I am not an expert, but I am told they will, if properly looked after (recharged after each use by a correctly designed balancing charger).
From:
Future of gliding - Front Electric Sustainer
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“A 1200W programable Li-Po charger is used for charging, together with active balancer unit. Balancer monitors the voltage of each cell in the pack and balance them all the time during charging, so that all cells are at same voltage with precision of 0,005V. Balancer could be used even when charger is not turn on. With active balancer, balancing is more precise and faster.
Charging time of one pack of batteries is only 2,5 hours if they are fully discharged. If you used only 50% than charging time is also 50% shorter. LiPo batteries are without memory efect, so you can charge them also if they are not fully discharged!
Unlike lead acid batteries, Li-Po batteries can be stored for months without significantly losing charge. Self discharge rate is less then 1% per month at room temperature!
At 1C rating (horizonatal flight) life expectancy of batteries is around 1500 charging cycles of maximum alowed discharged cells. After that the battery will still have 80% of the original capacity.”
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Chris N