Hopefully someone will make a genuine buyers guide.

And Thanks for the kind words

I posted a simple charger made from 2x DX products, this will go to 100% but will be slow, and has no cut off, only a green LED indicator that it is done.
I would be better to be able to modify the N900's charging system, i cannot remember if anybody has already done this...

As for chargers like the RC chargers to "experiment" with 3.7V systems, any RC charger will do in my experience even cheap crappy ones, it's when charging multiply cells the quality comes in to play, here you want a charger that can balance probably so all cells end with the same voltage -/+ as little as possible.

And i will be making several links in post 1-3# to other users mods, and chargers, if anyone wants to help here, just PM me the link to you mod in this thread.

Have Added Users Mods & Info in Post #2

Please PM me if i have missed anything, it was a fast look at all the pages....
Also PM me if the "title" of the links should be edited

Hey dr_frost_dk, thanks for answer and new nice ideas.

Another question related to your last post - using Your dual battery mod, we in fact get 2-cells battery, connected in parallel, yea? How about charge and voltage balance here? I know that using same type of new batteries is recommended if not necessary to get correct results, but what about charge-state of batteries in time of soldering them together? Should we just unload it to 3.3V / load to max in phone / whatever before soldering, or because they're parallel to each one, charge will balance on its own without any issues and we don't need to carry about that?

Another thing - many pages ago, you talked a little with zimon about connecting 2 cells before 1 protection circut vs. 2 batteries connected together AFTER their 2 protection circuits. Unfortunately i failed at understanding something - i know that You advised connecting 2 cells before 1 protection circuit (also that is what is intuitive for me), but can you post rationale for it? Of course if You recommend that just from Your personal experience i got nothing against it - but i like to know exactly what I'm modding and why, and there probably is some thing that i missed advocating about using 2 cell battery with 1 protection circuit (designed for single cell - does it matter at all?) vs two 1 cell batteries with their own circuits, connected in parallel.

*I use on purpose terms of one 2-cell battery with 1 protection circuit and two 1-cell batteries with their own 2 circuits - maybe I'm wrong, but that's technically all about 2 regular batteries vs 1 big battery - that is what i think we get after soldering 2 cells together, one big battery, where 2 cells with their own circuits are technically 2 batteries, yes? Yes, i know i messes it all upside down, but i think You know what i mean ;P Pros and cons of using 1 big battery or 2 small batteries connected i. e using 1 or 2 protection circuits.

Yes it is technically 2 cells, but when connected in parallel (and the battery's are the same) it is a big 1-cell battery, multi cells like 2 - 1000 cells in generally a term for a battery with more voltage, like a car battery which is a 6-cell battery (2V x 6), if we use a 2-cell Li-ion battery then it would be 7.4V not 3.7V
The voltage in the 2 battery's is not critical when connecting them together, meaning that if one is 3.7V and the other 3.9V then it would be ok, just don't go much "higher" then that, and this means not more difference then 0.2V between them
So it does not matter if they are 3.3V or 4.2V, the way i do it is just charge them both up to 4.2V.
Again just don't connect 2 battery's with a high voltage potential between them, like connecting a 3.3V and 4.2V this has a risk of damaging the battery's, and if you do this after the circuits it could destroy the circuits.

Connecting the battery's after or before the circuits should not be critical, use zimon or cantruchd mod if you prefer a less "destructive" mod
I posted the links in post #2

I prefer most destructive mods if there is not any rationale in keeping 2 circuits, i would go for detaching 1 and keeping it for further projects (to use with batteries that got nasty or not existent protection capacity, for example)

I just wondered if 2 protection circuits can help anything (I.e. circuit is designed also keeping capacity in mind), but if no, there is no problem. I don't plan to disassemble my dual battery again, and if even, i can solder that little pcb thing again...

Last question, i suppose - someone mentioned that li-po got low self ignition temperature - smth about 130 C. I feel very comfortable with soldering so i can do it fast, but should i also cool down cell itself during process (for example, by using ice in foil bag, of course water-proof, around cell during soldering), or this danger is overrated?

I just do the hole thing in basically one setting, if you feel that the battery's are getting very warm then take a break, i also put them together before soldering them together, this transfers a little heat from the battery that is being soldered to the one waiting, there by cooling it a little.

A good tip is to break off the circuit wire but still leaving some of it attached to the battery, if you don't do this soldering on the battery will be VERY hard.
Easy way to do this is to lift the circuit/plastic top up and then rocking it from side to side until the wire brakes.

I have not damaged any battery's so far, the only battery's i every had problems with was some crappy 18650 from DX, they "vented" meaning that the temp "fuse/valve" blew and i could smell the lithium, this causes the cell to dry out and capacity being lost little by little.
But i have not been able to do this on any BL-5J or similar battery's or other 18650 i have.

Anybody found any battery's that needs a closer inspection?

Just got a Scud delivered.
Sofar its working good. Lets see if I notice and better batterylife.

Well if you are used to have a stock (1320mAh) battery and you have the blue scud you will!!

hey is the scud battery exported in asia?