This thread has become voluminous to point of putting most eyeballs to sleep reading it all. so here's a quick review of conclusions so far ...
have posted this several times, but here goes again:
provided you actually need a new battery ...
for most folks, my advice is go with AGM. unless weight is totally critical. AGM has one of the main advantages of LiFePO4 which is very low self discharge. unless one has a large parasitic current drain. trickle charger will not be needed for LiFePO4 or AGM over the winter.
some bikes normally have a small self discharge. for those bikes a trickle charger will be needed regardless of what type battery is used. Your lead/acid battery charger may or may not properly charge LiFePO4 batteries.
if you've got a modern adventure bike and decide that it's worth $$$ to save 10 lb or so over AGM or Gel. forget the marketing hype mfg use to calculate which battery to use.
use actual amp hour rating less 25%. note this is for modern Adventure bikes, which has one of the highest battery demands of any bike. example, if factory ratings is 12 amp hour x .75 = 9 amp hour actual LiFePO4 amp hour rating.
some bikes that only are used in fair weather can get by with much lower LiFePO4 amp hour ratings. one advantage of LiFePO4 batteries is ability to deliver larger amps for size, while maintaining a very flat discharge cycle.
learning how to start your bike with LiFePO4 in cold weather is mandatory. yes procedures are different.
take mfg amp hour ratings with a bucket of salt... use real amp hour ratings to size your LiFePO4 needs. LiFePO4 batteries when sized properly are robust, super lightweight batteries.
use caution when replacing any battery substantially smaller than OEM. mount battery equally secure as OEM. taking extra care to make sure positive side cannot ground out.
Lithium batteries discharge at HUGE rates. Dead shorts are suspected in bike fires resulting in total loss.
LiFePO4 batteries that use cables to attach instead of fixed posts require special caution. positive connections need enough insulation, to where grounding out is not possible. including in the event battery gets lose. dead shorts can result in temperatures hot enough to weld with.
one of the advantages of Lithium batteries is it's ability to deliver HUGE amps.
but drawback is extra costs as compared in equal amp hour energy delivered. more amp hour capacity = more $$$
this is why LiFePO4 batteries found it's first non-electric vehicle acceptance in the marketplace in Motorcycles and not in applications like starting diesels or cars. to create a battery with enough amp hours to support those applications. costs would exceed benefit.
what's it worth to you to save say 10lbs.... for the weight wienie paying $$$ for carbon parts for his race bike and/or wanna be race bike. those are some of the cheapest lbs one can unload.
but for most folks ... best replacement battery still remains AGM. unless of course it's worth all the $$$ to save those 5-10 lbs.
yes ... one can successfully use LiFePO4 batteries in the most demanding applications. but the amp hour capacity has to be there. my recommendation is actual lead acid amp hour ... less 25%.
if you follow most lithium battery mfg suggestions. you'll end up with a battery that supports your bike in the summer. NOT for the winter.
R1200GS has some pretty demanding requirements. including needing reserve amp hour capacity to crank bike over repeatedly if your bike should go down from contaminated fuels, etc. there will be times pounding on fuel pump while cranking and cranking will get your bike back up again.
for cold weather, one needs to understand warm up cycles consumes amp hours. starting procedures has to be learned to start your motorcycle in cold conditions.
your heated gear doesn't understand all those fancy PB/EQ ratings battery mfg use. heated gear draws real amps... if your lithium battery say has only 4.6 amp hours. then your heated suit uses a chunk of that reserve just before you put bike away.... guess what happens next morning?
above is why for most folks ... my recommendation is to stick with AGM. but some of us are willing to pay the toll to save 10lbs. not likely someone trying to sell you a lithium battery will inform you... probably because they don't know better.
here's a chart listing voltages with corresponding battery charge state
Amp Hour capacity in LiFePO4 batteries and how important it is to properly size a lithium battery.
PB/EQ is most lithium battery mfg's attempt to capitalize on Lithium battery's ability to discharge at huge rates. without diving into all the technical reasons why this is so and putting most eyeballs to sleep in the process.
this video by Joel Wiseman, one of the most knowledgeable BMW tech's on Adv.
shows what happens when a LiFePO4 battery is undersized as compared to AGM batteries that are correctly sized.
a common question .... will a standard lead acid battery charger properly charge my LiFePO4 battery?
answer is it depends on the charger. for not all lead acid battery chargers work the same. it's best to use a charger designed specifically to charge LiFePO4 batteries. But one can improvise and use a charger designed to charge lead acid by carefully monitoring charge. then remove when charge gets close to full. being careful not to exceed max voltage of 14.4v for LiFePO4 batteries.
Cellpro Powerlab 8 is what I'm using. A favorite of the RC world. considered the most powerful/versatile of all hobby chargers with software to track charge cycle and generate graphs.
here's my charge station with a full electronics lab
Using Heated Gear with LiFePO4 batteries
heated gear don't understand PB/EQ. they draw real amps. Almost all LiFePO4 battery mfg like to use amp equivalents to lead acid batteries. that may be valid for starting requirements. but heated gear don't care... they draw regular amps.
listed amp/watts for Gerbings micro wire. even if you don't have Gerbings, amp draw will be real close. amp x volt = watts
1. Jacket 6.4 amp/77watts
2. Vest 4.5 amp/54watts
3. Pants 3.6 amp/44watts
4. Gloves 2.2 amp/27watts
5. Grips 3.0 amp/36watts
let's say you've got a heated jacket, heated gloves and heated grips = 11.6amp draw
let's say your LiFePO4 battery has an actual Amp Hour capacity of 6 amp hour. this means your battery will support your heated gear for about 1/2 hour before going dead.
then let's factor in alternator output and amp draw from rest of bike. on short rides using heated gear, it's quite possible to use more amps from your battery than Alternator has a chance to replenish.
when you put your bike away for the night after that short cold ride. your 6 amp hour battery may not be fully charged.
next morning it's say 30f degrees ... you go to start your bike with a half dead battery.... fail ... one automatically blames the battery. when the fault is putting bike away with a half charged battery.
this is where LiFePO4 batteries with BIG reserve capacities shine. Lithium batteries internal resistance goes way up with battery gets cold. this means substantially less amps will be delivered. cold start procedures calls for a load to be placed on LiFePO4 battery. this heats up battery reducing internal resistance, allowing more amps to be delivered.
ahhhh... but there is a catch... heating a cold LiFePO4 battery takes amps... battery must have enough reserve capacity to heat battery up and start your motorcycle.
clear as mud... nah.. it's not that hard to understand. Adventure bikes must have some of the hardest demands on a battery. if you've got a R1200GS and you are planing on climbing the Andes mountains and camping out.
go with an AGM or if saving 10lb+ is worth the trouble... go with largest LiFePO4 motorcycle battery available.