Battery performance, life time (service life) etc depends on many factors.
—Quality of the battery.
—Suitability of the battery (A car battery designed for cold climates are not the same as a battery designed for e-bikes in a warm climate).
—Usage. Is the battery deep cycled or not (Used till empty or nearly empty at regular intervals). Is the battery charged properly, is the battery maintained properly, is the battery used for that for which it is designed)?
Actually the last thing is the most important.

Common problems with e-bike batteries are:
— Deep cycling the batteries. That is depleting the batteries till below 30% remaining capacity. ( A lot of us have been brought up with early computers that had nickel cadmium batteries that needed deep cycling in order not to suffer from the "memory effect" these batteries had but all none NiCd batteries don't have this and actually suffer from completely draining them)

— Over charging (Most chargers coming with these bikes are, for cost reasons, not very sophisticated, that is they are no intelligent chargers that adapt the charging voltage and current to that what is optimal for the battery) To give an indication a proper charger would cost in the west between 300 and 500 USD. That is more than most people pay here for a charger and e-bike combined.
— Lack of maintenance (Also most batteries nowadays cannot be maintained and are basically a disposable item and suppliers rather have you buy a new set instead of maintaining them).
— Cumulative effect of all the above factors. That is once the battery is past its prime the deep cycling and overcharging have a stronger effect than before etc.

So indeed it depends on battery size, usage, regularity of recharging etc. Problem is that it is nearly impossible to determine where you are in your in the life cycle of your batteries.

Anyway-1. When you buy a second hand e-bike it is wise to presume that the batteries are dead or near dying and you will have to include the cost of a new set.

Anyway-2. Don't assume that using an e-bike is good for the environment.
— Batteries themselves are extremely polluting and the recycling methods used in China are not proper.
— The electricity most likely is produced in a dirty way. One might think that electricity in Yunnan is mainly hydro electric but hydro electricity plants destroy a lot of nature as well.

Conclusion: Use a bicycle

Just a note of warning.
The Hani Rice Terraces are near Xinjie some 20 Km further south then Yuanyang (They are called Yuanyang because that is the name of the district and the Yuanyang is the district capital. Yuanyang is just a boring town with nothing to see)

Not general available here or at all. One can get Watson Tonic at Walmart etc.

I did many double blind test with people we swear Scheppes is better but have not found anybody able to taste the difference.

Every day there are several trucks with foam coming from Yiliang to Kunming via the old road.
Old fashion highway robbery should do the trick ;-)

It is not allowed to take a rental car out of the country. So forget that option.