Nicad vs Nimh

[Paul Marsh]

I reckon the older Nicads had longer lives than the modern Nimh.

Although the Nimhs give a much larger capacity, even the good quality ones don't last nowhere near as long as most Nicads did. I wonder if it's a backward step.

For example, a couple of year old Nimh in my Aurora 9 only now gives around 800mah from it's 1300 nominal yield. The;ve been looked after. Today, charged up a 10+ year old Nicad pack. Not been charged for 2 years and wasn't completely flat. On the charger it put in 613 mah on a 650 mah pack - still giving 96% of it's capacity, even though it wasn't totally flat in the first place.

[Dave Bran]

NiCad technology is and shopuld be dead, no going back. Cadmium is a dangerous metal which must not be allowed to spread off into the environment, and HAS caused lasting damage where it has.

Its relative "life" compared to NIMH, true or not, has no bearing on the common sense of it.

[will -0]

Anyway you can't buy them anymore so that's that.

[brokenenglish]

Unfortunately, I suppose both the above posts are right.

There's no doubt that NiMH doesn't give anything like Nicad power or charge life.

The proof is that Nicads are still used where a lot of power is required (eg power tools), but our applications are only a hobby and not considered important enough to warrant an "exception".

I think it's still possible to obtain Nicads if you purchase from some remote source. I obtained some from Tower Hobbies long after they were banned in Europe (try Googling).

The options now are, for RC systems, NiMH but make sure you charge just before going flying or, where more power is required (which is my case for old engine ignition systems), we just have to learn LiPo technology.

[john stones 1 - Moderator]

and then there are Life's

[AJ]

Or enloops, although a type of nimh, completely diferrent performance characteristics.

Andrew

[brokenenglish]

I'm using Eneloops. I think they're just the best brand of NiMH and noticeably better than the others in performance, but they are still way below Nicad power and charge life.

Shame, but there it is. We just have to live with it...

Edited By brokenenglish on 14/01/2014 18:51:41

[stu knowles]

I bought one of the Futaba battery checkers which applies a load while testing. As a result I have binned off 80% of my NmH RX batteries, (nine batteries in total). They were a mix of NmH, Instants and one NiCad. Most were AA size cells but two were C size cells.

Some showed lower capacity when cycled but some were apparently OK. Some were good off charge but not safe to fly after a 12 hour 'rest' To begin with i thought that it was the battery checker that was duff but I no longer believe that.

I've been pretty careful about cycling batteries, checking capacities and always freshly charging before each session. On a simple capacity check, most of these batteries would have been deemed acceptable but applying the load (1 amp) makes a terrific difference.

I still have a few RX batts that have passed the tester but I am changing over to LI Fe / Li Po. Incidentaly a two cell LiFe shows the same voltage off charge as a five cell C size NimH so I haven't bothered with a battery regulator. Lipos obviously do need one.

You may choose to agree or disagree with the action that I've taken but I'm pleased that I made the discovery in the workshop and not after picking up the bits!

Roll on summer!

stu k

[Frank Skilbeck]

Stu, I'm with you there, having telemetry has shown me that some Nimh batteries while having a large nameplate capacity don't have any ummph when under load.

[Former Member]

[This posting has been removed]

[Erfolg]

I have just purchased a power pack from the manufacturers for my drill/screwdriver. The pack sent are Nicads, according to the label.

I know that cadmium coated bolts were banned in the 60s as a potential hazard.

What really is the danger from Nicads batteries, I do not know. Then again i suspect many others do not really know. Many of the bans coming via the EU although done on various environmental grounds are often less convincing when examined in detail.

Take for example Energy Saving lighting, it has now been demonstrated that many of the bulbs do not last any where near the claimed life. Then there is the equivalent light output, again often much lower than the Tungsten filament bulb, particularly initially. The quality of light is questionable. Perhaps the biggest issue is how efficient are they over a cycle? Some reputable researchers and engineers have been less than convinced about the claims. So what happens, they are leaned on, if out and out derision and shouting down is not effective.

