Boost-Buck Regulator Device

[Joerg]

Hello Jim,

Well, it has to work the same in winter AND summer. Say you get a nice
couple of weeks in June and July where you get 10 hours of decent sunlight a
day. 150 mA over a 10 hour span is 1.5 amp-hours. Over 10 days this is 15
amp hours on a battery that is only 35 amp hours to begin with. And gas
recombinant (sealed) to boot. With only a few mA per day of keep-alives
like clocks and such. I have seen damage like this under the right
conditions.

Provided that those little solar cells are cheap enough the easiest
method might be to design it for winter time and do some shunt
regulation in summer. SEPIC should work as well but EMC needs to be
muffled or people will ask where that 'weeeee' sound on their radio
comes from.

Regards, Joerg

 

[RST Engineering \(jw\)]

Section 21.303 (b)(2) of the FAA regs allows an owner or operator of an
aircraft the right to make parts for that aircraft. THerefore, everything
we sell we sell "Heathkit" form and let the owner "make" it.

JIm

 

[Joerg]

Hello Jim,

Section 21.303 (b)(2) of the FAA regs allows an owner or operator of an
aircraft the right to make parts for that aircraft. THerefore, everything
we sell we sell "Heathkit" form and let the owner "make" it.

That is a great option. One of our neighbors went a step further and is
currently building a pretty large four seater in his garage, Heathkit style.

How do you get insurance in case one of the kits is being blamed for
causing some major trouble?

Regards, Joerg

 

[Tim Williams]

How do you get insurance in case one of the kits is being blamed for
causing some major trouble?

Air-worthiness inspectors...




Yes. *Lots* of rivets to count.

Tim

 

[Zak]

Provided that those little solar cells are cheap enough the easiest
method might be to design it for winter time and do some shunt
regulation in summer.

Or disconnect it when voltage rises too much.


Thomas

 

[Rich Grise]

Hello Win,

However, Jim said that 150mA trickle could already fry an airplane battery
over time. Which really surprised me.

It's simple. The guy's a loon. There is no lead-acid battery that could be
damaged by a 150 mA trickle charge. (at least, not
airplane-battery-sized!) I almost cooked my DieHard the other day - there
were raindrops, so I went out to close my car windows. To close my car
windows, I have to turn on the ignition switch, unlike the headlights, who
are on their own circuit.

Anyway, I turned on the ignition, raised the windows, closed the rain
roof, and went back inside.

I forgot to turn the ignition off.

Next day, the car is sitting there with a "dead" battery. It turns out,
the shop has a handy-dandy Sears 10A battery charger in the utility
closet. So, I hook this 10A charger up to the dead DieHard, and turn it
on. Ten Amps, it reports. So, I figure, it's probably about a 55 Ah
DieHard, so I'll let it sit and charge for a couple of hours, and go
check on it. About two hours later, I go check (well, maybe three hours),
and the battery way _sizzling_. Actually, there was some gas escaping
from at least one cell, making a sort of sizzling noise, so I shut down
the battery charger and start fretting about whether I've killed my
DieHard.

No worries! Next day, I go out and the car just starts right up, and
everything is copacetic. I even get a very solid 13.6 on my dashboard
voltmeter.

So, if your airplanes are packing batteries that can be damaged by a
150mA trickle charge, you need to go invest in some proper batteries.

Good Luck!
Rich

 

[Rich Grise, but drunk]

Hello Jim,

Sure but that is cumbersome. A 'no worries' product would be nice where
people can tie down their aircraft and just forget about battery self
discharge. But AFAICT the regulatory burden and cost is so high that many
of those ideas never make it. One method of getting a foot in the door
would be to begin marketing in countries with lesser bureaucratic hurdles.
That's how we do it in medical.

This makes me wonder, just in a speculative vein, of course, if I could
take one of those solar panels off of one of those solar yard path light
things, and slap it on the roof or cowl or mid-fuse of a Cessna or Piper,
and declare it an "experimental aircraft?"

;-)
Thanks!
Rich

 

[Rich Grise, but drunk]

Section 21.303 (b)(2) of the FAA regs allows an owner or operator of an
aircraft the right to make parts for that aircraft. THerefore, everything
we sell we sell "Heathkit" form and let the owner "make" it.

<Geez, will you ever learn to stop top-posting? It's rude and off-putting,
and impugns your credibility>

You gotta be sh*tt*ng me!

Did you omit a little thing about getting FAA certs to fly the thing, or
do you also declare your customers "experimantal"?

Please elucidate.

Thanks!
Rich

 

[Rich Grise]

Gee, I dunno, let's do the math. About half the time I go into the hangar
the "charge" light is on with the linear design I did 25 years ago, so I
think a 50% duty cycle would probably be a good approximation.

And I current limited the charger at 150 mA at 13.4 volts, or about 2
watts when on; 50% duty cycle reduces that to an average watt.

So 1 watt an hour 24 hours a day times 365 days a year times 25 years is
219 kWh times $0.10 per kWh is $21.90.

You're on. Of course I expect on-site service for this sum.


No problem. Radio Shack is just down the road.

OK, you win.

But I'm still available to solve your problem for you, at $160/hour, plus
travel and expenses.

And you're still a thief.

The ball is in your court.

Cheers!
Rich

 

[boB_K7IQ]

No, but the more I think about it, the more I'm just going to go with a buck
switching converter. THis turkey solar cell is going to have enough trouble
keeping up with leakage current with a winter sun than enough and I can't
afford to throw linear power away during periods of good sunshine.

