Hobbyking Nano Tech Lipo battery problems

[Tomtom39]

I bought a new Nano tech 3s Lipo in August from Hobbyking checked this on receipt (although off balance on a cell) . I was advised that this was in tolerance - charged this up and did not use it. Went to use it to find that there was no charge in it at all ie totally dead!

I would be interested to see how people store their batteries . I have experimentated with discharge to 40% for winter/long term storage ie over 2 weeks . My batteries are kept in a storage box (In lipo bags) which is kept at between 15 and 17 deg C .

As an aside all the Nao tech batteries I have bought (max 40 cycles ) seem to have gone off balance . None of the Optipower ones have to date .

I have written to Hobbyking for their views and I am waiting for their response.

[Garbo]

Do you balance charge your batteries and to what % do you discharge the batteries to when flying?

[Tomtom39]

Hello Garbo,

My Lipo's are always balance charged (I run an Ultramet 60) and I normally run my batteries down to a minimum of 25% (normally 30%) ie batteries have never been run to 3V per cell. (I charge them all at 1C)

Hobbyking have just got back to me and have received standard response that as it's been over a month "please go whistle" or words to that effect!

As a member of the farts brigade (OFB) I also asked some of my club members for their opinions and for the last thirty mins have had great fun with checking the Turnigy batteries inc a Nano tech (9) belonging to one of my compatriots who swears by them (think he must have meant price!) He has gone home a little miffed as they were all out of balance (significantly) , having fully charged them this morning . We also found that one of the batteries bought three months ago was charging up to max of 85% (I log all charge cycles for my batteries in excess of 3s. - don't bother with smaller ones)

I am rather hoping that someone will carry out a suitable test and review of various batteries (enter Messers Ashby?)

[Garbo]

What's you parameters for out of balance .00000001v between the high and low or .5v? I have never had a pack go to .5v of any make. I have had a nanotech pack go weak, in that it would no longer give out 80amps but now use it in a Bixler which only draws 11

[Tomtom39]

Hello Garbo

Hobbykings parameter are .1V . I tend to use similar ( I have number of battery checkers - the best one I've found for ease of use has been the Bantam E-station two meter ) .

Having just checked outputs of various motors max draw has been 80amps on an EDF.

I'm interested in how people store their batteries ie charge level and their experiences with various makes. Do you discharge to a certain level to store?

[Garbo]

You got upset that the batteries were out of balance when the imbalance was less than .1v?

I am no expert but perhaps you are a little over concerned.

My charger has a storage setting and I use that for batteries that are not likely to be used for a while.

[Tomtom39]

Hello Garbo

Not sure if you read my original post in full. The balance was not the issue here. The fact was that having tested it (within limits!) It was charged and stored. When I went to use it the other day (I had not used it and I always check voltage prior to charging/using - having learnt the hard way!) There was nil voltage in all three cells.

[Robin Kearney]

Tom,

I store all my Lipos, including 4 nano tech 3s 2200 packs, fully charged, but I'd say they all get used within 3-6 months so we aren't talking really long term storage. I've never had one die in the way you describe, although I've had the odd cell puff up either during usage or during charge, if that happens I tend to charge and discharge the pack, paying close attention to the capacity it holds, and also not letting it out of my sit for obvious reasons!

 

You say you have a Ultramat 16, same as me. Have you tried a charge, dischargr cycle a couple of times? Does it hold the capacity you would expect and does it give that same capacity up during the discharge? I'd say if either the charge or the discharge cycle reports considerably less than C the pack is hosed and I'd talk to HK or simply bin it and move on.

 

Probably worth mentioning, I've never looked at the balance of any of my packs. I'm quite simple really  and tend to trust the Ultramat to do the right thing, I'd probably pay more interest if I had a pack doing something dodgy as you have though. 

 

r.

