Help! Can't charge my Lipo

[Richard Clark 2]

David,

I would like to add a little to Simon's excellent advice

1) Nobody has mentioned flying the plane. For all I know you may have previous glow engine plane experience.

IF NOT GET SOMEBODY TO TEACH YOU. Your chance of successfully learning to fly by yourself is effectively zero.

2) Safety. Electrics can start up unexpectedly. When connecting the battery make sure the throttle is 'low', hold the plane secure, keep your hands well away from the prop.

And a few 'incidentals'.

Duration. Simon has covered it but if you don't have a wattmeter try this before you go and then recharge the battery when done so you are ready to fly for real. Secure the plane in a safe space outdoors, set the throttle to 'low'. start a timer, if there is one on the transmitter or use a stopwatch or regular clock. Slowly and steadily open and close the throttle repeatedly over a 10 to 20 second period until full speed notably deteriorates or the ESC cuts the motor, whichever is first. That's a good guide to actual in flight duration on a 'regular' powered plane. A powered glider will be more.

Battery cut out voltage. The ESC will normally cut the motor automatically when the battery is low but if you get to that state you end up with a 'forced landing without power'.

[FlyinBrian]

Posted by Michael Kulagin on 10/07/2020 21:48:26:

First off I must confess that I have absolutely no experience of electric powered flight but I have been following this topic with a great deal of interest as electric power has been recommended for my latest model. I do, however, have over 35 years experience in aviation Quality Control, much of it in calibration. From the various posts I gather that we are talking about measuring volts to 0.01V and amps to 0.5A, and I feel you'll agree that we are talking about very small measurements. I have also gathered that, in the main, we are all cautious folks and would never knowingly do anything likely to place ourselves and others in a position of danger. Electricity, as it comes out of the socket, is variable. The volts and amps that is put through whatever is plugged in are always nominal values, good enough to run fridges, freezers and tv's etc. The electrical values involved in the charging operation indicates to me that the chargers must be able to control their output to the battery on charge irrespective of the incoming values. First question: are the battery chargers in use manufactured to a recognised standard that guarantees their performance? Second question: Are they calibrated? When they are manufactured it can be assumed that they are 'doing what it says on the box'. Assuming they don't go wrong, they can give good service for a number of years. How can we be sure that they are still performing as designed? Do they ever get checked (calibrated) to ensure that the volts to 0.01V and the 0.5A on the readout are actually what is going in to the battery? Safely charging batteries is reliant on accurate readings so without checking that the equipment in use is up to the job strikes me as being very risky especially as the end result can result in a fire.

Michael

First - Yes LiPo batteries come with a risk, we either accept it or don't use em. Mistreat them and they will hurt you, your pocket or others

Regarding callibration / ageing etc. I assume the same charger electronics / firmware are used to measure each cell voltage therefore any ageing error will affect all cells equally - ie read say 4.18 instead of 4.2v when full charged.

If this occurs across two or more batteries then you know the charger has a problem.

A few mV between LiPO cells is acceptable but say .1v or more is not and this will show up as the charger being unable to balance the cells or bring them to full voltage.

Of the chargers I have had over the last 15 years (5) any failures have been with the power input/output rather than monitoring and balancing. These are the heavy current users so get stressed more than the measuring / monitoring circuits.

Also just because a battery says you can charge it at 2 x C or even 5 x C does not mean you have to!. It is good practice to limit charging to 1C or even less, I charge 2200 mAH packs at 1.8 to 2 Amps. If the pack has been flown till there is about 40% Capacity left charging is still quick at those currents.

Regarding domestic power, yes the voltage does fluctuate but within the limits set by the IEEE and other standards Nominally this is 230V to bring us inline with Europe (We were staunchly 240V) however at the substation it is 240V and that is what you will measure at most socket outlets. Cables from the sub stn, the wiring in the premises and the leads to the appliances will add enough resistance to drop the voltage to c230V once a decent load is applied. If the load on a given cable causes the output from the sub stn to drop enough to risk going outside the allowed tolerance then automated switches alter the tapings on the SS transformer and boost the voltage slightly. You may have noticed the lights dimming slightly when switching on a kettle? followed a few seconds later by them returning to normal.

