Yes, 'too' old was probably a factor, and a couple of helping hands would have made it much easier, I think. I've replaced batteries on almost all of my previous cars, with little fuss, but this one was much more difficult for me, mostly because of the amount of wiring to the batteries in the PHEV, and the congested and deep placement of the battery - and, of course, me being 'too' old. I connected a Battery Tender to maintain 12V to the car electronics during swapout, using the Tender alligator clamps on the connectors, but throughout the swap, trying to keep the stiff wiring for both terminals out of the way of the battery, was very difficult, and I managed to dislodge the Tender negative lead twice. If I did it again, I would use the alternative Tender connectors bolted onto the leads. I found it impossible to get a hand under the battery to lift it, due to the congestion surrounding it. I had to lift it first by the top ridges, which was really precarious, but thankfully I got it up to a point where I could rest it on a ridge and reach under it. Installing the new one was a bit less difficult, but once I got it placed, I discovered that the tray under it wasn't stable, and I could rock the battery. I didn't want to pull the new one out again, and after much fussing with the positioning of the battery and tray, it finally dropped into a stable position. If I were to do it again, I'd be sure to remove the tray, after I removed the old battery, so that I could easily see the underlying support structure to establish the proper positioning for the tray. Having a battery lifting tool would also have helped tremendously. Connection to the battery terminals was not problem, but when I tried to start the car, I was not totally surprised to be hit with the Christmas tree of warnings and errors that others have encountered, including a TPMS problem, and TPMS Failure, System loss of Power and GPS recover,y Vehicle Stability Assist (VSA) Problem, Drive Carefully, etc.., presumably owing to the 12V disconnect during the swapout. I tried to Start several times, with essentially the same results. I tried the suggested trick of removing the Negative connection for 30 seconds and then securing it again, but that didn't seem to change anything. After some time, it seemed that the warnings had settled down, but the warning icons for TPMS, VSA, etc. were still lighted. At one point, it did show "Drive Carefully, system initializing….." I tried to do a TPMS Calibration, but it repeatedly responded that it Couldn't Start the Calibration. I eventually decided to just drive, to see how it would behave. After I drove about half a mile, the warning icons all went off, and everything seemed normal again. During the drive, I was then able to do the TPMS Calibration, and it reported that TPMS Calibration had started. In retrospect, I think that "Drive Carefully, system initializing…" message was intended to be taken literally, that the system needed me to drive to let it start rebuilding its history. I was relieved to find that most settings were still retained in the system, including presets on XM radio and my Bluetooth and Android phone connections. All in all, not one of my more fun projects, but I'm grateful to still have ten functioning fingers, and I didn't have to humiliate myself at the Honda dealer to get them to fix my problems. Next time, I'll pay the guys at our Honda dealer to do the job.