Matronics Email Lists Forum Index Matronics Email Lists
BBS Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Battery, Alternator, CB

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
arcticarrow(at)gmail.com
Guest





PostPosted: Mon Jan 01, 2018 3:01 pm    Post subject: Battery, Alternator, CB Reply with quote

Happy New Year!

The quest for understanding continues: Here’s the issue - A recent post described a situation where a field switch CB had been opened in flight accidentally and the battery had run down. When it was discovered and closed the alternator came back on line but opened the Alternator CB because it was rated less than the charging rate of the alternator. So there was no way to charge the battery. Hence the recommendation to size the alternator CB to the alternator capacity. But what about the battery capacity?

I believe its true that the alternator puts out is rated capacity whenever the field circuit allows it to operate. So after engine start a 70 amp alternator rapidly recharges the battery and the field circuit opens and closes to keep the system up to the set voltage of say 14.2. I’ve read elsewhere that the charging rate should not be over 40% of the amp hour capacity of the AGM batteries. So if I have a 70 amp alternator and a 35 amp hour battery it looks like it won’t last very long because of too high a rate of charging.

Do I understand what I’m writing about? Any suggestions?

Thanks to all of you,
Bernie


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
user9253



Joined: 28 Mar 2008
Posts: 1135
Location: Riley TWP Michigan

PostPosted: Mon Jan 01, 2018 4:38 pm    Post subject: Re: Battery, Alternator, CB Reply with quote

Find and read the battery manufacturer's charging recommendations. The concern is voltage, not current. The battery takes whatever current that it wants. The alternator capacity does not determine the current that charges the battery. Assuming voltage regulator set-point is correct, a 35 amp alternator will not charge a battery any faster than a 70 amp alternator (unless the battery is completely run down). I might not have explained it very well, but I do not think there is anything to worry about.

- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Joe Gores
Back to top
View user's profile Send private message
ceengland7(at)gmail.com
Guest





PostPosted: Mon Jan 01, 2018 5:30 pm    Post subject: Battery, Alternator, CB Reply with quote

On 1/1/2018 5:01 PM, Bernie Willis wrote:
Quote:


Happy New Year!

The quest for understanding continues: Here’s the issue - A recent post described a situation where a field switch CB had been opened in flight accidentally and the battery had run down. When it was discovered and closed the alternator came back on line but opened the Alternator CB because it was rated less than the charging rate of the alternator. So there was no way to charge the battery. Hence the recommendation to size the alternator CB to the alternator capacity. But what about the battery capacity?

I believe its true that the alternator puts out is rated capacity whenever the field circuit allows it to operate. So after engine start a 70 amp alternator rapidly recharges the battery and the field circuit opens and closes to keep the system up to the set voltage of say 14.2. I’ve read elsewhere that the charging rate should not be over 40% of the amp hour capacity of the AGM batteries. So if I have a 70 amp alternator and a 35 amp hour battery it looks like it won’t last very long because of too high a rate of charging.

Do I understand what I’m writing about? Any suggestions?

Thanks to all of you,
Bernie
I'd agree with Joe. 'Traditionally', field breakers have been around 5

amps, but some regulators can try to draw more than that to get the
alternator's output *voltage* up to the set point when there's a really
heavy load on its output (like all the electrical stuff operating and
suddenly hitting it with the load of a dead battery).

The alternator/regulator don't really control output *current*; they
just try to maintain setpoint *voltage*.  If a really big load is added,
like pitot heat + landing lights + etc etc, plus a totally dead battery,
then the alt/reg pair will try to supply whatever current is required to
keep the voltage at the setpoint. (Ohm's Law).

As Joe said, 14.x volts applied to a fully charged battery will result
in virtually no current flow into the battery. But the same 14.x volts
applied to a nearly dead battery will likely result in close to full
available current from the alternator into the battery.

The battery size vs alternator size 'waters' got muddied badly on
another aviation forum by a certain lithium battery company telling its
customers that they *did* have to limit alternator current capacity
based on the lithium battery's capacity. That battery has a charge
controller built in, so it shouldn't care about alternator size (just
like a little 0.01 amp LED lamp doesn't care if it's hooked to a battery
capable of 400 amps). Unfortunately, they've never been able to give a
rational explanation for their rule.

