Today's Message Index:
----------------------
1. 05:46 AM - Re: Dynamic propeller balancing sensor. (Roberto Waltman)
2. 06:19 AM - Re: Dynamic propeller balancing sensor. (Ken)
3. 10:46 AM - Small LiPo battery testing system.... (David Lloyd)
4. 12:29 PM - Re: Small LiPo battery testing system.... (Robert L. Nuckolls, III)
5. 01:07 PM - Re: Small LiPo battery testing system.... (Charlie England)
6. 01:59 PM - Re: 19v laptop power in vehicles (Ed Holyoke)
7. 02:23 PM - Re: 19v laptop power in vehicles (Robert L. Nuckolls, III)
8. 02:25 PM - Re: 19v laptop power in vehicles (Robert L. Nuckolls, III)
9. 05:21 PM - Re: 19v laptop power in vehicles (Ed Holyoke)
10. 06:23 PM - Re: Small LiPo battery testing system.... (Ken)
11. 06:55 PM - Re: Small LiPo battery testing system.... (David Lloyd)
Message 1
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| Subject: | Re: Dynamic propeller balancing sensor. |
Robert L. Nuckolls, III wrote:
> unless you could put the weights on the hub.
That's were they normally go. Small washers...
The blades are expected to be already statically balanced.
That is, same weight, but not necessarily same weight
distribution. That's why dynamic balancing is needed.
> I suspect the professional chasers of propeller
> shake use a methodology not unlike the old Bear
> alignment systems that used a strobe to mark wheel
> position when the heavy (or light) spot was straight
> up or straight down.
Modern system do not use a strobe light. An accelerometer
and an optical sensor are mounted near the prop, and a
reflecting tape is mounted on the prop itself, but not as a
reference for a strobe. A computer reads data from both and
provides vibration amplitude and phase information as a
guide to be used placing weights.
Products:
http://www.rpxtech.com/rpxweb/Dynavibe.asp
http://www.smartavionics.com/pb3/pb3.html
http://dssmicro.com/products/prod_mb_main.htm
http://dssmicro.com/products.htm
A field report (Vibrex):
http://www.dvatp.com/aviation/maintenance/dynamic_balancing/
Roberto Waltman
Message 2
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| Subject: | Re: Dynamic propeller balancing sensor. |
I have a commercial unit that uses the ADXL103 acceleration sensor. I've
also experimented with that chip (actually one channel of an ADXL203) to
do a little monitoring of propeller and bearing condition.
The overall concept is to bounce an infra red signal off reflective tape
on one prop blade to get rpm and the phase of the imbalance. Add a
weight and repeat the run. Compute a suggested change in phase and
magnitude which can be done in software or with a paper vector diagram.
ie. suggest a relative change in the size of the weight and how many
degrees of prop rotation to move it forward or aft.
FWIW on the few props that I've tested, I've yet to find a significant
improvement on Warp Drive props or on two blade metal props that were
already in obvious good condition. And I've greatly increased my opinion
of how sufficient static prop balancing can be. Graybeards can static
balance to within a few spray puffs of paint on the tips. That would be
with the prop on a horizontal mandrel and the mandrel resting on knife
edges.
It is easy to chase insignificant apparent imbalances that are different
at varying engine rpms but it was certainly educational.
Ken
On 06/09/2012 12:32 PM, Roberto Waltman wrote:
> <aero@rwaltman.com>
>
> I'm beginning to look into how difficult would it be to make my own
> "poor man's" dynamic prop balancer.
>
> Any recommendation for an of-the-shelf accelerometer to be used as sensor?
>
> Thanks,
>
> Roberto Waltman
>
Message 3
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| Subject: | Small LiPo battery testing system.... |
Bob and List members,
As a retired ol' guy from the electronics world of yesteryear, I have not
kept up with the modern, inexpensive electronics available today. One of
the hobbies I have returned to is model RC aircraft using electric motors
and Lipo battery as power.
I would appreciate suggestions for a smart rig to test my battery packs from
time to time to keep an aging history on them and know when to retire a
battery before it faults while in the air.
Building or buying a testing set-up are the options with the test data being
fed into a PC for normal review and file saving, etc.
The test would probably start with a 1C load for a few seconds to get
essentially an open circuit voltage reading as a start point.
And, then, switch to a normal load and operation in flight current for
lengths of time watching for battery capacity characteristics, etc. These
data would be fed to a PC for viewing, etc.
I am betting that there are ready made, inexpensive units to do this that I
do not now know about.
So, suggestions, ideas, directions from this forum group would be very
kindly appreciated.
Dave
Message 4
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| Subject: | Re: Small LiPo battery testing system.... |
>
>I am betting that there are ready made, inexpensive units to do this
>that I do not now know about.
This one has a lot of snort for the $
http://tinyurl.com/9jyfeyu
I use them here.
Bob . . .
