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#177371 - 07/23/09 06:54 AM Rechargeable blues
Tom_L Offline
Addict

Registered: 03/19/07
Posts: 690
Most of my portable electronic gear runs on AA batteries so instead of buying alkalines all the time I tend to rely on rechargeable NiMH cells.

NiMH batteries supposedly last a long time, don't suffer from the memory effect and can be recharged like a couple thousand times at least, or that's what it says on the box. But looking back, the actual performance seems to be a lot worse.

I have a few NiMH batteries 4 to 5 years old, they may have about a hundred cycles behind them at most but their capacity is now much less than what it used to be. I have a decent charger optimized for NiMH so I'm a bit disappointed. It's so bad that sometimes a freshly recharged pair of NiMH's will last just about 10 minutes in my camera or barely suffice to power up a flashlight.

All in all, I've become wary of relying on rechargeables. Very often a spare pack of alkalines has saved the day in the field when several pairs of freshly recharged NiMH cells just died within minutes.

Now I'm a bit at a loss. Maybe I should look for a better charger or maybe there are better brands out there and my NiMH batteries are just crap. But I would sure love to hear about your experience.

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#177372 - 07/23/09 07:06 AM Re: Rechargeable blues [Re: Tom_L]
Todd W Offline
Product Tester
Pooh-Bah

Registered: 11/14/04
Posts: 1928
Loc: Mountains of CA
Have you EVER fully discharged them?

A good battery conditioner will probably fix the majority of them but they still have a limit on the # of cycles they can handle.

Also there is a HUGE difference in battery quality between cheap expensive rechargeable.


I used to be into high end Electric RC Cars and would go through batteries, and wow there are TONS of different things to check when buying batteries... capacity, cell manufacture, rated # of cycles (normally related to manufacture and then the level battery you buy.)

Also charging, and making sure they are discharged prior to a recharge even though they don't need this it helps.

ETc Etc


Edited by Todd W (07/23/09 07:07 AM)
_________________________
Self Sufficient Home - Our journey to self sufficiency.

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#177376 - 07/23/09 10:13 AM Re: Rechargeable blues [Re: Tom_L]
celler Offline
Addict

Registered: 12/25/03
Posts: 410
Loc: Jupiter, FL
Try moving up to the newer low self-discharge NiMH like the Sanyo Eneloop. Some of your problems may be related to the NiMH battery staying in a discharged state for an extended period of time and the low self-discharge rate of these new batteries helps combat that. However, I'm with you, I always keep a set of alkalines, or better yet, lithiums, handy just in case.

Craig.

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#177378 - 07/23/09 10:21 AM Re: Rechargeable blues [Re: Todd W]
Eugene Offline
Carpal Tunnel

Registered: 12/26/02
Posts: 2823
You really only need to fully discharge once every 20 or so cycles is the rule of thumb I'm seeing now.
Couple issues, are you using highr capacity NiMH ir the newer low self discharge? The higher capacity (>2100mAh) obtain that higher capacity at a tradeoff. They tend to have a thinner insulator which causes faster self discharge and is more fragile. Some of the worst batteries are the 2500mAh but then there are some like the sanyo 2700mAh's that were released after the low self discharge and have some of that chemistry in them and they seem to be decent. Sanyo Eneloop (200mAh low self discharge), RayOVac Hybrid (2100mAh Low Self Discharge), Maha Imedion, uniross hybrios, etc are some of the newer technology which not only hold their charge better but are tested out to 1000 cycles.

