ICOM M31 update

[tugboat]

A couple of weeks ago there was a thread about handhelds where some peeps, myself included, were expressing disappointment about the M31 discharging it's battery while switched off. I contacted ICOM at the time re the problem and they suggested I hadn't charged my set for long enough - so I have done some tests. I charged for 8 hours (using the mains adaptor) and then left the set switched off. I switched on briefly once every 24hours just to check the voltage and was able to watch it slowly reduce. I'm happy to report that the set took 17 days to discharge the battery which was a vast improvement on what I had previously experienced. I then charged up again and left it switched on in receive mode and it took 28 hours to run out of juice. This still leaves the problem of the battery memory which means the thing must be run down completely before charging and thus leaving you potentially without comms in an emergency. I guess I will have the spare battery case fitted with AAs and kept ready in a plakky bag. Wonder if ICOM might think of doing a Lithium Ion unit for this set. Many of you forumites probably know all this stuff already, but some may not so hope my test results might reassure some of you and I still think the M31 is good value.
Cheers, Tugboat.

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[Moose]

So thats why mine is always flat!!! Mr ICOM, I want a refund!

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Moose

 

[Ships_Cat]

The NiCd memory effect is mainly a myth based on some very old specific use experiences with early batteries (repeated cycling of them down to around 20% capacity). I would not worry about it (and don't worry about it myself and never had a problem).

Fully discharging NiCds, as commonly (but not expertly) advised, can lead to problems if a cell gets driven into reverse voltage and I never do it.

My personal view is that most do not fully charge NiCds and that leads to downstream problems both from the point of view of usable time and battery life. Usually the charge indicators on radios, phones and things do not reliably show the full charge state, especially with NiCds as they have a flat voltage versus charge curve. So providing a very fast charger is not being used that will overheat the batteries if left too long on charge (most supplied do not) an overnight charge would not be, in my experience, too long.

John


<hr width=100% size=1>I am the cat but I am only 6.

 

[William_H]

Hello pussy You are right about discharging nicads if they are in a sealed battery then don't. If you can access the cells then it is a good thing to discharge and short out each cell for a period before charging. The standard for charging was regarded as 14 hrs at current AH /10. This rate seems to be ok to leave on charge permanently without damage. Yes you can get fast chargers and fast charge batteries but you can't leave them at high charge for too long or they overheat and as you say you can't rely on battery voltage to indicate a full charge in fact the voltage starts to fall if they overheat. So long charge over 14hrs is the best. regards will

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[Guest]

I opted for the Entel because the nice man at SIBS told me that a) the Icom has Nicads which, because of memory problems and generally bad charging habits by the user need to be replaced at regular intervals and this keeps Icom happy and more importantly b) the Icom batteries self discharge because a (test) circuit remains active even when the radio is switched off. The only way to avoid discharge is to partially slide off the battery pack. One advantage of the Icom is that you can dispense with the Nicads entirely and use duracells or similar. The Entel comes with a Li-Ion battery but there is not an option for a pack which takes AA batteries.

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[davehu]

I also had a similar problem and contacted ICOM service Manager, He told me that the M31 has a monitoring circuit even when the unit is switched off, hence it drains a very small amount out of the batteries all the time, this is also true of the dry cell pack so he advised removing the pack or nicad if you leave the set off when not on board. I have done this and the Nicad stays fully charged for a long time. Suggest you try this and see

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[Evadne]

I thought that NiCds had largely been superceded by NiMH (Nickel Metal Hydride) cells in new equipment? They still have a little memory problem, not being the wunder-battery they were first billed as, but it is greatly reduced in my experience.

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[Guest]

NiCD\'s / AA\'s etc.

<<The NiCd memory effect is mainly a myth based on >>
Not true - having flown model aircraft, raced model cars with NiCds etc. - memory problems are VERY real. The trouble is when a NiCD is not discharged properly and then recharged fully. Repeated part discharge will create a battery that only elivers part charge to that point, repeated part charging will create the same by becoming a less chargeable battery.

Fully discharging NiCD is better than part ..... and they should be exercised regularly - in a Model shop you can buy NiCD recyclers .... which cycle the batterys by discharging via a monitor, when they reach a set point they charge up. This cycle repeats till you take the cells out. It is common for NiCD's to gain performance after this

The NiCD has a flat discharge curve till it reaches near discharge at which it falls rapidly - BUT it does have a decay period sufficient for monitors to react - eg the above cycler.

Charging is important with NiCD's and should not be conducted at more than tenth of capacity rate .... unless it can be cooled during charge and also care taken to not exceed time. The Swiftech was supplied with a charger that cooked batterys if left for more than 5 hours !! I ditched that and use a Radio Control Charger at 125mA rate - which can be left for days ......

NiMH and Li-ion are far superior - but cost more - AND care must be taken as they are not actually the same voltage etc. - replacement of one with another has to be matched reasonably t ensure clean working. Many HH's and Notebook Computers for example have intelligent circuits piggy-backed onto the pack - so a change of type can throw this completely out ..... the notebook I am using now had its batterys changed to NiMH and it refused to work - I had to pay out for the more expensive Li-ion !!

