Trickle Charging w/ SparkFun LiPo Charger Plus Questions

I am working on a project that basically amounts to using energy harvesting to power a low-power sensor. Since the power source is pretty small and the sensor is going to be inactive most of the time, I was hoping to use a LiPo to be able to supply current for the bursts of power that occur during sampling. At the same time, I am trying to also trickle charge the battery to at least prolong the deployment time using the chargerhttps://www.sparkfun.com/products/15217. Because of this, I am worried that I may cause damage by leaving the battery permanently topped off. Is there any protection against this on the board or a way to set a lower final charge voltage?

This https://www.sparkfun.com/products/12885 would accomplish what you’re after…but only if it can be supplied by 6-20v source (perhaps add in a small solar panel?)

We normally carry this https://www.sparkfun.com/products/13777 but it’s out of stock :-/

It might be simpler/easier to just purchase a few extra batteries and replace them as time goes on