Charger can make a big difference and just because a charger is called a smart charger doesn't mean its all that smart. I had bought a $30 RayoVac PS4 charger a few years back which was a smart charger but started having short life from my batteries to the point I'd have to carry that charger around and top them off before using them. I got tired of that fast and stoped using NiMH for a while. Couple years later I started reading about these new low self discharge batteries and wondered if my charger would work with them so I started researching it. Turns out it was a known bad model (PS4) which never really put more than 75% of charge on the batteries. I had two or three other chargers before that, some simple trickle chargers, others so called smart chargers. I got rid of them all and bought a $40 Maha c401fs and ran my batteries through a slow charge on it, discharged them in a fashlight and slow charged them again. I put a few in our digital camera and it jumped from 50 pictures to 250 pictures from some old 1600mAh batteries. I bought a set of sanyo eneloops and started reaching 500 pictures on a charge.
A year later I bought a maha c9000 for $60 and started testing my batteries. I dug all the old ones out of my drawer and found the Sanyo's from 1999-2001 that were 1500-1600mAh rated were testing around 80% of that rating. Some 2000mAh rayovacs from 2004 or 2005 tested around 80%. Radio shack and energizers were all under 50%. This was early in 2008 when I bougth the charger so I had batteries from 7-9 years old that were just at the end of their useable life (80% is a general rule of thumb) even though they had not been well taken care of. I went and bought several packs of eneloops and replaced all my old batteries with them. I now run the refresh/test cycle ono the c9000 once a year and record the capacity so I can see how well they are doing.

Hopefully my post wasn't too long and your still reading but to sum it up if you buy cheap batteries and chargers then you can't exect great performance. Just like any other tool, you can buy a $5 china mart knife but can you expect to be great? I probably spent way more than $100 over the years on cheap chargers to not have them work well, its far less expensive in the long run to buy the better ones up front.

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#177382 - 07/23/09 10:44 AM Re: Rechargeable blues [Re: Eugene]
Tjin Offline
Pooh-Bah

Registered: 04/08/02
Posts: 1756
Originally Posted By: Eugene
You really only need to fully discharge once every 20 or so cycles is the rule of thumb I'm seeing now.
Couple issues, are you using highr capacity NiMH ir the newer low self discharge? The higher capacity (>2100mAh) obtain that higher capacity at a tradeoff. They tend to have a thinner insulator which causes faster self discharge and is more fragile. Some of the worst batteries are the 2500mAh but then there are some like the sanyo 2700mAh's that were released after the low self discharge and have some of that chemistry in them and they seem to be decent. Sanyo Eneloop (200mAh low self discharge), RayOVac Hybrid (2100mAh Low Self Discharge), Maha Imedion, uniross hybrios, etc are some of the newer technology which not only hold their charge better but are tested out to 1000 cycles.

Charger can make a big difference and just because a charger is called a smart charger doesn't mean its all that smart. I had bought a $30 RayoVac PS4 charger a few years back which was a smart charger but started having short life from my batteries to the point I'd have to carry that charger around and top them off before using them. I got tired of that fast and stoped using NiMH for a while. Couple years later I started reading about these new low self discharge batteries and wondered if my charger would work with them so I started researching it. Turns out it was a known bad model (PS4) which never really put more than 75% of charge on the batteries. I had two or three other chargers before that, some simple trickle chargers, others so called smart chargers. I got rid of them all and bought a $40 Maha c401fs and ran my batteries through a slow charge on it, discharged them in a fashlight and slow charged them again. I put a few in our digital camera and it jumped from 50 pictures to 250 pictures from some old 1600mAh batteries. I bought a set of sanyo eneloops and started reaching 500 pictures on a charge.
A year later I bought a maha c9000 for $60 and started testing my batteries. I dug all the old ones out of my drawer and found the Sanyo's from 1999-2001 that were 1500-1600mAh rated were testing around 80% of that rating. Some 2000mAh rayovacs from 2004 or 2005 tested around 80%. Radio shack and energizers were all under 50%. This was early in 2008 when I bougth the charger so I had batteries from 7-9 years old that were just at the end of their useable life (80% is a general rule of thumb) even though they had not been well taken care of. I went and bought several packs of eneloops and replaced all my old batteries with them. I now run the refresh/test cycle ono the c9000 once a year and record the capacity so I can see how well they are doing.

Hopefully my post wasn't too long and your still reading but to sum it up if you buy cheap batteries and chargers then you can't exect great performance. Just like any other tool, you can buy a $5 china mart knife but can you expect to be great? I probably spent way more than $100 over the years on cheap chargers to not have them work well, its far less expensive in the long run to buy the better ones up front.


