TPMS light flashes then solid - Dealer suggests new car battery

Unclemeaty

For the past ~2 weeks, my car has gone from bad to worse in the TPMS department. At first, I was driving the maximum speed limit for ~45 minutes, when the TPMS light started flashing. After a minute of flashing, the light came on solid. I checked the tire pressure and everything measured good. I went to the dealer where they reset all the monitors and told me the system was A-OK. After another day or so, the light flashed and went solid again. Sometimes the solid light disapears for a little bit, but then flashes/solid not so long after.

I did a search already, and seems a lot of people have this issue with this and other Nissan vehicles, but no real solution to the problem. I was of course hesitant, but since I had to get some warantee work done anyways, I asked the dealership if they could research the TPMS problem.

The dealer came back to me with the following diagnosis: a main battery on its way out. Not to be confused with the LiON batteries in the TPMS sensors - the dealership said those were absolutely not the problem. They diagnosed the main battery to only have ~300CA, where the battery should be rated for ~750CA. Trust had me at the dealer, as they recommended not a Nissan replacement, but an Optima Red/Yellow aftermarket battery.

Let me also say that I love accessories. I have an audio system capable of pulling about 125A, and an additional cooling fan on a thermostat (185 Degrees) for my oil cooler capable of about 5~10A.

I'm thinking I should guy an Optima battery now before my charging system starts to really strain, but wanted to post this first for any suggestions. Any?