The best "toy grade" ready-to-fly quadcopter systems right now

[bobkrech]

Photo of the charge controller consisting of four six-lead SMD packages (probably four identical charge controllers in parallel for increased current handling capacity considering they're such tiny packages) found inside one of my Hubsan X4 packs that I'm using in my Hubsan X4 battery-compatible YiZhan X4. That's a nickel in the background.

EDIT: I'll say that those are definitely ganged charge controller ICs seen in the photo but whether they limit max discharge to protect the pack from over-discharge if left in, for instance, a lost quad I'm not not at all certain about and tend to doubt. One person on the forums implies that toy grade quad battery pack over-discharge (low cell voltage) protection is located on (most) quad controller boards (which makes the most sense) while another claims that both the charge controller and over-discharge protection is built into the packs.

That definitely looks like some type of discharge/charge limiter. I'm amazed that they would put multiple units in parallel because of the cost....

Having witnessed the UN LiPo battery tests, the one that is really bad is overcharging at higher than 4.2 volts. If you follow the UN test procedure, in the battery test I witnessed the battery caught fire after 15 minutes! Even if the charging had been stopped prior to that, chances are the battery is already damaged and will fail catastrophically in the near future.

That's why you have to use a LiPo charger.....

Bob

 

[Winston]

That definitely looks like some type of discharge/charge limiter. I'm amazed that they would put multiple units in parallel because of the cost....

Having witnessed the UN LiPo battery tests, the one that is really bad is overcharging at higher than 4.2 volts. If you follow the UN test procedure, in the battery test I witnessed the battery caught fire after 15 minutes! Even if the charging had been stopped prior to that, chances are the battery is already damaged and will fail catastrophically in the near future.

That's why you have to use a LiPo charger.....

Bob

As I covered in my long post above, they're using the protection circuit of the single cell (3.7V) toy grade quad lipos as a charge controller. That protection circuit is meant to limit the max charge voltage of the cell in the event the user sets their charger's max voltage incorrectly or there's a failure of the charger that results in a too-high voltage, provides a max output current limit, and the lower limit of the discharge voltage.

The protection circuit's max charge voltage limit of 4.25V is set 0.05V higher that the normal 4.2V charge completion voltage of a lipo charger so as not to interfere with battery charger cutoff points. The max output current limiting is meant to protect the cell from thermal runaway in the event of a short on its output.

The max 500mA that can be supplied by a USB 2 port limits the charge rate to around 1C. The two protection circuits I tested with a bench power supply set to 5V limit the charge rate to 1A initially which results in an initial charge rate of 2.6C for the 380mAh pack and 1.5C for the 650mAh pack. The overall charge times for both packs using a that source to allow the protection circuits to charge the cell at their chosen rate rather than the max 500mAh limit of a USB 2 port resulted in a 40 minute charge for both packs which is a 60/40 = 1.5C average charge rate for both.

The recommendations for max lipo charge rates found in guidance online are all over the place, never providing any technical justification for their guidance. One PDF guide from an RC retailer says to never go over 1C, another semi-technical site says that the only thing lost in charging at 5C is that there are diminishing returns in time saved (i.e., it doesn't result in a 5 times quicker charge), another says the 1C limit is relevant to the earliest lipo battery technology only, many users say they have always charged at higher than 1C with no issues, a retail site says that their Turnigy 3.7V pack meant for a toy grade helicopter that uses a USB charger can accept up to a 15C charge rate, etc., etc. I can find nothing adequately technically definitive, so as I said in my long post, you charge at greater than 1C at your own risk.

That said, I have been charging these toy grade quad lipos from my special "3X" 1.5 amp USB 2 and 3 ports on my PC with no issues. That 3X USB port current supply capability was one of the reasons I chose the particular motherboard I built the system on.

 

[georgegassaway]

Don't know about the charger being discussed. I will say that it I had considered getting a Hitec X4 charger a year ago but never got around to it. But in recently flying a Blade QX micro copter using 150 mAh batteries, there was finally enough incentive to get one to charge 4 batteries at a time. And to make use of the features such as dialing in the charge rate (100 to 1000 mA), monitoring the voltage levels, the mAh put in during the charge, and the beeping and LED green light when each one is charged. I found that some of the batteries I had were bad, others very low in capacity, something the dumb four AA powered "plug and charge" chargers did not indicate. So, for some of you, it may be worth considering.

