Batteries

[Dave M]

I am new to all this, and have a question about batteries. I charge them overnight for the prescribed time before going flying the next day. But I only get a max of about 2 hours of flying in, (with my instructor) each day, so the batteries always have loads of charge left. Then I re charge them before the next days flying.
Is ths good for the batteries?

Should they be totally dis-charged / recharged occasionally?

If so how often?

Is a battery checker a good investment?

Can anyone recommended "smart" charger that will stop once the batteries are at peak charge, and perhaps have a discharge function as well. Lets go for broke,one that will charge faster than 10 - 12 hours like my current charger does?

Thank you for any advice.

[Michael Dearden]

The most important information is "what kind of batteries are they"?
If they are NiCad then you certainly don't want to keep recharging a partially discharged battery. They suffer from "memory" which in very basic terms means they remember how much you used it last time and then will only give you that amount of time next time, inspite of having a "full" charge.
NmHi are better (and tend to be more expensive), and they don't have so much of a problem.
I believe, and I have NiCads that are five years old now, that it is always a good idea to "work" a battery. Fully discharge it every time, and then re-charge.

[Danny Fenton]

Hi Michael, I have the same problem as Dave, if not worse at the moment as due to engine probs I am only getting 30 mins flight time, on my main Tx, my buddy Tx, and the Rx, you say it is wise to "work" or fully discharge a NiCd, how do you do this? leave all the gear switched on when you get home?

[001]

In my experience, (23+ years all seasons R/C) Basic r/c nicads for Tx or Rx will not suffer from being used for two or three 10 minute flights, or even two hours use, on and off, then charged overnight, over and over again.
Sometimes I just top them up for an hour or two as required.
The memory effect has never been proved in field conditions nor in the laboratory. (Ask the manufacturers and distributors). Try Googling 'Nicad memory' Unless you are flying fast or heavy models buy cheap cells, use them regularly, and frequently for four or five years then dispose of them. I have two Ripmax transmitter AA cell 9.6v packs that are at least 8 years old and still give ten minutes or an hours use, on and off, for sport flying, as required despite this type of 'abuse'.
I use cheap supermarket Nicad AA cells soldered up for use as receiver batteries and have never had any radio problems. Just beware of the black wire corrosion when your equipment is getting older or you have stored the batteries connected to any equipment for a few weeks.
(If you want to leave a transmitter switched on for any length of time, make sure the aerial is extended.)

[Danny Fenton]

Thanks Richard, I had heard from another member of this forum that just leaving the gear on until flat, once every couple of months or so will do no harm

[001]

Danny never completely 'flatten' Nicads. Battery packs with multiple cells in series should be operated well above 1 volt per cell to avoid placing the lowest capacity cell in danger of going negative. So if your transmitter has a digital readout, use it,(normally 8 cells per transmitter) and use a meter on your Receiver packs. Otherwise you will have an unreliable, if not dangerous system.

[Alistair Taylor]

Ooooh NiCAD memory effect - here come the smoke and mirrors.

I too wanted to find out more about NiCAD memory effect when I first heard about it.

My understanding is that it arose on satellites that used NiCAD batteries, charged and discharged on a PERFECTLY consistent basis. The charge/discharge was computer controlled/dictated by the unchanging timings of the satellite's orbit (if the timings of a satellite's orbit change by a cuple of iotas then it's due for splashdown or a distant liaison with the kuiper belt...).

If you can vouch that you have been charging/discharging your nicads EXACTLY the same amount evey week (i.e. moving the control surfaces EXACTLY the same amount, switching on/off for the same amount of time, charging for not one milliamp more, taking into account fluctuations in the power delivered by the national grid before, during and after Emmerdale Neighbours Street) then you might be at risk of the memory effect.

Much more deadly (and harder to see) is black wire corrosion, as Richard Bond has mentioned. NiCADs cause it, you can't see it unless you strip the plastic covering off a wire, and it can cause your radio to work one flight and go duff the next.

