3+ years with BMS disabled, no side effects and still on the original factory battery.

The BMS monitors the charge of the battery and controls the alternator charging. If it thinks the battery has enough charge it will stop the alternator output for the purpose of improving fuel economy. I saw no difference in fuel economy before and after. I turned mine off because I did not like that the battery might not be charging on a short trip.

Don’t you guys also get a small warning light on your dash when the BMS is disabled?

Yes basically it controls a fancy voltage regulator. The difference from this to an old school voltage regulator is that the old ones could only regulate output to not go over a certain voltage this system can control over and under and off if it deams appropriate. This in effect removes the load from the alternator so it just becomes a free spinning pulley reducing engine load. There are two systems, the BMS controls what I described and is what we turn off. Then you have the battery save system that cuts power to everything if you leave the lights or an accessory on to save enough power to allow the battery to start the engine. This is common on most modern vehicles and what most people are familiar with. This remains unchanged.

No