The main downside is that it only works for single LiPo cells, 3.7V. Thread with more info, and video, here:

https://www.rocketryforum.com/showt...harger-for-four-3-7V-LiPo-batteries-thumbs-up

 

[bobkrech]

As I covered in my long post above, they're using the protection circuit of the single cell (3.7V) toy grade quad lipos as a charge controller. That protection circuit is meant to limit the max charge voltage of the cell in the event the user sets their charger's max voltage incorrectly or there's a failure of the charger that results in a too-high voltage, provides a max output current limit, and the lower limit of the discharge voltage.

The protection circuit's max charge voltage limit of 4.25V is set 0.05V higher that the normal 4.2V charge completion voltage of a lipo charger so as not to interfere with battery charger cutoff points. The max output current limiting is meant to protect the cell from thermal runaway in the event of a short on its output.

The max 500mA that can be supplied by a USB 2 port limits the charge rate to around 1C. The two protection circuits I tested with a bench power supply set to 5V limit the charge rate to 1A initially which results in an initial charge rate of 2.6C for the 380mAh pack and 1.5C for the 650mAh pack. The overall charge times for both packs using a that source to allow the protection circuits to charge the cell at their chosen rate rather than the max 500mAh limit of a USB 2 port resulted in a 40 minute charge for both packs which is a 60/40 = 1.5C average charge rate for both.

The recommendations for max lipo charge rates found in guidance online are all over the place, never providing any technical justification for their guidance. One PDF guide from an RC retailer says to never go over 1C, another semi-technical site says that the only thing lost in charging at 5C is that there are diminishing returns in time saved (i.e., it doesn't result in a 5 times quicker charge), another says the 1C limit is relevant to the earliest lipo battery technology only, many users say they have always charged at higher than 1C with no issues, a retail site says that their Turnigy 3.7V pack meant for a toy grade helicopter that uses a USB charger can accept up to a 15C charge rate, etc., etc. I can find nothing adequately technically definitive, so as I said in my long post, you charge at greater than 1C at your own risk.

That said, I have been charging these toy grade quad lipos from my special "3X" 1.5 amp USB 2 and 3 ports on my PC with no issues. That 3X USB port current supply capability was one of the reasons I chose the particular motherboard I built the system on.

I have been dealing with LiPo compliance issues for 3 years so I understand everything you wrote.

We also conduct research on advanced LiPo cell design so I really understand what really goes on inside the cells.

What I am amazed at is that some Chinese manufactures actually are complying with the UN battery regulations......

Bob

 

[Winston]

I have been dealing with LiPo compliance issues for 3 years so I understand everything you wrote.

We also conduct research on advanced LiPo cell design so I really understand what really goes on inside the cells.

What I am amazed at is that some Chinese manufactures actually are complying with the UN battery regulations......

Bob

Cool, do you have any really technical info on that max charge rate issue? I have been able to find absolutely nothing technical about it, perhaps because Google search results are completely filled with page after page after page of "conventional wisdom" with zero supporting evidence or reasons for their claims. Since the charging process is endothermic, a high charge rate hazard can't be due to a thermal runaway problem, but could it be due to the reverse current handling capability within the cell, the capability of the cell chemistry to change quickly enough during the charge because of the cell temperature reduction becoming too extreme, or?

EDIT: On the Chinese compliance, I suspect it's because the EU is forcing them to comply through monitoring, at least that's what I suspect from anecdotes I've read.

 

[WAC_Hal]

Any suggestions for an inexpensive First Person View multi-rotor UAV? I would prefer one that has a display screen on the transmitter or at least one that I can attach a screen to my transmitter.

 

[bobkrech]

https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries Please note on their comments on charging voltages and lifetimes.

That is one technical view on charging LiPo batteries, but you need to be aware that there are several dozen variants of Li-Ion battery chemistry https://en.wikipedia.org/wiki/Lithium-ion_battery and almost as many battery constructions and the limits are different for each chemistry. How much current you can pump into a battery depends on the battery impedance because heat is the enemy of battery life. The lower the battery impedance, the more current you can put in without overheating as P = I^2 x R. Many high quality packs will take 2C to 5C charge rates if you are using a 4 stage charger, and if you limit yourself to 1C they will last for a very long time.

