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Charging circuit: Sanity check

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ceengland7(at)gmail.com
Guest

Posted: Fri Mar 25, 2016 2:29 pm Post subject: Charging circuit: Sanity check

Greetings,

I need a sanity check on my current thoughts for the charging circuit in my RV-7.

Please note that this is *not* a typical Lyc installation, so many of the assumed requirements/limits do not apply.Â 

Engine: Mazda Renesis automotive conversion with total electrical dependency.

Alternator(s): 2 ea identical ND internally regulated alternators, each rated at 60 amps.

(This choice was driven by both budget constraints and simplicity of installation)

My goals/choices are:

1. 'Unlimited' availability of electrical power, to avoid in-route diversion in the case of alternator failure. I accept a single battery,due to the very small likelihood of battery failure. Fuel will easily outlast any but very big/heavy batteries. A PC680 is good for only ~45 minutes with only the engine consuming electrons; much less time with avionics on line.

2.Redundant paths of power to the buss, due to the engine's total dependence on electricity.Â 

3. Ability to check both alternators for proper operation before flight.

4. Optional 'auto-start' for 2nd alt, if alt1 goes offline for any reason.

5.Since the auto engine accessory end allows the 'backup' alternator to be the same size as the primary, I'm willing to use one buss and shed individual loads manually, if multiple failures require it.

6.Continuous electrical load for the engine/fuel pump/instrumentation is ~15 amps at full engine output (yes, it varies). This may seem high, but with high pressure injection pumps and injectors, plus high energy automotive coils, this is pretty 'normal', and has been verified by others running similar systems.

7.Balance of additional avionics & other loads, assuming night flight with heated pitot on, would be an additional 27 amps, worse case. There's minimal likelihood of flying this plane in those conditions, but it could happen, so...

8. Intermittent loads of significance would be: fuel transfer pump (8A), flaps (10A), and landing light (5A).

The attached rough sketch shows the IR alternators controlled by regular continuous duty solenoids incorporating Bob's OV modules for OV protection.Â 

The two switches supplying (redundant) power to the buss are 50A DC rated toggles (not a hard requirement, but simpler than additional contactor/switch pairs).

The diode (high current Schottky's are cheap these days) is to prevent powering alt2's contactor control circuit unless alt2's switch was closed, but provide a redundant path from battery to buss.Â 



I desired 'autostart' for alt2, so I added the contactor circuit drawn below the buss. It's intended to be a normally closed relay, held open by the same circuit that supplies power to alt1's contactor.Â 

As I type this, I realize that the NC relay needs a diode between its output terminal and the 5A CB, so that it can't be required to carry buss loads when alt2's switch is closed.

Any issues with performing a 'mag check' (output check) of the two 50A switches and their alt's, with the engine near idle power & minimal loads? (I'm aware of 'load dump' issues when cycling IR alts at high power.)

A related question I'd like an answer to is this: If using internally regulated alternators, is there any issue with leaving both on line at the same time, if they are diode-isolated?

Sorry for the long post, but I thought a detailed narrative was required. Remember, auto engine, identical dual internally regulated alternators.



Thanks,

Charlie

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user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Fri Mar 25, 2016 5:16 pm Post subject: Re: Charging circuit: Sanity check

The relay under the bus will always be energized whenever the main bus is on, unless the 5 amp breaker is tripped or pulled off.  I do not understand its function.

It is my understanding that two alternators on line at the same time will fight each other and cause the system voltage to oscillate unless the voltage set-point of one of them is set a few tenths of a volt below the other one.

  Consider using contactors or heavy duty relays instead of 50 amp switches.  Relays allow remote control so that power can be shut off near the battery.  That feature is important in the event of a forced landing or crash to prevent sparks from igniting leaking fuel.

 Consider supplying power to the man bus at both ends.

_________________
Joe Gores

ceengland7(at)gmail.com
Guest

Posted: Fri Mar 25, 2016 8:25 pm Post subject: Charging circuit: Sanity check

On 3/25/2016 8:16 PM, user9253 wrote:

 	  Quote: 	
		   



 The relay under the bus will always be energized whenever the main bus is on, unless the 5 amp breaker is tripped or pulled off.  I do not understand its function.

 It is my understanding that two alternators on line at the same time will fight each other and cause the system voltage to oscillate unless the voltage set-point of one of them is set a few tenths of a volt below the other one.