Message 5
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| Subject: | Re: Small LiPo battery testing system.... |
On 09/08/2012 12:44 PM, David Lloyd wrote:
> <skywagon@charter.net>
>
> Bob and List members,
>
> As a retired ol' guy from the electronics world of yesteryear, I have
> not kept up with the modern, inexpensive electronics available today.
> One of the hobbies I have returned to is model RC aircraft using
> electric motors and Lipo battery as power.
>
> I would appreciate suggestions for a smart rig to test my battery
> packs from time to time to keep an aging history on them and know when
> to retire a battery before it faults while in the air.
>
> Building or buying a testing set-up are the options with the test data
> being fed into a PC for normal review and file saving, etc.
>
> The test would probably start with a 1C load for a few seconds to get
> essentially an open circuit voltage reading as a start point.
> And, then, switch to a normal load and operation in flight current for
> lengths of time watching for battery capacity characteristics, etc.
> These data would be fed to a PC for viewing, etc.
>
> I am betting that there are ready made, inexpensive units to do this
> that I do not now know about.
>
> So, suggestions, ideas, directions from this forum group would be very
> kindly appreciated.
> Dave
Not directly related to your question, but as a heads-up (if you're not
familiar with the battery properties), I'd suggest a fire resistant
area open to the outdoors as a charging station. A neighbor almost
burned down his machine shop when one caught fire while charging. It
took weeks to clean up the smoke damage to his machine tools (several
lathes, mills, etc). He's an experienced RC'er, & was using recommended
charging systems.
Charlie
Message 6
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| Subject: | Re: 19v laptop power in vehicles |
So, Bob,
The output is adjusted manually to 19v? Does input voltage affect output
as in alternator running/not running. Does a laptop battery know not to
overcharge itself.
Ed Holyoke
On 9/5/2012 12:21 PM, Robert L. Nuckolls, III wrote:
> We've had some discussions on the List about powering
> lap-tops without a great mish-mash of inverters,
> ac mains power supplies and their attendant cables.
>
> Here's a gizmo I bought these two offers off eBay:
>
> *http://tinyurl.com/bn3nkw9
>
> *http://tinyurl.com/7vwr4ur
>
> at very reasonable prices. I mounted the fan
> to the up-converter heatsink thusly.
>
> http://tinyurl.com/c7jc92s
> http://tinyurl.com/bqqxhy8
> http://tinyurl.com/c4kzeh4
>
> E6000 or JB Weld gets a good grip on the
> mounting surface. I'm going to us this in
> my van up behind the glove-box. I don't KNOW
> that it will benefit from forced cooling . . .
> but heat-sink performance jumps up by quantum
> values when subject to the smallest flow of
> air.
>
> This will allow me to put a 19V outlet on
> the panel that needs only a short jumper
> cord to the computer. This would no doubt
> work in you airplane as well.
>
> Bob . . .
>
> *
>
>
> *
Message 7
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| Subject: | Re: 19v laptop power in vehicles |
At 03:58 PM 9/8/2012, you wrote:
>So, Bob,
>
>The output is adjusted manually to 19v?
Yes, you set it before connecting your computer
to it.
> Does input voltage affect output as in alternator running/not running.
The power supply for laptops is not a highly
regulated device. The typical DC input to the
laptop goes immediately to a switchmode regulator
that produces a host of outputs needed by the
computer both for operation of the byte thrashing
hardware -and- charging the battery.
> Does a laptop battery know not to overcharge itself.
Sort of . . . battery charge, discharge and state
of current capacity are managed by a combination
of goodies on the computer and/or within the battery
itself. The battery is not an autonomous component
in the system.
All the adapter needs to supply is 19 volts. The
computer would probably be 'happy' with anything
over the range of 17-21 volts.
Bob . . .
Message 8
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| Subject: | Re: 19v laptop power in vehicles |
At 03:58 PM 9/8/2012, you wrote:
>So, Bob,
>
>The output is adjusted manually to 19v?
Yes, you set it before connecting your computer
to it.
> Does input voltage affect output as in alternator running/not running.
The power supply for laptops is not a highly
regulated device. The typical DC input to the
laptop goes immediately to a switchmode regulator
that produces a host of outputs needed by the
computer both for operation of the byte thrashing
hardware -and- charging the battery.
But the answer to your question is no. This power
supply is a switchmode boost device with a well
regulated output that varies little with changes
in load or input voltage.
> Does a laptop battery know not to overcharge itself.
Sort of . . . battery charge, discharge and state
of current capacity are managed by a combination
of goodies on the computer and/or within the battery
itself. The battery is not an autonomous component
in the system.
All the adapter needs to supply is 19 volts. The
computer would probably be 'happy' with anything
over the range of 17-21 volts.
Bob . . .
Message 9
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| Subject: | Re: 19v laptop power in vehicles |
Thanks, Bob.
I think I'll try one.
Ed
On 9/8/2012 2:24 PM, Robert L. Nuckolls, III wrote:
> At 03:58 PM 9/8/2012, you wrote:
>> So, Bob,
>>
>> The output is adjusted manually to 19v?