Today LiPo batteries are usually graded by the manufacturer. Due to production variations, not all batteries are the same. Battery with lower impedances have higher value, higher capacity and a longer cycle life than one's with higher impedance. The best source of maximum charge rate is from the manufacturer, however if you never full charge or discharge a LiPo battery, it will last through many more cycles that are fully charged and fully discharges.

This is the trick used in hybrid cars to get a minimum of several thousand cycles from the battery pack without loss of capacity. The NiMH battery chemistry is so repeatable that NiMH hybrid battery packs easily last for 150,000 miles or more.

Be nice to your batteries and they will be nice to you.

Bob

 

[bobkrech]

These are the UN/DOT required qualification tests that LiPo batteries must pass before being placed in commerce.

https://www.phmsa.dot.gov/pv_obj_ca..._Test_Manual_Lithium_Battery_Requirements.pdf

Bob

 

[Winston]

https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries Please note on their comments on charging voltages and lifetimes.

That is one technical view on charging LiPo batteries, but you need to be aware that there are several dozen variants of Li-Ion battery chemistry https://en.wikipedia.org/wiki/Lithium-ion_battery and almost as many battery constructions and the limits are different for each chemistry. How much current you can pump into a battery depends on the battery impedance because heat is the enemy of battery life. The lower the battery impedance, the more current you can put in without overheating as P = I^2 x R. Many high quality packs will take 2C to 5C charge rates if you are using a 4 stage charger, and if you limit yourself to 1C they will last for a very long time.

Today LiPo batteries are usually graded by the manufacturer. Due to production variations, not all batteries are the same. Battery with lower impedances have higher value, higher capacity and a longer cycle life than one's with higher impedance. The best source of maximum charge rate is from the manufacturer, however if you never full charge or discharge a LiPo battery, it will last through many more cycles that are fully charged and fully discharges.

This is the trick used in hybrid cars to get a minimum of several thousand cycles from the battery pack without loss of capacity. The NiMH battery chemistry is so repeatable that NiMH hybrid battery packs easily last for 150,000 miles or more.

Be nice to your batteries and they will be nice to you.

Bob

Thanks! What I read at the provided links goes along with the perception I gained from reading other non-technical sources that charging at a greater than 1C rate is to be avoided primarily because it reduces battery life and doesn't necessarily result in catastrophic failure as implied by those sources which warned "never charge at a rate greater than 1C!" and then don't give any reason why they use that exclamation point.

That modern 750mAh Turnigy pack's lipo technology I mentioned is claimed to allow up to a 15C charge rate, but who knows how badly that will affect the lifetime of the pack and how it will degrade it over time. In any case, if it's protection circuit allows a maximum 1A charge rate (1.33C) as I suspect it might, the excessive charge rate issue is moot anyway. I will be checking that allowed rate with my bench DC supply when I receive the ones I have on order.

 

[bobkrech]

Thanks! What I read at the provided links goes along with the perception I gained from reading other non-technical sources that charging at a greater than 1C rate is to be avoided primarily because it reduces battery life and doesn't necessarily result in catastrophic failure as implied by those sources which warned "never charge at a rate greater than 1C!" and then don't give any reason why they use that exclamation point.

That modern 750mAh Turnigy pack's lipo technology I mentioned is claimed to allow up to a 15C charge rate, but who knows how badly that will affect the lifetime of the pack and how it will degrade it over time. In any case, if it's protection circuit allows a maximum 1A charge rate (1.33C) as I suspect it might, the excessive charge rate issue is moot anyway. I will be checking that allowed rate with my bench DC supply when I receive the ones I have on order.

https://www.hobbyking.com/hobbyking...20D02S_QR_Infra_X_QR_W100S_US_Warehouse_.html

The above battery you suggested is rated for a 5C (12 minute charge) if you look at the bottom of the datasheet. If you have a voltage limited high current supply, you can set the current to some current C and to some Voltage V. The supply will supply the current C until it reaches the set voltage V and then the current will decrease with time to 0.

