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I've been reading this site a lot, trying to get educated for our (hopeful) Evora selection and purchase. One issue that has a lot of threads for multiple Lotus models is surprisingly fast battery discharge.

I'm an EE in real life and cannot understand why the quiescent current draw would be so unusually high. Most cars can sit for weeks, even months, without discharging the battery to the point where it will not start the engine. And they have all the usual systems... anti-theft, immobilization, RF receiver for remote key fob, sound system maintaining its station settings and clock, etc.

Why are ANY Lotus cars any different/worse in this regard? What is consuming all that passive current?

And... are the Evoras fixed in this area? I'm guessing not since the later years seem to come with a "free" battery maintainer.

Help a guy understand what is going on here. Thanks!
 

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Using regular cheap battery, every here and there leave it for 2-3 weeks and never had an issue.


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Once we have an Evora, I'll put a current sensor on the battery cables and publish some accurate data on the quiescent current draw. I'll do the same with, say, our Honda Pilot and see how they compare. That will be very interesting....
 

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Welcome!

Lotus is apparently very aware that the Evoras have a higher quiescent draw than most vehicles on the road. It's even stated so in the owner's handbook and the service notes. The microwave sensor is likely one of the higher drain components, so leaving the alarm disarmed reduces that draw.

My bet is on the ECU drawing power constantly. I've never had another vehicle that required a 30-min grace period after ignition shut off before disconnecting a battery. The service notes state it's to give all the associated sensors and sub-systems time to properly terminate. But there have been a few reported incidents of ECUs coming up blank/corrupted after a battery has run completely flat. Maybe their NVRAM is not so non-volatile?
 

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I think quiescent draw is ~40mA @12V. Does that sound abnormal? 2-3 weeks with a factory battery has never been a problem. I suspect the issue is the large number of cars that sit for > 2 months.

donour
 

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Seems a tad high, compared to what the service notes state:

1265115


I think with a fresh, properly maintained battery, sitting for 4 weeks should be fine. But some vehicles can go months without starting, and still fire up on the first try. I don't know that I'd trust my car to do the same.

The bigger problem with these vehicles is if the battery goes flat, you have very few options to gain access to it. Compounded with the potential for airbag lights, or even worse, a nuked ECU, I'd say leaving it on a tender is probably the best insurance there is.
 
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