[Richard Clark 2]

These chargers should be able to run accurately off a varying voltage be they mains or a nominal 12 volts DC,

But:

Accurate, calibrated to 10 millivolts over a wide temperature range and able to retain that calibration over time? Fifty quid including manufactures profit, packaging, freight charges, import duty, importers profit, retailers profit, 20% VAT, and from a company you have never heard of in 'Asia'? Don't make me larf

[Paul Marsh]

Really you need someone who does, and check everything over.

[Keith Miles 2]

David, just echoing what Richard has said, if you are new to model flying, I would not recommend trying to teach yourself, it is likely to end in tears, and possibly not just yours! Also, flying in close proximity to housing or the public is also not to be recommended and might, in fact, be either illegal or in breach of local bylaws, or both!

I am assuming that you are also aware of the new CAA regulations regarding registration of both model aircraft and pilots, regulations which have come about as the result of the Gatwick “drone” incident?

If not, you NEED to be before flying ANY RC model aircraft!

[Bruce Collinson]

David,

I was where you are four years ago. Some of what I have learnt, partly the hard way, might help.

Cheapo battery checkers are a godsend. My clubmate Richard Ashworth alludes to three checks per flight. I currently (sorry) have at least six checkers; both man caves, flightbox, spare in Tx case, always one next to the charger and the one which gets most use, in the baggage pocket of the flying trousers, always to hand.

The first two have just worn out, the button covers are falling off. I bought an expensive one with good reviews, Hyperion I think, and as far as I can tell it’s identical. It certainly gives the same readings as the cheap ones. They in turn tally with my multimeter. I am actively reducing my dependence on the PRC but these are an exception.

XT connectors are significantly easier to solder neatly than Deans are. I ended up taking my entire LiPo collection to my very helpful LMS who swapped the whole lot for me. Anti spark on anything above 4S, I found the crack unnerving.

A wattmeter is indeed invaluable, as are adaptors if you use more than one standard connector, so mine has XT 60s wired on and adaptors for Deans and XT 90. Sadly these are also probably Chinoise, but so are my I-Things ....

Have you visited 4Max? George Worley is a first rate supplier of absolutely anything electric and more besides, very helpful with setups and advice and I particularly like his LiPos which seem to me to be a lot less prone to puffing up. You will undoubtedly be able to shave a few percent off anything he sells, if that is your priority. Not mine, I had a return and he could not have been more helpful or fair. I have fallen out with Overloader. It is probably my own fault, everything is.

My LMS will always fit a socket on a LiPo when I ask them nicely. They do far more soldering than I do.

On balance (sorry) I think it wasn’t totally unreasonable for the retailer to direct you to the widely advocated method of reviving a low cell by zapping a NiMh charge into it, I’ve tried it, with initial success but ultimate failure.

Hobbyking (Australian owned, I am told) have battery charge indicators, a little plastic slider showing red or green, which are handy for grabbing a new LiPo and seeing if it’s supposed to be charged. Mind where you stick them if the LiPo is snug and always check with the ubiquitous battery checker anyway. Actually more of a help away from the site as you will check battery charge state before taking the battery out of the Mancave/LiPo bag/back of the wife’s car and always before opening the battery hatch and wrestling with recalcitrant Velcro. How do I know?

Treat an electric plane with a connected battery as though it has a screaming 2 stroke at full chat. Stand behind the wing to connect it and get a pedantic ritual established for installing, connecting and switching on. BMFA A prefers batteries connected on the flight line, not in the pits, but that’s hard with some models. Apparently any simple switch capable of handling the sort of electrickery needed for flight would weigh more than a house brick so isolators generally revolve around plug in connectors and some rewiring of the ESC/battery harness.

