Is it safe to solder these cells together ...
http://www.hobbyking.com/hobbyking/store/__18557__Turnigy_1000mAh_1S_20C_Lipoly_Single_Cell_.html


i have balance lead and main leads of my old batteries....... can they be used???
wont it be cost saving to by these cells and solder them instead of buying batteries??  

Yes you can solder these cells if you are good on soldering but what about Heat shrink tubes and other stuffs on original packs?

i found that the difference was 6$.... ie 330rs.....

http://www.hobbyking.com/hobbyking/store/__9265__Turnigy_3000mAh_3S_20C_Lipo_Pack.html


heat shrink hardly costs any thing..... for coating the battery standard electric tape maybe used...

what "other things" are inside the battery??..... is there any circuit board?? i mean, never dared to open one....

also the dimensions of adding the cells are favourable
3 CELLS  http://www.hobbyking.com/hobbyking/store/__18557__Turnigy_1000mAh_1S_20C_Lipoly_Single_Cell_.html

L           63
B           34
W 6*3 = 18



BATTERY http://www.hobbyking.com/hobbyking/store/__9265__Turnigy_3000mAh_3S_20C_Lipo_Pack.html
L           147
B           46
W          18

 

Yes, some battery pack has a small PCB to hold the cell in place along with the main leads.
i am not sure about thin shrink wrap if available.

u are comparing APPLES to PINEAPPLES....!!

u are looking at the wrong battery and trying make the other....

compare ur 3 soldered (home made ) battery to this
http://www.hobbyking.com/hobbyking/store/__6474__ZIPPY_Flightmax_1000mAh_2S1P_20C.html

this will be similar to the one u   will get after soldering 3*1s to get 3s....!

i thought mah wud add up like voltage.....

apples with pineapples

what an example vishvesh.

and sameer i recent got a 2s lipo which is not giving me enough backup so i will tear it up to check what is the issue.
will post pics though.
which can help you with this query you have.

I don't think soldering these cells is a good idea... The reason being that you can see on the ready batteries as Ω matched i.e. their internal resistance of the cells are matched and then soldered because as per my technical know how, you might get unequal current draw from the cells which in turn results in the malfunctioning. Simply, by ohms Law in electricity

V = I x R

Where V is voltage, I is current and R is resistance.

Even while charging you might face big problems because the cell with lower internal resistance gets charged earlier unlike the cell with higher internal resistance among them. But again if you are using an expensive charger, you can individually charge the cell in your DIY battery. Then also your problem during Discharge won't be solved due to current inequality.

But If you find consecutive cells with same values of internal resistance, then I can only say "They are made for each other"   

Thanks.

+1 to aerovishva...

apart, to be at a safer side (against hazards) i would never prefer soldering cells to make a battery pack...

i have removed a cell from my 3S and replaced with a new 1S from hobby king,


Now the lipo is working fine except the below issues
1. Cells are now of unequal capacity, so the old 2 S will discharge first than the new one
2. this also means while charging i have to do a balance charge and not the faster direct charge

So if you want to connect lipo together, go ahead but care is what you need while charging
you always would have to do a balance charge

If you are smarter check the total discharge available in each battery and then if you get simmilar values go for direct charging

It is a bad idea to mix and match cells.  If at all you wanted to do this, get a cell with is same mAH and same C rating from the same product line (+ manufacturer).

Definitive CONCLUSION: It wont be cheap at all ..... in case  u r buying all new cells and soldering them up.... its better to buy a new battery....

Provisional Conclusion:
It may however be tried incase u have just one cell dead in ur battery pack... and u r able to find cell of same specifications (mAh , manufacturer , and C rating)
 ... but still not the best option as the original cells might have grown old and have developed  different characteristics thanks to there age...

i.e. do it when u hav no better option left

Vote Of thanks
 all senior members and friends  who shared there valuable knowledge  

meanwhile waiting for Saahil   Sir's pics