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Paul Eckenroth
Joined: 29 Jun 2010
Posts: 14
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 Posted: Thu Aug 06, 2020 4:52 pm Post subject: Revmaster engine with EarthX battery |
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I have a Revmaster engine in my Onex which is not dealing well with my EarthX battery. The engine has a total of 12 coils arranged on the stator which consists of 2 each of 5 coils making up the dual generator and 2 coils powering the ignition. It all sounded good on paper with much redundancy but apparently the generator coils produce too much heat at full output which can cause them to short out. When used with the old fashioned lead acid battery the charge rate is less and therefore less heat. Is there any proper method to throttle the generator output or reduce the EarthX input to approach the charging rate of the lead acid battery and not cause the generator to create the excessive heat. I know the easy way is to just replace the battery but that would not be good for my W&B. Thanks for any help and suggestions.
Paul
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user9253
Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan
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| Posted: Thu Aug 06, 2020 6:30 pm Post subject: Re: Revmaster engine with EarthX battery |
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All you have to do is put a diode between the alternator and battery. That will
drop the voltage that the battery sees and limit the current.
An EarthX battery has very low internal resistance. When the battery is low,
it will take the full output of an alternator. That is why the size of the battery
has to be matched to the alternator size.
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nuckolls.bob(at)aeroelect
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| Posted: Thu Aug 06, 2020 6:46 pm Post subject: Revmaster engine with EarthX battery |
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At 07:52 PM 8/6/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: "Paul Eckenroth" <jeckenroth(at)nbn.net>
I have a Revmaster engine in my Onex which is not dealing well with my EarthX battery. The engine has a total of 12 coils arranged on the stator which consists of 2 each of 5 coils making up the dual generator and 2 coils powering the ignition. It all sounded good on paper with much redundancy but apparently the generator coils produce too much heat at full output which can cause them to short out. When used with the old fashioned lead acid battery the charge rate is less and therefore less heat. Is there any proper method to throttle the generator output or reduce the EarthX input to approach the charging rate of the lead acid battery and not cause the generator to create the excessive heat. I know the easy way is to just replace the battery but that would not be good for my W&B. Thanks for any help and suggestions. |
I've been hearing/reading about shortfalls in
the design of that alternator for years.
The thing is thermally marginal at best.
If you can acquire an adjustable regulator
for PM alternators, you can set the charging
voltage down such that the alternator is
not working quite so hard at the LOWEST
voltage that will still charge the battery.
The attached plot show EarthX test data from
some years back. A bus voltage of 13.0 falls
far short of fully charging the battery . . . while
voltages of 13.5, 14.0 and 15.0 will all
fully charge the battery. The BMS takes
care of moderating any 'excess' voltage but
its design rules will allow the battery
to accept any safe level of replenishment . . .
safe for the battery. Unfortunately,
that current value is more than your
alternator/regulator combination is able
to grunt without smoking the windings.
B&C has a new product that MIGHT be a
solution . . . albeit an unfortunate
'band aid' on the Revmaster's shortcomings.
https://tinyurl.com/y6mr4x7e
You would want to set the bus voltage
to 13.6 +/- 0.1 volts. I'm thinking this
MIGHT do the trick.
Give B&C a call and talk with their
technowienies about this.
Bob . . .
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nuckolls.bob(at)aeroelect
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| Posted: Fri Aug 07, 2020 5:15 am Post subject: Revmaster engine with EarthX battery |
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At 09:30 PM 8/6/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>
All you have to do is put a diode between the alternator and battery. That will
drop the voltage that the battery sees and limit the current. |
That's worth exploring . . . you could take one
of the bridge rectifiers commonly used as an
e-bus, normal feed path isolator and wire it
so that you have one or perhaps two diodes in
series with the regulator's output. You're
shooting for a bus voltage just barely higher
than what's required to fully charge the battery . . .
i.e. 13.5 volts. Even that may not 'fix' the
problem. The alternator can still be overloaded
by other system loads. This just goes to mitigation
of battery demands as one of those loads.
| Quote: | An EarthX battery has very low internal resistance. When the battery is low,
it will take the full output of an alternator. That is why the size of the battery
has to be matched to the alternator size. |
Not really a 'matching' problem so much as a
poor design in the alternator/regulator
combination. Too many folks have been burning
the alternators on these engines for some
time . . . it has little if any to do with
choice of battery.