    Consider using contactors or heavy duty relays instead of 50 amp switches.  Relays allow remote control so that power can be shut off near the battery.  That feature is important in the event of a forced landing or crash to prevent sparks from igniting leaking fuel.

   Consider supplying power to the man bus at both ends.



 --------

 Joe Gores



Joe,
	




Thanks for the reply. Just took another look at my rough sketch; I drew 

the switch arm incorrectly for the way it is intended to operate. The 

relay in question is SPDT; the 'on' state drives the switch element away 

from the load. Opening alt1's CB removes power, passing power through 

the other CB to alt2's contactor.



I haven't ruled out using contactors, but prefer the switch option. Not 

included in the rough drawing are planned fusible links on the lines 

feeding the 50A switches. I agree with the concern, but after a post 

mentioning similar setups in certified a/c (likely without fusible link 

protection), I decided to explore the option. The 'upside', at least in 

my head, would be removing all the extra failure points that show up 

with the extra components.  (The two alt contactors & starter contactor 

are all within a few inches of the battery and each other, so should 

need no extra protection.)



I've heard the same thing about regulator 'hunting' if there are two 

alts feeding the same buss, but the examples given seem to be of 

externally regulated alts. I do know there are twins with  I am curious 

about whether this will happen with internally regulated alts. Even if I 

must forgo simultaneous operation, I hope I can still do a pre-takeoff 

check by pulling alt1's CB & opening the switch (or contactor..) on that 

side. Not crazy about pulling the CB before each flight, but it *is* a 

pull-able breaker. And I'd probably only do it on cross countries, where 

I'd really need alt2 for endurance.



Charlie

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Sat Mar 26, 2016 8:48 am Post subject: Re: Charging circuit: Sanity check

If both alternators are online at the same time, 

over voltage on one alternator could cause both

over-voltage modules to short and trip their breakers.



Considering that many modern avionics can operate

between 12 and 30 volts, automatic over-voltage

protection might not be necessary.  The battery might

resist voltage rise for a minute until the pilot reacts to

the EFIS high voltage warning and shuts off the alternator.



There is no automatic switch over to alternator 2 because

that bottom relay will never drop out while the main bus

is hot unless alternator 1 breaker is pulled or tripped.



The bottom relay will have to be able to handle full main-

switch #2 current because very little will flow through

the diode.  The relay contacts short out the diode.

_________________
Joe Gores

ceengland7(at)gmail.com
Guest

Posted: Sat Mar 26, 2016 1:01 pm Post subject: Charging circuit: Sanity check

Thanks, Joe; responses inserted below.



On Sat, Mar 26, 2016 at 11:48 AM, 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)>

 

 If both alternators are online at the same time,

 over voltage on one alternator could cause both

 over-voltage modules to short and trip their breakers.

	
You're right, of course. Looks like the only option would be to diode isolate the alts outputs from each other, and do OV detection behind the diodes. Unfortunately, that induces up to .45V drop, even with Schottky diodes. Might be able to get away with that & still charge the battery properly; might not. Would be nice to be able to adjust an internally regulated alternator's output...

 	  Quote: 	
		   

 Considering that many modern avionics can operate

 between 12 and 30 volts, automatic over-voltage

 protection might not be necessary.Â  The battery might

 resist voltage rise for a minute until the pilot reacts to

 the EFIS high voltage warning and shuts off the alternator.

	
True, but I'd prefer not to depend on my reaction time if the event comes during at high workload time. Will keep that option in mind.



 	  Quote: 	
		   

 There is no automatic switch over to alternator 2 because

 that bottom relay will never drop out while the main bus

 is hot unless alternator 1 breaker is pulled or tripped.

	
Correct. I've been focused entirely on OV events, and neglected the *under*voltage possibility. Perhaps I can live with that; with undervoltage alerts from the EFIS and battery capacity, I should have a longer safe response window.

 	  Quote: 	
		   

 The bottom relay will have to be able to handle full main-

 switch #2 current because very little will flow through

 the diode.Â  The relay contacts short out the diode.

