6X18650 protected holder Q.

[alpg88]

hello battery experts.
i'm building a 6 cells holder with 2 pcb build in.
the reason for 2, is that i'm running 3s2p set up for my dualbored 4d maglite with 3xp7.
i already build this holder for 6 unprotected cells with no pcb, so far it worked just fine, but i want to build protected holder, just in case i have to let someone with no experience with li ion cell use the light for a while,

i have option of charging cells one by one, or charge them all at once in the holder.
i ordered these pcb
http://www.batteryspace.com/pcbfor111vli-ionbatterypackwithfuelgaugesocket3s5alimit.aspx

now, here is how i want to wire the whole thing.

now my question is, do i really need those diodes? can i parallel pcb's?????

now charging entire pack at once, i'll have to do before diodes (if i even need them) , this the charger i have in mind.
if anyone with experience sees why i shouldn't build the pack this way, or sees a mistake in my plan, please let me know, before i started building it. i'll pbly start not sooner that in a couple of weeks.

 

[Ray_of_Light]

Your project has a problem; due to the unavoidable tolerances of the two protection PCBs, you have no warranty of sorts that the current will be split in half between the two legs of the pack.

You need to use a single protection PCB for the entire pack.

The PCB you ordered provides over/under - voltage/current protection for the cells. It is not intended to act as a charger, as it doesn't provide charge balance.
Therefore, if you want to charge the cells in the pack, you need a balancing charger (hobby charger).

Anthony

 

[alpg88]

well, you got a point
however there are no pcb for 3s2p

now that i think of it, every laptop cell i took apart had this set up.

i'll try this set up than.

as for charging, i talk to rd dept. the pcb doesn't have balancing circuit, it will charge all cells, but will shut off if 1 cell hits the limit, same for discharging, if one cell hits low limit all will shut off.
so even thou it wont be balanced it is still perfectly safe to run.
he also said my first diagram with 2 pcb will be fine for discharging, but charging will be pita. i still have an option to charge them separately, the way i do it now, (have 3 wf139 chargers)