Today's Message Index:
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1. 12:31 AM - Re: AeroElectric-List Digest: 15 Msgs - 08/15/13 (Franz Fux)
2. 01:40 PM - Re: Re: Failed brownout battery experiment (Sacha)
3. 02:35 PM - Re: Failed brownout battery experiment (user9253)
4. 04:16 PM - Re: Failed brownout battery experiment (Eric M. Jones)
5. 05:43 PM - Re: Re: Failed brownout battery experiment (Richard Girard)
6. 06:12 PM - Re: Failed brownout battery experiment (user9253)
7. 07:26 PM - Re: Failed brownout battery experiment (nuckollsr)
8. 08:31 PM - Re: Failed brownout battery experiment (nuckollsr)
Message 1
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| Subject: | Re: AeroElectric-List Digest: 15 Msgs - 08/15/13 |
unable to respond to any mail until the 20th of August,
Message 2
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| Subject: | Re: Failed brownout battery experiment |
> How about an active option? A step up module
> like this one
>
> http://tinyurl.com/m7t78eh
>
> could be set up to supply say 19 volts to
> pin 15 of the Dynon, but would certainly
> support 14 watts for 500 milliseconds during
> a brown-out.
Did you mean 14 *volts*?
How can you tell that it would support that for a half a second brownout?
Message 3
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| Subject: | Re: Failed brownout battery experiment |
Today I tried using 2 "D" cells to boost the voltage during engine start. But
the Dynon D-180 still rebooted.
Next I tried 4 AA cells. Success!
With the ignition off, I cranked the engine. The D-180 did NOT reboot.
Now if I could only find some CR14505 3 volt AA batteries to go into my 2 cell
panel mounted battery holder.
I might take Bob's suggestion and use a DC to DC booster.
Schematic attached.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=406883#406883
Attachments:
http://forums.matronics.com//files/brownout_batt_174.pdf
Message 4
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| Subject: | Re: Failed brownout battery experiment |
Any electronic device that fails during engine start is not well designed for the
environment it is sold for.
An old Car Talk line: Ask the manufacture to fix it. If they say 'they're all like
that', just say 'fine; fix them all. Start with this one'.
Slumping voltage on power lines is easy to fix. Dynon certainly knows how to design
the circuit. It's a good place to use a supercapacitor if the slump is low
enough and long enough to warrant it, otherwise a capacitor will do.
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=406889#406889
Message 5
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| Subject: | Re: Failed brownout battery experiment |
Eric, Dang it! I was feeling like the kid at the back of the room who waves
his arm valiantly even though he's not entirely sure he has an answer. Good
to know I might have been learning something while I've been hanging out
here.
My question would have been, why not a capacitor to do the job rather than
a battery? Would not a capacitor be able to take a charge from the system
and then patiently wait to give it back when needed?
Rick Girard
do not archive
On Fri, Aug 16, 2013 at 6:16 PM, Eric M. Jones <emjones@charter.net> wrote:
> emjones@charter.net>
>
> Any electronic device that fails during engine start is not well designed
> for the environment it is sold for.
>
> An old Car Talk line: Ask the manufacture to fix it. If they say 'they're
> all like that', just say 'fine; fix them all. Start with this one'.
>
> Slumping voltage on power lines is easy to fix. Dynon certainly knows how
> to design the circuit. It's a good place to use a supercapacitor if the
> slump is low enough and long enough to warrant it, otherwise a capacitor
> will do.
>
> --------
> Eric M. Jones
> www.PerihelionDesign.com
> 113 Brentwood Drive
> Southbridge, MA 01550
> (508) 764-2072
> emjones(at)charter.net
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=406889#406889
>
>
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
Message 6
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| Subject: | Re: Failed brownout battery experiment |
I had thought about a capacitor. It would have to be isolated with a diode or
resistor or relay so that it does not give its energy to the starter motor. And
it would have to maintain at least 10 volts for 1/4 second. What amount of
capacitance is required? Super capacitors are expensive.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=406896#406896
Message 7
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| Subject: | Re: Failed brownout battery experiment |
Okay, it's pretty easy to run the numbers from the perspective of the transfer
of energy from a capacitor to some load. The energy stored on a capacitor is (C*E^2)/2
= Joules. We deduced a need for 7 Joules to be available to the D180
at 10V or greater.
The charging source is the battery. A fully charged battery would rest at about
13.0 volts. So energy stored at 13 volts minus remaining energy at 10 volts must
be 7Joules or more.
(C*13^2)/2 - (C*10^2)/2 = 7
169C/2 - 100C/2 = 7
69C/2 = 7
34.5C = 7
C = 7/34.5 = 0.2 Farads
The capacitor should be good for at least 15 volts unless you're going to disconnect
it with the alternator running. As you've noted, it would also need to be
diode or switch isolated from the bus to prevent back-feed. A diode would offer
significant impact to the e-squared nature of energy stored . . . so perhaps
relay or switch contacts should be used to unhook the capacitor from the bus
milliseconds before starter is engaged.
AA cells are not well suited to 1+ amp discharge situations but as you've discovered,
D-cells took the hit nicely. A d-cell array is certainly cost attractive
but gives you another battery to maintain. But it gets pre-flight tested every
start-up. I suspect service life on a d-cell array would be quite long. A
super-cap is maintenance free but not cheap and pretty hefty in size. The DC
to DC converter is small, maintenance free and the price is certainly right.
It appears you have a constellation of options to consider.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=406903#406903
Message 8
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| Subject: | Re: Failed brownout battery experiment |
[/quote] Did you mean 14 *volts*? How can you tell that it would support that for
a half a second brownout?[/quote]
The dc-dc converter in consideration is a step-up device with an input range of
3-32 volts, an output range of 5-35 volts. The only constraints on picking an
operating point is to have the output set to always be greater than the input
. . . which can in this case be as much as 15 volts. So some comfortable head-room
above 15 is in order. The higher the selection, the lower the current demanded
by the Dynon's switchmode power supply. 17 would probably work too. Here's
some input/output combinations the supplier says this critter will handle.
Test comparison sample reference:
Input 3V Output 12V 0.4A 4.8W
Input 5V Output 12V 0.8A 9.6W
Input 7.4V Output 12V 1.5A 18W
Input 12V Output 15V 2A 30W
Input 12V Output 16V 2A 32W
Input 12V Output 18V 1.6A 28.8W
Input 12V Output 19V 1.5A 28.5W
Input 12V Output 24V 1 A 24W
Our 'target low input' is on the order of 7 v so we're asking the little feller
to put out 14 watts max with 7v in and some output with headroom above 15volts
. . . 19 seemed like a handy number.
Actually if wired so the converter gets input power only with the starter button
pushed, we can eliminate the possibility of operation with the alternator running.
So adjusting for say 15 volts output would suffice for the fully charged,
unloaded battery case . . . with all bases covered for battery voltage profile
during cranking . . . especially during starter inrush.
Good question.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=406904#406904
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