	
Correct, and I noticed that as I was typing the 1st email. I think I mentioned an omitted 2nd diode.Â 

I've attached a revised drawing with the additional diode, and the NC relay in the correct position. I also Â added a fuse link to the feed line for the auto-transfer supply, for wire protection. Consider the auto-transfer components below the 'hash' line as optional, but desirable to me.Â 

As drawn, I should be able to pull alt1's CB, close alt2's main supply switch, and start the engine. (Start control not included in the drawing.) After engine start, verify 14V from alt2, then close alt1's main supply switch, open alt2's supply switch, and close alt1's CB. Then verify 14V from alt1.Â 

As mentioned in a previous email, I'm not crazy about resetting the CB every flight, but CB specs seem to indicate ~2500 cycle life for pullable CBs, so it might get the same treatment as Bob's 'battery rotation' concept and be replaced at every 4th or 5th annual. (Even that would be overkill for me; I don't fly that often.)

An OV fault should bring alt2 online automatically, and I'll add detection to the auto-transfer relay to get notification if it activates alt2.

I'll depend on the EFIS for under-voltage notification and bring alt2 online manually by pulling alt1's CB (would also remove any potential load caused by the defective alt1).

Still not locked-in to using the 50A switches, but am still leaning that way. Should have drawn the fuse links in this revision, but forgot. Won't forget to install them, though. 

Thanks again, Joe. Any more thoughts, anyone?

Charlie

trigo(at)mail.telepac.pt
Guest

Posted: Sun Mar 27, 2016 6:44 am Post subject: Charging circuit: Sanity check

Charlie

I didn't get your revised drawing.

Will you please re-post it?

Thanks

Carlos



Enviado do meu iPhone



No dia 26/03/2016, Ã s 16:53, Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> escreveu:

 	  Quote: 	
		  Thanks, Joe; responses inserted below.



On Sat, Mar 26, 2016 at 11:48 AM, 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)>

 

 If both alternators are online at the same time,

 over voltage on one alternator could cause both

 over-voltage modules to short and trip their breakers.

	
You're right, of course. Looks like the only option would be to diode isolate the alts outputs from each other, and do OV detection behind the diodes. Unfortunately, that induces up to .45V drop, even with Schottky diodes. Might be able to get away with that & still charge the battery properly; might not. Would be nice to be able to adjust an internally regulated alternator's output...

 	  Quote: 	
		   

 Considering that many modern avionics can operate

 between 12 and 30 volts, automatic over-voltage

 protection might not be necessary.  The battery might

 resist voltage rise for a minute until the pilot reacts to

 the EFIS high voltage warning and shuts off the alternator.

	
True, but I'd prefer not to depend on my reaction time if the event comes during at high workload time. Will keep that option in mind.



 	  Quote: 	
		   

 There is no automatic switch over to alternator 2 because

 that bottom relay will never drop out while the main bus

 is hot unless alternator 1 breaker is pulled or tripped.

	
Correct. I've been focused entirely on OV events, and neglected the *under*voltage possibility. Perhaps I can live with that; with undervoltage alerts from the EFIS and battery capacity, I should have a longer safe response window.

 	  Quote: 	
		   

 The bottom relay will have to be able to handle full main-

 switch #2 current because very little will flow through

 the diode.  The relay contacts short out the diode.

	
Correct, and I noticed that as I was typing the 1st email. I think I mentioned an omitted 2nd diode. 

I've attached a revised drawing with the additional diode, and the NC relay in the correct position. I also  added a fuse link to the feed line for the auto-transfer supply, for wire protection. Consider the auto-transfer components below the 'hash' line as optional, but desirable to me. 

As drawn, I should be able to pull alt1's CB, close alt2's main supply switch, and start the engine. (Start control not included in the drawing.) After engine start, verify 14V from alt2, then close alt1's main supply switch, open alt2's supply switch, and close alt1's CB. Then verify 14V from alt1. 

As mentioned in a previous email, I'm not crazy about resetting the CB every flight, but CB specs seem to indicate ~2500 cycle life for pullable CBs, so it might get the same treatment as Bob's 'battery rotation' concept and be replaced at every 4th or 5th annual. (Even that would be overkill for me; I don't fly that often.)

An OV fault should bring alt2 online automatically, and I'll add detection to the auto-transfer relay to get notification if it activates alt2.

I'll depend on the EFIS for under-voltage notification and bring alt2 online manually by pulling alt1's CB (would also remove any potential load caused by the defective alt1).

Still not locked-in to using the 50A switches, but am still leaning that way. Should have drawn the fuse links in this revision, but forgot. Won't forget to install them, though. 

Thanks again, Joe. Any more thoughts, anyone?