If your TX is getting on a bit (three years plus?), whip the back off and look for bubbles along the circuit board alongside the negative wire connection (or green fur). If your RX battery wiring is similarly getting on - check it, or even just replace it as a matter of course. This can often bring back an apparently past it NiCAD.

Alternatively replace the packs with high capacity NiMH packs (soldered up from consumer cells) that don't suffer from memory effect and that last for much longer than a flying day (or even weekend for that matter).


Alistair

[Sid Harrison]

Not exactly in context with this article but nevertheless very important is: I have been advised to cut off the nice, safe and secure plugs and sockets that came with my batteries, and swap them for seperate gold plugs and sockets, but no-one has offered a standard configuration i.e. one plug, one socket on the battery and ditto on the target equipment. Would they be in line or offset; would the male be on the battery positive. Or perhaps it is irrelevent!

[Alistair Taylor]

It's irrelevant, except that;

- Two male plugs on one battery is asking for short circuits

- two female plugs on the speed controller is asking for misconnection

- trying to use different wiring systems (e.g. one for speed 400 and a different one for speed 600 packs) is a sure fire recipe for meltdown.

I use a plug on negative battery terminal and a socket on the positive side. Find out what the people you fly with use, and copy them - then you can help each other out with charging if needs must.

Best practice is not only to use heat shrink tubing over the connectors, but also to heat shrink them together, side by side so that the plug cannot make contact with the socket while being shaken around in your battery box.

Alistair

[Dave M]

Thanks for your thoughts, I should have said that I have NiMH batteries.

[Patmac]

Unfortunately there's a lot of unsubstantiated "factoids" circulating within the hobby about Nimhs versus Nicads.
I did a little research using some of the munufacturers web sites & established that the so called memory effect is similar in both types of cell, they both self discharge at about the same rate, when they are near fully discharged the voltage in both types drop at about the same rate & both types have similar temperature dependant characteristics.
The main differences are : weight for weight Nimhs have a much higher capacity than Nicads; some Nicads can be charged & discharged at a higher rate but this advantage has been nearly eliminated with developement in Nimhs; Nicads contain the hazardous material cadmium & have virtualy been displaced from the retail market by Nimhs.
If you're interested in finding out more have a look at http://www.panasonic.com/industrial/battery/oem/chem/nicmet/index.html
There used to be similar info on Panasonic Nicads but they appear to have removed it recently.

Cheers,
Pat.

PS from personal experience black wire corrosion happens with Nimhs the same as Nicads.

[Owen Hailey]

Hi there slitly changing the subject this may be to some advatage to some of the more money concis amung us I have a Rayovac rechargeable alkaline battery charger this may upset the battery makers but I have found it quite safe to recharge duracel alkali batterys many times with out eny side afects to the batterys.

[Ernie]

Hi Dave, Its dead simple, if  bit tedious

Re Nicads, Every time I buy a new one, I number it (I use a small label covered in sellotape or similar) so that it doesn't get wiped off with glo fuel. On my PC I have a chart

No...Date...Purchased from...Intended use...Capacity...Capacity as tested...Comments

About once every 3 months I discharge, and then charge each battery. You can do this with a small  bulb, if you don't want to purchase a fancy cycler.  If it is more than 10% down on it's intended capacity, I do the same again to try to bring  it up to scratch. If it doesn't behave, its the bin....No chances with that wee essential component. 

Guess what, no problems (in that department) in ten years

Finally, there is a publication by the excellent Mainlink people called the battery book. It only costs a few sous, and explains the whole minefield

ernie    

[FlyinBrian]

 A decent charger / discharger is a good investment as you can check the capacity and be warned of when your batteries are starting to lose capacity.

 Great info on batteries here > http://www.rcbatteryclinic.com

and here > http://www.batteryuniversity.com/

[Alistair Taylor]

I remember those rechargers for Alkaline batteries.

 They sound an excellent idea.

The only things that have held me back from buying one for R/C use are:

 - I believe (I'm open to informed contradiction) that Alkaline batteries have a flat disharge curve followed by a very steep drop off in voltage once exhausted, whereas NiCads/NiMhs have a more gradual dropoff, giving you a bit more notice that you need to land. In practice it would mean that your TX could go from OK to dead in the space of one flight, your BEC cutting in would be followed very shortly afterwards by your RX going dead, etc etc.

