Hi,
E.g.:
Jim
I suspect that if you had one of the laptops these batteries fit, you could plug it in, let it charge, and it would work fine and you'd never know anything about what the starting voltage was when it came out of the box. I've had new just-bought-from-the-store laptops that took more than 8-10 hours to complete that first charge before first use.
Battery layout is 2p3s, correct?
I suspect you’re right.
I’m pretty sure it is 2p3s, but I didn’t get a chance to check the circuitry, because I kind of freaked out when I measured the voltages from the 1st one I opened, like “Why is it 1.9V?”, which is also why I spent most of last night doing that charge-discharge-charge thing. I now know how that other user feels (the person who posted about another battery deal that turned out to appear like a scam!), which, thankfully, I don’t feel like this one was :(…
I have at least one pic that I took, before I discovered the voltage, and then went off and started charging/discharging. I’ll upload the one or ones that I have in a bit.
Jim
Only one pic:
Jim
I think the only way to get 10.8v and 5800mah is 2p3s.
ohaya, has your machine reported capacities on the discharge cycles? I imagine they may be lower in the first cycle or two, but it would be nice to know.
EDIT: Cross posted with your pic. Thanks for sharing that.
So the total mAh/Ah rating of the pack is determined by the number of cells in parallel, right? I thought I had it figured out, then got confused somewhere, trying to get back to where I was before... :Sp
Yes, you are correct. The volts add in series and the amps add in parallel. 2P (2,900 x 2 = 5,800) and 3S (3.6 x 3 = 10.8).
EDIT: Not sure why a smiley is showing at the end above.
Sorry, I was so flustered by the voltage thing, that I didn’t bother to note the discharge results :(… I know you all are probably getting tired of hearing that, but trying to be candid here.
If you google the NCR18650 and MH12210, it looks like it comes up with a Panasonic 2900 mAh battery, with same wrapping style, so I think that that’s what these batteries are.
I have the next set going now, I’ll try to remember to check the discharge.
Jim
One last question ohaya. Sorry for all the questions. I’m wondering if the “C 9907” is date code. Usually the date codes are in faint characters that are formed by perforations going lengthwise on the side of the cell. Usually the last part is a date code. Do you see anything like that on the side of the cells?
Hi,
I may’ve mixed batteries from the 2 packs I have, but just pulled one battery, and it has:
Large “C” smaller “Y”, and under that
9926
another one has:
Large “C” smaller “Y”, and under that
9907
That lettering goes around the battery, near the - end of the battery.
So what do those date codes signify? Sounds like both are from 1999?
Jim
BTW, all the batteries have “Made in Japan” on the gray wrappers.
Jim
They will be much newer. The letters stand for the month and year. Y will be pretty recent, but I don’t have the date codes in front of me. I will get back on that.
I just looked through the Panasonic data sheets and such on these cells. They have all kinds of warnings, but not one mention of taking cells to low voltage being dangerous. The closes thing I could find was the following:
“Overdischarge can damage the performance of the battery. Equip the unit with a mechanism to
prevent overdischarge, especially in situations where the user may forget to turn the equipment off.”
Voltage falling due to long term storage should have much less negative impact than overdischarging it through an actual load, right?
Much better that the cells sit unused for 3 years than sit in a laptop that stays on the charger constantly for 3 years, too.
I’m assuming that discharge protection would have been in the Fujitsu battery pack circuitry?
I don’t think these have individual protection circuits. The wrappers on the negative end don’t go “around” to the flat part of the negative end, but only down the side, to within a couple of mm’s of the bottom, so I’m pretty sure about that.
Jim
Yes the pack's circuitry handles the protection function, and also does the balancing for charging - that's all the crazy little wires going every which way inside.
Looks like I was wrong about the letters being the month and year. That must be for Sanyos or some other maker. The four numbers are the date. Looks like yours were made in September 2009. Check out post #66 here:
Ok, thanks. Here’s a shot of 2 of the different pack batteries:
2009 is not so bad?
Jim
Just noticed the “12…” numbers in the picture. That’s not on all of the batteries though. The “4.12V” is my own notes.
I don't know if I'll buy any of those batteries, but I might buy some other Fujitsu stuff. Maybe another tablet to add to my pair of Fujitsu tablet pc's. :)
Hi,
I think that these are all gone already anyway… Last time I looked, that seller didn’t have the “new” ones anymore.
Jim