Charlie

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Sun Mar 27, 2016 9:10 am Post subject: Re: Charging circuit: Sanity check

Here is a schematic for you Charlie

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_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 10:34 am Post subject: Charging circuit: Sanity check

If both alternators are online at the same time,

 over voltage on one alternator could cause both

 over-voltage modules to short and trip their breakers.



  The B&C LR/LS series regulators are fitted with circuits to identify WHICH of two regulators is causing the OV condition. If a regulator is working right, the OV condition drives the field output votlage to zero . . . and OV trip for THAT regulator is inhibited.

  Hence, only the regulator with a runaway field output is allowed to exercise its circuit breaker.

 



 Considering that many modern avionics can operate

 between 12 and 30 volts, automatic over-voltage

 protection might not be necessary.Â  The battery might

 resist voltage rise for a minute until the pilot reacts to

 the EFIS high voltage warning and shuts off the alternator.



  We'd never be allowed to field such a system in TC aircraft. Given that it's so easy to deal with the dual alternator situation, there's no reason to loose much sleep over it.

  If you've installed two, bare-footed crowbar ov modules, then yes, you'd get a dual trip if both alternators are ON . . . then turn them back on one at a time . . . no big deal. If one alternator is a stand-by and OFF for normal ops, then only the operating alternator's ov protection would operate making diagnostics simpler yet.



 As drawn, I should be able to pull alt1's CB, close alt2's main supply switch, and start the engine. (Start control not included in the drawing.) After engine start, verify 14V from alt2, then close alt1's main supply switch, open alt2's supply switch, and close alt1's CB. Then verify 14V from alt1.



    Anytime somebody uses the word 'automatically', my

    little red head-flags go up. One should first

    identify the risk for allowing some otherwise

    automated condition to proceed while awaiting

    pilot notice and action.



    For example, suppose you had two, independently

    controlled alternators driving the same bus

    structure with one alternator held in reserve

    by keeping it's field supply open.



    When the first alternator craps, you get a low

    voltage warning light . . . if you've done due

    diligence with respect to your battery, you can

    finish your coffee, fold and stow a map and

    then bring the standby alternator on line 

    while taxing your stored battery energy to perhaps

    1% of total.



    In other words, what is the value of adding lots

    the bells, whistles, diodes, relays, etc. etc?

    System MTBF is inversely proportional to parts

    count . . . a part that is NOT installed will

    NOT be the part that caused you to drag

    out a toolbox.



    Do your FMEA study guys . . . and evaluate risk

    to comfortable completion of flight before you

    complicate the system.



    As a general rule, there is little or no value

    added to OBAM aircraft systems for having incorporated

    'automatic' features so popular with the purveyors

    of push-button systems over the counters at OSH.



 



 

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 12:34 pm Post subject: Charging circuit: Sanity check

At 05:27 PM 3/25/2016, you wrote:

  	  Quote: 	
		  Greetings,



 I need a sanity check on my current thoughts for the charging circuit in my RV-7.



 Please note that this is *not* a typical Lyc installation, so many of the assumed requirements/limits do not apply.Â 



 Engine: Mazda Renesis automotive conversion with total electrical dependency.



 Alternator(s): 2 ea identical ND internally regulated alternators, each rated at 60 amps.

 (This choice was driven by both budget constraints and simplicity of installation)



 My goals/choices are:

 1. 'Unlimited' availability of electrical power, to avoid in-route diversion in the case of alternator failure. I accept a single battery,due to the very small likelihood of battery failure. Fuel will easily outlast any but very big/heavy batteries. A PC680 is good for only ~45 minutes with only the engine consuming electrons; much less time with avionics on line.



 2.Redundant paths of power to the buss, due to the engine's total dependence on electricity.Â 



 3. Ability to check both alternators for proper operation before flight. 	


   Take a peek at this drawing



  http://tinyurl.com/zpww8ag



   and see if it doesn't do what you want.



   All engine stuff runs off battery bus. E-bus has dual

   feeds one of which mitigates loss of battery contactor.

   S/B alternator feeds battery directly which also

   goes to mitigating loss of battery contactor. Simple

   controls with no hazard to system for having more than

   one alternator active.



 

 

   Bob . . .

ceengland7(at)gmail.com
Guest

Posted: Sun Mar 27, 2016 1:40 pm Post subject: Charging circuit: Sanity check

On 3/27/2016 3:30 PM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		         At 05:27 PM 3/25/2016, you wrote:

               	  Quote: 	
		  Greetings,

           

           I need a sanity check on my current thoughts for the charging           circuit in           my RV-7.