Jim

Another way to go would be a diversion controller, where a FET or
relay turns on a load when the battery voltage goes above a max
threshold. This will hold the battery voltage down so it doesn't get
overcharged. Build some hysteresis in so it will PWM the switch.

Of course you can buy combination PWM series or diversion charge
controllers with multi-stage charging.

If your battery's amp hour rating is, say, 1/200th larger or so than
your solar panel's available output current (at the battery voltage)
then you may not be even able to overcharge that battery anyway.

A 150 mA output PV panel might be good for floating a fully charged
30 Amp-Hour battery, but probably wouldn't charge it very well.

boB

 

[Keith Williams]

Hello Jim,


That is a great option. One of our neighbors went a step further and is
currently building a pretty large four seater in his garage, Heathkit style.

It's done all the time. John Denver, anyone?

How do you get insurance in case one of the kits is being blamed for
causing some major trouble?

How about the "Experimental Aircraft Association"?

http://www.eaa.org/benefits/aircraft_insurance.html

FWIG, it's not hard to get such insurance. Liability isn't all
*that* big of a deal and there is some incentive to do it right.

 

[Boris Mohar]

Well, after twenty-five years of "borrowing" a miniscule amount of power
from a county power pole, some enterprising young building inspector noticed
the fairly well disguised extension cord going to some thirty hangars and
pulled our plug on the battery trickle chargers we use to keep the airplane
battery from going dead in the slow-flying part of the year and the coldest
also.

Be that as it may. Harbor Freight has a pretty nice solar trickle charger
for under $20, but it is possible for this 150 mA device to overcharge a
$150 aircraft battery and make another dandy paper weight.

Of course, in the grismal weather of winter, it is possible for this solar
panel to put out LESS than the 13.4 volts that the battery likes, so we've
got the worst of all possible worlds...solar panels putting out between 8
and 18 volts to charge a 12 volt (13.4 volt) battery.

Does anybody have a "pet" device that will take 8-18 vdc and put out 13.4
regulated volts at up to 150 mA? Preferably from a manufacturer that the
usual easy to access parts houses (Mouser, Digi-Key, etc.) stocks?

Jim

Have a look at this single inductor buck boost Bit of an overkill but I
like it.

http://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1042,C1116,P10090





Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

[maxfoo]

Well, after twenty-five years of "borrowing" a miniscule amount of power
from a county power pole, some enterprising young building inspector noticed
the fairly well disguised extension cord going to some thirty hangars and
pulled our plug on the battery trickle chargers we use to keep the airplane
battery from going dead in the slow-flying part of the year and the coldest
also.

Be that as it may. Harbor Freight has a pretty nice solar trickle charger
for under $20, but it is possible for this 150 mA device to overcharge a
$150 aircraft battery and make another dandy paper weight.

Of course, in the grismal weather of winter, it is possible for this solar
panel to put out LESS than the 13.4 volts that the battery likes, so we've
got the worst of all possible worlds...solar panels putting out between 8
and 18 volts to charge a 12 volt (13.4 volt) battery.

Does anybody have a "pet" device that will take 8-18 vdc and put out 13.4
regulated volts at up to 150 mA? Preferably from a manufacturer that the
usual easy to access parts houses (Mouser, Digi-Key, etc.) stocks?

Jim

Try a DC/DC converter from Synqor www.synqor.com they are awesome HP, Cisco and
Nortel use them in there telecom equipment.

 

[RST Engineering \(jw\)]

Go talk to the Concorde Aircraft Battery company, asshole. Be sure to
specify recombinant gas battery. It is their engineer's data upon which my
battery charger designs have been based.

Jim

 

[RST Engineering \(jw\)]

Sorry, forgot the full sig line.

Jim Weir
Airframe and Powerplant Mechanic, Inspection Authorization
Commercial/Instrument Pilot, Glider and Airplane
Flight Instructor, Glider and Airplane
Certificated Ground Instructor.

And no, I'm not shitting you. Go read the goddamned rule for yourself.

Jim

 

[Joerg]

Hello Keith,

How about the "Experimental Aircraft Association"?

http://www.eaa.org/benefits/aircraft_insurance.html

FWIG, it's not hard to get such insurance. Liability isn't all
*that* big of a deal and there is some incentive to do it right.

Have you ever tried to get that type of insurance? I can tell you from
my own experience that there are certain categories where the answer is
by default "decline to quote". And I've tried pretty much all US carriers.

Regards, Joerg

 

[Keith Williams]

Hello Keith,


Have you ever tried to get that type of insurance? I can tell you from
my own experience that there are certain categories where the answer is
by default "decline to quote". And I've tried pretty much all US carriers.

Certainly there are some insurances that are harder to come by than
others. No, I haven't tried to get insurance on experimental
aircraft, but I've known several who have. It's quite likely that
State Farm (or whatever) won't write such a policy but I gave you a
link to a site where they *will* write such insurance. They're
likely a self-insured pool though.

 

[Joerg]

Hello Keith,

Certainly there are some insurances that are harder to come by than
others. No, I haven't tried to get insurance on experimental
aircraft, but I've known several who have. It's quite likely that
State Farm (or whatever) won't write such a policy but I gave you a
link to a site where they *will* write such insurance. They're
likely a self-insured pool though.

What I meant was insurance for the company making or designing the
electronics kits. Then you are talking to the big ones such as agencies
that contract with Lloyds. Try it, and good luck. Been there, done that,
didn't work.

Regards, Joerg