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Old Jun 05, 2012, 10:29 AM
Epilepsy Awareness
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United States, MA, Malden
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HP, No sense swimming against the tide

Mike.
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Old Jun 05, 2012, 11:52 AM
Vroooom putta putta putta
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I'm guessing that cigarette lighter "charger" isn't a charger at all, and merely a cigar-to-USB adapter that a USB charge cable is plugged into. An actual charger would have a lipo-charge connector.

This means the "charger" here is that USB cable.

The only variable in this scenario is how much 5V current the adapter will source. A low-current USB port can starve a charger cable, but a port that can source more doesn't somehow magically "push more current" than is safe. The only way it could do that would be if it raised the voltage, which would be classified as a dangerously defective USB port.


When we talk about these Syma AC chargers we're in an entirely different arena. If their internal circuitry is halfway sophisticated (like a "real" lipo charger) they will indeed vary the charging voltage over time. But there is no 5V-to-charge-voltage conversion involved, unlike those passive USB arrangements.

So these AC chargers might be really dumb, slightly smart, or pretty smart, I don't know. But you can't compare them with any arrangement that involves a USB port (whether a real port or a fake "power adapter" port).


A device such as an iPhone that takes charging via a USB cable has the "smarts" if any built into the unit. The small-heli charge cables build what little there is into (a) the "pod" at the USB port end, and (b) those little "protection" PCBs on the battery (when they're there at all). The heli itself usually has little but a blocking diode (if that) for reverse-polarity protection.
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Old Jun 05, 2012, 12:10 PM
Vroooom putta putta putta
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Another consideration is that "standard" USB ports are supposed to provide smart curernt limiting. They should keep the voltage close to the nominal 5V and allow current to be pulled up to the maximum, which is 0.5A.

There are now "smarter" USB ports that can accept "signals" one way or another that tell it "this device is a charger." Then such a port is allowed to source 0.9A to as much as 1.5A.

Plugging a "dumb" device like a heli USB charge cable into a hacked "0.75A iPhone charge adapter" risks a meltdown since these heli cords were not designed to be used at the high currents. They are safe used with real USB ports because the ports won't source high currents unless specifically asked to.

Many of these AC-to-USB and cigar-to-USB charging adapters are not smart at all, and may well assume any attached device can handle high currents. They do not pay attention to device "signals" that are supposed to be present to permit high currents for charging.

See https://en.wikipedia.org/wiki/USB#Power

Do not assume those wacky power-to-USB adapter gizmos are smart. Many that are smart only work safely with the devices they were designed for (Apple in particular used a lot of bizarre non-standard signaling).
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Old Jun 05, 2012, 12:43 PM
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Quote:
Originally Posted by SubtleT View Post
Plugging a "dumb" device like a heli USB charge cable into a hacked "0.75A iPhone charge adapter" risks a meltdown since these heli cords were not designed to be used at the high currents.
assuming voltage is correct the current rating on those adapters (actually fixed 5v dc supplies) does not matter. i have ipod cubes that draw nearly 2a and others that look the same but only put out .4a and they all draw the same current with my s107 yellow cable. initially ~150ma with an empty cell then tapering off. it is voltage that determines current draw with the stock s107 charger and little danger of meltdown regardless of amp rating.

i have dismantled one of hps 800ma chargers and also stock v911 charger and they have actuall lipo charge ics so are not voltage dependent. they work properly with 12v in as well as 5v in unlike the "dumb" s107 cable which needs exactly 5v.

the white ipod cubes are my standard ac adpater for many things and for $1 imo best source of 5v for those yellow cables.
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Old Jun 05, 2012, 01:19 PM
Vroooom putta putta putta
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Originally Posted by dave1993 View Post
i have dismantled one of hps 800ma chargers and also stock v911 charger and they have actuall lipo charge ics...
Good to know. I think you did say that earlier in this thread didn't you?

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Originally Posted by dave1993 View Post
... so are not voltage dependent. they work properly with 12v in as well as 5v in unlike the "dumb" s107 cable which needs exactly 5v.
Er, those are AC chargers and plug in (110VAC/220VAC depending on model). There is no 12V or 5V involved except perhaps internally. Not the same issue at all.


As far as the USB charge cords (yellow) go, we've seen a number of reports of prople literally melting them. Using them in a current-limited standard PC USB port would be unlikely to do this, but without the specifics around an individual case we may just be guessing what went wrong. Could be the lipo just went bad for other reasons and shorted for all we know!

I'm not telling anybody to avoid AC/ciglighter-to-USB converters, just saying to keep an eye on things during charging.
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Old Jun 05, 2012, 02:03 PM
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[QUOTE=SubtleT;21809757]Er, those are AC chargers and plug in (110VAC/220VAC depending on model). There is no 12V or 5V involved except perhaps internally. Not the same issue at all.

the v911 has a plug that can accept whatever you put in. ive powered mine from 12v 9v and 5v. my point was when you have a real lipo ic it dont matter what you power them from.

Quote:
Originally Posted by SubtleT View Post
As far as the USB charge cords (yellow) go, we've seen a number of reports of prople literally melting them.
possibly defective units, physical damage, and clones w/reports of reversed polarity but not all credible. imo rare for them to explode. personally i do not use them anymore but not because of any fear of risk. they are just crummy chargers.

Quote:
Originally Posted by SubtleT View Post
Using them in a current-limited standard PC USB port would be unlikely to do this, but without the specifics around an individual case we may just be guessing what went wrong. Could be the lipo just went bad for other reasons and shorted for all we know!

