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Help! Can't charge my Lipo

RC6-VSR displaying cell voltage error

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Simon Chaddock10/07/2020 18:35:24
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David

Earlier you said your charger worked ok charging another 3 cell LiPo. Did you notice the cell voltages during that charge, were they at more or less equal and did they all show 4.2 V at the end?

If it showed sensible voltages during and at the end of that charge then clearly the charger is ok and it is the Overlander battery that is at fault in some way.

Bad luck that you are having problems with a brand new battery but it can happen just not very often. I would certainly expect your next 100 batteries all to work perfectly!

David Ramsden10/07/2020 19:34:05
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27 forum posts
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Thanks everyone.
Simon - I might be wrong but I don't think my charger displays the individual voltages of each cell during and at the end of charge (bear in mind this is my first time using any Lipo charger). It did though show the pack voltage during charge which I monitored.

I have just ordered one directly from Overlander.

To be fair to Wireless-Madness, they did sound reasonable on the phone and they've not hesitated in recommending a refund. On balance though (and being a cautious sort of chap), I'm not impressed with their advice. The amount of experience amongst forum members must be immense and you are all kind enough to give free advice (which I have followed on this and other questions). Thank you all very much indeed.

Keith Miles 210/07/2020 20:16:15
423 forum posts
6 photos
Posted by David Ramsden on 10/07/2020 19:34:05:

Thanks everyone.
Simon - I might be wrong but I don't think my charger displays the individual voltages of each cell during and at the end of charge (bear in mind this is my first time using any Lipo charger). It did though show the pack voltage during charge which I monitored.

I have just ordered one directly from Overlander.

To be fair to Wireless-Madness, they did sound reasonable on the phone and they've not hesitated in recommending a refund. On balance though (and being a cautious sort of chap), I'm not impressed with their advice. The amount of experience amongst forum members must be immense and you are all kind enough to give free advice (which I have followed on this and other questions). Thank you all very much indeed.

That’s what we’re here for, well, mostly!

Many things might be, or are, debatable but battery characteristics are established science and if you deviate from official instructions regarding their use you put yourself into experimental territory even if you have expertise and know what you are doing!

If you have no individual cell check facility on your charger, or even if you do, I can only again highly recommend a battery checker. They are not expensive but very useful for quickly and easily checking your batteries. And on that point, though some will disagree, be particularly wary of Far Eastern suppliers (of anything!) on E-bay and, preferably, buy from a reputable model shop or supplier who will provide you with a genuine article, not a clone, and a likely more reliable and professional customer service! You can probably add a checker to your Overlander order. Check their website and give them a call. And, no, I don’t work for them!

And finally, as well as this forum, there is plenty of information for beginners online regarding Lipos and electric RC in general which will provide you with a great deal of very useful basic knowledge about the hobby and the components used. Hopefully, you will be in a better position, then, to take a more informed view of advice received and to judge the possible motives that might be influencing it!

P.S. Just checked and Overlander still do a decent checker for £14.99. Add a Lipo bag and the optional temperature probe (if you don’t have one) for your charger and you will have all of the basic safety factors pretty much covered! Oh, and DO read all instructions!

Edited By Keith Miles 2 on 10/07/2020 20:48:49

Mike Blandford10/07/2020 20:29:50
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Posted by David Ramsden on 10/07/2020 19:34:05:

I might be wrong but I don't think my charger displays the individual voltages of each cell during and at the end of charge

Manual pages 16/17, press the INC button while charging to show the individual cell voltages.

Mike

Piers Bowlan10/07/2020 21:34:14
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2167 forum posts
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David, this is what I linked to earlier. A small investment and an invaluable and convenient tool for any leccy flyer.

Those voltages sound quite unbelievable (not that I doubt your word I hasten to add). Firstly, because surely the charger would auto-cutoff at 4.2v if 'LiPo' is selected from the charger menu and secondly, Is it chemically possible for a LiPo to reach those voltages irrespective of whether it catches fire or explodes? Could the charger be telling porkies?

Michael Kulagin10/07/2020 21:48:26
12 forum posts

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.

David Ramsden10/07/2020 21:55:57
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27 forum posts
13 photos

Thanks Keith Mike and Piers. I shall certainly get one of those Piers. Good tip. And great tip Mike about the inc. button while charging. I'll try that. Now the panic is over I shall take more time to get my head around the manual.