Make your throttle kill switch a priority and if your radio permits, a locking one which needs a toggle to be lifted will reduce the potential for accidental power ups, most likely in my observational experience when lifting a plane from its restraint and carrying it to the flight line. I never taxi out with electrics, I’m too mean despite being only an adoptive Yorkshireman.

I hope this helps and very best of luck.

BTC

[David Ramsden]

Thanks again Simon and Richard. I flew IC powered r/c and slope soarers in the 70's and took up slope soaring again just recently. This is my first electric set up.

I like the idea of a watt meter. Can I use my multi meter(?) and if so how, or, is it better to buy something more dedicated to the task - maybe something that could connect into the Deans connectors? Do such things exist?

Thanks

David

[Keith Miles 2]

Posted by Bruce Collinson on 11/07/2020 10:15:38:

David,

I was where you are four years ago. Some of what I have learnt, partly the hard way, might help.

On balance (sorry) I think it wasn’t totally unreasonable for the retailer to direct you to the widely advocated method of reviving a low cell by zapping a NiMh charge into it, I’ve tried it, with initial success but ultimate failure.

A few points.

Learning from other people’s mistakes is certainly good advice and in that context.....

It was (sorry) a mistake, and arguably irresponsible, for a retailer, especially, to advise a “widely advocated” as opposed to a manufacturer approved method of charging a Lipo. As you said yourself, you tried it, and failed, presumably, and perhaps luckily, without injuring yourself or causing damage, so your support of the retailer, in this case, seems somewhat contradictory.

It is also not reasonable for a retailer to fail to immediately offer a refund for, or replacement of, goods that are clearly faulty, as supplied, especially relatively volatile Lipo batteries!

As I alluded to in an earlier post, any deviation from a manufacturer’s advice or instructions puts us in experimental territory and we only have ourselves to blame if the experiment fails or results in a serious incident.

[Keith Miles 2]

Posted by David Ramsden on 11/07/2020 10:48:18:

Thanks again Simon and Richard. I flew IC powered r/c and slope soarers in the 70's and took up slope soaring again just recently. This is my first electric set up.

I like the idea of a watt meter. Can I use my multi meter(?) and if so how, or, is it better to buy something more dedicated to the task - maybe something that could connect into the Deans connectors? Do such things exist?

Thanks

David

Ah, so not a complete beginner, then? Welcome back! Sorry if I told you anything you know already!

I doubt that your multimeter will be of much use, in this context, unless it has a high current capability and substantially sized cables!

For the average electric model you will be measuring tens of amps, at least, at full power e.g. 500 watts on a 3s battery equates to a current draw of 45 amps and 500 watts on a 2s battery would be almost 68 amps.

And bear in mind, as already mentioned that it would take about six minutes to totally flatten a 1600 mah battery at a continuous current of just 16 amps and similarly, a 2900 mah battery would be totally flat after six minutes at a continuous current of 29 amps. It is not good to discharge a Lipo more than 75% and not good to fly a model until any low voltage cut-off operates!

For current measuring, you could use a clamp meter although decent ones are not cheap.

Yes, such things as wattmeters do indeed exist (available from model shops or online) but you might need to solder on your own preferred connectors to suit your set up or make up adaptor leads (with appropriately current rated cable) as required. Electric flight does have more complexities than IC or non-powered gliders and slope soarers. Connector types are numerous and soldering equipment and skills are an inherent part of it. And it doesn’t end there as you are already discovering!

The wattmeter’s primary role is to ensure that you are obtaining maximum efficiency from your power set up as well as ensuring that you do not pull more current than the components and the wiring will withstand and a very easy way to create overload, and possible fire, is by fitting a prop of greater diameter or pitch without monitoring the increased electrical load!

A ready to fly model, however, should not need such checking if left as it is, unless of course, a fault is suspected so you might not yet need to buy a wattmeter at this stage.