Is this an older production engine? Has Revmaster
offered any positive response to fixing this?
Bob . . .
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ceengland7(at)gmail.com
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| Posted: Fri Aug 07, 2020 6:17 am Post subject: Revmaster engine with EarthX battery |
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On Fri, Aug 7, 2020 at 8:20 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 09:30 PM 8/6/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>
All you have to do is put a diode between the alternator and battery. That will
drop the voltage that the battery sees and limit the current. |
That's worth exploring . . . you could take one
of the bridge rectifiers commonly used as an
e-bus, normal feed path isolator and wire it
so that you have one or perhaps two diodes in
series with the regulator's output. You're
shooting for a bus voltage just barely higher
than what's required to fully charge the battery . . .
i.e. 13.5 volts. Even that may not 'fix' the
problem. The alternator can still be overloaded
by other system loads. This just goes to mitigation
of battery demands as one of those loads.
| Quote: | An EarthX battery has very low internal resistance. When the battery is low,
it will take the full output of an alternator. That is why the size of the battery
has to be matched to the alternator size. |
Not really a 'matching' problem so much as a
poor design in the alternator/regulator
combination. Too many folks have been burning
the alternators on these engines for some
time . . . it has little if any to do with
choice of battery.
Is this an older production engine? Has Revmaster
offered any positive response to fixing this?
Bob . . .
|
If it's the coils in the alternator that are dying due to overcurrent (and Revmaster won't help you), a 'bandaid' might be a current regulator in series with the alt output (actually, the rectifier/voltage regulator output). Set it for the alt's max survivable current. The regulator would lower voltage to limit current, and as the battery slowly charges and demand drops, voltage will rise to normal preset level.
But you need to be aware that under excessive loads, voltage will sag to keep current at the regulator preset current. Additional failure mode, so a way to switch around it might be needed if alt output is critical to flight, which adds complexity....
Are the coils failing due to overcurrent, or heat? Yeah, they are related, but if you can cool the coils with blast tubes...
Charlie
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N509RV(at)eckenroth.com
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| Posted: Fri Aug 07, 2020 11:40 am Post subject: Revmaster engine with EarthX battery |
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Thank you for all of the comments and suggestions. The Revmaster engine is their latest iteration. The generators are rated at 18 amps each but have the ability to open a 30 amp fuse located before the regulator. Revmaster has suggested possibly reducing the number of wire layers in each coil to 2 from the current 3 which I assume would lower the peak current and therefore heat but I don't know what that will do to the final output.After testing the generators today for continuity, I believe that I may have avoided the need for a new stator. So my plan going forward is to buy and install the B&C adjustable regulator. Install a current probe. And try to fly the plane without burning up the generators. EarthX suggested setting the voltage as low as 13.3 which would also reduce available amps.
I would certainly appreciate any additional suggestions.
Paul
On Thu, Aug 6, 2020 at 10:54 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 07:52 PM 8/6/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: "Paul Eckenroth" <jeckenroth(at)nbn.net (jeckenroth(at)nbn.net)>
I have a Revmaster engine in my Onex which is not dealing well with my EarthX battery. The engine has a total of 12 coils arranged on the stator which consists of 2 each of 5 coils making up the dual generator and 2 coils powering the ignition. It all sounded good on paper with much redundancy but apparently the generator coils produce too much heat at full output which can cause them to short out. When used with the old fashioned lead acid battery the charge rate is less and therefore less heat. Is there any proper method to throttle the generator output or reduce the EarthX input to approach the charging rate of the lead acid battery and not cause the generator to create the excessive heat. I know the easy way is to just replace the battery but that would not be good for my W&B. Thanks for any help and suggestions. |
I've been hearing/reading about shortfalls in
the design of that alternator for years.
