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The battery only drains when it's not in the ecu. With ignition off, it's still using the car's power.
The chemistry of the battery means they have a limited life, and they generally won't run flat before the battery dies. Put it this way - their life will not be shortened by constant use.

I've had a couple die at about 5-6 years of age, but others are over 10 years old and still going.
when you're happy with your tune, burn it to a memcal and stick it in your glovebox. That way if your car won't start one day and the high speed fan comes on with ignition, you can pop the backup memcal in and be going again in a few minutes.

I run nvram full time in my race car (drag racing) so certainly not a rough setup like yours, but none the less its been pretty reliable for years!

thanks guys, I'll order another setup for this car then

Good idea once done to write it to an EEPROM, the NVRAMs can be corrupted, where the EEPROMs provided are genuine good ones will last many many decades.

If you need some genuine SST27F512 I have a few or can point you to a US ebay seller who sells genuine ones. I have tested my lot and can take shit loads of cycles no probs.

festy wrote:The battery only drains when it's not in the ecu. With ignition off, it's still using the car's power.

With the ignition off the 5V to the NVRAM is off, so its draining the battery. But with a > 10 year life its not a problem for awhile!

The main processor has a 5V feed with ignition off to preserve its RAM, but this is not on the memcal header.