 

Edited By Keith Miles 2 on 11/07/2020 14:31:42

[Geoff S]

Posted by David Ramsden on 11/07/2020 10:48:18:

Thanks again Simon and Richard. I flew IC powered r/c and slope soarers in the 70's and took up slope soaring again just recently. This is my first electric set up.

I like the idea of a watt meter. Can I use my multi meter(?) and if so how, or, is it better to buy something more dedicated to the task - maybe something that could connect into the Deans connectors? Do such things exist?

Thanks

David

Highly unlikely that your multimeter has a current rating high enough to use as a wattmeter - the usual maximum is 10 amps and a lot of electric setups, even relatively modest ones, draw currents of aound 30 amps - it's not unusual to be double that. Moreover a wattmeter measures and displays both voltage and current for which you would need either to make 2 measurments or have 2 meters.

A wattmeter usually has a battery test facility which allows measurement of individual cells via the balance plug (something that would have been useful for you) and gives an indication of the charge state (though not necessarily an accurate one). I always check my batteries both before and after a flight - first to be sure I'm installing a charged pack and second to check I haven't discharged the pack too much during use.

They're not expensive and could be classed as an essential tool for electric flight. Get one!

Geoff

Geoff

[Mike Blandford]

You haven't mentioned what radio gear you are using. Many modern radios include telemetry back from the model. With suitable sensors you can get the flight pack voltage and the motor current displayed (and even spoken). This may well avoid the need for a wattmeter. I have one, but haven't used it for a long time as I use the telemetry.

Recently I've started using FrSky Neuron speed controllers with FrSky radio gear. The Neuron has built in sensors and sends voltage, current, RPM, capacity used and temperature back.

Mike

[David Ramsden]

Thanks Keith and Geoff.
Okay. I'm convinced. Please can you recommend a good value Watt meter for electric models? What make/model do you use?

PS I am using a new Futaba T6K and for this model I bought the upgraded receiver and extra cable for monitoring the Lipo voltage in flight (although I'm not using that bit yet - still need to solder it in to the esc cables).

I just did the maiden flight(!). Noticed that the motor was constantly windmilling during the glide. Looks like esc braking is my next challenge(!) and should probably be the subject of a new conversation thread.

Thanks
David

Edited By David Ramsden on 11/07/2020 18:47:08

Edited By David Ramsden on 11/07/2020 18:48:50

[Richard Clark 2]

Posted by David Ramsden on 11/07/2020 18:40:11:

Thanks Keith and Geoff.
Okay. I'm convinced. Please can you recommend a good value Watt meter for electric models? What make/model do you use?

PS I am using a new Futaba T6K and for this model I bought the upgraded receiver and extra cable for monitoring the Lipo voltage in flight (although I'm not using that bit yet - still need to solder it in to the esc cables).

I just did the maiden flight(!). Noticed that the motor was constantly windmilling during the glide. Looks like esc braking is my next challenge(!) and should probably be the subject of a new conversation thread.

Thanks
David

Edited By David Ramsden on 11/07/2020 18:47:08

Edited By David Ramsden on 11/07/2020 18:48:50

Yippee!!! Success. (The braking should be in the ESC instructions (maybe in a 'glider' section if it has one) and is not usually the default so you will need to set it to 'on'.

My wattmeter is distributed by J Perkins Distribution (who don't sell direct,  only to model shops, physical  and online)  and is called the EnErG Power Analyser and it's fine. It's got Deans sockets at each end so you would probably  have to make up a short 'plug to plug' lead for  the  battery (power input)  end.  You can also use it as a balancer (if you can find a suitable lead) and a battery checker but I've never tried either.

Edited By Richard Clark 2 on 11/07/2020 19:06:50

Edited By Richard Clark 2 on 11/07/2020 19:12:36

[EarlyBird]

Well done Dave

I am looking forward to your braking thread as it is on my list of what I need to do.

