Best rechargeables for Jetbook?

[GA Russell]

Originally Posted by Ken Maltby

...I installed the Ansmann 2500mAh.
They are showing as 3/4 full on the factory charge, in the JBL...

My Duracell rechargeables also showed 3/4 full on the factory charge, but they have shown 4/4 full when recharged.

[Ken Maltby]

Good, I expect it will be the same for these. The JBL power indicator doesn't give
us much info.

What I am planning for the test:

I'll be comparing these "Ansmann" "maxE+" NiMH 2500mAh batteries (Made in China)
charged with a "Powerex" MH-C204W charger overnight (at least 12 hours) - against the very common "Energizer" NH15 1.2v HR6 2300mAh batteries (Made in Japan) charged
with an "Energizer" Model CHDC8 charger for about 3 hours.

The test run will be from installing the batteries until the replace batteries warning box
appears on the JBL. I will record the install date and time, the date and time for the
start and end of each period of use, and the date and time of the warning message.

From that we should see the actual performance between the two batteries tested.
( The actual use and standby times will vary for each run, so it won't be an exact
comparison but will reflect normal usage.) I plan on posting the results after each of
the first two runs (one for each battery), then do four more runs, so I can average the
results, before posting a summary.

I will also, record and report the period from the removal of the battery set, from the
charger, and its use on a test run.

Luck;
Ken

[GhostHawk]

Anybody have anything to say about these?

http://www.thomasdistributing.com/sh...rje23bagil4pd3

It would appear on the surface to be an ideal setup.

[DJHARKAVY]

Originally Posted by GhostHawk

Anybody have anything to say about these?

http://www.thomasdistributing.com/sh...rje23bagil4pd3

It would appear on the surface to be an ideal setup.

They sound good... I might buy them next time I have some spare $$

[Ken Maltby]

4x1.2=4.8v 4x1.5=6v 4x1.6=6.4v was the worry. It was pointed out that the
JBL has a power regulator, so it should handle the difference in voltage, but there
could still be an issue of how the JBL handles the discharge curve. You would
expect that it could do a little better than the 1.5v primary batteries, but who
knows? I haven't encountered the lock-up that some reported, but these new
batteries could be a way to avoid that, as well.

I've wanted to try these, myself. (Three sets of batteries and chargers? Well
why not? I've got a few things that use them.)

Thanks for the heads up.

Luck;
Ken

[GhostHawk]

Well Ken it seems to me that the 1.6v dropping over discharge rate would just work better long term than the 1.2 of normal rechargeable batterys. I think if in a few more days I've not heard any reason not to try them I'm going to go ahead.

Will let you all know how it goes.

[Ken Maltby]

Originally Posted by GhostHawk

Well Ken it seems to me that the 1.6v dropping over discharge rate would just work better long term than the 1.2 of normal rechargeable batterys. I think if in a few more days I've not heard any reason not to try them I'm going to go ahead.

Will let you all know how it goes.

Great, and if you don't have any bad surprises, in say a week of use,
I will grab a charger and eight batteries, myself. I'll also add three test
runs of those to what I'm doing now. (After I finish, these.)

Luck;
Ken

[chainring]

Originally Posted by GhostHawk

Well Ken it seems to me that the 1.6v dropping over discharge rate would just work better long term than the 1.2 of normal rechargeable batterys. I think if in a few more days I've not heard any reason not to try them I'm going to go ahead.

Will let you all know how it goes.

I'd check with the Ectaco folks. Higher voltage can kill, whereas lower generally means shorter runtime if the device isn't built with rechargeable in mind.

[jrl007]

I ended up using some rechargeables that I'd gotten for my wife to use in her camera. Kodak brand from WalMart, nothing special and about 2 years old. Lasted about a week, one bar down, then about 3 more days and it went to 1/2 (2 bars).