The thing is thermally marginal at best.
If you can acquire an adjustable regulator
for PM alternators, you can set the charging
voltage down such that the alternator is
not working quite so hard at the LOWEST
voltage that will still charge the battery.
The attached plot show EarthX test data from
some years back. A bus voltage of 13.0 falls
far short of fully charging the battery . . . while
voltages of 13.5, 14.0 and 15.0 will all
fully charge the battery. The BMS takes
care of moderating any 'excess' voltage but
its design rules will allow the battery
to accept any safe level of replenishment . . .
safe for the battery. Unfortunately,
that current value is more than your
alternator/regulator combination is able
to grunt without smoking the windings.
B&C has a new product that MIGHT be a
solution . . . albeit an unfortunate
'band aid' on the Revmaster's shortcomings.
https://tinyurl.com/y6mr4x7e
You would want to set the bus voltage
to 13.6 +/- 0.1 volts. I'm thinking this
MIGHT do the trick.
Give B&C a call and talk with their
technowienies about this.
Bob . . .
|
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dj_theis
Joined: 28 Aug 2017
Posts: 56
Location: Minnesota
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| Posted: Fri Aug 07, 2020 2:55 pm Post subject: Re: Revmaster engine with EarthX battery |
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>B&C has a new product that MIGHT be a
>solution . . . albeit an unfortunate
>'band aid' on the Revmaster's shortcomings.
I own the Revmaster R2300 with the same alternator. (I've asked for advice from the forum on my project the past.) I also considered using the B&C regulator to provide an adjustable voltage regulator in a more robust package than what Revmaster provides. One thing that makes me pause is this thought process:
1) the original R/R is a half wave recitifer design.
2) The noted problem is an underdesigned PM alternator unable to reject heat produced with both sides running. So, what's recommended is to run only one side at a time.
Isn't running one PM alternator with full wave rectification about the same current / heat level as two regulators, each with a half wave rectifier?
Attached is my simpified sketch of the revmaster's PM alternators (for reference) with a design I cleaved from Bob's Z16 drawings, including overvoltage protection and switching (overvoltage not shown). I think my drawing is finding it's way around the "net," which is fine. I'm pretty sure it depicts the R2300 alternator accurately.
BTW, I do like the current limiting idea, despite it's possible drawback with added complexity.
Dan Theis
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Revmaster voltage regulators.pdf |
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Dan Theis
Scratch building Sonex #1362
Still working on the Revmaster Alternator improvement |
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nuckolls.bob(at)aeroelect
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| Posted: Sat Aug 08, 2020 2:15 pm Post subject: Revmaster engine with EarthX battery |
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I'm confused . . . this drawing does not illustrate
location of rectifier/regulators in the system.
Also, are the crowbar modules pulling down against
the energy of a dynamo or energy of the battery?
Bob . . .
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dj_theis
Joined: 28 Aug 2017
Posts: 56
Location: Minnesota
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| Posted: Sat Aug 08, 2020 2:55 pm Post subject: Re: Revmaster engine with EarthX battery |
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>I'm confused . . . this drawing does not illustrate
>location of rectifier/regulators in the system.
>Also, are the crowbar modules pulling down against
>the energy of a dynamo or energy of the battery?
I'm honored by your response, but crushed by the fact that my drawings are obscuring what I am trying to convey.
The rectifiers / regulators are part of the circuit, depicted in the lower left and lower right. The rectifiers are modeled as a box with an SCR and a control circuit that simply open the charging path for the PM alternator.