Edited By Robin Kearney on 28/10/2012 20:44:56

[Tomtom39]

Hello Robin,

Under normal circumstances I tend to fully charge and store (I usually fly at least twice a week weather permitting!!!) . However I always check before using (having had the pleasure of losing a model due to my stupidity some years ago!). This Nano tech is pretty much as it came - no sign of puffiness or any physical damage. The battery was stored individually in a lipo bag in a fire proof container - I must admit I'm totally perplexed! (The battery in question had not been used at all on a motor ie checked when received - then charged and left in storage)

Sorry I typed in wrong Graupner charger model . I use an Ultra Duo plus 60 for home and the Ultramat 16s for field charging. I'm unable to get either to work as it comes up with "battery voltage too low". I have also tried it on my Bantam BC8 DP charger (backup) with similar resort. Tried an E-flite charger which charges via balance lead and this comes up as error (have also tried to charge with balance lead not connected - no joy!)

Going back to my original question as there seem to be an awful lot of contradictory advice - I was interested how the forum members stored their Lipos ie fully or partially charged and what results they have had over long term.

I have also been in touch with my credit card company to advise them that the battery I had bought is not "fit for purpose " and have requested a refund . They are sending me a form to complete.

[Robin Kearney]

it does sound rather like it was DOA doesnt it? Trying to get a refund/replacement is certainly what I think I'd do.

I'm also interested in how people store LiPos, I do wonder if storing them full for months on end is harming them in some way, although as I said I've not had what I would consider to be an inordinate amount of failures.

r.

[Tomtom39]

Hello Robin,

The problem is that when it arrived (and from my previous experience with HK ) I immediately checked the battery. Which seemed ok although one cell was slightly out - but within HK's stated tolerance levels) . As mentioned I fully charged it (100%) . Checked balance again(no problems) and stuck into a lipo bag.

The issue of refund is another matter (HK advise not their problem as warranty is one month only . Great having a lawyer in the family. Have left matter in the hands of a suitable "Bulldog!". Usual run around from their help desk (wonder if they have part time jobs in other call centres!)

I'm rather hoping (if possible) to see if RCME would consider doing a review on various batteries (I've just spent last few hours trawling the Internet to see how this could be done and also to set appropriate parameters.).

[Martin McIntosh]

I have found the mortality rate of lipos to be very high, either cheapos or otherwise. Indeed I have had a couple of unbranded packs for some years now and they still operate at fullish capacity - not so some of the so called better ones. I try to store most at the recommended 3.9V per cell but even so they just die on me or puff up. I normally charge at 1C, balance the cells and never exceed the discharge rate for the pack . The few nano-tech I have seem OK so far. Overlander Extreme also perform very well.

Note that you will be pushed to find a laptop, mobile etc. using other than Li-on cells, although they do not have the oomph of lipos.

One question that I have yet to find an answer for.

A Ni-cad requires 1.4 times the discharge capacity to charge, so why do Lipo packs only take in as much as you can expect to get out of them? I have put this to a charger manufacturer and could not get an answer.

Had problems with Eneloops as well but that is another story.

Martin Mc

[Tomtom39]

Hello Martin,

Same issue as you. Having gone down the route of electrifying a large number of my models. I have not found any degree of consistency . An example ( I tend to use specific Lipos for particular models. In this case I bought 2x 6s lipos - Thunderpower to power a scale WW1 aircraft.. Both have been cycled 58 times - all my batteries are logged. One has puffed up and yet I also have some Turnigy 6s that are still fully functioning after 3 years on 179 cycles . Its dropped 2% - ie 98% charge input)

Well I'm learning about the dark arts of "elecy". Sorry can't be of any help with Ni-cads.