           

           Please note that this is *not* a typical Lyc installation, so           many of the           assumed requirements/limits do not apply.Â 

           

           Engine: Mazda Renesis automotive conversion with total           electrical           dependency.

           

           Alternator(s): 2 ea identical ND internally regulated           alternators, each           rated at 60 amps.

           (This choice was driven by both budget constraints and           simplicity of           installation)

           

           My goals/choices are:

           1. 'Unlimited' availability of electrical power, to avoid           in-route           diversion in the case of alternator failure. I accept a single           battery,due to the very small likelihood of battery failure.           Fuel will           easily outlast any but very big/heavy batteries. A PC680 is           good for only           ~45 minutes with only the engine consuming electrons; much           less time with           avionics on line.

           

           2.Redundant paths of power to the buss, due to the engine's           total           dependence on electricity.Â 

           

           3. Ability to check both alternators for proper operation           before           flight. 	
       

         Take a peek at this drawing

       

                http://tinyurl.com/zpww8ag

         

         and see if it doesn't do what you want.

       

         All engine stuff runs off battery bus. E-bus has dual

         feeds one of which mitigates loss of battery contactor.

         S/B alternator feeds battery directly which also

         goes to mitigating loss of battery contactor. Simple

         controls with no hazard to system for having more than

         one alternator active.

       

       

                

             Bob . . .                	
     Looks good, but do I need multiple busses, when I'll be running 2     identical alternators? The auto conversion engine has the advantage     that I'm not restricted to a vacuum pad mount for the 2nd alt, like     a Lyc would be. So the entire aircraft's electrical loads can be     supported by either alternator.

     

     I'd prefer internally regulated alternators, as well. I've followed     others' issues with them in the past, but I've used them on my     RV-4's for years and I'm comfortable with them. I won't be 'load     dumping' unless the alternator has already failed. My only real     concern would be pre-flight testing of both alternators. My hope     would be engine start with only the backup alternator on line, check     for proper operation, then take the backup off line (while operating     at low power) and bring the primary on line to verify its operation.

     

     Do you see any issues with this?

     

     Thanks,

     

     Charlie

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 2:30 pm Post subject: Charging circuit: Sanity check

Looks good, but do I need multiple busses, when I'll be running 2 identical alternators? 



  Not sure what you mean . . . eliminate the e-bus? Sure, you can do that.



 The auto conversion engine has the advantage that I'm not restricted to a vacuum pad mount for the 2nd alt, like a Lyc would be. So the entire aircraft's electrical loads can be supported by either alternator.



  Understand. The drawing as submitted supports that requirement.



 I'd prefer internally regulated alternators, as well. I've followed others' issues with them in the past, but I've used them on my RV-4's for years and I'm comfortable with them. I won't be 'load dumping' unless the alternator has already failed.



  That's what I have illustrated . . .

  Load dumping damage is a will-o-the-whisp that arose from the smoke with alternators popular in the RV crowd many years ago. I think those were some product offered by Van's. Read the chapter on alternators for a description of how ANY alternator remanufactured by ANY reputable shop demonstrates MULTIPLE max rpm, max load, max temperature load dumps.



 My only real concern would be pre-flight testing of both alternators.



  You can do that. In fact, the airplane can be  routinely flown on either alternator.



 My hope would be engine start with only the backup alternator on line, check

 for proper operation, then take the backup off line (while operating at low power)

 and bring the primary on line to verify its operation.



  That or any other combination of switch-flips are equally valid . . .



  I've revised the drawing to eliminate the e-bus. You still want to connect the s/b alternator directly to the battery so that shutting down the DC PWR MASTER gets the electrical system max-cold . . . for smoke in the cockpit events. See  http://tinyurl.com/zm46jzm

    Bob . . .

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Sun Mar 27, 2016 3:21 pm Post subject: Re: Charging circuit: Sanity check

One bus is OK, but consider:

Is it possible for that bus to lose power?

If it does lose power, what are the symptoms?

If loads critical to flight safety get power from

that bus, what is the backup plan?

Having two alternators does not necessarily mean that the

main power bus will not lose power.  It all depends on how

the aircraft is wired.

The ignition and fuel pump of an electrically dependent

engine should be powered directly from the battery.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 4:16 pm Post subject: Charging circuit: Sanity check

At 06:21 PM 3/27/2016, you wrote:

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



 One bus is OK, but consider:

 Is it possible for that bus to lose power?

