LiFePo4 charging process

[mihai_atanasiu]

Can anyone help me with the balancing charge for Turnigy Accucell 8150 ?
I have an 36 V 20 AH battery pack made from strings of 3.2 cells (18 per string);
I am not sure how to connect the balance wires; I want to balance six cells in series; in the Accucell manual there isn't any information about the balance connectors; all I know is that I have to connect each pin to each cell; but I don't know where to start: from left to right to the plus pole of each cell ? the six balance connector has seven pins; also I have to connect the main charge wires ?

 

[jdcburg]

I have an Accucel 8150 that I use with my 8 cell (24V) LiFePO4 pack. I plug the JST-XH into the balance port of the 8150 and the main charge connectors to the + and - of the pack. I use a Celllog to monitor the pack during use and it is the Celllog JST that I plug into the 8150. The connection diagram for the JST is on page 4 of the Celllog manual at http://www.hobbyking.com/hobbyking/store/uploads/794399700X164982X17.pdf.

I shut off the timer so it can take its time to balance the pack. I had a couple of cells get high (4.2V) using a different charger so now I'm pretty careful. I set the 8150's ah limit at just below the ah I used and charge at a higher rate, then finish using balance charge at 2.5 amps - jd

 

[mihai_atanasiu]

Thanks jdcburg; I will order today a JST connector for 6 cells; but the question still remain: how to connect the wires from the JST connector to the cells ? can you look to your Accucell and tell me; lest say you look straight to the left side of the charger; the 6S connector it is on the second row; from the left to right can you tell me the pins ?

 

[mihai_atanasiu]

jdcburg you said that you connect the charger with the celllog; then the pin number 1 from celllog that is a minus goes to the first pin in the charger JST connector from left ?

 

[jdcburg]

I unplug the Celllog and plug that connector (from the pack) into the 8150. I have uploaded the diagram below. I have an 8 cell pack so I use the 9 pin diagram on the left. With a 6 cell, I think you would use a 7 pin connector and connect it like the 5s diagram in the middle, with the additional cell in the 6s position and pin 7 connected to its + pole. The pack minus should go to pin 1 and the others to the series jumpers, as the diagram shows. Others please correct me if I am wrong - jd

edit: I think it should be the minus from the 6s pack, not from the entire pack.

 

[mihai_atanasiu]

ok; it is clear: the left most pin from each balance port from the Accucell 8150 is the minus of the first cell; this first cell is from the minus of the battery pack;
I put a picture;
Also please correct me if it is wrong.

 

[mihai_atanasiu]

Hello again; after almost a month I have some news; I received the new cell string from V-power; in this time I also bought a Ping battery;
I was very busy with it; I made a aluminum case for it; the original battery case is about 5 mm shorter; bad luck; I asked Ping to send me an extra BMS because I wanted to change the v-power huge BMS with the signalab BMS which is smaller and better I think;
I made the connections and start to charge the pack; because the cells were charged with the RC charger each one it took only 1 hour to complete the charging process; only one cell remain uncharged; the rest 11 cells - including the new one - was charged and the leds from the BSM stays red;

I tried to discharge the pack with some car bulbs connected in series and parallel; the discharge current was about 3.5 A; the total discharge was: first time about 12 AH and decrease to about 6 AH after the second charge and discharge process;
in previous posts, cell_man recommended me to put a 1 ohm power resistor across the charged cells; now I think is the time to do this but I have some questions:

1) I have five 1 ohm 17W power resistors; can I put one piece across all the charged cells ? ( in parallel) or I have to put for each cell a resistor ?;
2) I use in this case the charger and the BMS ?

Please help me because I don't know what to do with this cells;

thanks.