The direct answer to your question about too much charge current is that
it shouldn't be dead in a flying airplane. Smile Seriously, the fact that
it was allowed to go dead while in flight created a 'no good answer'
situation, since an a/c charging system isn't designed to do a
conditioned recharge of a dead battery.

Charlie

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
nuckolls.bob(at)aeroelect
Guest





PostPosted: Tue Jan 02, 2018 3:36 am    Post subject: Battery, Alternator, CB Reply with quote

At 05:01 PM 1/1/2018, you wrote:
Quote:
--> AeroElectric-List message posted by: Bernie Willis <arcticarrow(at)gmail.com>

Happy New Year!

The quest for understanding continues: Here’s the issue - A recent post described a situation where a field switch CB had been opened in flight accidentally and the battery had run down. When it was discovered and closed the alternator came back on line but opened the Alternator CB because it was rated less than the charging rate of the alternator. So there was no way to charge the battery. Hence the recommendation to size the alternator CB to the alternator capacity. But what about the battery capacity?

I believe its true that the alternator puts out is rated capacity whenever the field circuit allows it to operate. So after engine start a 70 amp alternator rapidly recharges the battery and the field circuit opens and closes to keep the system up to the set voltage of say 14.2. I’ve read elsewhere that the charging rate should not be over 40% of the amp hour capacity of the AGM batteries. So if I have a 70 amp alternator and a 35 amp hour battery it looks like it won’t last very long because of too high a rate of charging.

Do I understand what I’m writing about? Any suggestions?

The alternator b-lead breaker protects the b-lead
wire . . . it has no duties with respect to limiting
output of the alternator. B-lead protection is best
accomplished under the cowl with a current limiter
(really FAT fuse) thus keeping the alternator's
b-lead out of the cockpit. This has be common practice
on TC aircraft for 50 years.

That admonition for limiting recharge rate on ANY
battery is the fondest fantasy of the battery
designers . . . a condition that may well maximize
battery service life in deep discharge applications
but doesn't apply to service as a cranking battery
in vehicles.

Suggest you move your b-lead protection out to the
firewall adjacent to the starter contactor as illustrated
in Z13/8

https://goo.gl/BKufLb

. . . and other z-figures. Protect with a current
limiter rated for 50-70A. You can get miniature
devices off eBay at reasonable prices . . .

https://goo.gl/wG73m1

You can build a fuse holder with 10-32 or 1/4-28
hardware and some suitable base material.

https://goo.gl/cMQtA4

For years during the changeover from generators
to alternators, TC aircraft featured b-lead
breakers on the panel DESIGNED to nuisance
trip under certain conditions as explained in
the narrative for Figure 17-2 of the 'Connection.

[img]cid:.0[/img]

Current limiters are EXCEEDINGLY robust for their
'current carry ratings' . . . A 50A limiter will
carry 90A indefinitely. But opens in about 300
milliseconds with a 200A load.

[img]cid:.1[/img]


The battery-sources hard fault will be hundreds of
amps . . . the current limiter will open very quickly
while being immune to nuisance trips for normal, expected
operating conditions.


Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



180ce3d7.jpg
 Description:
 Filesize:  355.53 KB
 Viewed:  311 Time(s)

180ce3d7.jpg



180ce3e6.jpg
 Description:
 Filesize:  216.03 KB
 Viewed:  311 Time(s)

180ce3e6.jpg


Back to top
arcticarrow(at)gmail.com
Guest





PostPosted: Tue Jan 02, 2018 8:13 am    Post subject: Battery, Alternator, CB Reply with quote

Bob,Makes sense, ordered Aero Connection for a back up.
Bernie

Sent from my iPhone

On Jan 2, 2018, at 2:35 AM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:
At 05:01 PM 1/1/2018, you wrote:
Quote:
--> AeroElectric-List message posted by: Bernie Willis <arcticarrow(at)gmail.com (arcticarrow(at)gmail.com)>

Happy New Year!

The quest for understanding continues: Here’s the issue - A recent post described a situation where a field switch CB had been opened in flight accidentally and the battery had run down. When it was discovered and closed the alternator came back on line but opened the Alternator CB because it was rated less than the charging rate of the alternator. So there was no way to charge the battery. Hence the recommendation to size the alternator CB to the alternator capacity. But what about the battery capacity?

