Author Topic: Probably a "non Imtelligent Question" (Read 1172 times)

Bill Little · « **on:** January 05, 2011, 06:26:42 PM »

Is a "power source" for a lipo battery charger anything like an AC/DC adapter?

Thanks,
Bill "lost in the Dark Ages" Little

Tim Wescott · « **Reply #1 on:** January 05, 2011, 07:04:48 PM »

An AC/DC adapter will work, if it supplies the right voltage and current. Your battery charger should have it's input power requirements specified, either on the charger or in the documentation someplace. Usually it's 12V, at some current. Some chargers will either work from 12V or from AC, in which case you're made in the shade.

If you've got an input voltage and current level listed, then you just get a 12V supply that's good for that much or more (I'd try to go at least 10% or 20% over on the current rating, just to be sure).

Having said that, I checked the documentation for my old Great Planes Triton -- and what do you know! There's no input power listed! (@#$%).

If it just lists the input voltage, then either search around on the net or ask here, and maybe someone will know how much input current it takes.

Bill Little · « **Reply #2 on:** January 05, 2011, 07:13:53 PM »

Thanks, Tim. "Power Source', Wall Warts, etc, are all new "terms" to me. I made an "AC/DC converter" as a kid (with directions). I have old train transformers that put out 12 v. and are variable, but I ain't suggesting that I would use one for this purpose, just that I am being enlightened on "new terms".

Just like the term "water closet".......

Big Bear

John Cralley · « **Reply #3 on:** January 05, 2011, 07:42:12 PM »

Bill,

Yep but!! You want a DC 12 volt output (actually a bit more like 13-14 volts) power supply that will, in the case of the USA run off of a regular AC 110-130 outlet. But you want a nice steady supply which can deliver the needed amps to drive your charger. Most suitable power supplies are not cheap but the requirements are very much like those of a desktop PC which uses "switching" power supply that will deliver a stable voltage to the motherboard and to various components. Here is a link to several videos and references on how to convert an old PC power supply for powering a Li-poly battery charger. You can often get a cheap used PC power supply form PC repair shop or Recyclers or free if you strip it from that obsolete/defunct PC in your or your friend's basement/garage. I've been using one that I converted to power my Cell Pro 4 charger for several years with no problems. You can get the parts from Radio Shack for $5 to $10.

Note: The common ATX PC power supplies from recent computers will need a load resistor to work properly whereas older AT PC power supplies will not.

Disclaimer: This is not hard to do but you need to be careful that you do it right!!

John

https://sites.google.com/site/tjinguytech/charging-how-tos/convert-pc-ps

https://encrypted.google.com/search?q=Li-po+charger+DC+power+supplies&hl=en&client=firefox-a&hs=bDg&rls=org.mozilla:en-US:official&prmd=ivns&source=univ&tbs=vid:1&tbo=u&ei=QyYlTaz8IprenQfX6eT2AQ&sa=X&oi=video_result_group&ct=title&resnum=1&ved=0CCoQqwQwAA

Bill Little · « **Reply #4 on:** January 05, 2011, 09:21:53 PM »

Quote from: John Cralley on January 05, 2011, 07:42:12 PM

Bill,
(snip)
Disclaimer: This is not hard to do but you need to be careful that you do it right!!

John

Thanks, John.

I will "do it right". That's a guarantee, and why I have done nothing so far.

I had a real "Senior" moment during all this. My Dad still has his full faculties, and he was an aviation electronics/avionics instructor for the NAVY. Served as the NCO on the Polaris missile guidance system program, among other things. Came by on the way to DC back around 1960-61 with a brief case that I couldn't look into.

I have not even thought of asking him about any of this. That is dumb on my part........

BTW: the airframe is done for the ARF Electric Super Clown. Got that done today, it only took a few hours! It went very quickly since I didn't have to worry about fuel proofing anything! LOL!!

Thanks, again
Bill

Tim Wescott · « **Reply #5 on:** January 05, 2011, 11:17:05 PM »

Quote from: John Cralley on January 05, 2011, 07:42:12 PM

https://sites.google.com/site/tjinguytech/charging-how-tos/convert-pc-ps

That looks like a clear set of instructions, and certainly fits with what I know about these supplies.

So, Bill: your kid has all the electronic's tech training and disavows knowledge of it -- does your dad, too?

Bill Little · « **Reply #6 on:** January 06, 2011, 12:07:45 AM »

Quote from: Tim Wescott on January 05, 2011, 11:17:05 PM

That looks like a clear set of instructions, and certainly fits with what I know about these supplies.

So, Bill: your kid has all the electronic's tech training and disavows knowledge of it -- does your dad, too?

Nope. He will tell you, if asked, what he knows.

When we got married, we bought a used blk/wht TV. Something went wrong within about 3 months. No twiddling of the knobs would do any good (and it was one of those you had to stick a screwdrier in the back and turn the knobs.. Dad was still active duty and during one of our phone conversations, I told him the problem.. He told me to go in the back and take out three different "tubes" and go test them, 'cause it had to be one of those. It was. Not so crazy a tale, but I has already asked a friend's Dad who had been in TV repair since they came out, and he said he had o no clue, would have to tear it down... With that fix, the TV worked another 25 plus years.

