Have this little scooter, it has a 8Ah lead acid battery for start and light. Not so good anymore, years and years, long without charge, burned dry one time, refilled with distilled water, so needs a new one. I do not like that stuff, all the (it is sealed, but not really) so started googling for Lifpo4 replacement.
Now there, it seems these days we no longer specify Ah, but obfuscate things by mentioning Wh, some calculation showed that what is sold on ebay as replacement for an 8 Ah lead acid is actually a 2.4 Ah lifpo4.
But where did I see this 2.? Ah, oh yes, I have a 11.1 V 2.2 Ah lipo pack for my model airplane. Some checking of the max discharge current convinced me that it _should_ be able to start the motor. Cut the wires, added some alligator clips (big), and tried it,. And YES, it started the motor. Of course these lipos are extremely dangerous can catch fire and explode, burn whole cities down, and maybe even the whole planet, and lifepo4 is so much safer and does not do all those things, but hey I just saved what was it > 65 Euro or so. What I still have to figure out is if the charge circuit in the scooter.. well you now, but that electronix shoot not be that hard to make, in fact I already have a charger.
Size and weight, this one fits in your pocket. Tried it again this morning, (after recharging last night on a real lipo charger with cell balancing), works great.
So then I thought somebody else must have thought of this, and sure enough google found the jump starter lifepo4 packages....
sigh
Only thing that got hot recharging was the charger, even though I discharged that 11.1 V pack 8.4 V.
Disclaimer, if you are small and they are big, I do these experiments knowing the sun will finally engulf the earth and it all will be on fire anyways, so if you want to do other things before that think twice and ask y'r mama and papa first. AND even if they say yes, do not do this at home OK?