They are good also, but it is not the big one, the one you link to comes in at 1400mAh where the 1450mAh ones comes in at 1520mAh, so you want to look after the 1450mAh not the 1350mAh.

With N900 itself, it's possible to charge @ 1250 mA MAX, by using either bq2415 module from latest kernel-power (and setting proper sysfs entries to boost it charging rate) or charge21.sh script by ShadowJK (again modified).

Quite handy, for charging dual-scuds (or any other biog batteries) - I'm using it exclusively for charging for more than a month now, without any ill-effects.

/Estel

// Edit

You can also charge normal batteries with 1250 mA, but it's less healthy for them (it's charging them with almost 1C), and doesn't provide real benefit - you're hitting saturation charge much earlier, so total reduce of charging time is like 7 minutes or so.

when charging big batteries, like 3000 mAh ones, it provides *real* benefits, as You start hitting saturation after ~2 hours, which mean more than 1/3 reduce of total charging time.

I've found another source for 1450mAh SCUDs which presently claims to have them in stock: http://www.enjoygadget.com/scud-37v-...es_p12494.html. The website is lousy and their English is worse, but they accept PayPal so it doesn't seem like a huge gamble. I've ordered one and I'll report back when it arrives.

Also, some observations on battery degradation in active use and the possible wisdom of replacing your batteries on an annual basis. I replaced my original Nokia 1320mAh battery with a 1420mAh Scud in early September last year, when the phone was about one year old. At that time, testing with bq27200 showed the outgoing Nokia battery at 1271mAh and the incoming Scud battery at 1471mAh. I decided back then that this was a worthwhile improvement, and that I would replace the Scud battery when capacity dropped below 1300mAh and an improvement of >= 10% might be anticipated from doing so.

Fast forward one year (in fact, a couple of weeks less than a year) and I'm still using the same N900 and the same Scud battery, but the battery life isn't what it was. I tested it again last week and got a figure of 1298mAh, so a capacity loss of ~12% over a year's usage. This is completely within expected parameters for Li-ion batteries, but I've lost most of the gains that were to be had from the extra capacity of the Scud.

It seems a bit wasteful to replace a battery on the strength of a 12% drop in performance, but an extra 200mAh made a noticeable difference before and would do so again, so I've ordered up a new Scud and will relegate the old one to my backup phone. This does make me wonder whether Li-ion batteries should simply be treated as consumables and replaced on an annual basis... thoughts?

Well you normally replace them when they do not work for you anymore, and in this case it is kinda legit :P, but since there are many applications other then phones then it really depends on the application.
In an ideal world your battery should have 100% capacity until set cycles where it will suddenly drop hard and after few cycles it will just die, but this unfortunately will not be the case, also other lithium battery's have a longer life, like LiFe but i don't know if phone makers will ever use them....

But extending the life of a battery like for the N900 can be done in various ways:
Charge to 4.10V - 4.15V, you will loose a few % capacity but according to study's this will extend life.
A bigger battery will be charged less and will result in less cycles being used, here im thing about XL/Dual battery's, if by the end of the day you still have >=25% left vs. <=5% for a single battery this will also extend life + give more runtime

Any thoughts that the secret of the Scud is that they tread further into the safety or longevity charge/discharge margins of the battery.

The "secret" is that they are thicker and that's why they hold more capacity, else not much more to say, they loose capacity over time with charge cycles like all other Li-ion/LiPo, i do the capacity tests it will be a hole other ballpark if i had to include number of tested cycles and capacity after that, not to mention that it will take considerable longer to test battery's.

Updated Post #1 with new design, still a work in progress, hope you like it, old results can be found in post #6

EDIT: Polarcell is apparently not accurate anymore, it seems that they have updated their battery to a 1500mAh, i have ordered this along with a scud from a site suggested lately, so will be adding some new info soon.

I better update post #1's note with total $ spent so far.......

I'm trying to calibrate my Dual scud. Well I'm getting this error with any script

/usr/sbin/i2cset: not found

the file that is avaiable is i2cget. Any solution??
Using kernel 50

Install i2c-tools package from -devel.

BTW, what i2cset have to do with calibration? Afaik, it's required only for charge script?

/Estel

Yeah I know that but without using script I cant calibrate My battery because VDQ goes to zero before My battery discharge (about 30%) and never goes to EDVF=1). Instead bq27200.sh show that I do a full cycle when VDQ=0 and show charge capacity before my battery discharge. So I decided to test some script as auto_calibrate.sh (drfost script) some post ago.