Such a useful forum!

David

Richard Ashworth10/07/2020 23:10:23
105 forum posts
70 photos

David. Can I echo Piers advice that if you are going electric, get a battery checker. They have dropped a lot in price over the last 5 years and Overlanders checker is not overpriced at £12 for their Backing on service and support.

What has not been said (That I have spotted) is the checker gets used on at least 3 occasions in each cycle of a Lipo.

First, I always use mine to check its correctLy charged when it comes off the charger after being recharged just before a flying session.

At the field you should check the battery is a charged battery and the cells are aligned JUST BEFORE you put it into your model. Well done to anyone who hasn’t accidentally picked up a battery used earlier in a session thinking it was unused. If you are lucky you can feel that the power is down on takeoff and land after a circuit, otherwise you risk discharging the battery to the point where the motor stops on low voltage failsafe and you are doing an unplanned deadstick landing.

Lastly checking how much power remains after a successful flight tells you whether you could have flown longer or shouldn’t have flown as long as you drained the battery too much. I don’t know what safety margin others use but I set my tx timer for the plane /battery so that it goes off at about 30% capacity remaining. You then have enough power left for two or three go arounds if needed.

Batteries and planes aren’t cheap. The more you look after them the longer they last.

Enjoy the hobby.

Richard

David Ramsden11/07/2020 00:54:23
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27 forum posts
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Thank you Richard.
I have ordered the checker recommended by Piers Bowlan (above) and shall certainly use it as you suggest.

With the receiver for this model I also have an extra bit of kit which will eventually give me a voltage reading of the lipo on the transmitter which should help in flight. I've not soldered it into the ESC wires yet. Thought I'd wait until the ESC has proved itself to be the right one.

In my reading and watching youtube videos about setting up brushless systems, one thing that nobody seems to talk about is battery duration in flight. Not being part of a club, I have no idea whether a typical flyer takes one two or three charged batteries with them when they go for a few hours flying. I guess no one gives guidance because there are too many variables and generalisations can be misleading. Guess I'll just learn by experience.

Hoping to have the maiden flight of my first electric model tomorrow, not with the 2900mah battery as planned(!) but with the 1600mah which charged up fine plus some lead in the nose to make up the weight difference. The rimfire 400 certainly produced an impressive amount of thrust when I tested it in the hanger.

Wish me luck! (And thanks again to everyone)

19.jpg

Simon Chaddock11/07/2020 01:26:12
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5737 forum posts
3034 photos

David

You friend is a Watt meter. It is plugged in between the battery and the ESC. It measures the amps, the volts and calculates the Watts. Most give the peak readings achieved as well.

With this information after a short (10 second) full power run you can determine how close the amps are to the limits of the motor, ESC and battery.

If you divide the battery capacity (Ah) by the peak current reading it will give the full power duration. It is likely to come out at no more than 1/10 hr (6 minutes). Treat what ever figure you get as a good duration limit for the first few flights. By noting how much you put back into the battery after a flight to reach full charge will give an indication of how much you actually used and thus how much longer you could fly for. It is not uncommon to be able to fly for at least double the full power duration figure with a bit of throttle management.

Powered gliders can of course stay up for much longer as they can glide power off for many times the length of the power run.

However be warned never fly so that the LiPo is exhausted. You will wreck it.

It is good practise not to go below 40% capacity. It takes a bit of trial and error to get to know what duration is acceptable.

Richard Clark 211/07/2020 06:25:16
424 forum posts

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'.

FlyinBrian11/07/2020 07:40:52
645 forum posts
4 photos
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 211/07/2020 08:36:14
424 forum posts

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 Marsh11/07/2020 09:20:41
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4072 forum posts
1225 photos

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

Keith Miles 211/07/2020 10:06:14
423 forum posts
6 photos

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 Collinson11/07/2020 10:15:38
543 forum posts

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 Ramsden11/07/2020 10:48:18
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27 forum posts
13 photos

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 211/07/2020 11:16:13
423 forum posts
6 photos
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 211/07/2020 14:28:12
423 forum posts
6 photos
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 S11/07/2020 14:31:23
3701 forum posts
29 photos
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

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