Hello,

I am just a newbie in electronics so I will ask you to talk to me in simple words...hehehe.
I want to build a RC bait boat and I found a Chinese supplier of cheap LiFePo4 cells.
Looking about the mounting of the cells in order to get the 12,8V pack I found that I have to mount a balancing circuit for the charge.
I have read some threads in this forum and in other places and it seems that its not so easy to diy.
I have one idea...surely stupid but maybe not.
While my cells are 3,2V (different intensity), first I must create a block of 4 cells in series in order to get the 12,8V and then connect in parallel those blocks in order to get my wanted intensity.
What if I build a double connection?
The first, one I described before.
And the second connect all the cells in parallel. This will be used to charge them. Since all are in parallel, while one is getting full will cut the electricity by himself.
Connecting in parallel means that my charger will put 3,2 V (or the V that producer says) but needs a lot of intensity...for example if I have 8 cells 3,2A 5A, 2 blocks in parallel of 4 cells in series...this will give me a pack of 12,8V-10A.
But for charging I will need a 3,2 V-40Amp charger.
This could be possible?

 

You will spend many weeks getting this to work and many dollars building it.
Buy a commercially available unit. Unless the voltage of lithium iron phosphate is much different that the lithium polymer (I don't think so). $20 and done.

http://www.horizonhobby.com/other-accessories/lipo-voltage-checker-and-balancer-hrc44173

 

Not if your cells does not have charging circuits built in which by the way I do not think it has when you buy cell only.

A balance charger is necessary since each cells takes different charge and the circuit monitors each cell separately. Disconnects them one by one when they are fully charged.
A cell without a charge monitor will bulge when parallel charging with others.
As voltage is applied without current limit to a fully charged cell while other may not be close to full charge..Hence a balance charger is required to prevent cell over charge and lion and lipo are very sensitive buggers