Ronda’s Li-polymer battery pack has the advantage of good cell consistancies and cell balancing, which is the guarantee of multiple series and multiple parallels. By using good Seiko IC and protection circuit, our battery packs can cycle over 500 times and longer discharge time.
For 3.7V lithium ion polymer battery pack, we need to understand customers' requirements. Usually, there are 3 types:
1) Directly leads out from the pack. Customers have their own protection circuit (over-charging and overcurrent protection)
2) With PCM and leads. Leads come out from the middle top or the top left or right according to the actual application
3) With PCM and plastic casing. Some cases need ultrasonic welding, some not.
For Li-ion polymer battery pack, we need to connect in series or parallels to meet some electronic equipments's requirments for different power consumption or operation voltage reasons. Usually, Li-ion polymer battery packs are very stringent on the cells' consistancies (voltage, capacity and internal resistance). If any one of cells in the pack fails, it will causes the uneven voltage and current division on all the cells. Thus it brings the degrading of the whole pack performance and even complete fail to the pack. Hence Ronda pays mcuh attention to the matching principle as follows:
1) In the mass production, all cells are kept between 3.80V-3.83V. 100% SOC operation is prohibited. Cell voltage difference is within 0.01V in each battery pack.
2) 0.8% capacity tolerance is acceptable in each Li-ion battery pack
3) The internal resistance of each cell needs to be less than 3mohm.