29 September 2009

Charge time at 240 volts 12 amps

A few days ago I posted results from running the battery way down past zero.  And then I charged it over night at 12 amps with the big 240 volt charger.

It took about 12 hours to go from zero to 100%.  This is much less than half of the  charge time at 120 volt 12 amps, which I measured at well over 30 hours back in the heat of summer.  See an older post.

But it is cooler now, and the battery fan runs much slower.  I suspect that is the major difference.

One of these days I will analyze my log file (now posted in with the blog links on the right) and see if I am getting noticeably more juice into the battery at work in this cooler weather.  But I can't do it right now, I am spending too much time driving my Mini E.

By the way, I am noticing some trouble getting the Mini E to start charging from the 240 volt big box when the car is set for 12 amps.  Sometimes it starts and stops, and I have to pull out the plug and put it back in, sometimes twice.  At first I thought that was because I had run the battery down so far in the experiment a few posts back.  But now I notice it even when the battery is above 25%.  Maybe it has always been like this, and I only noticed it with the small 120 volt charger that can only be used at 12 amps.  It is only recently that I have started just leaving the car set for 12 amps almost all the time because it usually charges fast enough overnight to reach 100% by morning.  The idea is to draw most of the power late at night when the grid load is low.

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