I believe its true that the alternator puts out is rated capacity whenever the field circuit allows it to operate. So after engine start a 70 amp alternator rapidly recharges the battery and the field circuit opens and closes to keep the system up to the set voltage of say 14.2. I’ve read elsewhere that the charging rate should not be over 40% of the amp hour capacity of the AGM batteries. So if I have a 70 amp alternator and a 35 amp hour battery it looks like it won’t last very long because of too high a rate of charging.

Do I understand what I’m writing about? Any suggestions?

The alternator b-lead breaker protects the b-lead
wire . . . it has no duties with respect to limiting
output of the alternator. B-lead protection is best
accomplished under the cowl with a current limiter
(really FAT fuse) thus keeping the alternator's
b-lead out of the cockpit. This has be common practice
on TC aircraft for 50 years.

That admonition for limiting recharge rate on ANY
battery is the fondest fantasy of the battery
designers . . . a condition that may well maximize
battery service life in deep discharge applications
but doesn't apply to service as a cranking battery
in vehicles.

Suggest you move your b-lead protection out to the
firewall adjacent to the starter contactor as illustrated
in Z13/8

https://goo.gl/BKufLb

. . . and other z-figures. Protect with a current
limiter rated for 50-70A. You can get miniature
devices off eBay at reasonable prices . . .

https://goo.gl/wG73m1

You can build a fuse holder with 10-32 or 1/4-28
hardware and some suitable base material.

https://goo.gl/cMQtA4

For years during the changeover from generators
to alternators, TC aircraft featured b-lead
breakers on the panel DESIGNED to nuisance
trip under certain conditions as explained in
the narrative for Figure 17-2 of the 'Connection.

[img]cid:.0[/img]

Current limiters are EXCEEDINGLY robust for their
'current carry ratings' . . . A 50A limiter will
carry 90A indefinitely. But opens in about 300
milliseconds with a 200A load.

[img]cid:.1[/img]


The battery-sources hard fault will be hundreds of
amps . . . the current limiter will open very quickly
while being immune to nuisance trips for normal, expected
operating conditions.


Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



180ce3d7.jpg
 Description:
 Filesize:  355.53 KB
 Viewed:  307 Time(s)

180ce3d7.jpg



180ce3e6.jpg
 Description:
 Filesize:  216.03 KB
 Viewed:  307 Time(s)

180ce3e6.jpg


Back to top
nuckolls.bob(at)aeroelect
Guest





PostPosted: Tue Jan 02, 2018 10:23 am    Post subject: Battery, Alternator, CB Reply with quote

I'd agree with Joe. 'Traditionally', field breakers have been around 5 amps, but some regulators can try to draw more than that to get the alternator's output *voltage* up to the set point when there's a really heavy load on its output (like all the electrical stuff operating and suddenly hitting it with the load of a dead battery).

The current draw of a regulator is no greater
than the maximum current draw of the alternator
field . . . which in turn is limited by its
resistance. Few alternators of any size will exceed
4A of field current, most are in the 3A range.

The alternator/regulator don't really control output *current*; they just try to maintain setpoint *voltage*. If a really big load is added, like pitot heat + landing lights + etc etc, plus a totally dead battery, then the alt/reg pair will try to supply whatever current is required to keep the voltage at the setpoint. (Ohm's Law).

Only up to the alternator's inherent current limit
which is set by the design of the alternator. Generators
used to require independent output current limiting . . .
they would willingly grunt a load far in excess of
their ratings often resulting in burned armature
wires and commutators.

An alternator is inherently current limited. If
you discover an alternator with burned stator
wires and/or fused diodes, then yes . . . it was
no doubt subjected to loads in the upper range
of its ratings . . . BUT INADEQUATELY COOLED.

As Joe said, 14.x volts applied to a fully charged battery will result in virtually no current flow into the battery. But the same 14.x volts applied to a nearly dead battery will likely result in close to full available current from the alternator into the battery.

A lead-acid battery, fully charged, sitting at room
temperature presents an open circuit terminal
voltage of about 13.0 volts. Applying an external
source at slightly above 13.0 will not charge the
battery (i.e. convert the state of its chemistry)
but it will SUPPORT any self discharge currents
inherent in the physics of ANY lead-acid battery.

This is what a maintainer does . . . got a couple 100a.h.
batteries in the shop right now. One sitting on Battery a
Tender showing a green light (charged), it measures
13.11 volts; the other sitting open circuit for the past
week, it measures 12.88 volts.

