Depending on discharge depth, a Lithium battery can do 5x as many cycles as lead acid. It can handle 80% depth of discharge (DOD) while lead acid handles 50%. If replacing a lead acid battery under two years old due to deep-cycling damage, you'll save in the long run switching to Lithium-ion.

If you run lith-ion below 80% it shortens their life.

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'03 X5 4.4 Sport, last of the M62s (8-03 build date)
I believe in deadication to craftmanship in a world of mediocrity!