Excess voltage is the bad actor when charging LiPo cells/batteries. Anything higher than 4.2 volts per cell will permanently degrade the cell and battery. Please read the reference I supplied and it shows that you can put in a lot of current until the battery is charged to some voltage and then you have to operate in the fixed voltage mode. Figure 2 indicates the % of Capacity that can be recharged in the constant current mode and how long it will take in the constant voltage to fully charge the battery. For rapid cycling of quadrotor battery, if you were to use a 5C charge rate to 4.0 volts, you could restore 75% C in ~10 minutes and it would take another 140 minutes to bring the battery up to 80% C. If you increased the voltage limit to 4.1 volt, in ~10 minutes your would restore the battery to 80% C and take 155 minutes to charge it to 90% C. If you increase the voltage limit to the maximum 4.2 volts, it will take ~10 minutes to restore 85% and another 170 minutes to recharge to 100% C. So in my example, I hope you are smart enough to recognize that a 10 minute charge to 75% to 85% of the Rated C is much better than waiting a lot longer for a marginal increase in C.

You may not be able to charge any cell/battery at 5 C at 4.2 volts per cell without getting the batteries hot, but I'll guess that even a B-grade LiPo will not get excessively hot at 3.9 to 4.0 volts per cell. If you have an adjustable current LiPo charger with an adjustable voltage setting, you could do the optimization easily.

The Turnigy nanotech batteries are premium hand-picked cells so they have a measured low impedance. A good indication of this is the discharge current rating. The higher the discharge rating, the better the battery will be at higher charging currents.

If you understand the batteries, you can often shorten the gross recharging time by increasing the current in the voltage limiting mode. For folks without a high level of understanding, you have the electronic circuitry that is on some batteries that prevent the well meaning from setting fire to the battery. Setting fire to a LiPo is not what you want to do because water does not put out the fire......

Bob

 

[Winston]

https://www.hobbyking.com/hobbyking...20D02S_QR_Infra_X_QR_W100S_US_Warehouse_.html

The above battery you suggested is rated for a 5C (12 minute charge) if you look at the bottom of the datasheet.

Yes, that's why I said they claim that the lipo technology they're using was capable of 15C charge. In any case, since those packs are intended for a toy grade RC helicopter that uses a USB charging dongle, I suspect they may have a protection circuit built into then that will limit the charge rate to below 5C anyway. We'll see as soon as I get mine.

Excess voltage is the bad actor when charging LiPo cells/batteries. Anything higher than 4.2 volts per cell will permanently degrade the cell and battery. Please read the reference I supplied and it shows that you can put in a lot of current until the battery is charged to some voltage and then you have to operate in the fixed voltage mode. Figure 2 indicates the % of Capacity that can be recharged in the constant current mode and how long it will take in the constant voltage to fully charge the battery.

From the stepped current curve I saw when using the bench DC supply, this seems to be what the protection circuit was doing.

For rapid cycling of quadrotor battery, if you were to use a 5C charge rate to 4.0 volts, you could restore 75% C in ~10 minutes and it would take another 140 minutes to bring the battery up to 80% C. If you increased the voltage limit to 4.1 volt, in ~10 minutes your would restore the battery to 80% C and take 155 minutes to charge it to 90% C. If you increase the voltage limit to the maximum 4.2 volts, it will take ~10 minutes to restore 85% and another 170 minutes to recharge to 100% C. So in my example, I hope you are smart enough to recognize that a 10 minute charge to 75% to 85% of the Rated C is much better than waiting a lot longer for a marginal increase in C.

All moot since the toy grade packs I've some across all use that protection circuit I've outlined and for those much larger "hobby grade" packs I own which don't, my microcontroller controlled hobby grade charger will handle a proper charge.

You may not be able to charge any cell/battery at 5 C at 4.2 volts per cell without getting the batteries hot, but I'll guess that even a B-grade LiPo will not get excessively hot at 3.9 to 4.0 volts per cell. If you have an adjustable current LiPo charger with an adjustable voltage setting, you could do the optimization easily.

I've never used the "Rapid Charge" capability of my hobby grade charger and have never had a lipo of any size get hot during the charging process since that process is exothermic. The batteries always get cooler.

For folks without a high level of understanding, you have the electronic circuitry that is on some batteries that prevent the well meaning from setting fire to the battery. Setting fire to a LiPo is not what you want to do because water does not put out the fire......