Yes, Revmaster installs two rectifiers, one for each PMA. The R/R they supply confused me at first, as they are 3 wire devices (actually shown in the Revmaster manual as two wires with the body of the recifier being grounded). I've spent a considerable amount of time trying to understand their operation and believe what I'm showing (a series, 1/2 wave rectifier / regulator for each PMA) is accurate. I'm happe to be shown the error in my understanding and depiction of the charging circuit. Maybe a better understanding will expose a weakness beyond poor heat rejection for the design.
I've attached a larger drawing that shows the full circuit with your very elegant crowbar, overvoltage protection.
I've not cleaned up this version so it likely has numerous wire size and details errors. If you can overlook these shortcomings, hopefully the full drawing is more easily
Kind regards,
Dan Theis
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Z16M Revmaster 2300 r10a-pg1.pdf |
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Dan Theis
Scratch building Sonex #1362
Still working on the Revmaster Alternator improvement |
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N509RV(at)eckenroth.com
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| Posted: Sun Aug 09, 2020 4:32 am Post subject: Revmaster engine with EarthX battery |
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Dan
your schematic as depicted is exactly how my Onex is wired. I would caution you to use a lead acid battery if you can unless a good solution materializes that will keep the generator from developing full throttle. I think the B&C regulator is essential since it has adjustable voltage output.
Paul.
On Fri, Aug 7, 2020 at 7:05 PM dj_theis <djtheis58(at)gmail.com (djtheis58(at)gmail.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: "dj_theis" <djtheis58(at)gmail.com (djtheis58(at)gmail.com)>
>B&C has a new product that MIGHT be a
>solution . . . albeit an unfortunate
>'band aid' on the Revmaster's shortcomings.
I own the Revmaster R2300 with the same alternator. (I've asked for advice from the forum on my project the past.) I also considered using the B&C regulator to provide an adjustable voltage regulator in a more robust package than what Revmaster provides. One thing that makes me pause is this thought process:
1) the original R/R is a half wave recitifer design.
2) The noted problem is an underdesigned PM alternator unable to reject heat produced with both sides running. So, what's recommended is to run only one side at a time.
Isn't running one PM alternator with full wave rectification about the same current / heat level as two regulators, each with a half wave rectifier?
Attached is my simpified sketch of the revmaster's PM alternators (for reference) with a design I cleaved from Bob's Z16 drawings, including overvoltage protection and switching (overvoltage not shown). I think my drawing is finding it's way around the "net," which is fine. I'm pretty sure it depicts the R2300 alternator accurately.
BTW, I do like the current limiting idea, despite it's possible drawback with added complexity.
Dan Theis
--------
Scratch building Sonex #1362
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=497570#497570
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dj_theis
Joined: 28 Aug 2017
Posts: 56
Location: Minnesota
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| Posted: Sun Aug 09, 2020 5:19 am Post subject: Re: Revmaster engine with EarthX battery |
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[quote]Dan
your schematic as depicted is exactly how my Onex is wired. I would caution you to use a lead acid battery if you can unless a good solution materializes that will keep the generator from developing full throttle. I think the B&C regulator is essential since it has adjustable voltage output.
Paul.[/quote]
Thanks Paul,
I appreciate the advice and am doing exactly that (using the Oddesey PC680)
I like the idea of the variable regulator, as noted by you and Bob, offered by B&C. It would take a little fanagling to wire two PMAs through a single regulator but certainly possible (i.e., I'm suggesting using a single B&C RR wired through relays so only one PMA is active at at time. All this to avoid the space, weight and cost of two regulators).
I am planning (hoping) on adding temperature sensors to the stators on my engine, before I modify the circuit with a different regulator. My thought is that in many instances, (Glen Bradley's Thatcher, for example) the R2300 has ran for many hours (again, 600 plus in Glen's case) without any issue. Again, in Bradley's case, he had an event where (I think likely) the stars aligned and his alternator went up in smoke. He had been running with both PMAs active up until then and I suspect the charging system worked hard to re-charge the battery, one too many times.
