Batteries

[Danny Fenton]

Timbo I thought your hearing was better than that LOL

Hi Myron, I notice a difference on lipos after just 5 or 6 cycles, they start to go down hill as soon as you start using them in fact. A friend that used to sell them, also found that they deteriated even if not used ie on the shelf, and the capacity dropped. I am just saying that they are really only good for 50 or so cycles and the 50th wont be a patch on the first if you know what I am saying. I assumed your phone was charged once a week (my Motorola from new has to be charged every other day) so 1 year = 50 odd cycles M1 are good for over 1000 cycles

[Tim Mackey]

They do seem to vary wildly. I have some original "issue 1" 2000ma KOKAMS from about 4 years ago

( I date label all mine on purchase ) and although not absolutely as new, they still take in around 1800m/a and deliver a good punch. These had no balancer plugs on them in those days. They have been pushed quite hard - around 12C  ( 15C packs ) and had maybe..... 75- 80 flights ??

My Flight Power packs have generally been good for around 2.5 - 3 years. 

[christopher small]

Timbo You recommended changing my batteries NOW.What should I go for next,NiMh ,Lion or stick with Ni cads.

I have had a lot of trouble with Ni Mh in my digital camera,they seem to go all of a sudden,and then you can`t charge them up,its down to the shop where they came from and change them.It seems they don`t like being charged more than a couple of times.The Charger by the way is a Uniross for NiCads and NiMH.

At least my ancient NiCads have never let me down.Slightest problem and they are binned,as I did earlier this year with my Rx pack ,wouldn`t charge fully.I want reliable batteries .(which my old ones are)

[Former Member]

[This posting has been removed]

[christopher small]

Hi Eric

Nice to know I am not the only one having trouble with NiMH batteries.

I too have blue shrink wrapped button cells,they ended up in an old radio.Mine are about 30 years old or more.

I always charge my batteries as slow as possible,interesting bit about NiCads liking constant current and NiMH liking constant voltage,more special chargers.

Most new radios,if not all come with nicads, so I shall stick with them for now.

[Ultymate]

Not for much longer Nicads are slowly being withdrawn from the market due to their heavy metal content ie cadmium.

[Tim Mackey]

I think you find that NiMh is pretty much the standard these days, NICADS, as Ultymate says is dyng off thanks to the green brigade

As a dedicated and exclusive LiPo user in everything, I of course,  would recommend LiPo

[christopher small]

What will they replace them with?

I don`t like Ni MH ,had too many probs with them.Certainly wouldn`t want those in my planes.

[Tim Mackey]

I think you find that NiMh is pretty much the standard these days, NICADS, as Ultymate says is dyng off thanks to the green brigade

As a dedicated and exclusive LiPo user in everything, I of course,  would recommend LiPo

http://www.modelflying.co.uk/news/article/mps/UAN/222/v/1/sp/

[christopher small]

Excellent report on LiPo batteries Timbo,ideal for Park Flyers I should think being lighter.

Might get a pack for my Slow Stick when i get one,just to try them out and learn a bit more about them.

As for my other radios there should be some cheap nicads in the shops soon for them.

[David Martin 2]

Sorry chaps, long(ish) post, but this is my 2p on the subject... 

I used standard Nicad packs for 20 years for all my radio gear in all my models and never ran anything over 600mah, all ok for a good 4 10 minute flights on 4 servos and 3 1/2 hours with a slope soarer, giving up only due to the Tx battery getting low.

 I think these days, the Nimh cells have made us all well over capacity everything, fair enough, we haven't gained any more weight through it and extra anything with no loss has to be a good thing.

I know that my Acrowot's Sanyo 1700mah AA Nimh Rx pack would be able to give me 3 weekends flying without getting anywhere near the red on the voltspy monitor, but I bet we all charge everything right up again before the weekend......One thing to watch with Nimh's though is their high self discharge trait, there is a new type of Nimh cell out now that has all but illiminated this called 'Instant cells' and only dissipate 15% of their charge over 12 months. I have a set of these (2000mah) in the Tx of my micro helis and have only charged it once so far since September..! These models carry a Lipo pack that have an almost infinite charge retention, so I know I can just pick them up on a fine day and go play...marvellous.

 http://www.component-shop.co.uk/html/instant.html

Nimh cells can be charged 100's of times to full capacity and don't in my experience gain anything from being cycled, they show no signs of memory effect, unlike Nicads, through partial discharge/quick charging (used to show up a lot with our old video camcorder packs).

What will kill them very quickly, unlike Nicads, is being over charged, they get hot rapidly if charged passed their peak or at too high a rate. Nimh cells give a much reduced peak than Nicads at full charge and so the charger must be sensitive enough to detect it and terminate the charge. They lose capacity retention indefinitely if overcharged in my experience or charged at a rate over about 1 x their capacity, i.e full charge in less than an hour.

One disadvantage of Nimh over Nicads and Lipos is their higher internal resistance, this means that they're limited in their ability to off load high currents. An example being my Piccolo heli used to have a great performance on all my 7x 250mah Nicad AAA packs but only ran for 3 minutes due to low capacity. My 7 cell 950mah Nimh AAA's run for 10 minutes but only a few makes are caperble of supplying the amount of amps required for flight. A way round it was to increase the voltage to the motor by adding an extra cell to the pack, but then there were motor burn out issues so upgrades were also required.

