View Single Post
Old 05-30-2013, 12:17 AM   #324
Beastly Adventurer
Joined: May 2010
Location: Interior BC, Canada
Oddometer: 1,077
Originally Posted by _cy_ View Post
Joel has not been very active lately .. so I'll try to help.
note test mule in my LiFePO4 testing thread is an R80G/S .. Joel is the F8 guy!

16 cell = 9.2 amp hour actual, 20 cell = 11.5AH actual
new style A123 are 2.5AH per cell, old style 2.3AH.

with heated gear actual amp hour comes into play in terms of reserves remaining to start next morning. especially in cold conditions.

LiFePO4 reaches full charge at 14.6V ... operating range is 13.3v to 12.85v (20%)

think water flowing in a pipe ... voltage = pressure amp/current = flow

LiFePO4 battery will charge at 13.8v, but rate of charge will be slow. at 14.2v current will be pushed into battery faster, resulting in a fully charged battery quicker.

to check what state your battery is being charged to:

after your normal ride, put bike away .. next morning before starting bike, measure resting voltage. (assuming no excess parasitic drain) note it's important to use a known to be correct meter. cheap $15 meters are fine, if it's been checked against a known meter like a Fluke.

chart below will show state of charge for your LiFePO4 battery.
if your battery shows say 13.6V after resting overnight. it's fully charged, it's probably OK.

Thanks for that _CY_

Joel gave me some advise last fall in preparation for my trip. I knew he wasn't around here as much so I just thought I'd see who jumped up.

I'm a little confused. You say operating range is 13.3v to 12.85v but it will charge slightly at 13.8v. When mine gets below 13.5v the little meter on my bike has pretty well gone solid red which I thought was pretty close to the end of the world. Was 12.85v a typo?

At what voltage does the battery start being discharged?

I checked the voltage of my battery yesterday after the bike had sat for 5 days after a 4 hour ride. Voltage was 13.6v.

Checked it again today after running it about 30 minutes yesterday and it was 13.7v

Did some tests yesterday and today and with everything off that can be turned off, the voltage climbed to 14.3v and stayed there. With everything turned on including both the jacket and grips on high, the voltage dropped down to 13.5v - 13.7v @ 4000 rpm. I didn't leave it there for a long time but the voltage seemed to be deteriorating.

So, does it make sense that the system seems to be struggling to power 290 watts worth of bike and gear?

By the way, my meter is a cheapy $50 meter. I've never checked it against a good meter but, I'm sure I have to go into town tomorrow and maybe I'll see if I can find someone to calibrate it for me.
__________________ - RexBuck's Latin America
Information on travelling in Latin America.
Includes links to ride reports to Mexico and to South America
RexBuck is offline   Reply With Quote