch for BAT and 2 Alternators?

Bob,

The manufacture of Advanced Flight FFIS' recommends the IBBS system

and provides inputs to their systems for tje IBBS. For me it mainly a

brownout battery to keep the two EFIS alive during starting. The EFIS

system is the only source of oil pressure measurements. The re-boot

for the EFIS takes longer than the time I am willing to run the engine

without knowing the oil pressure.   I have the z12 system minus the

battery buss and e bus. I noticed that the standby alternator is

connected to the starter contactor via a fusible link that uses a #16

wire as the fuse.The feed to that link is a #10 wire. I thought that

the normal design was to use a fuse link 4 sizes less than the feed.

Is it ok to use #14 wire or is the #16 there to protect the alternator

from putting out enough current to damage the alternator The B&C kit I

bought included a 40 amp anl which also makes me wonder about the #16

fuse link. Thanks in advance for any explanation.

On Mon, Aug 27, 2018 at 4:17 PM Robert L. Nuckolls, III

<nuckolls.bob(at)aeroelectric.com> wrote:

 	  Quote: 	
		  

 At 06:22 PM 8/26/2018, you wrote:



 



 IBBS is a small Lithium battery.

 http://www.tcwtech.com/ibbs_integrated_backup_battery_system_3ah_6ah.html



 --------

 Joe Gores

   Okay, thanks.  I just downloaded the patent on the

   ibbs  (8,189,305) along with 'related patents' citen

   on their website. I wonder if the circuitry in their

   patent truly represents the product . . . it's

   REALLY busy!  The patent is pretty long in the

   tooth . . . and much simpler approaches

   to a similar product are on the market.



   Okay, installation instructions do include

   YEARLY checks for continued air worthiness.

   I presume one would check the chip's battery

   at the same time . . . which means the operator

   needs to develop his/her own airworthiness

   verification protocols.



   Igor, what size IBBS are you installing

   and have you established your projected loads

   and design goals for endurance?





   Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Wed Aug 29, 2018 3:29 am Post subject: Re: DPDT Toggle switch for BAT and 2 Alternators?

In any circuit it is OK to use a smaller fuse than specified as long as it doesn't nuisance blow.  Same is true for a fuselink as long as it doesn't get too hot or drop too much voltage.  It should be OK to use a 14AWG fuselink.  But why not use 16AWG?  You could also use the ANL 40 instead of a fuselink.  The purpose of a fuse or fuselink is not to protect the alternator, but to protect the battery and wires.  An alternator does not need to be protected because it is self current limiting.   It can not put out more current than it is capable of.  The connected load determines the current.  An alternator will only put out what the load demands.

_________________
Joe Gores

donvansanten(at)gmail.com
Guest

Posted: Wed Aug 29, 2018 9:04 am Post subject: DPDT Toggle switch for BAT and 2 Alternators?

Thanks Joe, I used to know that. I got fooled by the warning in the B&C manual that says the standby alternator must be kept below 30 amps to avoid damage. It is a 40 amp alternator de-rated to 30A.



On Wed, Aug 29, 2018, 04:34 user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:



 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 In any circuit it is OK to use a smaller fuse than specified as long as it doesn't nuisance blow.  Same is true for a fuselink as long as it doesn't get too hot or drop too much voltage.  It should be OK to use a 14AWG fuselink.  But why not use 16AWG?  You could also use the ANL 40 instead of a fuselink.  The purpose of a fuse or fuselink is not to protect the alternator, but to protect the battery and wires.  An alternator does not need to be protected because it is self current limiting.   It can not put out more current than it is capable of.  The connected load determines the current.  An alternator will only put out what the load demands.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=482765#482765

 

 

 

 

 

 

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user9253

Joined: 28 Mar 2008
Posts: 1927
Location: Riley TWP Michigan

Posted: Wed Aug 29, 2018 3:02 pm Post subject: Re: DPDT Toggle switch for BAT and 2 Alternators?

The danger to alternators is over heating when heavily loaded. A blast tube can help.

_________________
Joe Gores

donvansanten(at)gmail.com
Guest

Posted: Wed Aug 29, 2018 4:10 pm Post subject: DPDT Toggle switch for BAT and 2 Alternators?

Thanks. My load analysis has me below 20a at night vfr and also ifr. After some hot starts especially those that take longer than usual I have seen as high as 45a on my primary alt. Have flown this way for over 2 yrs. Do not see any real issues. Was just wondering why Bob picked 16awg instead of 14 on z12.



On Aug 29, 2018 16:09, "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)> wrote: 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 The danger to alternators is over heating when heavily loaded.  A blast tube can help.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=482783#482783

 

 

 

 

 

 

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