Remembering the problems that some folks had if the batteries died while in the reader, when it hit 2 bars, I swapped them out for another set of rechargeables that I picked up at Target, 4 for $10 (Radio Shack wanted $20 for 4). Can't remember the brand, Everready or something like that. Labeled as "green"

We'll see how they do this week. I usually read about 2 hours a day, not all at once, 10 mins here, 20 mins there, whenever I get a chance to sit down for a bit, I grab my JBL.

[Ken Maltby]

Removed from charger (overnight charge) 14 Mar 1649hr

9 days 6hrs of shelf time later:

Installed 23 mar 2300hr (showing full charge in JBL)

at the 6hr 25min of reading point dropped to three bars

at the 21hr 34min of reading point dropped to two bars

at the 21hr 40min of reading point the low battery warning appeared
[ending the test run] on 08 Apr (batteries test at 1V and in the "?"
to the edge of the "Good" in the 1.5v battery test function)

SO; 21hr and 40min of actual use time and ~16 days standby time.

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

The JBL's power monitoring may be limiting the useful time of rechargeable
batteries in general, but these tests show what each battery type tested
provide running under the 0.15 firmware. It appears the dropping below 4v
triggers the replace batteries routine of the JBL.

I have started the testing of the 2300mAh Energizer rechargables which
were given a regular 2hr charge on 14 Mar. Giving 24days 16hrs of shelf
time, before they were installed at 0140hr 08Apr. They show as full in the
JBL.

My order of NiZn 1.6v rechargeables and charger are due tomorrow and
I'll add in their first testing run after this energizer run.

Luck;
Ken

[clerky96]

Waiting patiently for your "test results" of both the energizer and the 1.6v rechargeables. I want to get rechargeables, but want to buy the best for my money. Thanks for your tests.

[Ken Maltby]

I am near the end of the first Energizer test run, I think. (They are at 20hrs and 3bars)

I'll post here the Energizer final results of their first run, just like I did for the
Ansman eMax+ first test run.

The next test run will be for the Made in China PowerGenix NiZn 1.6v 2500mAh. I'll
post the results of their first test run, as well.

Then I'll make two more test runs for each of the three and do a summary post in its
own thread with the averaged results.

[GhostHawk]

I have not been scientific about it, but I'm getting about 6 days on average with my JBL and the NiZn rechargeables. Almost double what I used to get with a Jetbook.

And best of all, when it gives me the low battery warning, I just go swap out the battery's and go back to reading inside 5 min. Instead of having to put it on charge for 4 hours.

[jj2me]

The crossover point where a typical LSD (low self-discharge) is longer-lasting than a typical traditional NiMH (with its higher capacity), is given by this heuristic on Wikipedia:

However, after only a few weeks of storage, the retained capacity of low-self-discharge batteries often exceeds that of traditional NiMH batteries of higher capacity.

which references this website that tested 4 AA Eneloops vs. 4AA "well respected brand" traditional NiMHs.

I over-analyzed from this tiny sample by doing the following crossover point calculations using the charts in that reference (white charts for Eneloops, scroll down for pink charts for traditionals):

• Nominal capacity (Eneloops | Traditional): 2000 mAh | 2500 mAh.
• Measured capacity after 5 and 4 charge/discharge cycles at 1.2A (Eneloops | Traditional)): 1848 mAh | 2172 mAh
• Charge retention (Eneloops (mAh) | Traditional (mAh)):
  • Day: 99.8% (1844 mAh ) | 99% (2150 mAh)
  • Week: 98.7% (1824 mAh) | 93.3% (2026 mAh)
  • Month: 94.3% (1743 mAh) | 73.8% (1602 mAh)

Assuming approximately a straight line storage discharge curve (taking some liberty when looking at this site's non-linear NiMH Battery Retention Curve), we come out to approximately three weeks of storage, whereupon a 2000 mAH LSD NiMH retains more capacity than a 2500 mAh Traditional NiMH.

[GA Russell]

I've been recharging my NiMH Duracells three days before I expect to need them. May I assume that they lose close to nothing during that three day period?