Whatever the source of trouble (low battery internal resistance, low battery charge or simply poor heat rejection) the PMAs cannot be run together and possibly cannot be run at their "natural" current limit without the risk of self destruction.
I'll eventually have data on the internal temperature characteristics of the alternator and [b]DO[/b] plan on upgrading the RR if needed to address the problem.
As my previous note mentions, I have to ask if putting a full wave rectifier (the B&C design) will effectively put the PMA into a similar overheating condition?
I look forward to hearing how your RR change works out.
Dan Theis
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Dan Theis
Scratch building Sonex #1362
Still working on the Revmaster Alternator improvement |
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N509RV(at)eckenroth.com
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| Posted: Sun Aug 09, 2020 5:38 am Post subject: Revmaster engine with EarthX battery |
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Dan
According to Revmast, even the Odyssey may cause problems. They want you to use the old lead anchor. lead acid. The difference in weight especially considering lithium is dramatic.
Paul
On Sun, Aug 9, 2020 at 9:24 AM dj_theis <djtheis58(at)gmail.com (djtheis58(at)gmail.com)> wrote:
| Quote: | --> AeroElectric-List message posted by: "dj_theis" <djtheis58(at)gmail.com (djtheis58(at)gmail.com)>
| Quote: | Dan
your schematic as depicted is exactly how my Onex is wired. I would caution you to use a lead acid battery if you can unless a good solution materializes that will keep the generator from developing full throttle. I think the B&C regulator is essential since it has adjustable voltage output.
Paul. |
Thanks Paul,
I appreciate the advice and am doing exactly that (using the Oddesey PC680)
I like the idea of the variable regulator, as noted by you and Bob, offered by B&C. It would take a little fanagling to wire two PMAs through a single regulator but certainly possible (i.e., I'm suggesting using a single B&C RR wired through relays so only one PMA is active at at time. All this to avoid the space, weight and cost of two regulators).
I am planning (hoping) on adding temperature sensors to the stators on my engine, before I modify the circuit with a different regulator. My thought is that in many instances, (Glen Bradley's Thatcher, for example) the R2300 has ran for many hours (again, 600 plus in Glen's case) without any issue. Again, in Bradley's case, he had an event where (I think likely) the stars aligned and his alternator went up in smoke. He had been running with both PMAs active up until then and I suspect the charging system worked hard to re-charge the battery, one too many times.
Whatever the source of trouble (low battery internal resistance, low battery charge or simply poor heat rejection) the PMAs cannot be run together and possibly cannot be run at their "natural" current limit without the risk of self destruction.
I'll eventually have data on the internal temperature characteristics of the alternator and DO plan on upgrading the RR if needed to address the problem.
As my previous note mentions, I have to ask if putting a full wave rectifier (the B&C design) will effectively put the PMA into a similar overheating condition?
I look forward to hearing how your RR change works out.
Dan Theis
--------
Scratch building Sonex #1362
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=497595#497595
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dj_theis
Joined: 28 Aug 2017
Posts: 56
Location: Minnesota
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| Posted: Sun Aug 09, 2020 7:39 am Post subject: Re: Revmaster engine with EarthX battery |
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| Quote: | | According to Revmast, even the Odyssey may cause problems. They want you to use the old lead anchor. lead acid. The difference in weight especially considering lithium is dramatic. |
Excellent point Paul, I had forgotten that but now recall that (anecdotal) warning from Revmaster.
If the issue that Joe (Revmaster founder) is worried about is battery charge current due to the low internal resistance, how about just adding an artificial resistance to the charging circuit. From professor Nuckolls’ book, (chapter 2, page 7). A comparison of the RG versus a wet lead acid battery internal resistance is 11.5 vs 4 milliohms, respectively. Adding 6.5 milliohms (total of 11.5 milliohms) would bring the RG to a similar effective battery resistance and, i’m assuming, similar charge current.
