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nuckolls.bob(at)aeroelect
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 Posted: Wed Dec 24, 2008 9:35 am Post subject: Anyone done Bob Nuckoll's CBA modifications? |
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At 10:35 PM 12/23/2008, you wrote:
| Quote: | I have used the West Mountain unit a few times. No worries. I didn't know there was a mod. I bought mine about a year ago and have used it with an 11 ah battery and a few other smaller ones. I am getting ready to try it out with my new Oddessy 625. Maybe in a week, after the holiday. I have loaded the Ver 2 software, but have not tried it out.
Sam Hoskins
Murphysboro, IL
www.samhoskins.blogspot.com
On Tue, Dec 23, 2008 at 9:53 PM, CamLight <jmuchow(at)camlight.com (jmuchow(at)camlight.com)> wrote:
--> AeroElectric-List message posted by: "CamLight" <jmuchow(at)camlight.com (jmuchow(at)camlight.com)>
Hello all,
After seeing a few units burn out unexpectedly (including one of mine), I've been doing an analysis of the West Mountain Radio CBA II. I was wondering if anyone here had done the MOSFET switch (from IRL2910 to IRFP2907) detailed in Bob Nuckoll's 4/10/05 analysis of the CBA II? Thanks! |
I own 2 of these devices. The first was damaged
when I tried to do a 4a discharge on a 24v battery
(well within the rated 100W power handling capability
of the CBA II). After a determination that the
active power load transistor had shorted, I jury-rigged
a pair of FAT transistors onto an external heat
sink and secured enough functionality to complete the
task at hand. It was not intended to be a modification
to upgrade the device. I subsequently purchased a
second unit and I've been using both for a several
years.
I had some discussions with the head-shed at
West Mountain Radio about the marginal design
as demonstrated by my experience. The fellow seemed
to believe I was the only one who was having any
sort of problem and offered to repair mine under
warranty. I'd chopped and hacked it so didn't feel
like I was worthy of a warranty action. I ultimately
replace the jury-rigged "fix" with a slightly
more robust FET in the TO220 package. Both of my
cap-meters have performed as advertised since
on 12v or smaller batteries.
I'm having trouble recalling how my "mod" got
loose in the wild. I don't recall posting it to
my website but I may have shared a picture and
text with someone who has passed it along. Over
the years, I've had several inquiries about my
"mod" wherein I was unable to back-track the
information trail.
Suffice it to say that the CBA-II performs well
and as advertised on 12-volt and smaller batteries
and may well work on most batteries of higher voltage.
It's my opinion that the TO-200 case power FET used
as a load resistor is marginally applied to this
product. If I were building a similar product,
it would be more robust in this regard.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
[quote][b]
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CamLight
Joined: 19 Dec 2008
Posts: 11
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| Posted: Wed Dec 24, 2008 9:30 pm Post subject: Re: Anyone done Bob Nuckoll's CBA modifications? |
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| nuckolls.bob(at)aeroelect wrote: |
I own 2 of these devices. The first was damaged
when I tried to do a 4a discharge on a 24v battery
(well within the rated 100W power handling capability
of the CBA II). After a determination that the
active power load transistor had shorted, I jury-rigged
a pair of FAT transistors onto an external heat
sink and secured enough functionality to complete the
task at hand. It was not intended to be a modification
to upgrade the device. I subsequently purchased a
second unit and I've been using both for a several
years.
I had some discussions with the head-shed at
West Mountain Radio about the marginal design
as demonstrated by my experience. The fellow seemed
to believe I was the only one who was having any
sort of problem and offered to repair mine under
warranty. I'd chopped and hacked it so didn't feel
like I was worthy of a warranty action. I ultimately
replace the jury-rigged "fix" with a slightly
more robust FET in the TO220 package. Both of my
cap-meters have performed as advertised since
on 12v or smaller batteries. |
That's good news! I've heard of about 8 units that have blown their FETs and couple that also took out the driving op-amp and some resistor/capacitors too. I ended up using an Infineon IPP048N06L MOSFET for its great continuous rating for use as a load (DC plot line in the SOA graph). Seems that it's both the higher wattages and higher voltage batteries that can cause problems. Makes sense though. The first is due to temperature and the second due to hotspotting and thermal runaway.
| nuckolls.bob(at)aeroelect wrote: |
I'm having trouble recalling how my "mod" got
loose in the wild. I don't recall posting it to
my website but I may have shared a picture and
text with someone who has passed it along. Over
the years, I've had several inquiries about my
"mod" wherein I was unable to back-track the
information trail. |
Well, I can give you the trail I followed. 
A friend had told me about seeing an analysis of the CBA but forgot where. A Goodle search led to an archive of a thread here on, IIRC, April 10, 2005. In that thread you provided a link to your analysis in the Articles section of your site. But the document was no longer there. This link though gave me the file name and my search led to an individual who had the document available from their site. I don't remember who.
| nuckolls.bob(at)aeroelect wrote: |
Suffice it to say that the CBA-II performs well
and as advertised on 12-volt and smaller batteries
and may well work on most batteries of higher voltage.
