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Old 01-16-2013, 10:07 AM   #323
_cy_ OP
Beastly Adventurer
Joined: Sep 2011
Location: Tulsa, Oklahoma
Oddometer: 6,439
Originally Posted by frogy View Post
PS Why the larger size batt. for longer trips? I might be replacing the batt. on my 02 R1150RT soon,and I usually travel 4-7 hours to Rallys.Are you worried about overcharging?
not worried about overcharging look closely at chart below. LiFePO4 batteries in 4s config charges to 14.6v (full charge). then if battery is equipped with internal BMS. volts will drop down to about 13.8v range. LiFePO4 battery without BMS will typically self discharge overnight to 14.1v range. note very little power loss from 14.6 to 13.85v

a normal motorcycle charges at 13.8v to 14.2v range. so long as charging voltage remains in normal range. your LiFePO4 battery will not overcharge.

LiFePO4 li-ion batteries are inherently stable and very hard to cause it to catch on fire. vs lithium cobalt li-ion batteries catching on fire Boeing 787 in the news.

keep in mind airhead (non- fuel injected) motorcycles takes longer crank times when temps dips down. LiFePO4 batteries degrade in the cold.... much as 50% degradation in amp hour capacity within range of motorcycle riding temps. most folks don't go riding at -10c (14f) degrees, but it's not unusual for folks to ride below that.

so a short cold ride with headed gear and long crank times = worst case scenario for a LiFePO4 battery. keep in mind I'm dealing with actual amp hour not wildly inflated amp hour listing by most battery mfg. PB/EQ or lead acid equivalent.

both Shorai LFX21 and Earth-X ETX24 failed next morning... after being subjected to long crank times at 25f to start R80G/S followed by a 15-20 minute ride with full heated gear on. then bike was parked outside for several hours while temps fell to 20f. then R80G/S was started and ridden home 15-20min with full heated gear (Gerbing heated jacket, heated pants, heated gloves and BMW heated grips)

next morning R80G/S with both Shorai LFX21 failed to start R80G/S at 20f. repeated same scenario with Earth-X ETX24 which also failed next morning.

R80G/S used a voltage regulator from that charges at a slightly higher (14.4v) voltage to increase output. R80G/S has an upgraded 400watt alternator (from have changed back to normal voltage regulator since then. changed battery out to larger Shorai LFX36 and have had NO further problem with battery not having enough amp hour reserves. one year later and LOTS of short cold rides with heated gear.

this is why for folks who takes their adventure bikes (pigs) on extended trips ... Earth-X ETX36 and Shorai LFX36 are the only two batteries I would recommend. by the way for modern high tech fuel injected bikes ... yes when things are tuned and running perfect. bike starts with a few seconds of cranking even when cold. ah .. but what happens when that fancy bike's fuel pump decides to take a dump??? and/or you get a bad load of fuel.... sometime cranking and cranking and cranking while beating on the fuel pump will get you going again.

all that takes amp hours! ... an Odessey AGM for BMW 28 AH, weight 22lb. vs ETX36 weight 3lb 11oz, LFX36 slightly heavier. both measure out actual about 13 amp hour. that's a whooping 18lb saving. original BMW gel battery is 19AH.

_cy_ screwed with this post 01-16-2013 at 10:31 AM
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