Steve

[EarlyBird]

This is how to brake.

How to set brake on.

He does it a 5 min.

Looks easy.

Steve

[EarlyBird]

How to set the brake

Another one with a better explanation of the beeps.

Steve

[Keith Miles 2]

Posted by Mike Blandford on 11/07/2020 16:06:00:

You haven't mentioned what radio gear you are using. Many modern radios include telemetry back from the model. With suitable sensors you can get the flight pack voltage and the motor current displayed (and even spoken). This may well avoid the need for a wattmeter. I have one, but haven't used it for a long time as I use the telemetry.

Recently I've started using FrSky Neuron speed controllers with FrSky radio gear. The Neuron has built in sensors and sends voltage, current, RPM, capacity used and temperature back.

Mike

Telemetry is all well and good if you are prepared to buy and fit the necessary sensors or the type of ESC you describe to each and every model and it can be fully justified as opposed to it being just a fancy and unnecessary additional gizmo.

Each to their own, but I also prefer not to have too many potential distractions when I’m flying! I prefer to pay attention to what I and the model are doing rather than be tempted to pay undue amounts of attention to the transmitter.

Also, for some, a wattmeter, being a universal device, is simpler, perfectly adequate and probably more cost effective especially if you only fly models that are already set up or fitted with the recommended components which should not need in-flight monitoring.

Beginners are also better off with simplicity than complexity, in my view.

[David Ramsden]

Thanks Early Bird for the info on setting the esc brake on. Looks easy. I'll do it in the morning. She already glides well and hopefully without the windmill she should float even better.

Just went out for an evening flight and tried constant power just to see how long the 1600mah would last. Managed 17 mins continuous running mostly at 50% throttle some 100%. Is 17 mins good? After that the lipo was slightly warm and the esc cool.
On this afternoons maiden flight, which was actually three shortish flights, the 1600 battery managed 5 full power climbs to about 250' and about 8 mins of half throttle.
I'm guessing the 2900mah (when I get a good one!) will last nearly twice as long.

Enjoyed my first-ever day of electric flights.
Thanks for the help everyone.
David

[Mike Blandford]

Keith: I use audio reports so don't need to look at the Tx while flying. Most are enabled by a switch so I can turn them off. The one item I find most useful is capacity used. That way I know how much battery is left.

Mike

[Keith Miles 2]

David, sounds very good indeed as long as you didn’t over-discharge the Lipo! Unlikely if you have a working voltage cut-off in the ESC, something which is probably best not tested in the air! As far as I am aware, if this cuts in, the motor should stop but leaving just enough power for the receiver and servos to get you back to terra firma!

A point about battery capacity checking, something which has come up in this forum in the past. The capacity check facility is a bit of a misnomer because it is, in fact, measuring voltage and, as such, is not as reliable or accurate as monitoring the amount of charge (mah) that you put back into the battery after a flight. There is no means of measuring capacity directly whatever you might hear to the contrary.

On battery care, and opinions may differ, I would say keep no less than 25% capacity in reserve in order to extend the life of your batteries, more if possible. Discard any Lipo with any cell at 3v or less. Never charge Lipo cells above 4.2v (correct charger setting will prevent this). Use “Balance Charge” for all multi-cell Lipos. Do not store Lipos discharged. Do not store fully charged Lipos for more than a few days but use the “Storage Charge” facility of your charger (it is there for a reason). And Lipos are not dangerous if you treat them with due respect and care!

Oh, and warm, or cool, components are fine. Hot ones aren’t!

Happy landings!

Edited By Keith Miles 2 on 11/07/2020 22:50:08

[Keith Miles 2]

Posted by Mike Blandford on 11/07/2020 22:12:22:

Keith: I use audio reports so don't need to look at the Tx while flying. Most are enabled by a switch so I can turn them off. The one item I find most useful is capacity used. That way I know how much battery is left.

Mike

Again, fine, if you have a suitably capable transmitter, or are willing to buy one!

