Best rechargeables for Jetbook?

[chainring]

Very good summary, and only some additional points.

Originally Posted by jj2me

Just to sort of summarize: There are basically three types of rechargeable AAs available today (ignoring the older NiCad because of its lack of any real advantage):

NiCd, while being difficult to find these days, still do offer an advantage. They're robust and incredibly tolerant of abuse. Even with that advantage, there's too many downsides to consider them: price, lower capacity, bad for the environment.

• low self-discharge NiMH, like Eneloops, Rayovac Hybrids, Rayovac 4.0, etc. Advantage: slow discharge when not in use.
• regular discharge NiMH, losing 1% charge per day. Advantage: comes in higher mAh ratings.
• rechargeable alkaline. Advantage: 1.5V instead of 1.2V.

• Slow discharge translates into less maintenance to keep them vibrant.
• Watch out for cells over the 2000 - 2100mAh rating. There's tons on the market claiming high capacity, but the reality is lots of them are overrated quite a bit. Maha PowerEx 2700 mAh AA's are very good in testing close to their rating.
• Rechargable alkaline: rechargeable or non, if your device wasn't made for NiMh or NiCd, you're generally stuck with alkaline or primary lithium. You *may* get away with a really good performing NiMh, but the device will probably go to a low battery condition before depleting the battery's full charge.

Rule of thumb:
- Use Eneloops et al. if you often don't use your reader for days.
- Use higher mAh rated regular NiMHs in a device requiring more juice, like a digital camera. Also use them in a reader that you use daily, though I don't know at what level of use the plot of the higher mAh/higher self discharge battery crosses that of the lower mAh/lower self discharge battery.
- Use rechargeable alkaline only if your device requires 1.5V, and won't work on anything lower, and you prefer rechargeables. Rechargeable alkalines are also slow self discharge, which made them attractive before low self-discharge NiMHs were invented. But rechargeable alkalines have several disadvantages: not popular and not sold many places anymore, require special charger, offer many less recharge cycles before they're bad (maybe as few as 12), lifetime number of cycles is lessened substantially by deep discharges, offer less mAh with each charge cycle. I suspect most people would rather just use regular non-rechargeable alkalines.

- Nothing to add since the Eneloop has been covered enough already.
- Just a point of clarity between Eneloop/LSD (low self-discharge) and higher capacity non-lsd NiMh. It's not so much that the traditional cell is better suited to devices that require more juice (read: high drain), because the LSD cells, especially Eneloop, can sustain high amperage draws (up to 10A). It's that the higher capacity non-lsd cells are just that, higher capacity. With something like the Maha 2700's, that will translate into more runtime than the Eneloop, all else being equal, and both being hot off the charger.
- Alkaline batteries, either primary or rechargeable, have one huge and serious disadvantage for me. They LEAK! I've had new ones leak, not so new that leaked, and old ones that leaked (understandable). Regardless of the age, leaking alkaline and the possibility of it happening just isn't worth it to me. I have some Stabila electronic levels (expensive level with a digital module) that came with some high end Duracell alkaline. Upon receiving the levels, I replaced the alkaline with Eneloop's.

[smithno]

I too like enloops the best. I also bought a couple of packs of Ray-O-Vac 1000mha NiMH batteries. i consider them bottom of the barrel, but I get a week+ out of a set. I average reading my JBL about 2 hours a day. I rotate them every weekend regardless. So, while I'll probably only buy enloops in the future, just about any quality battery will do for the JBL.

I did a bunch of research before buying a charger from Thompsons. It seems that slow charging the NiMH batteries significantly increases the number of times that they will recharge compared to fast charge-type chargers.

[Ken Maltby]

Originally Posted by smithno

I too like enloops the best. I also bought a couple of packs of Ray-O-Vac 1000mha NiMH batteries. i consider them bottom of the barrel, but I get a week+ out of a set. I average reading my JBL about 2 hours a day. I rotate them every weekend regardless. So, while I'll probably only buy enloops in the future, just about any quality battery will do for the JBL.

I did a bunch of research before buying a charger from Thompsons. It seems that slow charging the NiMH batteries significantly increases the number of times that they will recharge compared to fast charge-type chargers.

OK; so do the 2000mAh Enloops last twice as long in the JBL as the
Ray-O-Vac 1000mAh?

Do you see any real difference/improvements as a result of the "low discharge" feature, with regard to use in the JBL? How has it shown up in use? Is there a noticeable difference between the Enloop and the Ray-O-vac, in this regard?


--------------------

I have ordered some batteries and a charger from Thomas Distributing
and will be comparing their performance, in the JBL, with the grocery
store Energizer rechargeables, over the next few months.

Would this charger meet your description of a slow charger?
Maha MH-C204W White World Battery Charger

The batteries I will be using for this test:
ANSMANN 2500 AA LOW DISCHARGE NIMH

Luck;
Ken

[wackywalt]

This will be interesting. I want to stop using the standard (non-rechargables) akalines.

[chainring]

Originally Posted by Ken Maltby

OK; so do the 2000mAh Enloops last twice as long in the JBL as the
Ray-O-Vac 1000mAh?