It's my opinion that the TO-200 case power FET used
as a load resistor is marginally applied to this
product. If I were building a similar product,
it would be more robust in this regard.
Bob . . .
|
I completely agree. My analysis of two CBA's was pretty extensive (43 page document) and led me to conclude that it shouldn't be used at over 65W for long-term reliability and 86W to prevent the MOSFET from exceeding its max rated operating temperature. I also found out that the CBA's stock MOSFET isn't even rated for use as a load and was susceptible to hotspotting and thermal runaway (resulting in the MOSFET burning out) at well below the CBA's 100W rating when discharging at higher voltages.
A MOSFET change, over to the IPP048N06L, and a fan change were the mods I made to bring the CBA's continuous power rating up to 106W at up to 48V without worrying about exceeding any of the MOSFET's specs. The extra fan also helped to keep the fuse and fuseholders from dropping out of the circuit board too when discharging at 30A or so. It happened more than once to me (and others) before we finally found ways to cool the circuit board and fuse. Very frustrating.
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John M.
Owner
CamLight Systems |
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Fri Dec 26, 2008 7:58 am Post subject: Anyone done Bob Nuckoll's CBA modifications? |
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| Quote: | Well, I can give you the trail I followed.
A friend had told me about seeing an analysis of the CBA but forgot
where. A Goodle search led to an archive of a thread here on, IIRC,
April 10, 2005. In that thread you provided a link to your analysis
in the Articles section of your site. But the document was no longer
there. This link though gave me the file name and my search led to
an individual who had the document available from their site. I
don't remember who.
|
Okay, I found it. I don't know why it was taken off the
website. It's still on the CDRom image of the website
as it existed some months ago. I've put the article back
up at:
http://www.aeroelectric.com/articles/WestMountain_CBAII.pdf
| Quote: | I completely agree. My analysis of two CBA's was pretty extensive
(43 page document) and led me to conclude that it shouldn't be used
at over 65W for long-term reliability and 86W to prevent the MOSFET
from exceeding its max rated operating temperature. I also found out
that the CBA's stock MOSFET isn't even rated for use as a load and
was susceptible to hotspotting and thermal runaway (resulting in the
MOSFET burning out) at well below the CBA's 100W rating when
discharging at higher voltages.
A MOSFET change, over to the IPP048N06L, and a fan change were the
mods I made to bring the CBA's continuous power rating up to 106W at
up to 48V without worrying about exceeding any of the MOSFET's
specs. The extra fan also helped to keep the fuse and fuseholders
from dropping out of the circuit board too when discharging at 30A
or so. It happened more than once to me (and others) before we
finally found ways to cool the circuit board and fuse. Very frustrating.
|
I had some extensive conversation with WMR. First
with regard to the FET failure and a second attempt to
discover the communication protocols on the USB
connection that controls the CBA-II and then gets
reported data back.
I offered to craft an engineer's version of battery
test software that would provide watt-seconds instead
of amp-hours displays, conduct battery impedance tests,
etc. I even told him I would share the software for
him to use as I saw fit. He said similar plans were
already in work in his facilities and he declined
to share any information.
The new software was 3 years in the making and still
falls short of what I would like to do with his product.
Further, the software reads the serial number of the
specific CBA II and you have to purchase separate
registered copies of the software to use each CBA II.
I have three computers and two CBA II that I would like
to use in interchangeable combinations but I'm not going
to buy a second software package when it still doesn't
do the things I would like to do and offered to him for
free.
Bob . . .
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CamLight
Joined: 19 Dec 2008
Posts: 11
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| Posted: Fri Dec 26, 2008 5:40 pm Post subject: Re: Anyone done Bob Nuckoll's CBA modifications? |
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I had tried to contact you via e-mail last month regarding my analysis. Some of my test results and recommendations differ from yours and I wanted to ask if you might be interested in discussing them?
| nuckolls.bob(at)aeroelect wrote: |
I had some extensive conversation with WMR. First
with regard to the FET failure and a second attempt to
discover the communication protocols on the USB
connection that controls the CBA-II and then gets
reported data back.
I offered to craft an engineer's version of battery
test software that would provide watt-seconds instead
of amp-hours displays, conduct battery impedance tests,
etc. I even told him I would share the software for
him to use as I saw fit. He said similar plans were
already in work in his facilities and he declined
to share any information.
The new software was 3 years in the making and still
falls short of what I would like to do with his product.
Further, the software reads the serial number of the
specific CBA II and you have to purchase separate
registered copies of the software to use each CBA II.
I have three computers and two CBA II that I would like
to use in interchangeable combinations but I'm not going
to buy a second software package when it still doesn't
do the things I would like to do and offered to him for
free.