[EarlyBird]

David

17 min is excellent on a 1600mah battery. Yes a 2900 will last 1.8125 times as long if you fly exactly the same and conditions are the same that gives 30 min. But as the bigger battery is heavier the flight time will be reduced slightly.

The way I work is to aim for a 3.8v/cell target link my timer to the throttle use, set the timer down at 5 min then fly. Check the voltages after and adjust the timer accordingly. Fly again test adjust timer fly again..... a reiterative process that works for me.

For me the flight time I achieve is not important I focus on the post flight battery cell voltages thereby extending the life of my batteries, I hope. This advice came from an experienced pilot who showed me his four year old batteries with no swelling and no loss of power. He also takes his batteries home and puts them on storage charge never leaves them fully charged. Following this advice my batteries are two years old have had hundreds of flights and are still good. Except for one that was damaged when I destroyed my first Riot.

With regard to the number of batteries needed. I was told three was the minimum, one in the plane one cooling down after flying and one on charge. So I bought four to make sure, but that's me being over cautious again.

If you are slope soaring and some distance from your car and charger then you need as many as the number of flights you intend to do. On that basis I bought eight. I had not allowed for flight times being extended as in the right conditions the motor will not be used all of the time.

How you set the brake could be different mine is that model in the link. I searched for 'Volantex Phoenix 2000 esc brake'.

Hope this all helps.

Steve

[Piers Bowlan]

I would say a Watt meter is pretty essential for anyone even dabbling in electric flight. How do you know what current your setup (prop/motor/ESC/battery) is drawing without one? This knowledge will pay for itself by avoiding burning out motors and ESC's. as well as finding a combination that will be reliable and efficient. They can be very cheap like this one or you can pay a lot more but essentially they do the same job. This one is much nicer!  Alternatively, here but you might have to wait a while for it to arrive!

I switched to XT60 (and XT90 for higher Amps) connectors for all my LiPos after using Deans for years. Tip:- always plug male to female connectors together when soldering and use a big soldering iron as the heat will wick away very quickly along the wires otherwise. You need to be quick to avoid melting the plugs. I also prefer leaded solder, not led free.

Just my 2p worth.

 

Edited By Piers Bowlan on 12/07/2020 10:48:33

[EarlyBird]

Posted by Piers Bowlan on 12/07/2020 10:30:40:

I would say a Watt meter is pretty essential for anyone even dabbling in electric flight. How do you know what current your setup (prop/motor/ESC/battery) is drawing without one? This knowledge will pay for itself by avoiding burning out motors and ESC's. as well as finding a combination that will be reliable and efficient. They can be very cheap like this one or you can pay a lot more but essentially they do the same job. This one is much nicer! Alternatively, here but you might have to wait a while for it to arrive!

Edited By Piers Bowlan on 12/07/2020 10:39:03

Although this is good advice and I do understand your reasoning.

I don't have a watt meter and never had a problem but then all of my setups are either RTF or follow the recommendations for ARTF. I have witnessed what happens when a setup is over propped, smoke!. Yes if one wants to indulge in this experimental way of working or maximum efficiency is important then again yes a watt meter is essential.

The problem I have with this technology is that my old brain does not understand so for me it is simple if I want to fly longer I fit a higher capacity battery. But considering my maximum concentration span is six min long flight times are not an issue for me.

It is time for me to go flying.

Steve

[David Ramsden]

Well I guess this thread is drawing to a close now. It's been an education. I've learned a lot about lipos, charger use, and performance monitoring gadgets. And as a small bonus, I got my esc to apply its brake without any trouble at all. Once I had her (my new Kloudrider) trimmed to glide at minimum sink rate I even discovered that it's possible to slope soar without a slope(!). But that's another story...

Thank you everyone!

David

Edited By David Ramsden on 12/07/2020 23:59:09

Edited By David Ramsden on 13/07/2020 00:06:36