 If it does lose power, what are the symptoms?

 If loads critical to flight safety get power from

 that bus, what is the backup plan?

 Having two alternators does not necessarily mean that the

 main power bus will not lose power.  It all depends on how

 the aircraft is wired.

 The ignition and fuel pump of an electrically dependent

 engine should be powered directly from the battery.

 	


   As a general rule, the reliability of a

   well crafted bus structure is as robust

   as prop-bolts. The reason for multiple busses

   in the z-figures speaks efficient utilization

   of a limited resource . . . in the case of Z-11,

   batty only flight. In the case of Z-13/8, limits

   of output on an 8A PM alternator. In the case

   of electrically dependent engines, running all

   the engine stuff from the battery bus keeps

   the fan blowing with all other electrical system

   shut down. 



   Z-12 is illustrative of bus structure on thousands

   of TC aircraft flying an SD-20 s/b alternator. One

   battery, two alternators, one bus . . . oh yeah,

   they DO have an avionics bus but those don't count . . .

   they serve no practical or necessary energy

   management purpose.



   In no instance was a bus added to 'back up' another

   bus. It's existence facilitates partitioning energy

   delivery onto narrowly defined tasks under specific

   circumstances.



 



 

 

   Bob . . .

chaskuss(at)yahoo.com
Guest

Posted: Sun Mar 27, 2016 4:17 pm Post subject: Charging circuit: Sanity check

snipped

 The auto conversion engine has the advantage that  I'm not restricted  to a vacuum pad mount for the 2nd alt, like a Lyc would be.  So the entire aircraft's electrical loads can be supported by either  alternator.

snipped



Are both these alternators going to be belt driven? If so, when one belt breaks, it often fouls the belt for the second alternator and causes it to jump off it's pulleys. Thus, a single belt failure can disable BOTH alternators. Bob's been designing this stuff for over 30 years. How much time/thought did you put into your design? In a failure of all the power generating sources [alternators/dynamos/generators] it would behoove you to have an essential bus, to rapidly shed unneeded power. Also consider a smaller, secondary battery, to power this bus.



Charlie

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 27, 2016 5:35 pm Post subject: Charging circuit: Sanity check

 	  Quote: 	
		  

 Are both these alternators going to be belt driven? If so, when one belt breaks, it often fouls the belt for the second alternator and causes it to jump off it's pulleys. Thus, a single belt failure can disable BOTH alternators. 	


   Excellent question . . . if this is a high-risk

   event irrespective of probability, then replacing

   the belt every 100 hrs or so seems prudent. Also,

   use Gates belts if you can get 'em . . . 



   Plan B might include a detailed load analysis after

   having shed all non-essential loads while maintaining

   battery capacity at useful endurance levels. 



 

 

   Bob . . .

ceengland7(at)gmail.com
Guest

Posted: Sun Mar 27, 2016 6:06 pm Post subject: Charging circuit: Sanity check

-------- Original message --------

From: "Robert L. Nuckolls, III"  

Date:03/27/2016  8:31 PM  (GMT-06:00) 

To: aeroelectric-list(at)matronics.com 

Subject: Re: AeroElectric-List: Charging circuit: Sanity check 

  	  Quote: 	

 Are both these alternators going to be belt driven? If so, when one belt breaks, it often fouls the belt for the second alternator and causes it to jump off it's pulleys. Thus, a single belt failure can disable BOTH alternators. 	

   Excellent question . . . if this is a high-risk

   event irrespective of probability, then replacing

   the belt every 100 hrs or so seems prudent. Also,

   use Gates belts if you can get 'em . . . 

   Plan B might include a detailed load analysis after

   having shed all non-essential loads while maintaining

   battery capacity at useful endurance levels. 

   Bob . . .  

Sorry I haven't been on much today; intermittent house power all day. 

Typing on my phone. 

Both will likely be belt driven, but I haven't lost a belt on any of my vehicles in at least 30 years of neglecting them. Not ignoring the possibility, but I can't complain about the odds.  

I am considering direct drive for one. Cruise rpm will be 5500-6000 so should be enough to keep charging even direct drive. 

Charlie

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Mar 29, 2016 7:10 am Post subject: Charging circuit: Sanity check

Correct. Most automotive products are magnetically

    'geared' for full rated output in the 5000 rpm

    range.



 

   Bob . . .

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