A deeply discharged battery floated on a 13.8v charger
will eventually accumulate a charge at or near 100% of
rated capacity . . . it might take weeks. For example,
the two batteries cited above were purchased in July
and installed in a friend's John Deere road grader . . .
two 100a.h. batteries in series for 24v system.

I became aware that the grader had not been used in
several months. Went out to his ranch and absconded with
both batteries. Just for grins, I put them both on Battery
Tenders (0.75A charge rate). It took about a week
for the BTs to show a green light . . . but they DID
ultimately boost the batteries tot he 14.4 or so
volts that causes the BT to transition from CHARGE
to MAINTENANCE.

[img]cid:.0[/img]

I am pleased to suggest that the little Battery Tender Jr. should
not be discounted as a useful charge/maintenance tool for just
about any size battery. Oh, yeah . . . the plot above was measured
as an exemplar BT recharge profile . . . it was not taken on the
batteries cited.

The battery size vs alternator size 'waters' got muddied badly on another aviation forum by a certain lithium battery company telling its customers that they *did* have to limit alternator current capacity based on the lithium battery's capacity. That battery has a charge controller built in, so it shouldn't care about alternator size (just like a little 0.01 amp LED lamp doesn't care if it's hooked to a battery capable of 400 amps). Unfortunately, they've never been able to give a rational explanation for their rule.

Pretty simple . . . not all lithium ion products are the same
irrespective of their common chemistry. LiFePO4 is the chemistry
of choice for robustness and generally 'airplane friendly' resistance
to catching fire. However, the cell's ability to either sink or source
high current values for extended periods of time is related to
internal resistance (i.e. losses expressed as heating).

There are LiFePO4 cells specifically tailored to accept and/or
deliver large currents . . . an ESSENTIAL quality for miniature
motive power (models, etc.) For example, this A123 product is
speced to accept/deliver 30A

https://tinyurl.com/yanszgtb

This is approx 28 times the a.h. rating of the cell. This
cell . . .

https://tinyurl.com/y88ca38m

while 'rated' at 9x the capacity of the A123 would toss in the towel at
10A of either charge/discharge. Most of the Lithium suppliers
for light aircraft cranking batteries are using ROBUST cells.

The direct answer to your question about too much charge current is that it shouldn't be dead in a flying airplane. Smile Seriously, the fact that it was allowed to go dead while in flight created a 'no good answer' situation, since an a/c charging system isn't designed to do a conditioned recharge of a dead battery.

This goes to the core of the alternator vs. battery size
discussion. When you crank an engine, the battery is generally
tasked to the tune of about 5% of the contained energy. Yes,
when the alternator comes on line, it will happily deliver
whatever it can to meet the battery's acceptance rate which
could be quite high . . . for a minute or so whereupon it begins
to taper off. When operated in this 'normal' set of circumstances,
even the smallest batteries are not damaged by what might otherwise
appear to be an abusive recharge rate.

However, allowing the ship's alternator to recharge a deeply
discharged battery is another matter. This generally NEVER happens
over the lifetime of the battery in your car . . . or your airplane.
Most manuals for TC aircraft call for removing the deeply discharged
battery from the airplane for bench recharge and inspection
for airworthiness.

The short answer: Select a lithium battery fabricated from
robust cells. Be wary of "jump starting" the airplane and allowing
the ship's alternator to stuff electrons back into a deeply
discharged chemistry. If you can, go for the more sophisticated
lithium products that emulate the features built into batteries
qualified for TC aircraft . . . i.e. adequate, built in protection
for over discharge, over charge, excessive current draw, etc.

EarthX is one such product . . . there may be others by now. Haven't
been tracking the market.


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



198205df.jpg
 Description:
 Filesize:  127 KB
 Viewed:  306 Time(s)

198205df.jpg


Back to top
ceengland7(at)gmail.com
Guest





PostPosted: Tue Jan 02, 2018 1:35 pm    Post subject: Battery, Alternator, CB Reply with quote

On Tue, Jan 2, 2018 at 12:22 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:
I'd agree with Joe. 'Traditionally', field breakers have been around 5 amps, but some regulators can try to draw more than that to get the alternator's output *voltage* up to the set point when there's a really heavy load on its output (like all the electrical stuff operating and suddenly hitting it with the load of a dead battery).