I think anyone who doesn't fit that criteria stopped reading a long time ago. And, as I mentioned many times in my original post, lipo fires will not result in a good day.

 

[Winston]

These packs which have been recommended in various videos and RC forum posts for use with Syma X5C quadcopters and their clones ARE NOT safe to charge with your USB charger since they DO NOT contain the required protection circuit to allow that. A simple current sensing USB charger of the type included with most toy grade quadcopters will dangerously overcharge these:

https://www.hobbyking.com/hobbyking...20D02S_QR_Infra_X_QR_W100S_US_Warehouse_.html

 

[Gary Byrum]

Yeah, quads are NOT easy to learn to fly, at least I didn't find them to be. Much harder than RC planes in my experience.

It's the quad's orientation vs its reaction to control inputs that's the trick to learn. Best to do the Quadcopter 101's training sequence. Learn to hover well and accurately via initial TX trim and your gentle control inputs (which includes getting those precise throttle inputs to maintain a given altitude), then do things related to yaw (rotation around the quad's central axis) and pitch (tilt of the quad which produces horizontal travel). A gentle hand on the throttle is important since many of these quads can climb very rapidly.

Well lo-and-behold, my son in-law was outside kicking around and finally got that copter down before Christmas dinner. Looked pretty good considering it spent just over 8 months in the tree with the drenching rains we've had this year. The battery was swollen, so I am recycling that. Took it partly apart and let it dry out, stuck in a new battery and was blown out of the saddle when it lit up. Everything seems to be working well, with the exception of any skills I had learning to fly it. Got enough time this afternoon to trim it out before the sun went down. Looks like I'm back in the game with this one. YAY!

 

[Mushtang]

I got a Syma X5C for Xmas and have been really loving flying it around the house and the yard. I had a bunch of Syma helicopters in the past which both helped me and hurt me with the controls. I'm able to fly it around the house without crashing because I'm used to being careful with the controls and making small moves, but the movement on the heli controls to turn it around only moves the quad left and right. I don't doubt that soon I'll be able to fly the quad without having to concentrate so hard on what controls do what.

My 10 year old son, who had a smaller quad already, is like an expert on this thing. Really makes me wonder if I'm one of those old men that complains how I can't set the VCR clock and has to get a 10 year old to set up my new laptop.

The only thing I really keep getting wrong is the video recording. I've turned it on, recorded, and then gone to watch the video several times only to find out there was a problem and the file either isn't there or is corrupt. The biggest problem was the driver on my laptop card reader needed to be upgraded. Then it took a few failed attempts to realize that you HAVE to stop the recording before you turn off the controller and/or the quad or else the video file gets corrupted and won't play. The final lesson is that you HAVE to have the SD card actually in the camera for it to record. If you leave it in the laptop and forget to put it back in the camera nothing records and I don't know why. Heh.

Seriously, that happened.

Also, I wish there was a way to look at the controller and know if the video was recording or not. The instructions say there's an indicator light but I don't see anything changing.

 

[Mushtang]

Well lo-and-behold, my son in-law was outside kicking around and finally got that copter down before Christmas dinner. Looked pretty good considering it spent just over 8 months in the tree with the drenching rains we've had this year. The battery was swollen, so I am recycling that. Took it partly apart and let it dry out, stuck in a new battery and was blown out of the saddle when it lit up. Everything seems to be working well, with the exception of any skills I had learning to fly it. Got enough time this afternoon to trim it out before the sun went down. Looks like I'm back in the game with this one. YAY!

That's actually pretty awesome! I would never have expected the electronics to survive that long. The batteries are pretty cheap so having to replace one isn't that big of a dead for sure. I'm impressed!

 

[dlb]

What no Bebop drones?
I love mine, like the idea of Wifi controlled, Yes I have a range extender.
Batteries could last longer, I have some higher current versions coming. Hoping to get 18 to 20 mins fly time..

 

[Flyfalcons]

I got my brother in law a Hobbyzone Zugo mini quad w/camera for Christmas. Got it set up and test flew it in my dining room. Very stable flight on easy mode, didn't take it outside to try the advanced modes. I haven't tried the camera yet but it seems like a pretty solid choice for a reasonably priced quad. Might have to get one for myself now.