Rechargeable AAs

[stuartgmilton]

Hey guys,

What is the best rechargeable AA battery to use in a flashlight which is being used daily as a bike light.

Cheers,

Stuart

p.s. Just bought a BL700 charger for them.

 

[DM51]

I'll move this to the Batteries section for you.

 

[worldedit]

Eneloops are pretty good. I would need to know more about this light to make a better suggestion.

 

[roymail]

Lots of help information on these threads.

 

[Niconical]

All you need to know - click here

 

[1dash1]

StuartGMilton:

The factors I look for in NiMH rechargeables are (1) manufacturer quality; (2) low self-discharge rate, i.e., shelflife; (3) capacity; and (4) price.

Best bang for the buck are probably Eneloops. Excellent quality. Excellent shelf-life. Okay capacity. Reasonable price.

However, personally, my AA-battery-of-choice is the Maha Powerex 2700. Excellent quality. Reasonable shelf-life (holds 80-85% of its charge after 3 months). Excellent capacity. Expensive.

A Powerex 2700 that has been on the shelf for three months has more residual capacity than a freshly charged Eneloop. For me, the 1/3 greater capacity is worth the trade-offs in price and discharge rate.

But, then again, I use my flashlights for 1 to 3 hours every night. If your usage is less, the Eneloops would probably be a better choice for you.

 

[Savvysteve]

You can get a nice energizer charger and 2200 or 2400 mah batteries for the $30 range from Wal-Mart. These are probably one of the highest rated batteries you will find easily in town. I specifically bought these for my digital camera and have been very pleased with them. Not only do they last a long time when using them, but also keep a charge very well. The charger I got is black and folds up and you can charge the batteries independently if I remember right and there is a LED battery icon for each cell to tell you they are ready.

I also have a cheaper version Rayovac charger with batteries that are 2200mah I think, I use them with my GPS and they work very well. They also hold a charge for a long time.

The new chemistry of these batteries really is great. Hope this helps.

 

[Alan_P]

If you are going to recharge every day or every few days then go for a higher capacity NiMh like the 2700 mah Powerex or Sanyo. You will have longer run times. The advantage of the eneloop is the low discharge which is an advantage if you are going to not use the light for extended periods of time (emergency only light).

 

[snakyjake]

I never understood advantages of low self-discharge NiMH. The advantages of the low self-dishcharge seem to appear between 5 to 6 months. The disadvantage is lower capacity.

I figure that if I don't use the device for 5+ months, or for only emergencies, why not cheap alkaline batteries or disposable lithium? Or, I'll just charge up my higher capacity NiMH batteries before use. Some of these chargers only take 1 hr to charge, and you can even use the 12v in your vehicle to charge.

And there are rechargeable alkaline batteries too. The big problem with rechargeable alkalines is that you lose capacity when rechrarged. Something like 100 charges is all you can get.

Jake

 

[f22shift]

I never understood advantages of low self-discharge NiMH. The advantages of the low self-dishcharge seem to appear between 5 to 6 months. The disadvantage is lower capacity.

I figure that if I don't use the device for 5+ months, or for only emergencies, why not cheap alkaline batteries or disposable lithium? Or, I'll just charge up my higher capacity NiMH batteries before use. Some of these chargers only take 1 hr to charge, and you can even use the 12v in your vehicle to charge.

me too. although i would buy them for my parents.
i for one always charge before a task :twothumbs

 

[roymail]

This forum is all about helping to understand the available options. It's up to you to choose what works best for your according to your needs.

It's not about this being better than that!

 

[drmaxx]

I never understood advantages of low self-discharge NiMH. The advantages of the low self-dishcharge seem to appear between 5 to 6 months. The disadvantage is lower capacity.

I figure that if I don't use the device for 5+ months, or for only emergencies, why not cheap alkaline batteries or disposable lithium? Or, I'll just charge up my higher capacity NiMH batteries before use. Some of these chargers only take 1 hr to charge, and you can even use the 12v in your vehicle to charge.

