Cell balancing in Bq78PL116

Deepak,

Here are some answers to your questions.

1) You have Algorithm Enable set to = 000A, so Pump Mode (bit #2) is set to "Normal". Pump Mode must be set to "Testing" to force All Cells North or South. (see the PL 116 TRM page 60)

2) same as 1).

3) You are correct, you disable pumping with the System Control register.

4) Pumping is enabled and disabled at a rate and it can vary. The EVM average current will be less than the pump current.

5) I typically see the cell-to-cell voltage variation to be less than 50mV, but it may take the pack awhile to get there. I also see less current than you have noted on my EVM, but it is not that much lower. The currents listed in the datasheet are typical and there will be some variation.

6) The EVM should be disconnect in the reverse sequence used to connect the cells. You are basically preventing internal diode from getting forward biased and damaged.

I hope that this helps.

Regards

Tom

Tom,

1. Algorithm Enable ="000A", so lower nibble is "1010", Pump mode bit is zero i.e at "testing", & Pump Algo[1:0] =10. ?

2. So removal is connection is reverse & all this has to be done in 20 seconds? Till now I have taken approach by first removing bat+, then high cell connector & then lower cell connector & then bat-. e.g in EVM with 6S configuration I remove bat+, then connector having 5 & 6 cell at once, & then connector with 4,3 2, & 1 cell at once & then bat-.

3. In case of cell simulator pack with resistors, all voltage points including bat+ & bat- will be turned on & turned off at once.?

Deepak,

1) You are correct, I misread my bits. :) The device should be pumping south with this setup. I tested it on my EVM and it is working. Are you using the TI EVM? Are you using FW Build 720 and Firmware version 6000.

2) I do not know that there is a specific time frame, but it should be completed after you have started the process. e.g. Do not start connecting cells, then go off to lunch before finishing the process. If you are using the EVM with cells connected to the terminal blocks, then you can disconnect the cells as you described.

3) You can turn them all on and off as you described.

Regards

Tom

Tom,

1. Sorry I forgot to mention. I am doing cell balancing test on Bq78PL114 with FW build 12, Firmware ver 5000 & Bq-wizard 3.2. Yes its an TI EVM.

    Will check on  Bq78PL116 & revert back for the same to you. But I think both are very much same in functionality.

2. On Page 19 -SLUU275, time frame is given 20 sec. For removing cell connections in reverse order as given on Page 18 on SLUU275?

Regards

Deepak

Tom,

Please clear my doubt about cell removal in time frame of 20 sec as mentioned in EVM. Is it mandatory?

Deepak,

There is nothing specific about a 20 second window, such as having a timer monitoring that the cells have been removed. The intent is that you remove the cells in an expedient manner to reduce stress across active devices in the event that they were to get forward biased.

Regards

Tom