[Tomtom39]

Hello Robin,

Strange enough was thinking of previous post to you as found a whole load of Wansted MFC stickers from my time in your part of the world in the late 80's

[Garbo]

Hobbyking have a barcode on each battery so that the day the battery arrives when checked if there is a problem a warranty claim can be entered (I never check mine, me bad)

The battery warranty T&C's are HERE dont know how fare they are but it does suggest that its probably best to check on arrival and load test in a model before the 30 day limit is up

[scott cuppello]

High discharge Lipo's like Nano-Tech must not be stored fully charged, likewise, they should never be allowed to go into LVC, the very nature of high discharge lipo's is that they will hold voltage until the pack has expired, the drop in cell voltage once exhausted is swift and will damage cells, do not ever rely on ESC Low Voltage Cut Off programs, they are rarely that accurate, use a timer as you would an IC plane after you have established with a particular pack/plane combo what a safe running time is that will allow you to land with around 20% capacity remaining, if the pack is going to be layed up for a while, use "Storage Charge" mode on your charger until you re ready to use it again.

I can't comment on this particular pack until we see it, although I can offer that it is returned to Elmsett and if it is found to be faulty, I will ask CS to credit it for you. Our warranty on Lipo's is as fair as it can be made given the simple fact that user error is the biggest cause of failure.

[Peter Beeney]

Martin, - To answer the last part of your question on charge times, it might about the different chemistry of the cells. Lead-acid and nickel cells can accept a degree of overcharge, lithiums are strictly limited to a maximum voltage of 4.2V/cell. Once they’ve reached this point any further charging will raise the voltage further and so will inevitably be detrimental; and I believe in an extreme case can result in a fire.

So you charge a nickel pack with a constant current charger, the final voltage doesn’t matter, if the rate is less than one tenth C, that’s 0.1% of Capacity, any overcharge is dissipated as heat, which it can do safely. The 40 - 50 - 60% overcharge, (many pack advise 14 - 16 hours), is used to ‘balance’ the cells, it just ensures that they are all fully charged at the end of the charge. Lithium cell cannot do this, so they have to be balanced separately, that’s just all the voltages raised to 4.2 volts. These are charged with a constant voltage charger, 4.2V/cell, with a current limit over the first part of the charge which regulates the charge rate to whatever you set it at. Lead acid batteries, when they are on ‘float’ duty, such as the 12V on your car, will be charged by a constant voltage charger, the alternator. This is theoretically a 13.8V level, but in practise it’s around 14 volts, the load on the alternator can be very high in the winter.

The lithium pack will return virtually what you put in, but it’s certainly less than what you’ve actually taken out of say the car battery to charge it. The charger will be less than 100% efficient, say around 60 - 80%. And then there’s the efficiency of the engine to convert the petrol or diesel into power to drive the alternator to charge the car battery, this is a poor ratio, it can be around the 25% mark, I believe. So overall in some ways an expensive system.

Like the lithiums, both lead acid and nickel cells in good condition will return what you put in, they don’t really need the overcharging period, so they appear to be quite efficient energy supplies, but to get the true picture you have to consider what you’ve taken out of the charging source. This is always going to to be a greater amount.

Another aspect is that if you discharge a pack at a high rate it will reach it’s lower limit very quickly, before it’s exhausted all it’s available capacity. In the case of a NiMH pack that would be 1V/cell. If you allowed it to rest for a while and then tried again you would get a further short discharge. You can do this trick until it’s finally completely flat, and then if you add all these bits up they will probably amount to the full capacity. But in some cases this is not very useful, the only recourse is to install a larger capacity battery; or accept the lower capacity.

I think maybe there are more lipo’s around than you think. I don’t have a phone, but I have asked around in the past, out of curiosity, and it seemed about half of them were driven by lipos. But that might be just coincidental. The two laptops I’ve owned, Mac’s, have lipos, and the MacBook Air I have at the moment runs on lithium polymer batteries that are generally considered to last 7 - 10 years; I believe all portable Mac’s use lipos.

