Battery woes.

swanseamale47

swanseamale47

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wayne clarke
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I have been using rechargable batteries since the 1970's with no problems.... well untill recently that is.
Towards the end of last year I needed to replace my ageing Ni-cads, it seems nicads are out of fashion, I couldn't get any only NMH, supposedly miles better, no memory etc etc. I have bought about 5 or 6 packs, different prices different makes, and 3 different chargers, they all have one thing in common, their crap! None of the packs lasted more than a few charges with all the batteries still working, and rather supprisingly they don't hold the charge well when they work either.
This is getting silly, what on earth is going on?? is it that my good old Metz is just to heavy going for them, or does everybody have this problem (seems hard to believe) Anybody know where I can get good old fashioned Ni-cads??? Wayne
 
Hi,

Obvious question but I assume your using high quality and high maH batteries. Its worth checking your charger too, alot of chargers act purely on charge time so don't fill high mah batteries (sorry not very technical) but better quality chargers measure the input to the battery and finsih charging based on that.

Hugh
 
All I know is there are bad NiMH and there are good NiMH batteries. Not being funny but most of the bad ones come from China and the good ones from Japan. I have heard a lot of guff being spoken about having to pay high prices for camera labelled batteries, equivalents being cheaper. Personally having tried some of the equivalents, I would not buy anything other than the pukka camera labelled ones any more.
I know your application is not for a camera but the technology is still the same.
 
Byker28i said:
... I've moved over to the Annsman Max-e, as they don't suffer the discharge problems when not being used.
Click to expand...

All NiMH cells will self discharge, it's simply the chemistry that makes them work that makes them discharge...usually by around 1%/day when fully charged and dropping to 0.5%/day when the charge level gets to lower levels.

NiMH also have a "memory effect" and will need an intelligent charger to get the best from them. It's important not to overcharge them...they will be damaged...so use a charger that discharges them prior to charging and then only charge for the published time (unless the charger has a cut off).

Bob
 
There is a recent thread in Lighting regarding rechargables.

In response to the OP's question why he can't buy NiCd batteries any more, cadmium is highly toxic and was banned in electronics by the EU in 2004.
 
Wow that was quick guys, thanks. I tried a few different makes (all fairly large capacity) some were quite pricy, but all seemed equally bad.
Bob I thought one of the selling poits was that NMH didn't have the memory effect like ni-cad? I also didn't realise they could over charge, never had that problem with ni-cads.
If I have to keep buying regular "pink bunny" batteries, my bank managers going to throw a wobbler. Wayne
 
I'm trying some Sanyo Eneloops at the moment - come ready to go fully charged and supposedly hold their charge for many weeks, if not months. Too early to tell you if they're any good, but Sanyo is a top manufacturer in the rechargeable market. Available from Amazon.
 
swanseamale47 said:
Bob I thought one of the selling poits was that NMH didn't have the memory effect like ni-cad? ....
Click to expand...

The "memory effect" is caused by a degradation on the surface of the nickel electrode (very fine crystals). As both NiCad and NiMH both use nickel electrodes then the effect will be similar although it may well be that the NiMH suffer the problem to a lesser degree. I've seen the reports (advertisments) saying that there is no memory effect but this is simply waffle. I suspect that using the term "memory" would be the get out clause if it was challenged.

I was looking around for some basic but pertinent details of charging and Wiki comes up with a good precis.....look at the charging section on this link. There's a little more available elsewhere but this should give you some food for thought ...especially about the quality of your charger (your cat could be eating your canaries!)

Bob

Edit...always find the stuff just after you need it. This is from a tech report;

The memory phenomenon can be explained in layman’s terms as expressed by Duracell: “The voltage drop occurs because only a portion of the active materials in the cells is discharged and recharged during shallow or partial discharging. The active materials that have not been cycled change in physical characteristics and increase in resistance. Subsequent full discharge/charge cycling will restore the active materials to their original state.”

When NiMH was first introduced there was much publicity about its memory-free status. Today, it is known that this chemistry also suffers from memory but to a lesser extent than the NiCd. The positive nickel plate, a metal that is shared by both chemistries, is responsible for the crystalline formation
 
Buy Hybrio rechargeable batteries, so much better at holding charge over a long period.
Make sure you still pick a leading brand.
 
Thanks for the replies.
Bob, the link is very informative, couriously I had noticed the batteries getting quite hot in one of the chargers, this may be the root of the problem, I didn't think anything of it as my nicads used to get quite hot in a fast charge, but it seems this can damage NMH. Wayne
 
heavy reading in places ,so feel free to skip the boring bits.

http://wolfeyes.com.au/news/?p=6


you say you have 3 chargers is that three good chargers ?

i've found it's worth investing in 1 of these" intelligent" chargers that monitor the batteries rather than the sort that simply work on a timer etc

[ EDIT ],you posted as i typed . batteries getting hot on a fast charge not good ,at all be gentle with the poor little souls.
 
Sanyo Eneloop 4 pack £3.99 Argos Llanelli. 2 packs showing in stock. http://www.argos.co.uk/static/Product/partNumber/9801389.htm


Charger and batts £9.99 http://www.argos.co.uk/static/Product/partNumber/9801509/c_1/1|category_root|Home%20entertainment%20and%20sat%20nav|12108813/c_2/2|cat_12108813|Clearance%20Home%20entertainment%20and%20sat%20nav|12745373.htm?storeId=10001&referredURL=http%3A%2F%2Fwww.argos.co.uk%2Fstatic%2FProduct%2FpartNumber%2F9801509%2Fc_1%2F1%7Ccategory_root%7CHome+entertainment+and+sat+nav%7C12108813%2Fc_2%2F2%7Ccat_12108813%7CClearance+Home+entertainment+and+sat+nav%7C12745373.htm&jspStoreDir=argos&referrer=COJUN&cmpid=COJUN
118-9801509SPA70UC488225M.jpg
 
I assume that you have a reasonably fast charger? MiMh cells need much higher charge current than NiCd cells.
 
I had the same problems as you describe Wayne, I was at that time using Jessops nimh's and a cheap fast charger, all these batteries are now in the bin. I got new ones (cheap as well) from 7 day shop along with a smart charger & all is well now -oh joy.
 
Charge too fast with high current and you will reduce the battery life due to heat build up.

the recommended charging current for a NiMh battery to avoid damage and to preserve the life is
charging current (mA) = Capacity (mAh)/10
Charging time = 10/0.66 = hours

The 0.66 is the charging efficiency of the battery at C/10, increase the charging current and you will reduce the charging time but also the charging efficiency.

If you have a 2500mAh battery the best way to charge it is at
Charging current = 2500/10 = 250mA
Charging time = 10/0.66 = 15 hours

This will not damage the battery charging as long as the battery started flat, overcharging also won't do as much damage with a low current like this. Charging quicker will damage the battery slightly due to the heat build up but overcharging at the higher current will seriously damage the battery and shorten its life.

If you can possibly wait for batteries to charge then the longer they charge the better for their life. Fast chargers will not fully charge your battery and will affect its life. Get a good charger with microprocessor control if you can which will monitor the all the things like, temp, current, time etc. If you don't want to spend so much the slower the charger the better it is for your batteries :)

Look up NiMh charging guides on the net you'll find a lot of good info and better presented than what I've put here. Radio controlled model pages are good sources of info for battery care and maintenance :)
 
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