I've researched quite a bit but could not find a definitive answer to this.
Background: My old bike (already sold) had a starting problem - after a few months it would barely spin the engine up and require a replacement (8Ah). Most likely a decompressor problem since the starter was already exchanged, the terminals were clean, there was no measurable voltage drop over the wires. The cause of this issue is not my question.
The bike would ALWAYS start without a hitch if a small 2Ah 3S LiPo RC battery - or a normal car battery - was used in parallel. Without this help, the voltage would drop to 6-8V while cranking.
My question is: would a LiFePo4 battery replacement provide higher cranking current over the original gel battery, over a period of several months/years? For reference, the standard was a Yuasa YTX9-BS, but all lead-acid batteries I've tried performed almost exactly the same (Yuasa, Varta, Polo and Louis re-branded, no-name).
I've heard that AGM is "the best" and that LiPo is "even better" but "much more expensive". However, a standard maintenance-free battery is 30-50€, a LiFePo4 is 40-90€, AGM is >150€. I haven't seen standard LiPo in this size for sale, not through the usual suspects.
Are there any charts comparing standard lead-acid with LiFePo4 and AGM? Or at least some long-term experiences?