But as far as the relative low current drain of our Tx/Rx's, Nimh have given me sterling service so far. I always charge with a Prodigy charger set to Nimh and 1/10th the capacity of the cells, or as near as I can get. That way, I can monitor what they absorb each charge and they are cool to the touch at switch off.

I may be wrong here, but I think the reason our old mobile phone Nimh packs only had limited lives was because they relied on the cells warming up after their peak to trigger a bimetallic strip and terminate the charge. Hence their charge retention seemed to get less and less over a compartively short period of use.

Since only buying Sanyo Nimh, I've not had a cell failure yet....

Ok...you can all wake up again now...carry on chaps...

[Tim Mackey]

Some of the better quality NiMH cells can deliver extremely high currents - Puffin Hi-Flow 4000m/a sub C cells for instance ( the ONLY non liPo cells I own, as I use them in onboard glow drivers ) can deliver  a whopping 80A ( 20C ) AND can be charged at 1.5C

The "rumour" about memory effect of nickel based cells has never actually been proved, but it is true that NiMH can tolerate being charged up from a partially full state much better than Nicad. 

[Myron Beaumont]

Timbo   Definately not changing from Nicads having read all the mishaps etc that folks have had (very expensive too) Long live castor oil/methanol etc. etc 'til you're all happy about" the dark side & the unpredictable"

[Alistair Taylor]

aaaw go on Myron

Take a walk on the wild side

Buy a Picoo Z

Just make sure you hide it when any "real" modellers come to visit

AliT

[Myron Beaumont]

Is the"WILD SIDE"another name for N.Wales & by the way what is a Picoo Z  Am I supposed to be missing out on swandering more cash on an ARTF  Should I sell off all my wood & join the happy band of consumers of  plastic far east importers of toys ?   Must admit that 'er indoors bought me a tiny helicopter t'other day Infra red & all that .Trouble is there 's not enough room in the camper  van & its too windy outside ! Seriously thinking of starting to make up my b--t kit she got me.

[Myron Beaumont]

PS  I shall use a good old lead - acid battery in it if I do So there ( funny that no-one is using Lipos etc in proper cars/ a/c / etc./etc !!!)

[Alistair Taylor]

Good on yer

 By the by, Maplin are selling a car starter unit for £20 that incorporates a sealed lead acid battery normally only sold on its own for substantially more than that.

Ali

[Myron Beaumont]

Thanks Alistair  Do you know the Amp hours of it  I'm very interested knowing what a 7 ah unit costs for starters/ glow /fuel pump / MOTOR BIKE costs

[Myron Beaumont]

PS

looking forward to the introduction of a low maintenance Lipoo for reliable use in every thing that we need to work first time and every time with no problems like they had a century or so ago

[Alistair Taylor]

It's 17AH

And the two jump leads are permanently live - so you can just attach your charger'c crop clips to them and go. Bloomin' ideal.

Ali

[Chris Ireland]

Hi Guys, I've been catching up on this thread but it doesn't seem to provide the answer to my question. Having said that, reading between the lines has never been my strong point so here goes......  LiPo's are where I'm at so this is a specific LiPo question.

 I charged my 1800mAh battery and two brand new 2300mAh batteries on a Wednesday expecting to be able to fly my chopper (well, flying is a very loose term for what I'm able to do with it at the moment... hopping about like a cricket with lead up it's bum is closer to the mark) on the next day or day after. None of this happened and on the Saturday I went away for a week. It is now the following Saturday and I want to fly tomorrow or Monday, 10 or 11 days after the batteries were last  fully charged. All are 11.1v 3s devices if that makes any difference and have been stored, unconnected, in my flight case since they were charged.

Should I expect much loss of chage in 10 days (I can't tell as I have only got a simple balancing charger with LED indicators and have not yet invested in a sophisticated device which gives 'health' readouts)?Do I top them up, or just go out and use whatever is left in them?

As ever, your advice would be appreciated.

 CJ

[Tim Mackey]

Very little drop will have have occured. Assuming thet were fully peaked out at 12.6V they are umlikely to be much below 12.4 by now...and 12.4v - 12.6v is considered fully charged.

I take it you have seen this ?

capacity /charge states etc

[Chris Ireland]

Hi Timbo,

Many thanks for that. I've captured it as a word doc so there should be no excuses from now for me not knowing.

I take it that I can put a voltmeter across the terminal leads to check the voltage until I get kitted out with a bit fancier charger than the one which came with the model ?

I've read your review of the Li-Pro Imax 6 Balancer/charger and all of the comments following it. I suspect that it retains it's title as the current value-for-money leader as there are no comments to indicate otherwise.

 CJ
 

[Tim Mackey]

Yes a voltemeter can be "prodded" carefully at the respective pins - I sometimes do this on the balance plug too....just to get a DVM reading of the individual cell voltages, confirming the charger /balancer readouts for individual cells.

[Tim Mackey]

My new kid on the block charger is a GT8 - which is even better than the B6 in severalways. Does cost a few bob more though, yet still EXCELLENT value for its capabilties ( up to 8s Lipo and150 watt total )

I think David said he was gonna pop a "first look" thingy on the front page soon.