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Old 03-04-2013, 08:05 PM   #9 (permalink)
Ryland
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Join Date: Jan 2008
Location: Western Wisconsin
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honda cb125 - '74 Honda CB 125 S1
90 day: 79.71 mpg (US)

green wedge - '81 Commuter Vehicles Inc. Commuti-Car

Blue VX - '93 Honda Civic VX
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For longest battery life you don't want to draw the batteries down past 50% DOD so that leaves you with 30% buffer to draw them down to 80% DOD, so you will never be stranded!
I wouldn't bother trying to figure out your state of charge with your batteries at rest because while you are driving you are putting a higher load on them then they were really designed for so you really do want to know that voltage while under load and also watch how quickly that voltage bounces back up, but after you remove all loads it will keep climbing for an hour or more! but if you get your pack voltage to low while under load, that is where you do damage and it doesn't matter if your pack is fresh off the charger or if you are at the end of your trip.
As HampsterPower pointed out, at 45mph, under IDEAL conditions you have a 44 mile range, that is 80F battery pack, one person in the car, good new batteries, no strong winds, so making a trip that you can charge up as soon as you get there that is 40-45 miles on a nice summer day might be reasonable, but I would not do it every day if you want your pack to last more then a few years.

I average 10 to 15 miles of driving per day and charge at work and my pack will be 4 years old this summer and I seem to have a 30 mile range where 40 miles was what they said it was when my car was new, but people who drive cars like mine 30 miles per day are lucky to have their battery pack last 3 years.
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