Bob . . . |
Sigh...you're not the only one frustrated with WMR's policies! The requirement to assign the software to a particular CBA II is maddening. And within a day or two after its release, a couple of us over at the RC Group forums found several obvious bugs in their version 2 software.
Our biggest frustrations now? They've had at least 6 releases of the beta and "final" version 2 software since 10/28 and none of them have listed the changes from the previous release. Arggghhh!
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John M.
Owner
CamLight Systems |
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nuckolls.bob(at)aeroelect
Guest
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| Posted: Sat Dec 27, 2008 6:29 am Post subject: Anyone done Bob Nuckoll's CBA modifications? |
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At 07:40 PM 12/26/2008, you wrote:
| Quote: |
nuckolls.bob(at)aeroelect wrote:
>
> Okay, I found it. I don't know why it was taken off the
> website. It's still on the CDRom image of the website
> as it existed some months ago. I've put the article back
> up at:
>
> http://www.aeroelectric.com/articles/WestMountain_CBAII.pdf
>
I had tried to contact you via e-mail last month regarding my
analysis. Some of my test results and recommendations differ from
yours and I wanted to ask if you might be interested in discussing them?
|
Yes, I recall that. I must have been 'snowed' at the
time and the List comes first. We could discuss it here
on the List . . .
| Quote: | Sigh...you're not the only one frustrated with WMR's policies! The
requirement to assign the software to a particular CBA II is
maddening. And within a day or two after its release, a couple of
us over at the RC Group forums found several obvious bugs in their
version 2 software.
Our biggest frustrations now? They've had at least 6 releases of
the beta and "final" version 2 software since 10/28 and none of them
have listed the changes from the previous release. Arggghhh!
|
That's unfortunate. I know there are a lot of
folks out there with time, talent and resources
willing to help him refine the product. Push
comes to shove, we could do our own.
I've got PIC's with USB engines that I've integrated
into some proposed projects for TC aircraft. A
retired programmer from NCR/Symbios/LSI lives right
behind me (my father in law). He's been doing
some other projects for me and would be please
to have this one.
Our hammer-n-tongs version need not be pretty,
only utilitarian. I think I'd opt for a board
that could drive any practical number of power
FETS. The user could scale his/her version
to the desired task. The only variable in the
software would be to insert a shunt constant
for current interpretation.
The battery tester itself is stone simple.
The sexy part is the application that manages
it. John went out and bought VBasic.net a few
months ago but we've not had occasion to use
it yet.
Bob . . .
----------------------------------------)
( . . . a long habit of not thinking )
( a thing wrong, gives it a superficial )
( appearance of being right . . . )
( )
( -Thomas Paine 1776- )
----------------------------------------
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CamLight
Joined: 19 Dec 2008
Posts: 11
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| Posted: Sat Dec 27, 2008 8:37 pm Post subject: Re: Anyone done Bob Nuckoll's CBA modifications? |
|
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| nuckolls.bob(at)aeroelect wrote: |
Yes, I recall that. I must have been 'snowed' at the
time and the List comes first. We could discuss it here
on the List . . . |
No problem, I understand.
In another thread I'll post a link to the analysis and a couple of things I'd love to discuss.
| nuckolls.bob(at)aeroelect wrote: |
That's unfortunate. I know there are a lot of
folks out there with time, talent and resources
willing to help him refine the product. Push
comes to shove, we could do our own.
I've got PIC's with USB engines that I've integrated
into some proposed projects for TC aircraft. A
retired programmer from NCR/Symbios/LSI lives right
behind me (my father in law). He's been doing
some other projects for me and would be please
to have this one.
Our hammer-n-tongs version need not be pretty,
only utilitarian. I think I'd opt for a board
that could drive any practical number of power
FETS. The user could scale his/her version
to the desired task. The only variable in the
software would be to insert a shunt constant
for current interpretation.
The battery tester itself is stone simple.
The sexy part is the application that manages
it. John went out and bought VBasic.net a few
months ago but we've not had occasion to use
it yet.
Bob . . . |
I think that's an idea worth exploring!
I've developed a 500W (400W continuous) electronic load that can be used to extend the capabilities of any analyzer or discharger (http://www.rcgroups.com/forums/showthread.php?t=938266) but there's a real need for "host" software and a load in the power range of the CBA, perhaps 100W-200W. This would be perfect for most DIY'ers and could easily be paralleled for higher power handling.
The software would have to be very graphics-capable as the plotting and graphing features would be extremely important. I'd love to see it not require a huge installation just to run. But, the options may be limited.
The CBA software has a nice light footprint though. An executable, help file, settings file, three DLLs for USB comms and forms handling. It may have some registry keys or other files in public directories but it doesn't seem to require the NET framework. MileHighWings' eFlightWatt logger had a single executable file that did everything, no installation needed. Something like this for an open source tester would be terrific.
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_________________
John M.
Owner
CamLight Systems |
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