  The current draw of a regulator is no greater
  than the maximum current draw of the alternator
  field . . . which in turn is limited by its
  resistance. Few alternators of any size will exceed
  4A of field current, most are in the 3A range.

The alternator/regulator don't really control output *current*; they just try to maintain setpoint *voltage*.  If a really big load is added, like pitot heat + landing lights + etc etc, plus a totally dead battery, then the alt/reg pair will try to supply whatever current is required to keep the voltage at the setpoint. (Ohm's Law).

  Only up to the alternator's inherent current limit
  which is set by the design of the alternator. Generators
  used to require independent output current limiting . . .
  they  would willingly grunt a load far in excess of
  their ratings often resulting in burned armature
  wires and commutators.

  An alternator is inherently current limited. If
  you discover an alternator with burned stator
  wires and/or fused diodes, then yes . . . it was
  no doubt subjected to loads in the upper range
  of its ratings . . . BUT INADEQUATELY COOLED.

As Joe said, 14.x volts applied to a fully charged battery will result in virtually no current flow into the battery. But the same 14.x volts applied to a nearly dead battery will likely result in close to full available current from the alternator into the battery.

  A lead-acid battery, fully charged, sitting at room
  temperature presents an open circuit terminal
  voltage of about 13.0 volts. Applying an external
  source at slightly above 13.0 will not charge the
  battery (i.e. convert the state of its chemistry)
  but it will SUPPORT any self discharge currents
  inherent in the physics of ANY lead-acid battery.

  This is what a maintainer does . . . got a couple 100a.h.
  batteries in the shop right now. One sitting on Battery a
  Tender showing a green light (charged), it measures
  13.11 volts; the other sitting open circuit for the past
  week, it measures 12.88 volts.

  A deeply discharged battery floated on a 13.8v charger
  will eventually accumulate a charge at or near 100% of
  rated capacity . . . it might take weeks. For example,
  the two batteries cited above were purchased in July
  and installed in a friend's John Deere road grader . . .
  two 100a.h. batteries in series for 24v system.

  I became aware that the grader had not been used in
  several months. Went out to his ranch and absconded with
  both batteries. Just for grins, I put them both on Battery
  Tenders (0.75A charge rate). It took about a week
  for the BTs to show a green light . . . but they DID
  ultimately boost the batteries tot he 14.4 or so
  volts that causes the BT to transition from CHARGE
  to MAINTENANCE.

[img]cid:.0[/img]

  I am pleased to suggest that the little Battery Tender Jr. should
  not be discounted as a useful charge/maintenance tool for just
  about any size battery. Oh, yeah . . . the plot above was measured
  as an exemplar BT recharge profile . . . it was not taken on the
  batteries cited.

The battery size vs alternator size 'waters' got muddied badly on another aviation forum by a certain lithium battery company telling its customers that they *did* have to limit alternator current capacity based on the lithium battery's capacity. That battery has a charge controller built in, so it shouldn't care about alternator size (just like a little 0.01 amp LED lamp doesn't care if it's hooked to a battery capable of 400 amps). Unfortunately, they've never been able to give a rational explanation for their rule.

  Pretty simple . . . not all lithium ion products are the same
  irrespective of their common chemistry. LiFePO4 is the chemistry
  of choice for robustness and generally 'airplane friendly' resistance
  to catching fire. However, the cell's ability to either sink or source
  high current values for extended periods of time is related to
  internal resistance (i.e. losses expressed as heating).

  There are LiFePO4 cells specifically tailored to accept and/or
  deliver large currents . . . an ESSENTIAL quality for miniature
  motive power (models, etc.)  For example, this A123 product is
  speced to accept/deliver 30A

https://tinyurl.com/yanszgtb

  This is approx 28 times the a.h. rating of the cell. This
  cell . . .

https://tinyurl.com/y88ca38m

  while 'rated' at 9x the capacity of the A123 would toss in the towel at
  10A of either charge/discharge.  Most of the Lithium suppliers
  for light aircraft cranking batteries are using ROBUST cells.

The direct answer to your question about too much charge current is that it shouldn't be dead in a flying airplane. Smile Seriously, the fact that it was allowed to go dead while in flight created a 'no good answer' situation, since an a/c charging system isn't designed to do a conditioned recharge of a dead battery.