What can I say about Aaron? He's 35 now, worse than being 16! LOL!!

Larry Cunningham · « **Reply #7 on:** January 18, 2011, 09:40:53 AM »

Quote from: Bill Little on January 05, 2011, 06:26:42 PM

Is a "power source" for a lipo battery charger anything like an AC/DC adapter?

Thanks,
Bill "lost in the Dark Ages" Little

Bill, I believe these chargers for *LiPo* batteries are more sophisticated than simple DC power converters (which are often a transformer and a diode bridge). If you were talking about something
like a car battery, the crudest transformer and two-diode circuit with an output of about 14 volts
would be usable.

But more exotic batteries, even NiCads need a charger with appropriate current limiting circuitry, some even with multiple .charging rate contours based on the actual voltage of the battery and other factors. I know about this because I saw some very sophisticated charge controllers involved for high altitude payloads using several types of batteries.

Further, to ensure optimum battery life and safety, more sophisticated chargers may include "exercise" modes which alternately charge and discharge batteries as they are stored and prepared.
LiPo batteries can be dangerous if not treated with TLC.

Buy a .quality charger, instead of trying to roll your own. The big picture for cost has to include the batteries themselves, which are generally not cheap.

L.

"A girl phoned me the other day and said.. 'Come on over, there's nobody home.' I went over. Nobody was home." -Rodney Dangerfield

Tim Wescott · « **Reply #8 on:** January 18, 2011, 10:07:46 AM »

Quote from: Larry Cunningham on January 18, 2011, 09:40:53 AM

Bill, I believe these chargers for *LiPo* batteries are more sophisticated than simple DC power converters
(snip)

Bill's talking about getting something to plug his charger into when he's at home, since most LiPo chargers are designed to clip onto a car battery.

John Cralley · « **Reply #9 on:** January 18, 2011, 10:09:33 AM »

Larry,

I am not talking about a charger for Bill's batteries. I am talking about a "power supply" to use to supply 12+ volts with ample amps to the actual charger which in turn will charge the batteries. Computer power supplies are sophisticated switching power supplies not to be confused with transformer based supplies used for some car battery chargers.

John

Larry Cunningham · « **Reply #10 on:** January 18, 2011, 02:55:53 PM »

It would help if I actually READ the sentence that Bill wrote! Apologies.
Can I blame it on low blood sugar? ;->

Depending on what the current requirements are, you might consider this
relatively inexpensive solution: buy a small battery, say for a motorcycle
and a battery charger. The charger can typically be set to "trickle" (say a
couple of amps) and keep the battery charged. Depending on how much
current you actually require, you can may flip the battery charg rate to "Hi"
(say 4-6 amps as I recall).

The battery will be a great regulator, and supply extra current if you need
it. Although your LiPo charger can probably tolerate a fairly wide range of
voltage, the motorcycle battery will maintain it at the expected fully charged
value of 13 to 14 volts.

Lead acid batteries are pretty robust and can deliver quite a bit of current
for a fairly long period.

I could put you onto a beautiful lightweight Lambda 15V (adjustable) power
supply that would definitely work, is available online from Digikey (when
last I looked), but it is more costly.

These little switching supplies are lightweight, compact, and mighty, with
impressive regulation and output current.

L.

"I came from a real tough neighborhood. I put my hand in some cement and
felt another hand." -Rodney Dangerfield

Tim Wescott · « **Reply #11 on:** January 18, 2011, 05:40:12 PM »

That's one gross animated GIF!

If you want to mess with power supplies (and not go as far as hacking a PC supply), Marlin P Jones usually has surplus 12V switchers for (relatively) cheap -- less than you'd get a new-production one from DigiKey. Or you can waltz over to Radio Shack and get a 13.8V supply.

I like the motorcycle battery idea -- not so much as a solution for permanent use in one location, but as a solution for something you can chuck in your car and use for charging between flights.

William DeMauro · « **Reply #12 on:** January 18, 2011, 06:08:11 PM »

Tim,
The problem with the motorcycle battery is that they don't hold enough capacity in them to get more than one or two of the batteries that we use charged. If we were flying parkflyers they are great as that is what I use at the field when I fly those. I posted a powersupply solution in another thread. http://stunthanger.com/smf/index.php?topic=20031.0.

Author Topic: Probably a "non Imtelligent Question" (Read 1172 times)

Bill Little

Probably a "non Imtelligent Question"

Tim Wescott

Re: Probably a "non Imtelligent Question"

Bill Little

Re: Probably a "non Imtelligent Question"

John Cralley

Re: Probably a "non Imtelligent Question"

Bill Little

Re: Probably a "non Imtelligent Question"

Tim Wescott

Re: Probably a "non Imtelligent Question"

Bill Little

Re: Probably a "non Imtelligent Question"

Larry Cunningham

Re: Probably a "non Imtelligent Question"

Tim Wescott

Re: Probably a "non Imtelligent Question"

John Cralley

Re: Probably a "non Imtelligent Question"

Larry Cunningham

Re: Probably a "non Imtelligent Question"

Tim Wescott

Re: Probably a "non Imtelligent Question"

William DeMauro

Re: Probably a "non Imtelligent Question"