>
>
> Yes, you set it before connecting your computer
> to it.
>
>> Does input voltage affect output as in alternator running/not running.
>
>
> The power supply for laptops is not a highly
> regulated device. The typical DC input to the
> laptop goes immediately to a switchmode regulator
> that produces a host of outputs needed by the
> computer both for operation of the byte thrashing
> hardware -and- charging the battery.
>
> */ But the answer to your question is no. This power
> supply is a switchmode boost device with a well
> regulated output that varies little with changes
> in load or input vo/*ltage.
>
>> Does a laptop battery know not to overcharge itself.
>
> Sort of . . . battery charge, discharge and state
> of current capacity are managed by a combination
> of goodies on the computer and/or within the battery
> itself. The battery is not an autonomous component
> in the system.
>
> All the adapter needs to supply is 19 volts. The
> computer would probably be 'happy' with anything
> over the range of 17-21 volts.
>
> Bob . . .
>
> *
>
>
> *
Message 10
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| Subject: | Re: Small LiPo battery testing system.... |
I use the so called genuine version of the IMAX B6 from hobbyking
electronics. Around $24. Less for the knockoff version. More for the one
that has a built in AC power supply. It does Li with charge balancing,
NiMH, NiCad, and LeadAcid. The optional software is limited but does
plot out a charge or discharge voltage vs. time chart. Haven't used the
temperature sensor yet as I don't leave the batteries untended while
charging and you can't use the temp sensor at the same time as the
plotting software.
There is a somewhat similar heavy duty device available from them as
well that handles large amperage.
Ken
On 08/09/2012 1:44 PM, David Lloyd wrote:
> <skywagon@charter.net>
>
> Bob and List members,
>
> As a retired ol' guy from the electronics world of yesteryear, I have
> not kept up with the modern, inexpensive electronics available today.
> One of the hobbies I have returned to is model RC aircraft using
> electric motors and Lipo battery as power.
>
> I would appreciate suggestions for a smart rig to test my battery packs
> from time to time to keep an aging history on them and know when to
> retire a battery before it faults while in the air.
>
> Building or buying a testing set-up are the options with the test data
> being fed into a PC for normal review and file saving, etc.
>
> The test would probably start with a 1C load for a few seconds to get
> essentially an open circuit voltage reading as a start point.
> And, then, switch to a normal load and operation in flight current for
> lengths of time watching for battery capacity characteristics, etc.
> These data would be fed to a PC for viewing, etc.
>
> I am betting that there are ready made, inexpensive units to do this
> that I do not now know about.
>
> So, suggestions, ideas, directions from this forum group would be very
> kindly appreciated.
> Dave
>
>
Message 11
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| Subject: | Re: Small LiPo battery testing system.... |
Charlie,
You are quite correct....rapid charging of Lipo's can be a dangerous
situation. I don't charge at much above than 1 or 2C. I keep the Lipo in a
surplus ammo can while charging. I have a buddy that is a expert helio RC
guy. He was charging Lipo's at a rapid rate and left his garage to answer
the phone. By the time he got back his garage was on-fire and he lost
everything inside....!! Good warning about charging a Lipo at high "C"
rates.
________________________________________________
----- Original Message -----
From: "Charlie England" <ceengland7@gmail.com>
Sent: Saturday, September 08, 2012 1:06 PM
Subject: Re: AeroElectric-List: Small LiPo battery testing system....
> <ceengland7@gmail.com>
>
> On 09/08/2012 12:44 PM, David Lloyd wrote:
>> <skywagon@charter.net>
>>
>> Bob and List members,
>>
>> As a retired ol' guy from the electronics world of yesteryear, I have not
>> kept up with the modern, inexpensive electronics available today. One of
>> the hobbies I have returned to is model RC aircraft using electric motors
>> and Lipo battery as power.
>>
>> I would appreciate suggestions for a smart rig to test my battery packs
>> from time to time to keep an aging history on them and know when to
>> retire a battery before it faults while in the air.
>>
>> Building or buying a testing set-up are the options with the test data
>> being fed into a PC for normal review and file saving, etc.
>>
>> The test would probably start with a 1C load for a few seconds to get
>> essentially an open circuit voltage reading as a start point.
>> And, then, switch to a normal load and operation in flight current for
>> lengths of time watching for battery capacity characteristics, etc.
>> These data would be fed to a PC for viewing, etc.
>>
>> I am betting that there are ready made, inexpensive units to do this that
>> I do not now know about.
>>
>> So, suggestions, ideas, directions from this forum group would be very
>> kindly appreciated.
>> Dave
> Not directly related to your question, but as a heads-up (if you're not
> familiar with the battery properties), I'd suggest a fire resistant area
> open to the outdoors as a charging station. A neighbor almost burned down
> his machine shop when one caught fire while charging. It took weeks to
> clean up the smoke damage to his machine tools (several lathes, mills,
> etc). He's an experienced RC'er, & was using recommended charging systems.
>
> Charlie
>
>
>
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