I agrea. I have a Voltcraft IPL-7 charger. It charges mine batteries much beter than the cheap chargers ever did. I'm currently swithced to eneloops and recycko's for all mine AA's and AAA's.
_________________________


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#177392 - 07/23/09 11:55 AM Re: Rechargeable blues [Re: Tjin]
Tom_L Offline
Addict

Registered: 03/19/07
Posts: 690
Thanks for all the feedback (no Eugene, that wasn't too long, in fact I did read all of your post smile )! Part of the problem could be most of my rechargeables are high capacity. Currently the ones I trust the most are Sanyo 2700mAh, but that's because I only bought them pretty recently. Haven't tried the Eneloops yet but they look promising.

Being used to NiCd I do tend to discharge batteries fully before recharging. Part of the problem could be the "smart" charger, though. I've got about 4 different chargers right now and I'm not really happy with any of them. Have been thinking about getting a better one and probably will very soon. But another issue is that I use much of my portable electronics on a fairly sporadic basis so self-discharge is definitely a problem.

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#177396 - 07/23/09 12:21 PM Re: Rechargeable blues [Re: Tom_L]
Grouch Offline
Enthusiast

Registered: 07/02/08
Posts: 395
Loc: Ohio
I've been very happy with my Lacrosse BC-900 charger when used with Eneloop 2,000 mAh AAs. The charger will go down to 200 mA (default) for a gentle charge rate that is easy on the batteries.

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#177407 - 07/23/09 03:26 PM Re: Rechargeable blues [Re: Tom_L]
JohnN Offline
Old Hand

Registered: 10/10/01
Posts: 966
Loc: Seattle, WA
Weird. I wrote a reply to this thread and get:

Quote:

Bad Request

Your browser sent a request that this server could not understand.
Apache Server at forums.equipped.org Port 80


When I try to submit it. Anyone see this before?

-john


Edit: Since I can post *this*, must be something in the content of my post?! Weird.


Edited by JohnN (07/23/09 03:27 PM)

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#177410 - 07/23/09 03:47 PM Re: Rechargeable blues [Re: Grouch]
Lono Offline
Old Hand

Registered: 10/19/06
Posts: 1013
Loc: Pacific NW, USA
+1 on the Lacrosse charger and Eneloop strategy, that or the Maha model cited should go a long way to restoring your rechargables.

I do confess that I will not rely entirely on rechargeables in an emergency, although I have several means (solar, auto, local power inverter) to recharge cells without a power source. I also buy a 32 pack of alkaline AAs every year, and use these for incidental uses along the way. If I lost power tomorrow, I have about 28 AAs to rely on without dedicating any thought to a recharging strategy. For $8 its a reasonable insurance of sorts. It may not be entirely environmentally sound, but I do use the NiMHs on an every day basis.

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#177411 - 07/23/09 03:53 PM Re: Rechargeable blues [Re: Lono]
JohnN Offline
Old Hand

Registered: 10/10/01
Posts: 966
Loc: Seattle, WA
I think the problem is something to do with the links. Here is the post w/o the links:

You need a good, independent cell charger:

candlepowerforums.com > Flashlight Electronics - Batteries Included > Flashlight Electronics - Batteries Included - Threads of Interest > Charger Comparison

And good batteries:

candlepowerforums.com > Flashlight Electronics - Batteries Included > Flashlight Electronics - Batteries Included - Threads of Interest > NiMh Battery Shoot Out

candlepowerforums.com > Flashlight Electronics - Batteries Included > Flashlight Electronics - Batteries Included - Threads of Interest > NiMh Battery Shoot Out Part II

AND YET, keep in mind these batteries *will* self discharge.

What I do is I have two bins, a "charged" and a "discharged". Once the discharged bucket is empty, I just switch buckets and start over.

You also need to "right size" your battery collection. Don't have too many batteries, otherwise you'll run afoul of self-discharge. And of course, you want enough to get the job done.

You are better off with a smaller collection of good high capacity batteries than a larger collection IMO.

I'd say the Sanyo 2700 batteries with the Maha C9000 or AccuManager 20 would probably be good. I have a MH-C401FS, and while it isn't the latest, greatest, it does OK.

Oh, buy your stuff on-line. Buying rechargeable in a store both limits your choices and you end up paying more. I've had good luck with:

thomasdistributing.com

For both batteries and chargers.

FWIW, I've switched to lithium ion wherever possible. It has almost no self-discharge or memory effect. The only gotcha is you need devices that are designed for it.

Good luck,

-john


Edited by JohnN (07/24/09 12:20 AM)

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