I'm not telling anybody to avoid AC/ciglighter-to-USB converters, just saying to keep an eye on things during charging.
most of the 20 or so ipod adapters i tested for work put out about 600-700ma which is not too different from the 500ma of a "legal" usb port. not too risky. i never hesitate to recommend them or any cheapo 5v supply. theres more concern for damaging a $500 notebook. we agree on care with all electrical appliances.
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Old Jun 05, 2012, 08:35 PM
We NEED a LiPo w a USB plug!!!
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Orland Park, Illinois
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Originally Posted by Heli Pad View Post
Mike, I didn't think you would approve. But I think you mis-read what IceRail was saying. His charger is rated for 0.75A, which is 750mA, or 5C for a 150mAh battery. I don't think you would go for that.
You nailed it. Like SubtleT said, it's just a cigar-to-USB adapter that I plug the Syma (and v911) USB charging cords into. I should've been clearer.


A couple things prompted me to buy them.
After reading through the last argument ... disagreement ... discussion about exactly how much you can feed these little LiPo's I saw the lighter to USB thingys on sale at Meritline (90% sure it was Meritline,.. could've been Newegg).
I'm painfully aware how easy it is to fry a battery; I've murdered more batteries than I like to admit.
I took the chance, knowing I'm liable ruin a few batteries (or start a fire on the truck again, etc).

The ones I bought were on sale because there were so many complaints about the output being too low for iPhones. Everyone was grouching about the things taking too long to charge phones (I think "real" iPhone chargers put out two or three amps - the description for these clearly said 750 ma).

I've only used them on the cheesy yellow Syma charging cords and the v911's that I usually keep in the truck (never tried charging anything else with them).


They seem to be working pretty well,............ so far. I know 750 ma is kind of hot for these little batteries, and I honestly do know it diminishes battery-life, but it's a lot easier than carrying the B6-Pro around.
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Old Jun 06, 2012, 03:22 AM
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Hi, this has probably been spoken of somewhere here but I'll ask it anyway. Is it possible and has anyone tried to adapt a 7.4 2s lipo to power the transmitter in lieu of the 6 AA's?
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Old Jun 06, 2012, 09:00 AM
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I have a two cell LiPo in one of mine. You have to grind the ribs down and add a connector or solder the leads. It will be a long time before it will need a charge.

In my house if I can fit a LiPo in then I do, battery guitar amp has two 1000 mha two sell, cordless drill has two three cell 2200mha making it a 24 volt. Dave
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Old Jun 06, 2012, 04:18 PM
Heli Mania
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Quote:
Originally Posted by SubtleT View Post
I'm guessing that cigarette lighter "charger" isn't a charger at all, and merely a cigar-to-USB adapter that a USB charge cable is plugged into. An actual charger would have a lipo-charge connector.

This means the "charger" here is that USB cable.

The only variable in this scenario is how much 5V current the adapter will source. A low-current USB port can starve a charger cable, but a port that can source more doesn't somehow magically "push more current" than is safe. The only way it could do that would be if it raised the voltage, which would be classified as a dangerously defective USB port.
Exactly ... you could have a 1000 AMP power source, but if the charger is regulating the voltage/current going into the battery, then the battery will only charge as fast as that regulated charger will allow, regardless of how many milliamps or amps are available from the power source.
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Old Jun 06, 2012, 04:32 PM
Vroooom putta putta putta
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Except that the USB charge cord dealies that ship with cheap helis aren't very smart about limiting current at all. In many cases there seems to be nothing but a resistor to drop 5V to approx 4.2V. Everything else just seems to be a simple circuit to drive the "charged" state LED indicator.
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Old Jun 06, 2012, 05:49 PM
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Back in business, my replacement batterys came...(faster than I thought from RC TOY VILLAGE)...plus they sent 2 motors (free).....all in 4 days time....awesome....
I gotta admit...I sure missed flying my s107
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Old Jun 06, 2012, 06:07 PM
Heli Mania
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Quote:
Originally Posted by SubtleT View Post
Except that the USB charge cord dealies that ship with cheap helis aren't very smart about limiting current at all. In many cases there seems to be nothing but a resistor to drop 5V to approx 4.2V. Everything else just seems to be a simple circuit to drive the "charged" state LED indicator.
The battery will only draw as much current as the limiting charge voltage of 4.2 volts will allow. It's the voltage that drives the current into the battery. When the battery is near fully discharged, the current draw will be highest, and taper off to zero as the battery voltage climbs to 4.2 volts. The battery voltage as it charges up and gets closer and closer to 4.2 volts basically regulates the amount of current flow into it during a charge.

If the charger puts out more than 4.2 volts, then the charging current will higher if the current is unregulated.
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Old Jun 07, 2012, 06:36 AM
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Originally Posted by Lockley View Post
I have a two cell LiPo in one of mine. You have to grind the ribs down and add a connector or solder the leads. It will be a long time before it will need a charge.

In my house if I can fit a LiPo in then I do, battery guitar amp has two 1000 mha two sell, cordless drill has two three cell 2200mha making it a 24 volt. Dave
Cool. I have a connector to mate with the lipo connector. I will add longer wires to it and try it out. I hope I can get the solder to stick to the metal tabs in the transmitter
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Old Jun 07, 2012, 10:11 PM
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United States, TX, Arlington
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At Participating 7- Eleven Stores

Everyone,

Participating 7-Eleven stores are selling SYMA S-107G for $29.99 + tax.

Colors:
Red
White
Blue
Yellow

Comes with 2 extra rotor blades and 1 tail blade.
60 day manufacturer warranty.

Get a brain freeze with your S-107G
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