Help identifying bad modules

Ive got one failing battery and one i presume has failed as it was just given to me. On both i cant seem to locate the bad modules. Ive tried watching Dr. Prius, both in operation and after letting it sit for 24 hours. My problem with the failing battery may be that it is a frankenstien reconditioned back that has several almost failing modules from different packs. The other, i presumed dead pack was corroded so i cleaned and let sit for days but voltages all still seem super close. Im going to load test them with a headlight bulb and beyond that i dk how to spot the bad module... At this point my failing battery goes a long while before throwing P0A08 and P3000 and i know continuing to reset this with the 12 volt is unsafe so im trying to be proactive, but the car runs decent for the abuse it has taken. Any tips? Should i just find a local who knows more about these batteries and pay him? I did that before in CA and i got really lucky to just NOW be experiencing problems. But id rather learn to play whack a mole and what equipment i need to do so. Thanks for advice in advance