  This goes to the core of the alternator vs. battery size
  discussion. When you crank an engine, the battery is generally
  tasked to the tune of about 5% of the contained energy. Yes,
  when the alternator comes on line, it will happily deliver
  whatever it can to meet the battery's acceptance rate which
  could be quite high . . . for a minute or so whereupon it begins
  to taper off. When operated in this 'normal' set of circumstances,
  even the smallest batteries are not damaged by what might otherwise
  appear to be an abusive recharge rate.

  However, allowing the ship's alternator to recharge a deeply
  discharged battery is another matter. This generally NEVER happens
  over the lifetime of the battery in your car . . . or your airplane.
  Most manuals for TC aircraft call for removing the deeply discharged
  battery from the airplane for bench recharge and inspection
  for airworthiness.

  The short answer: Select a lithium battery fabricated from
  robust cells. Be wary of "jump starting" the airplane and allowing
  the ship's alternator to stuff electrons back into a deeply
  discharged chemistry. If you can, go for the more sophisticated
  lithium products that emulate the features built into batteries
  qualified for TC aircraft . . . i.e. adequate, built in protection
  for over discharge, over charge, excessive current draw, etc.

  EarthX is one such product . . . there may be others by now. Haven't
  been tracking the market.

 

When I said 'try', that's what I meant; that it would *try* to supply whatever it *could* to keep the voltage at setpoint.
The OP did say that his *field* breaker tripped. There have been several cases reported on various forums of 5A field breakers popping under high alternator output loads, and IIRC, someone actually posted on one of the forums (don't recall if it was here or elsewhere) at least one alternator spec sheet showing its field current could run very close to, or even above, 5A. I've never experienced the problem, but apparently others have, on multiple occasions. 
The mfgr I referenced that was muddying the waters on battery cap vs alternator cap is, in fact, EarthX. I've swapped posts with their public face on the VAF forum several times, and it would seem that even if they have a perfect product, their marketing face has no idea how it works. Scroll to the chart near the bottom of this page:
earthx

Charlie


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



198205df.jpg
 Description:
 Filesize:  127 KB
 Viewed:  301 Time(s)

198205df.jpg


Back to top
Eric Page



Joined: 15 Feb 2017
Posts: 90

PostPosted: Tue Jan 02, 2018 1:56 pm    Post subject: Re: Battery, Alternator, CB Reply with quote

nuckolls.bob(at)aeroelect wrote:
This cell...

https://tinyurl.com/y88ca38m

while 'rated' at 9x the capacity of the A123 would toss in the towel at 10A of either charge/discharge. Most of the Lithium suppliers for light aircraft cranking batteries are using ROBUST cells.


I just want to point out, hopefully before anyone orders them, that these cells are most assuredly fakes. It's a symptom of a common problem with electronic components and "modules" from Chinese sellers; they frequently, and sometimes grossly, exaggerate the ratings or capabilities of their products. "High capacity" 18650s like these always test very poorly, often under 1,000maH.

The highest legitimate capacity rating for an 18650 Li-Ion cell at present is the Panasonic NCR18650G at 3,600maH, but those are exceedingly hard to find in the wild. The highest capacity cells that are readily available are the LG MJ1 at 3,500mAh (rated 10A discharge) and the Panasonic NCR18650B at 3,400maH (rated 4.875A discharge). Generally speaking there's an inverse relationship between cell capacity and maximum discharge rate, though the MJ1 is challenging this notion.

If you need 18650 cells for a project, you should stick to Panasonic, Sanyo, LG, Samsung, Sony or A123. Many of the other names-you've-never-heard-of brands use cell manufacturer and battery pack producer rejects, or used/salvaged cells (from laptop and tool batteries, typically). Some of these are stripped and re-wrapped to look like genuine high-spec OEM cells. Some sellers will even rewrap genuine cells of lower capacity (and cost) to look like high-spec cells.

About 18 months ago there was a shortage of Samsung HG2 cells (3,000mAh, 20A discharge) when the factory shut down for retooling, and Chinese counterfeiters quickly began rewrapping HE2 cells (2,500maH, 20A discharge) as HG2s. Since the HE2 costs about $1 less in bulk and looks identical except for wrapping color, it was an easy moneymaker.