As regards AA packs ------ if you have a faulty Battery pack spare - break it opoen and you'll be surprised what you find inside .... and often easily replaced cells with either rechargeables or AA's etc............. 8 NIMH's at £3 each, bit of solder = £24. New pack from dealer ????? £40 or more !!



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[Ships_Cat]

Re: NiCD\'s / AA\'s etc.

I have never had a problem with NiCds and the experts say no memory effect. All one does if one cycles the batteries more than is necessary by doing needless discharges and charges is shorten their life as they, like NiMH, have a finite number of cycles lifetime.

Which gets onto the other myth about the superiority of NiMH's. While NiMH batteries hold about twice the charge per mass of battery than NiCds (which people interpret as meaning a better battery) they only have around half the number of recharge cycles in their life but energy delivered in their lives is about the same - so their main advantage is either smaller mass for the same capacity or more capacity for the same mass. At the moment, for the lifetime energy delivered from small batteries/cells, NiMH are dearer to run than NiCds taking their lifetime into account.

While I have heard the above from a number of professional sources I have somewhere an excellent article by an engineer who designs spacecraft battery systems which also says the same.

There are plenty of references on the internet that claim either that memory effect exists or that it doesn't. Those that claim it doesn't usually base their argument on controlled experimental tests or other technically based evidence. Those that claim it does always give no technical basis whatsoever for their claim - because it is a myth. What most put down to "memory effect" are other effects resulting from abuse of the battery such as continued overcharging, completely discharging a battery in use so that a cell is driven into reverse voltage, temperature problems, etc.

Not bad for a cat don't you think?

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[Guest]

Sorry - don\'t agree ...

Many moons ago in Radio Modeller a lot of tests were carried out specifically on this subject ....

It was found that the cells develops a crystaline structure through the sinters and medium depending on the internal construction. Short sharp shorting will destruct the structure and give temp. life back from NiCD ....... so the mags looked at this and asked why loss of cell performance etc. etc.

Result was confirmation of Memory effect and also the expected demise of a cell by thoughtless part charging etc. On eo the biggest cuplrits was over-time charging as well as too high a rate.

Radio modellers commit hundreds of pounds of gear into the sky, not only is it expensive if mistake made with the batterys - can also be highly dangerous if control is lost.

Wherever possible I prefer NiMH or Li-ion as NiCD's are too liable to loss of performance .......

We use various makes of VHF HH's in or work ..... most have NiCD's and I am tired of having to 'jump' them into action again ---- the NiMH / Li-ion ones we have no trouble with.

I totally agree that charging and misuse is the biggest and main reason for loss of NiCD capacity / use ...... but whatever is no consolation to anyone who has a VHF with NiCD's and he loses use of it through not performing a charge schedule. If he has NiMH or Li-ion - he can suffer bad charging routine much more and usually get away with it.

I also do not agree with your statement about plenty of Expert evidence against memory and no evidence for ...... it was in fact the industry that first pointed out the fault and advised about charging routines etc. to get best performance.

MAYBE the namimg > memory effect < is bad - maybe it should be re-named charge capacity fault or something else ?

Finally for myself - I was religious about care for my RC NiCD's and witnessed over a period decline in them - similar to other users. Visit any RC Modellers site / club and talk to them about it and I am certain that you will be smothered in NiCD info etc.

I am sorry if you may be connected to battery industry or have lots of books and info on it - but I have seen and experienced NiCd along with other forms and knwo what I saw etc. I also value the articles written by experts helping RC Modellers ....

That reminds me one of the Swiftechs is in for battery replacement ..... NiMH's by the way will replace the NiCD's .....


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[Guest]

Re: NiCD\'s / AA\'s etc.

Other "experts" would refute your "experts" with reference to mythical memory of nicads. Furthermore, at some time or other, many of us would have experienced this mythical memory on nicads as being very real. Poor charging habits by users would inevitably lead to a longevity issue with rechargeable nicads.

On the second point; the argument concerns Li-Ion batteries (as used by some other comparable radios such as Entel) not NimH.



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[Ships_Cat]

Re: NiCD\'s / AA\'s etc.

So be it, I am only a cat, but I have yet to see an expert with a contrary view.

However, you have to understand that I couldn't care a toss what batteries you use and how you charge them - you can make your own mind up on that. But perhaps a few others may be prompted to have a more open view and seek out some more knowledge about it. No doubt they will then make their own minds up one way or another.

Sorry about the Li-Ion bit, didn't know anyone was arguing about them, think they are pretty neat batteries myself. Not sure what your "On the second point is" about them, was there a first?

John

<hr width=100% size=1>I am the cat but I am only 6.

 

[Guest]

Re: NiCD\'s / AA\'s etc.

Wow! I seem to have ruffled your feathers.....sorry fur.

The point you may be missing is that it does not really matter what the experts say. In practice, many will have experienced longevity problems with nicads.

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[dickh]

Re: NiCD\'s / AA\'s etc.