I’m not very much into electric flying, although that may be about to change, but I have a friend that is. He’s used lipo’s from the day they first appeared, the first chargers had no provision for balancing anyway, so he doesn’t bother to balance; and he’s always after performance, so they get a constant belting, EDF etc. He simply charges and then goes flying, he wouldn’t take any particular preventative or precautionary measures at all. He has his share of failures, but certainly no worst than anyone else. I’ve interfered with a few packs for other folks, though, one problem with standard chargers is that when the cells are a bit outside the limits they won’t fire up, this as always been a snag. There are a few tricks to overcome this; I have a bench supply, so I can turn the wick up a smidgin and I’ve managed to persuade one or two reluctant new packs to wake up, which the charger has originally thrown out as faulty. Once they get going through a few cycles they seem to be perfectly ok.

To sum up, I think the whole question of quality can be questionable. Battery manufacture is one of the largest industries in the world, and because a great deal of the trading is done with standard consumers, people that have no knowledge or means of checking the quality a lot of rubbish is produced. We use rechargeable’s, but I have read there are similar problems with dry cells, too. The temptation to make a fast turnover must be great. Batteries are constantly being cycled, and perhaps mostly in the sense that there is a permanent requirement and pressure to keep selling new ones!

PB

Edited By Peter Beeney on 29/10/2012 09:33:07

[Tomtom39]

Hello Scott,

Thank you very much for your response and guidelines. With exception of leaving the battery fully charged (point taken re Nano Tech) all the others, I do carry out as normal course of use (I have learnt the hard way - having listened to other modellers at the field !!!)

I have sent you a message re return of pack for inspection.

Much appreciated.

[Tomtom39]

Hello Garbo

Many thanks . I will in future also check the batteries under load.

[Tomtom39]

Hello Peter

Thank you for a very enlightened and interesting post (been learning an awful lot over the weekend re batteries - its quite a minefield!)

I have gone down the "electric" route primarily due to noise restrictions at our site . Its been an expensive learning curve to date!

[Martin McIntosh]

Hello Peter, thanks for your detailed reply.

Ni and Pb I am very conversant with and have had a lot of commercial training on over the years and accept that you do not get something for nothing: i.e. you need to put in 1.4 times the amount that you expect to get out as a minimum. The rest is just wasted on heat but generally does no harm.

Lithiums on the other hand just appear to take in the same mA/h as the output capacity which is what puzzles me. We seem to be getting back exactly what we put in regardless of (heat) losses etc.

I usually charge Rx Ni packs on an intelligent charger so that I know that the cells are OK and take the expected charge for a given previous usage. A wall wart charger will just thump it in anyway and you have no way of knowing if a cell is down.

The `flashing across` process for an under voltage pack has also worked well for me.

Martin

[Tomtom39]

Just a note for all those that have followed this thread.

Scott Cuppello of HobbyKing UK (and forum member) was kind enough to get in contact with me and arranged for one of his tech staff (Jake) to telephone me and discuss my problem (Jake is also a keen flyer and understood my concerns - he was also good enough to give me some advice - full marks!). The outcome of this being that I'm returning the battery to HK for them to investigate - they have advised that they will offer me a refund/credit/replacement if the problem is with the cell.

Having had a very rational discussion I have to say that I have great deal more confidence in HK (UK) being able to deal with problems with any of their products. I understand from Scott that the UK warehouse will in due course be supplying the full range of products found in their International site (Hong Kong)

[Martin McIntosh]

Great news about the HK UK warehouse.

[Tomtom39]

Hello Martin

It was . I think that a lot of UK distributors will have to wake up . As to date biggest failing with HK had been their customer service . This looks to be changing!

[Brian Austin 1]

I have had a problem with a Nanotech 1300 3 Cell 45-95C battery. I had flown the particular model in a comp on Whitsun Bank Holiday Saturday, in an E Soaring contest where the motor was run for 30 seconds max, then on the glide from there. On checking out the battery a week later it was totally dead, nothing regisered on the meter. It transpired that the No2 cell was flat, so the battery is junk now. OK they are not expensive but the model they are used in most certainly is. The model was disconnected so it had happened in storage.