Finding a seller with genuine name-brand cells can be a challenge on eBay, and the problem isn't limited to Chinese sellers since they wholesale their fakes to resellers around the globe.

Be careful out there...

Eric


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Tue Jan 02, 2018 2:16 pm    Post subject: Battery, Alternator, CB Reply with quote

Quote:

The OP did say that his *field* breaker tripped. There have been several cases reported on various forums of 5A field breakers popping under high alternator output loads, and IIRC, someone actually posted on one of the forums (don't recall if it was here or elsewhere) at least one alternator spec sheet showing its field current could run very close to, or even above, 5A. I've never experienced the problem, but apparently others have, on multiple occasions.

Hmmmm . . . I'd like to know which brand/model of alternator
has so high a power requirement. Recall that an alternator's
output is de-rated by what ever current is required to excite
the field. I.e. a 60A ND alternator is 'really' ginning out
63A at minimum speed for full output. This is the condition
where the regulator is full-ON and field voltage is equal
to bus voltage.

5A of field current would dump 5 x 14 = 70 watts
of no-value-added heat into the alternator's interior
or about 10% of total energy.

When a field breaker opens in flight, the first thought
questions whether or not the system is fitted with crowbar
ov protection . . . and they have suffered a nuisance trip.
Another question explores the possibility of a shorted
field winding where apparent field resistance goes down
and potential field current goes up to compensate for the
'lost turns'.

I've got a situation like that right now in my Minivan.
A/C was popping clutch fuse . . . every so often. Measurement
of current through the 7A fuse showed that clutch current
was about 9A. Fewer turns of wire . . . but higher current . . .
and the a/c continued to function if I put a 10A fuse in
the holder.

Ordered a new compressor/clutch assembly and put it on
the shelf in anticipation of needing to replace it soon.
The system ran though the rest of the summer . . . so
I don't have to go turn any wrenches until spring.

I have no foundation from which to argue with anyone's
observations . . . but if they were suffering nuisance
trips of a 5A breaker on an alternator field, I think it
VERY likely that the 5+ amp draw is not related to
the field current requirements of a normally functioning
alternator.


Bob . . .


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
ceengland7(at)gmail.com
Guest





PostPosted: Tue Jan 02, 2018 2:30 pm    Post subject: Battery, Alternator, CB Reply with quote

On Tue, Jan 2, 2018 at 4:15 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
Quote:
Quote:

The OP did say that his *field* breaker tripped. There have been several cases reported on various forums of 5A field breakers popping under high alternator output loads, and IIRC, someone actually posted on one of the forums (don't recall if it was here or elsewhere) at least one alternator spec sheet showing its field current could run very close to, or even above, 5A. I've never experienced the problem, but apparently others have, on multiple occasions.Â

  Hmmmm . . . I'd like to know which brand/model of alternator
  has so high a power requirement. Recall that an alternator's
  output is de-rated by what ever current is required to excite
  the field. I.e. a 60A ND alternator is 'really' ginning out
  63A at minimum speed for full output. This is the condition
  where the regulator is full-ON and field voltage is equal
  to bus voltage.

  5A of field current would dump 5 x 14 = 70 watts
  of no-value-added heat into the alternator's interior
  or about 10% of total energy.

  When a field breaker opens in flight, the first thought
  questions whether or not the system is fitted with crowbar
  ov protection . . . and they have suffered a nuisance trip.
  Another question explores the possibility of a shorted
  field winding where apparent field resistance goes down
  and potential field current goes up to compensate for the
  'lost turns'.

  I've got a situation like that right now in my Minivan.
  A/C was popping clutch fuse . . . every so often. Measurement
  of current through the 7A fuse showed that clutch current
  was about 9A.  Fewer turns of wire . . . but higher current . . .
  and the a/c continued to function if I put a 10A fuse in
  the holder.

  Ordered a new compressor/clutch assembly and put it on
  the shelf in anticipation of needing to replace it soon.
  The system ran though the rest of the summer . . . so
  I don't have to go turn any wrenches until spring.

  I have no foundation from which to argue with anyone's
  observations . . . but if they were suffering nuisance
  trips of a 5A breaker on an alternator field, I think it
  VERY likely that the 5+ amp draw is not related to
  the field current requirements of a normally functioning
  alternator.


  Bob . . .

That could well be the case. There are a lot of 'alternative facts' on the interwebs these days....


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group