My experience with a cheap B&Q 12v drill -bought about 5 years ago for $24.99(made by Hilka) is very good. I have used it constantly, but I always make sure that it is completely flattened before recharging for exactly 5 hours using the charger supplied, plugged into a cheap timer. It is only now just beginning to not last as long as when new - but I'm very impressed with it. I picked another identical drill & battery pack from a car boot recently for £1.50 and although the battery does not hold it's charge for long, I use it until flat then recharge it and it is gradually improving.
My experience with my Swiftech VHF is the complete opposite though, even if I regularly discharge & recharge it, it doesn't hold it's charge for long.
WHY cant these cheap chargers they supply have a built in timer which stops charging after the specified time? - can't be expensive to make in the factory?
And some don't even give a charging time!!

<hr width=100% size=1>dickh
I'd rather be sailing... /forums/images/icons/smile.gif

 

[Anwen]

Agree with Nigel

I am still an active radio flyer, and use Nicads and NiMH packs to provide transmitter and receiver power for my models. There are pros and cons with all the rechargable battery technologies, except lead acid, which are too heavy and therefore don't pass go!

Nicads have some advantages over NiMH cells, principally they are able to deliver much more current as they are discharged. Model planes which use electric motors as the motive power can run at currents of 100 amps at 12 volts using 10 x 2400mAh cells. Depending on the construction, nicads can also be fast charged, at currents up to 5C (5 x rated capacity), which makes them useful for rapid discharge/ recharge applications. A special peak detect charger is required for rapid charging. Most domestic applications trickle charge at C/10. The main disadvantage with nicads is that the cadmium is environmentally toxic, so the EU is working to a) increase recovery and recycling of cells at the end of their life b) encouraging phase out.

NiMH's generally have more capacity than nicads of the same dimension, but as noted above have limited ability to deliver the current. They also cannot be fast charged at a current above their capacity, so a 1000 mAh cell can only be charged at an amp for an hour. More amps = bang. They are more environmentally benign, which is why they have been pushed.

Li-ion are not as robust as many people believe, and in fact are very delicate when it comes to recharging. Those used in mobile phones and laptop computers have power management circuits built into them so that they are recharged correctly. incorrect charging of Li-ion cells usually leads to gassing of the cell, and often results in the cell catching fire, which is problematic, as they have their own oxygen source once they get going, and a fire extinguisher won't work on them. Hobbyists using these cells are advised not to recharge them unattended, just in case. They also have shorter working lives than nicads - my IBM laptop that my company provides is on its third Li-ion pack, and Apple have had a lot of warranty claims from the early i-pod MP3 players where the Li-ion pack has died.

Bottom line... None of them are perfect. You pays your money and takes your choice, but don't think that nicads are inferior technology, and make a purchasing decision based on the fact that the radio has a nicad pack.

Jon



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[chas]

I have a Garmin handheld. It has a bracket with a built in charger that you are meant to leave the radio in when you are not using it. It always seems to be topped up and has not let me down yet - and that includes taking it away for a day or so in the tender. In view of all the comments below, should I leave it in the charger?

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[Guest]

Swiftech charger ....

It overheats the battery pack by charging at too high a rate. It is designed for 50 hr max. This is too high and only way to help the pack is basically put it in freezer while charging !!

Best charger for this pack is a slow standard Radio Control Radio charger - using the Tx connection at 9.6v nominal.
You will find that this charger can be left for long periods without damage to pack.


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[Guest]

I would in my case .... leave the radio out of the charger bracket when not essential to have charged fully ... to allow the battery to run down and be 'exercised'. When it has been out -switched on of course- and sufficient time elapsed that battery is way down - put it back and charge it back up again.
As long as its done regularly you should find a good life from the battery.

What you have in fact is like the Dust Buster idea ..... held in bracket / charger ready for use....... but I am sure that there are enough on the forjm who have had to replace Dust Buster battery cells or in fact sometimes its cheaper to buy another Dust buster than the replacement battery pack !! That's the case with my battery powered drill ....... cost me $40 for 14.4V Battery drill set 7 yrs ago .... battery gave up about 6 months ago and only lasts about 5 mins. Replacement battery pack is $45 ....... so had a butchers for another ...... got a better set with 2 battery packs same 14.4V drill ..... for again $40 ........

Crazy isnt it !!

The trick is to exercise the battery and not just leave it to stand .....


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[tugboat]

It is my understanding that the charger (if screwed down) is a useful place to keep the handheld secure when not in use. However the charger should not be left switched on all the time. There was a recent article where the tester (Don Alexander I think) buggered his battery that way. He kept it by the wheel on charge and switched on and his battery lasted 2 years. He got a new battery, and fitted a cord to the old battery case so that he could plug it into the ship's supply. Just needed to change the battery case over when leaving the boat.

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[tugboat]

Gawd, my brain hurts!/forums/images/icons/frown.gif I've been very interested to read your debate with Ships_Cat. No disrespect to him but my experience tends to support your argument. My mobile phone which is several years old (almost steam-driven) and seldom used, definitely displays 'memory' characteristics. If recharged before complete discharge, it lasts a considerably shorter time for the next couple of cycles. Only when it has been fully discharged a couple of times does it return to it's normal duration. I know battery technology moves on with new types being developed, but I presume a NiCad is a NiCad is a NiCad and they all behave the same whatever their age (within reason)

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