Originally Posted by _cy_
that depends on your budget $$$ and how important saving weight is?
main advantage of LiFePO4 batteries are weight savings and low self discharge rate.
Lead acid batteries have advanced too. if weight savings is not a concern AGM batteries also has low self discharge rates at sightly higher $$ with excellent performance.
disadvantage of LiFePO4, technology is still fairly new, where marketing may not meet with reality.
exaggerated amp hour ratings are a valid complaint. what battery mfg recommends is usually too small. one may need to go several sizes up to match performance of original wet lead acid battery.
if LiFePO4 battery is going on say a motocross bike, savings several pounds is pretty appealing. especially if that motocross bike is only ridden in fair weather.
new gen high tech adventure bikes have highest requirement of needing weight savings, cold weather and extreme cranking performance for extended crank cycles. as in recovering from bad fuel and/or diagnosing failed component(s).
so if saving weight is not a concern. my recommendations is go with a high quality AGM motorcycle battery.
airheads are not known for high output charging systems. so amp hour ratings especially come into play if one is running heated gear and doing short runs.
if you should decide to go with much lighter LiFePO4. smaller LiFePO4 batteries may start your motorcycle fine, but do so with very little amp hour in reserve. my recommendations is to go with the largest LiFePO4 battery that you can afford. especially if you planning on riding your bike during the winter.
if goal is to duplicate performance of original OEM battery (new gen adventure bike). say bike originally came with a 16 amp hour wet lead acid battery. replace with a equivalent 16 amp hour AGM. if going with LiFePO4, currently my recommendation is downgrade actual amp hour ratings by about 75% = 12 amp hour actual rating for LiFePO4 if replacing a 16 amp hour lead acid battery.
I can spend 100 on AGM or 200 on LiFePo. The money aspect is tertiary.
Of primary concern is reliability, secondary is weight & size
By reliability I mean everything from hour blast around downtown to day long trip around the majestic Midwest.
I'm also lumping in service life under reliability. I'd want at least a couple of years out of the battery.
So that leaves me with option A - 100 to 120 for Deka, WestCo, Oddyssey or whatever else AGM and
Option B - 150 to 300 (ideally somewhere in the middle) Ballistic, Antigravity, Shorai, Sycl, Zippy or whatever else LiFePo.
So, what do I get?
EDIT: for clarity. Bike is '74 R75/6.