Wind turbimes are another area where the case is less than convincing.

Yet in general there is no sensible option than accept that Nmh are the best that is generally available to me as a man in the street. Be it right or wrong. At the end of the day, they may not be the best, but they work well enough.

[john stones 1 - Moderator]

I think it is the cadmium mining that is causing the big problems ?

[Chris Bott - Moderator]

Yet in general there is no sensible option than accept that Nmh are the best that is generally available to me as a man in the street. Be it right or wrong. At the end of the day, they may not be the best, but they work well enough.

In my humble opinion Erfolg, NiMh are the worst that are available. For all the reasons stated in the thread above.

Where I use a Rx battery in a model, it is always LiFe these days. The voltage is fine wherever a 5cell NiMh would have been OK. Self discharge is minimal. They are light, and reliable. The only downside, if you can call it that, is the need for a balance charge now and again.

This is a particularly light one at 41g, but other capacities are available.

Or for bigger models where you really need a punch for heavy duty servos, A123's are ideal.

[Chris Bott - Moderator]

Plenty of Nicads here at a UK seller.

[Peter Beeney]

I’ve always been of the opinion that had the battery industry started a proper recycling scheme way back at the beginning then nicads would have never been seen to be the sort of hazard they are today anyway. Fortunately lead batteries generally had an automatic turnaround, the scrap value was always a good incentive to recycle; although this now seems to have largely disappeared. However, judging from what I see at our local Civic Amenities Site a vast number of batteries of all types, including lipos, are now recycled.

Like tin/lead solder, nicads are still legally obtainable at reputable outlets, although perhaps they are not right in the forefront of the popular advertised brands. If they are recycled at the end of their useful life then maybe they wouldn’t be seen as any more unsafe than any other type. I believe that their presence in landfill sites, in terms of possible contamination, is one of the reasons for their decline. Also I suspect the military still use nicads for many applications, I’m not sure that as yet there is a replacement with a better all round extreme conditions performance.

Certainly their service life can also be very acceptable, I have an industrial torch powered by nicads which is now close to 40 years old. So far it shows no signs of flagging, on it’s last use, (last night), it was as good as gold. Having said that, for years I’ve also been using homemade nimh receiver batteries, 5 cell, 800mAh Uniross AAA cells, which with a little bit of occasional tlc will last faultlessly for up to 10 years. Mine have anyway. Plus a homemade Sanyo large capacity nimh pack in my MPX tx also lasted for many years. But for the sheer ease of use, price and the fact that they are becoming much more popular, I’m changing over to 2 cell LiFe packs for receivers. A colleague did this way back and has never looked back for one instant.

Erfolg, If you think about it for a while, the way in which the environment in most of today’s living accommodation is controlled soon says that it makes not the slightest difference whether you use tungsten light bulbs or any other kind of bulb. The energy used will be exactly the same in each case. So, as you say, contrary to what is often said, I’m also convinced the science is not yet proven. But who would ever take any notice of any explanation, I suspect it would be all be very stony ground indeed…

PB

[Frank Skilbeck]

Nicd batteries have been phased out as the waste from the mining/manufacturing process is very toxic, even the Chinese are phasing it out, do a web search on Cadmium poisoning and it will turn out lots of articles.

BTW as regards light bulbs, I've just bought some high power LEDs which use less power than the compact fluorescent, boy are they bright!

As regards wind power, with all the gas we can extract by fracking the case for wind power is not as strong, but again look at the Chinese they are installing more wind power than anybody in the world today and I don't think they are bound by any ecological political dogma.

[Lee Smalley]

i am not really quite sure what you are all whinging about really i have been using NimH for over 5 years now and in sport models they have been absolutely fine, i always use 5 cell packs and they hold the charge for months on end, i only really use vapatech instants or sanyo eneloops, but i have had faultless service from them, i have found out that you can really only charge and discharge them at 500mah constant otherwise you get a false delta peak detect, but other than that, totally faultless service, i do however use Life batteries in my more advanced models that use lots of digital servos, but that is just because of the increased current draw.

are we all sure we are not just regurgitating what we have heard, rather than our experiences ???

