I did mine just using a Battery Tender, 1.25A It had a lithium setting, but no documentation as to what voltage that produced. Based on experimentation it stops at ~14.3 V and turns off. Since you haven't top balanced yet, be Extremely careful. It will take several days (140 ah (50% SOC?) = 1.25 A * 112 hrs) to get close. Once the pack gets to ~13.5 V it will take off like a rocket and at least one cell will already be near 3.65V. Don't leave it alone. You can then cycle the charge on /off and let the BMS bring the cells into balance. Very tedious and tricky. But it can be done. The one benefit - it lets you learn first hand about the balancing capabilities (and limitations) of your BMS. But what will you charge with the next time? Shouldn't you just get that now?