Charging 18650 Lithium Ion Cells (3S 4P) using MPPT SCC + Balancer

Charging 12 pieces 18650 lithium-ion cells wired in 3S 4P configuration using an MPPT Solar Charge Controller plus a battery balancer.
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The cells used here are Panasonic NCR18650. The battery pack is comprised of 3 banks in series. Each ‘bank’ consists of 4 pieces 18650 cells wired in parallel. With brandnew and fully-charged cells, the 12.6-Volt pack is estimated to have about 10.8Ah of battery capacity

http://tinyurl.com/3S4PBattPack

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Take note though that the cells used in this experiment are salvaged cells from laptop battery packs so as expected, the actual capacity is no longer the same as brand new ones’ rated capacity of 2700mAh.

http://tinyurl.com/BattPackNCR18650

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Panasonic NCR18650 data sheet

http://tinyurl.com/NCR18650Specs

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Here is a photo showing the actual runtime of battery pack and consumed capacity of the attached 2pcs 1.5W 12V LED bulbs…

http://tinyurl.com/3s4pRC3w

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The first part of this clip shows you the voltage of cells in each bank and the charge current while in Bulk stage. The battery pack is not yet charged at this point in time with voltage @ 3.87V (on the DVM) or about 3.86V (on the battery balancer).
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I think the ‘balancer’ gadget seems to be doing a pretty good job here making sure the voltage of each cell stays balanced or as close as possible with each other until the target voltage is reached, so yeah, that’s good news.
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The balancer works like HobbyKing’s Battery Medic. Its a 3in1 LiPo battery discharger, voltage indicator and balancer. Bleed current is about 200-450mA.
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With the help of the VictronConnect Android app, the 15Amp MPPT Solar Charge Controller was set to utilize a ‘Maximum Charge Current’ of 2 Amperes only. Such output current is just near the vicinity of 1925mA max charge current of the Panasonic NCR18650 cell @ 25°C.
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As the pack approaches a fully-charged state, the voltage of each cell rises to about 4.20V as shown on the DMM or 4.17V on the balancer. The charge current also falls down to 0.01 Ampere.
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Weeks back, I did a similar video but only used 9 pieces 18650 cells in 3S 3P config. Lo and behold, no ka-boom moments in there so I thought of upgrading and doing it this time with 12 cells.
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Check link below for the video:

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The 12 pieces 18650 cells remain cool in the entire charging duration. By the way, I tried this methodology with 20Amp Epsolar/ Epever PWM (LS2024B) and MPPT (Tracer 2215BN) solar charge controllers using MT50 and ‘User’-defined voltage profiles but felt uneasy considering the fact that the charge current on those SCCs are not configurable to my preferred (low) charge current. In effect, the pack gets concerningly lukewarm to touch during the charging session @ ~4.5A charge current.
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Thanks for watching.