 - Alkalines pump out 1.5v - which I reckon is pretty irrelevant but I though I'd mention it anyway

 - anyone know what the internal resistance of alkaline batteries is as compared to NiCad/Nimh?

AlistairT

[christopher small]

Regarding NiCads my JR radio is 18 years old Tx battery still going,Rx battery changed this year.Futaba Challenger 15 years old  batteries still going.Always disscharged after flying and recharged.

NiMh batteries in digital camera packed in after a few charges.

Have got 4 D size Ni Cads 26 years old still going,although 2 others packed in after 10 years

[Tim Mackey]

I would advise changing the tr' packs NOW.

[Former Member]

[This posting has been removed]

[Ultymate]

Quote Christopher Small ,

"Regarding NiCads my JR radio is 18 years old Tx battery still going,Rx battery changed this year.Futaba Challenger 15 years old  batteries still going.Always disscharged after flying and recharged.

NiMh batteries in digital camera packed in after a few charges.

Have got 4 D size Ni Cads 26 years old still going,although 2 others packed in after 10 years" 

    Sorry Christopher but all you're proving to me is that you're tight with your money, you're risking your models and the safety of anyone who's around when you're flying by stretching the life of your batteries to that extent. for what battery packs cost it's just not worth it

[Danny Fenton]

I have to agree, I have converted my Tx to LiPo and have not had to recharge since August, takes away the worry of NiCds and Nimhs going flat just by existing and before you ask they have circuitry built in to protect against accidentally leaving the tx switched on

Danny

[Myron Beaumont]

Danny     The only Lipo I own is in my one year old phone & it now holds its charge for one day .!   I've only ever used Nicads for flying but am thinking about going "up market" to NiMh stuff since I was given a 6 pack from a toy aeroplane  I've altered it to a 4pack (abou t 5 volts on load on my trusty 360 ma drain bulb ) Half the weight but the same mahs Ideal for a small trainer m/c 3 or 4 channel. I recycle all of them (Nicads that is )at least every 6 months on my trusty bulb set up --- never any problems at all .If anything the voltage seems to creep up by 0.1 V most times after a cycling ! Forget the memory debate just recycle as per described & don't worry .By the way I draw graphs of time v on-load voltage for every pack I have to keep these checks &^ info up to date .That way I'll know if there might be a fall off in capacity / anything abnormal .Takes away the/any uncertainty

Grumpy Myron

[Tim Mackey]

Danny...I left one of my trs on all weekend a few weeks ago and despite the claims of the PCM guard, it went so flat it would not register a thing on the DVM. I tried trickle charge, fast burst, and everything else my fancy chargeres could muster, but after finally accepting a charge, and showing 2000+ ma input, it "collapsed" to 9.5V immediately upon applying a 500m/a load. Cycled and recharged/balanced again, exactly the same. I dismantled the pack, removed the PCM boards frome each cell, tried them all individually, and was still unhappy- so I ditched it and fitted a new one - at the price we are paying from H/C it was not worth risking it, especially in my Tr !!

[Danny Fenton]

ahh well done Timbo, at least we now know the PCM boards don't work LOL surely the TX was squeeling like crazy as soon as you hit 9/10v ??? and cos its lipo it was probably squeeling for a long time......

Myron for flying the serious sized models, I use A123 M1 nano phosphates, much better than Nimhs and half the weight of NiCds. (also can be fast charged in just 10 Mins)

LiPos in my experience don't have a very long life expectancy, your mobile lipo probably had a fair few charges, my Tx has had just one in 4 months of use, I guess horses for courses

[Myron Beaumont]

Danny   Thanks for info. The mobile battery has ONLY been used for maybe 50  photos over the year & about 5 calls .Is that overuse ?

[Tim Mackey]

Hi Danny, yes I am sure it was squeeling like a stuffed pig - however, as I was over a hundred miles away at the time, at my age, I just failed to hear it