There's also the fact that high capacity NiMH are more fragile. Especially if you use them hard, charge them fast (1h) or drop them a lot then they loose their advantage relatively fast. I have a whole bunch of 2600 mAh that don't deliver much more then 2100 - 2200 mAh and that's not that far away from the LSDs.
Eneloops are not only LSD but they just seem to be high quality and robust.

Just an other thought to consider, when you decide for your favourite rechargables.

 

[snakyjake]

I've been reading about fancy (complicated) battery chargers that "refresh" and "break-in" batteries. Something about needing to break-in batteries that haven't been used for X months, and refreshing for batteries that haven't been used in Z weeks.

After reading about this battery charger, sure made me wonder how much trust I can put in a NiMH battery.

 

[DM51]

This forum is all about helping to understand the available options. It's up to you to choose what works best for your according to your needs.

It's not about this being better than that!

Excellent post!

 

[odessit]

If you are going to recharge every day or every few days then go for a higher capacity NiMh like the 2700 mah Powerex or Sanyo. You will have longer run times. The advantage of the eneloop is the low discharge which is an advantage if you are going to not use the light for extended periods of time (emergency only light).

It is not quite "recharge every few days"
For new batteries, at 45 days, Sanyo 2700 is still better than Eneloop (2348 vs 1840 mAh)
But it remains to be seen if Sanyo 2700 will hold it's charge with many cycles. AFAIK, such test has not been done yet.

 

[Yoda4561]

The 2700 batteries have been good so far, much better than the 2500's in any event. Assuming you handle them carefully (don't drop on a hard floor!) and don't overcharge/discharge them too much, they may be the best option for you. Just in case though, have a couple alkaline or lithium AA's in your pocket/pack. That way you won't be caught without light if they decide to die like the 2500's did.

 

[Mr Happy]

It is not quite "recharge every few days"
For new batteries, at 45 days, Sanyo 2700 is still better than Eneloop (2348 vs 1840 mAh)
But it remains to be seen if Sanyo 2700 will hold it's charge with many cycles. AFAIK, such test has not been done yet.

There have been reports of Sanyo 2700 cells developing a high rate of self discharge. Here are some such reports, for example:

http://www.candlepowerforums.com/vb/showpost.php?p=2701846&postcount=4
http://www.stevesforums.com/forums/view_topic.php?id=110429&forum_id=51
http://www.amazon.com/review/R225RWN0GMBONV/ref=cm_cr_rdp_perm

Maybe not every Sanyo 2700 will fail that way, but there seems to be a higher than average probability that some of them will.

 

[JakeyCakez]

I have some energizer and duracell 2500mAh cells that at one point wouldn't hold a charge for 3 days. after cycling them quite a few times it seems to be improving a little.

It wouldn't be so bad if it was just one cell that's failed like that, so far I've had near 100% fail rate.

I have some duracell (very old- around 4 or 5 years?) 2050mAh cells that have been like tanks, surviving heavy use, deep discharge, and sitting for months without use and they haven't given me a single problem?

 

[mdocod]

Here's my theory:

1. If you plan on using cells almost every day, then cycle life and cell reliability are important.
2. If you use the light infrequently, then low-self-discharge is important.

The answer to both scenario's is eneloops.

High capacity cells have proven themselves to be short term investments for many people here. Evidence has shown that heavily used high capacity cells, from many brands, can potentially develop self-discharge problems. Those self-discharge problems can become so dramatic that even day-to-day use is no longer reliable.

The problem with numbers, is that we often gravitate towards bigger numbers when comparing products. Numbers rarely tell the whole story, and more often than not, are just hiding the truth. Numbers look good to consumers because they seem solid, reliable, like something that sits on solid ground, nothing could be further from the truth when it comes to consumer goods.

 

[snakyjake]

Is it possible that some of the problems people experience have something to do with the charger? Just look at all the settings and configurations the Maha 9000 has for charging, refreshing, breaking-in, etc.