I have twice now had the problem that when trapped in gridlock traffic on hot days, the continuously running cooling fan current exceeds charging capacity, and the battery becomes discharged.

Last summer, I had to be towed for this, and today the engine quit due to lack of electron potential after about 20 minutes stuck in traffic, fans running..

It is not the battery's fault, but the failure of the charging system to keep up with the fans on high speed.

I have the Motocross brand (Yuasa) battery, which I can highly recommend now.

I adapted to the YTZ14S battery long ago.

My battery is 6 years old, and though probably due for replacement, has been starting strong and just fine, except for in this situation which is not the fault of the battery. A new battery will still become discharged in this situation, maybe giving a few more minutes time until failure.

I am still running the stock regulator/rectifier and stator.

I have taken care of the reg/rec terminals and use heat sink paste on the back. It has not fried yet.

Also, the Futura is known for charge voltage being even lower at high RPMs, than at idle, so I am not sure raising the RPM's would do anything other than heat up the engine even more.

I suspect this is a fault by (poor) design, and has been so since birth. I just did not encounter the conditions to expose the problem until recently.

I do wonder if anything in the charging system has degraded over time.

I am interested to hear others' experiences and solutions.