1000mAh can't be correct for a AA NiMh. There exists 1000 mAh AAA's though. Probably a typo since the JBL takes AA.

Would this charger meet your description of a slow charger?
Maha MH-C204W White World Battery Charger

The C204 is not classified as a slow charger. Slow charging is generally defined as:
1. Done on a dumb charger, as in timed, not with smart termination.
2. At a rate no greater than C/10 for 14-16 hours. C being capacity of the cell divided by 10. Take the Eneloop AA 2000 mAh, for example. 2000 mAh divided by 10 gives 200 mA for a slow charge lasting 14-16 hours.

The 204 though, is generally regarded as a good choice of charger. Very complete, as in thorough, charge.

The batteries I will be using for this test:
ANSMANN 2500 AA LOW DISCHARGE NIMH

From the little bit of discussion I've read, they seem to be pretty decent, capacity wise. In that thread, a dealer of the Ansmann product stated they are more of a hybrid between high capacity standard cells and true low self-discharge cells.

And one more link.

[smithno]

Sorry for not responding sooner; haven't been on for a couple of days.

I was wrong about the Ray-O-Vacs; they are 1800mAh AA batteries. It is in such small print that it sure looks like 1000 to my old eyes. I just dug out a magnifying glass to check. Sorry!!

I bought a LaCross BC-900 charger about a year ago. It lets you set the charging rate. Default is 200mA charging, but can be bumped up 1800mA. I always use the 200mA setting. Charging a dead set takes a while on this setting.

The enloops do last longer. I should actually time how long each lasts. The Ray-O-Vacs go from 4 to 3 marks on the battery indicatory after a couple of hours and the enloops go much longer. At the end of a week my normal reading both still read 3 marks on the indicator, which is "good enough".

[mitchwah]

Originally Posted by Ken Maltby

I have ordered some batteries and a charger from Thomas Distributing
and will be comparing their performance, in the JBL, with the grocery
store Energizer rechargeables, over the next few months.

Would this charger meet your description of a slow charger?
Maha MH-C204W White World Battery Charger

The batteries I will be using for this test:
ANSMANN 2500 AA LOW DISCHARGE NIMH

Luck;
Ken

I will look forward to your review. Very interesting.

[jj2me]

Originally Posted by chainring

- Alkaline batteries, either primary or rechargeable, have one huge and serious disadvantage for me. They LEAK!

chainring, thanks for the corrections and additions. Especially about alkalines leaking. Yes, they've leaked on me, but I never put it together that they leak much more than other types.

Originally Posted by smithno

I bought a LaCross BC-900 charger about a year ago. ... I always use the 200mA setting.

I also have this charger, and because of all the reports of these chargers frying batteries and self destructing, I only use it on a tile floor. It scares me. Just bought it, shoulda done more research. They say the BC-700 doesn't have such failure reports.

And thanks for the 200 mA advice. I think it's the heat during charging that lessens the number of cycles. Some fast (15- or 30-min.) chargers, like my Duracell Accu 30-min., have a fan right in the charger bay blowing air at the cells to keep the temperatures down. Sometimes worth it for the time savings.

[Ken Maltby]

OK; the MH-C204W charger came today, so I have the components for the testing.

Don't expect any quick result, the nature of what I am trying to measure makes it
a lengthy process.

As soon as my current set of Energizers runs out I will start the testing and record
keeping. The first run will be of the Ansmann maxE+ 2500mAh, on their factory charge.

( If their claim of "more than 1 year standby" means anything, I guess they really are
"Low self discharge".)

Luck;
Ken

[chainring]

Originally Posted by jj2me

chainring, thanks for the corrections and additions. Especially about alkalines leaking. Yes, they've leaked on me, but I never put it together that they leak much more than other types.

You're welcome. Many moons ago, I've seen NiCd leak, but in normal operation and with normal (<1C) charge rates, I've never seen a NiMh leak. I've seen LiIon cells vent, but it was a defective cell. Alkalines though, I just don't trust 'em. If the device is low drain, or I might forget about a rechargeable I'll stick in an Eneloop. I've NEVER seen a report of a leaking Eneloop.

I also have this charger, and because of all the reports of these chargers frying batteries and self destructing, I only use it on a tile floor. It scares me. Just bought it, shoulda done more research. They say the BC-700 doesn't have such failure reports.

Yep, good charger, but watch it closely. Tile floor is an excellent idea, and for anyone who doesn't have that luxury, run to Home Depot and get some tiles.

You're correct about the BC-700 not being a known offender. The BC-900 and the BC-9009 are the potential culprits. FWIW, I have a BC-900 as well, and it's been good, but not used much since I received the Maha C-9000's.

And thanks for the 200 mA advice. I think it's the heat during charging that lessens the number of cycles. Some fast (15- or 30-min.) chargers, like my Duracell Accu 30-min., have a fan right in the charger bay blowing air at the cells to keep the temperatures down. Sometimes worth it for the time savings.