Coincidentally, two 100 milliohms shunt resistors rated at 20 amps continuously, would add the 6.6 milliohms. Finally, a justification for adding shunt resistors! You can monitor your charge current, not once but on redundant, in-line circuits!!
https://shunts.com/collections/shunts/products/mka?variant=6973635067959
All kidding aside, what-ya think?
Dan Theis
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Dan Theis
Scratch building Sonex #1362
Still working on the Revmaster Alternator improvement |
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dj_theis
Joined: 28 Aug 2017
Posts: 56
Location: Minnesota
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| Posted: Sun Aug 09, 2020 7:46 am Post subject: Re: Revmaster engine with EarthX battery |
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Oops,
| Quote: | ...comparison of the RG versus a wet lead acid battery internal resistance is 11.5 vs 4 milliohms, respectively......
|
I reversed the comparison. The RG has (of course) the lower internal resistance of 4 milliohms.
Dan Theis
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Dan Theis
Scratch building Sonex #1362
Still working on the Revmaster Alternator improvement |
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dj_theis
Joined: 28 Aug 2017
Posts: 56
Location: Minnesota
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| Posted: Sun Aug 09, 2020 8:04 am Post subject: Re: Revmaster engine with EarthX battery |
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Double oops.
I meant to do my math correctly and hope Matt adds math-check to the “spell-check” feature soon.
7.5 added to he RG battery's 4 milliohms would be 11.5.
Adding two 3.3 milliohm resistors would bring it to 10.6 milliohms.
Dan Theis
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Dan Theis
Scratch building Sonex #1362
Still working on the Revmaster Alternator improvement |
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user9253
Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan
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| Posted: Sun Aug 09, 2020 10:14 am Post subject: Re: Revmaster engine with EarthX battery |
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Why not follow the battery manufacturer's recommendations?
https://earthxbatteries.com/dual-bus-lithium-battery-design
Based on extensive testing, the maximum charge rating will never be
exceeded using this simple and reliable diode isolation design.
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Joe Gores |
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nuckolls.bob(at)aeroelect
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| Posted: Sun Aug 09, 2020 12:38 pm Post subject: Revmaster engine with EarthX battery |
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| Quote: | | BTW, I do like the current limiting idea, despite it's possible drawback with added complexity. |
I've been pondering the current limiter idea. It wouldn't
have to dissipate much energy. We're only talking about
a 1 to 2 volt drop at what . . . 18 amps?
A SIMPLE limiter requires a current-sense resistor
that will drop 0.6 volts in the limit-mode . . .
(0.033 ohms) not a big deal since we're wanting to toss off
a volt or so anyhow. But that same resistor is
in series with the alternator's output 100% of
the time . . . so it will drop as much as
0.033 x 17 = 0.56 volts in the non-limit
mode.
Just might be 'tolerable'.
I did a little sharp pencil work on a concept.
Cartoon attached. I'll see if I can refine
it to the prototype fabrication stage.
This is FAR preferred to down-adjusting the
alternator. I'm finding that 4-cell stacks
of LiFePO4 cells are just barely charged
when floated across our legacy 14.4v bus.
A maximally charged LiFePO4 needs a 4.2
volt supply. Stack four cells in series and
you now need a 16.8v bus!
Take a peek at the capacity vs. charge voltage
plots. A 3.6 volt charge (14.4v bus) would
charge an LiFePO4 to about 25% of its
potential chemical potential capacity.
Reducing the bus voltage to mitigate battery
charge limitations on the alternator only
exacerbates the problem. Tailoring the
alternator system to the battery makes
more sense.
Bob . . .
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ceengland7(at)gmail.com
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| Posted: Sun Aug 09, 2020 1:27 pm Post subject: Revmaster engine with EarthX battery |
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On Sun, Aug 9, 2020 at 3:48 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | | Quote: | | BTW, I do like the current limiting idea, despite it's possible drawback with added complexity. |
I've been pondering the current limiter idea. It wouldn't
have to dissipate much energy. We're only talking about
a 1 to 2 volt drop at what . . . 18 amps?