[john stones 1 - Moderator]

no problems with Nimh's either, I use 6v in all but small stuff.

have just bought a new charger thinking it was iffy, because I was not getting a full charge

only for the new one to do the same, didn't happen when batteries were new

I've also lowered the charge rate, battery's are o.k. and I've got a spare charger

buying new or replacing old ones its life's.

like that I can leave in model and not worry about fire risk

[Frank Skilbeck]

Posted by Lee Smalley on 15/01/2014 09:55:34:

are we all sure we are not just regurgitating what we have heard, rather than our experiences ???

Based on real experience with me, no actual brown outs in flight but my telemetry voltage alarm has gone off with freshly charged batteries, mainly high capacity AA size, the sub Cs are fine and obviously the 5 cell packs while dropping significant voltage because of their higher starting voltage don't reach critical levels, But I have some 3,000 mah sub C cells that will quite happily maintain over 1v per cell at 5 amps and AA cells which drop below 0.7v per cell at 0.5 amps.

[PatMc]

Frank you really need to look at the specifications of high capacity, small size nimhs before deciding if they're suitable for high current applications. Unfortunately some well known battery suppliers don't seem to then sell them made up for unsuitable applications. Horses for courses.

In 2010 I changed some vintage models from 8 cell nickel batteries to 3s lipos, rearranging the hardware layout to maintain the cg. Whilst having a clear out last year I cycled the old batteries, none of which had been re-charged in about 10 months. Only one of 5 nicads were re-usable whereas all of the 7 nimhs were OK, in fact some of the nimhs still retained a fair charge & discharged virtually full capacity within a single cycle.

[brokenenglish]

Gentlemen,

Respectfully, we're not all discussing the same question...

If the question is: "are NiMH batteries OK for "general" RC applications, providing you charge just before use?" Then the answer is obviously "Yes, they're usable".

If the question is: "are NiMH batteries as good as Nicad in terms of power and remaining charged?" Then the answer has to be "No, they're not" (but we have no choice!).

I'm using batteries for two "non-standard" applications, and NiMH are not satisfactory. They don't give enough power for a spark ignition circuit, whereas Nicads did, and I haven't found any small sizes for lightweight airborne pack power (looking for suggestions here!). Small, diesel powered planes used to fly great with 120 or 240 mAh Nicads weighing only a few grams. Now, the trade imposes that all small planes are supposed to be electric powered, so my only reasonable solution is Lipo with a voltage regulator... I was amazed to see the post above in which 41 g was considered light for an airborne battery... I'm looking for half that weight, at the most.

[Paul Marsh]

Weight is not an issue, usually I find when balancing a model, prefer to use a larger battery pack as ballast, then weight.

Problem with Lipo/Life, they're too light and apart from motive power, a heavy sub c battery has been used on a smallish model, just to get the cofg, even though a AA pack would do. But on the other hand, Sub c has a much higher current capability, so not a bad thing, although for some reason Sub c aren't available in the low discharge variety. I wonder why? A LSD Sub C pack would be ideal...

[PatMc]

Posted by brokenenglish on 15/01/2014 15:06:06:

If the question is: "are NiMH batteries as good as Nicad in terms of power and remaining charged?" Then the answer has to be "No, they're not"

No it doesn't !
That's merely your opinion.

[brokenenglish]

Posted by PatMc on 15/01/2014 15:38:54:

Posted by brokenenglish on 15/01/2014 15:06:06:

If the question is: "are NiMH batteries as good as Nicad in terms of power and remaining charged?" Then the answer has to be "No, they're not"

No it doesn't !
That's merely your opinion.

OK. Try them in a spark ignition circuit and see what you get. Nicads will work OK and NiMH are very iffy indeed (they sometimes work, a little, but mostly not). They just don't have the power of Nicads.

I think you're confining your opinion to "general" RC applications, which as I mentioned, are OK.

[PatMc]

"Confining" to "general" , isn't that a bit of a contradiction ?