Keep an eye on them when charging at 200mA as that's not within the normally recommended charging rate for a smart charger. Basically, a full charge on NiMh should end up with the cell at a maximum of 126 degrees F...MAXIMUM. Ideally, you should be around 10 degrees F over ambient. 0.5C - 1.0C is the range you need to be for a reliable full charge detection

Basic terminology:
C = capacity
C/10 = capacity divided by 10
0.5C = Say you have an Eneloop AA at 2000 mAh. 0.5C would be 1000 mA. Easy, right?
1.0C is the industry recognized standard fast charge rate. It's how long a fully depleted cell will take to be charged in one hour.

Regarding the super fast chargers (15 - 30 min), especially the 15 min versions, those will reduce the total life if used continually. There was an extensive test that concluded with cells put through the abuse of an Energizer 15 min charger would get around 150 cycles vs. more than twice that number at 1C or less rates. Like you said, the 15 min is really good for convenience and the "I need it now" type of situation.

[jj2me]

Originally Posted by chainring

Keep an eye on them when charging at 200mA as that's not within the normally recommended charging rate for a smart charger. Basically, a full charge on NiMh should end up with the cell at a maximum of 126 degrees F...MAXIMUM. Ideally, you should be around 10 degrees F over ambient. 0.5C - 1.0C is the range you need to be for a reliable full charge detection

Basic terminology:
C = capacity
C/10 = capacity divided by 10
0.5C = Say you have an Eneloop AA at 2000 mAh. 0.5C would be 1000 mA. Easy, right?
1.0C is the industry recognized standard fast charge rate. It's how long a fully depleted cell will take to be charged in one hour.

Didn't know smart chargers had a range different from other (slow?) chargers. I just followed the BC-900's instructions, which doesn't seem to take into account the batteries' capacity: "In general, 200 mA is a recommended charging current if rapid charging is not necessary. It is definitely safe and optimum to the rechargeable batteries."

Thanks again. This is terrific info you've given us in this thread.

Quite glad that I shouldn't be charging at 200 mA, since using the BC-900's "Refresh" cycle at 200 mA is an overnight experience with the worry of an exploding cell.

And really, losing 200 cycles because you fast charge? Is that really such a big deal for the average consumer, who might only go through 50 - 100 cycles/year? That's still 3 - 6 years (instead of 5 - 10).

[chainring]

Originally Posted by jj2me

Didn't know smart chargers had a range different from other (slow?) chargers. I just followed the BC-900's instructions, which doesn't seem to take into account the batteries' capacity: "In general, 200 mA is a recommended charging current if rapid charging is not necessary. It is definitely safe and optimum to the rechargeable batteries."

Like I said, a true "slow" charger is dumb, in that it has no charge termination smarts other than a timer. "Smart" chargers, as they're known, have different methods of detecting a fully charged cell. The most popular is a change in voltage, known as delta V, or -dV (negative delta Voltage). If you plotted the voltage of the charge, it would eventually rise to a point, then fall. That fall is what the charger is looking for, and once seen it will end the charge cycle. To generate a sufficient drop in voltage most chargers need to be operated at the 0.5 - 1.0C range. Some are better than others, but they may also employ temperature to aid detection and as a safety.

Thanks again. This is terrific info you've given us in this thread.

No problemo, glad I could help.

Quite glad that I shouldn't be charging at 200 mA, since using the BC-900's "Refresh" cycle at 200 mA is an overnight experience with the worry of an exploding cell.

Stick with 0.5C charge rates and you won't damage the cell, nor will you be tying up the charger forever.

And really, losing 200 cycles because you fast charge? Is that really such a big deal for the average consumer, who might only go through 50 - 100 cycles/year? That's still 3 - 6 years (instead of 5 - 10).

I agree, it's not that big of a deal in the whole scheme of things, especially when weighing in the added convenience. If I were relying on some batteries for a business use, you'd be hard pressed to find me using the 15 min charger on them, but I don't have that sort of use... Keep a spare set of Eneloop's charged up and you won't be presented with that kind of situation in the first place.

[GA Russell]

Sanyo today announced their new Eneloop Lite rechargeable NiMH batteries. They can be charged 2,000 times.

They will go on sale in Japan June 22.

http://www.engadget.com/2010/03/08/s...re-cheap-less/

[jj2me]

Originally Posted by GA Russell

Sanyo today announced their new Eneloop Lite rechargeable NiMH batteries. They can be charged 2,000 times.

They will go on sale in Japan June 22.

http://www.engadget.com/2010/03/08/s...re-cheap-less/

Good info. But these are not ideal for use in the Ectaco, as they will run out sooner in such use (950 mAh compared to regular Eneloop's 2,000 mAh). They are intended for low-drain devices, like clocks and remotes.

2,000 charges! Pass them down several generations. If they power a clock and last 6 months on a charge, that's 1,000 years!

[Ken Maltby]

OK the Energizers finaly ran out and I installed the Ansmann 2500mAh.
They are showing as 3/4 full on the factory charge, in the JBL. I will go
ahead and charge them instead of starting the test on the factory charge
as I had planned.

Luck;
Ken