BR 20A/300W Charger not charging BR Lithium Ion Pack to 16.8v?

Regarding the 20A/300W 0620AC-R1 Charger, I have some assorted LiPo batteries that all charge correctly to 16.8v using the LiPo Balance charge setting - no issue there. I understand that with the BR LI-4S-18AH-R3-RP (Black Battery Pack) I’m also supposed to use the LiPo setting. However, with these batteries, the charger (LiPo Balace Charge) ramps down to about .1A at ~16.4V and will not get to 16.8V. But, when do a LiPo Regular Charge (balance leads disconnected) it will charge to 16.8v and when I charge these black packs with my old iMax B6ACv2 charger on LiPo Balance Charge setting, it brings them up to 16.8V just like the other assorted LiPo packs.

Any idea why the BR charger won’t charge the BR black batteries to full voltage in the LiPo Balance Charge setting?

Hi @jerfox-ratw,

Our 4S 18Ah battery pack is Lithium-Ion, not Lithium Polymer. Our guide for the old charger does recommend using that setting, but perhaps that’s primarily to lengthen the life of the battery? I’ve asked internally for confirmation/reasoning.

It’s also possible that it’s charging to 16.8 V, just very slowly once it’s above 16.4 V.

Following up on this, I’ve been informed that it’s not expected to stop at 16.4 V, and should continue to 16.8 V, but if the cells are very out of balance it will take a long time to complete because it can only discharge the higher voltage cells slowly.

Can you check the individual cell voltages? You should be able to cycle through them by pressing “Inc”.

Thanks for looking in to this. Had it happen again and checked the voltages: 4.00, 4.17, 4.17, 4.20. So maybe the imbalance is the issue and it was just taking a long time? Curious why the old imax charger seems to be able to do it faster though?

That seems like a reasonable conclusion, given there’s a 5% charge difference between the highest and lowest cell levels, particularly since the charger was still showing a slow charge rate.

That’s not a charger I’m familiar with, but I’d guess it would either be because of

  • a higher discharge capacity, or
  • being less careful/stringent about cell balancing, or
  • not balancing the cells at all