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Discussion Starter · #1 ·
My car is on the road, and I'm trying to get a better feel for what kind of range it has...I'm charging the 2014 Leaf cells to 4.1V as "full" and I'm treating 3.6V as "empty". When the average is around 3.7V or maybe 3.8V, I find the voltage dips below 3.6V readily when I accelerate.

I understand that for the same power, lower voltage means higher current, and higher current means voltage sag...but can anything be improved? I feel like I'm losing 20% of my range to sag. Is it less bad to dip below 3.6V due to sag than it is through constant, lower current drain? Is it extra bad to pull a lot of amps when the cells are low on charge?

I suspect it's just physics, and I'll need to add batteries (or use better batteries), but I figured I'd raise the question...It's tough to figure out the remaining range when the second half of the fuel tank drains much more rapidly than the first half...
 

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You might consider an amp-hour counter rather than just looking at voltages. Of course voltages are important, but they don't give a great capacity indicator (especially, as you have learned, under load).
If you had a regular Leaf on hand you could use Leaf Spy to see how much sag Nissan is okay with. Or maybe someone over on the Leaf forums has done that already.

I don't know how the batteries are supposed to behave under load.
Tesla batteries sag like crazy (at 1500 amps). 2.7 per cell apparently: What is the 'voltage sag' at max amps ?
I had a terrible experience with Leaf batteries, but that's probably because I got them from an eBay seller and they delivered about 30Ah max (and some were less, causing unpredictable range).

Also, I missed the great announcement of your running car! Congrats!
 

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Discussion Starter · #3 · (Edited)
I do have a current sensor that is taken into account for my "fuel gauge", but it seems...quite optimistic. It showed somewhere between 20-30% when I was starting to dip below 3.6V...I'm just concerned about stressing the batteries out. Good call on the Leaf forum, they seem to get into this shit pretty heavy at times...

Thanks! There's still a lot to do, but it's a fun little fucker...
 

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Discussion Starter · #5 ·
Oo, thanks—I shall peruse...

I'm currently using 30 of 48 modules (216-246V)...I was hoping to hold there to keep weight down, but I'd like 50 miles of range easy from 80% to 20%, taking into account AC and other convenience draws...
 

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Right, the Mini probably doesn't like the weight very much. Though the Leaf drivetrain would probably like more volts.
15KWh isn't much at all - even at 300Wh/mi you'll still need 100% to hit 50 miles.
Maybe throw a few modules up front to help with traction?
 

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Hi I'm using the volt modules - and using the voltage as my fuel gauge

What I do is I take my foot off the throttle to see how much "fuel" I have left -
When I'm driving the voltage drops when I accelerate so I ignore that number and concentrate on the no throttle number

My "full" is 340 volts (4.05 v per cell) and my empty is 294 volts (3.5 v per cell)
When I'm driving it can drop below the 294 volts - not a problem it's just the sag

Taking my foot off is not that accurate - it does go up a wee bit after a couple of minutes - but it errs on the conservative side so that is all right
 
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