A SIMPLE limiter requires a current-sense resistor
that will drop 0.6 volts in the limit-mode . . .
(0.033 ohms) not a big deal since we're wanting to toss off
a volt or so anyhow. But that same resistor is
in series with the alternator's output 100% of
the time . . . so it will drop as much as
0.033 x 17 = 0.56 volts in the non-limit
mode.
snipped
Reducing the bus voltage to mitigate battery
charge limitations on the alternator only
exacerbates the problem. Tailoring the
alternator system to the battery makes
more sense.
Bob . . .
|
What about active current management? More complicated from a total parts count, but might be dirt simple to implement, for less than $20. Something like:
current limited supply
Charging lithium tech batteries is right there in their product description. This was the 1st one I hit on when I searched, and it's limited to 15A continuous (20A peak), but the alt in question isn't surviving at higher currents, anyway. Set its current limit for whatever current the alternator can survive at, and the system can't draw more than that from the alternator/regulator pair.
The questionable thing about some of these 'switchers' is that some have functional limitations if input & output grounds are common in the circuit, and those limitations are sometimes lost 'in translation' in the sales documents. That issue would need to be explored, of course.
Incorporating something similar to this into the BMS is something that companies like the big EX *should* have done from the outset. Boost between alt and battery, to allow full charge of the lithium tech, and buck on the output, to return battery voltage to a safe level. Then their somewhat buried alternator size limit could go away, since the BMS would *truly* manage the battery, instead of just pretending. Would require a 3 terminal battery, of course.
Charlie
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sun Aug 09, 2020 5:24 pm Post subject: Revmaster engine with EarthX battery |
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At 01:14 PM 8/9/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>
Why not follow the battery manufacturer's recommendations?
https://earthxbatteries.com/dual-bus-lithium-battery-design
Based on extensive testing, the maximum charge rating will never be
exceeded using this simple and reliable diode isolation design. |
Are we talking about the same 'victim'? The
limiting hardware are the stator windings
in the PM alternator. The typical rectifier/regulator
for these systems has no electronic current
limiting . . . and unlike the inherent
limits set by the physics of a wound-field
alternator, the PM alternator CAN be
over-loaded.
In this case, the antagonist 'load' is not
made up of electro-whizzies but the battery
itself. In a low state of charge, battery
recharge loads combined with ship's loads
are too much for the alternator's stator
windings.
Reducing available charge voltage to the
battery will most certainly reduce its
demands during recharge but at a cost
of giving up capacity.
It seems a more reasoned approach to fix
the charging system as opposed to starving
the battery.
Bob . . .
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kenryan
Joined: 20 Oct 2009
Posts: 426
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| Posted: Sun Aug 09, 2020 6:19 pm Post subject: Revmaster engine with EarthX battery |
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But lithium batteries prefer to be stored at less than a full charge, so in that regard not filling them up is a plus. Why not use the diode and use whatever size battery provides required capacity? Battery will be happy, generator will be happy, and weight will be controlled.
On Sun, Aug 9, 2020 at 5:30 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 01:14 PM 8/9/2020, you wrote:
Are we talking about the same 'victim'? The
limiting hardware are the stator windings
in the PM alternator. The typical rectifier/regulator
for these systems has no electronic current
limiting . . . and unlike the inherent
limits set by the physics of a wound-field
alternator, the PM alternator CAN be
over-loaded.
In this case, the antagonist 'load' is not
made up of electro-whizzies but the battery
itself. In a low state of charge, battery
recharge loads combined with ship's loads
are too much for the alternator's stator
windings.
Reducing available charge voltage to the
battery will most certainly reduce its
demands during recharge but at a cost
of giving up capacity.
It seems a more reasoned approach to fix
the charging system as opposed to starving
the battery.
Bob . . .
|
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