Seestar's battery consists of two cylindrical LiNiMnCoO2 (NMC) cells in parallel, each nominally 3.7V with a 3Ah capacity so that the total capacity is 6Ah at 3.7V. LiPo is the shorthand for a lithium polymer battery which is NOT what the Seestar uses. It uses cylindrical cells not pouch cells as I said and the electrolyte is a liquid not a polymer which is used in LiPo cells.
I beg to differ with Seestar support on one point. If you attach an external power source to the Seestar and the internal battery is charged to 100%, the internal battery will not be charged by the external battery. I have tested this configuration and the Seestar icons clearly show that the internal battery is not charging from the external battery even when the Seestar is running on power from the external battery. If it is, then ZWO needs to correct the charging/not charging icons to show that charging is taking place even though the internal cells are already at 100% state of charge (SOC), i.e. simultaneously charging and discharging. Also, when I power from an external source with the internal cell at less than 100% SOC the power draw from the external power source is higher than it needs to be to both charge the internal batteries and power the Seestar until the SOC icon reaches 100% at which point the external power draw drops down to the lower value needed to just power the Seestar. So, I do believe that if the internal batteries are fully charged they just sit there and do nothing while the external power source provides all the power needed for the Seestar to operate.
It is true that lithiium ion battery life will be shortened if you store it either fully charged or fully discharged because these states put more stress on either the cathode (fully discharged state) or the anode (fully charged state). So, continually running from an external power source keeping the internal battery at 100% state of charge (SOC) is not good in the long term.
And yes, to get the rated 500 full discharge cycles you should not charge the internal battery with too high of a current. Every lithium battery manufacturer recommends 0.2C charging current with a maximum of 0.5C. 1C for a 6Ah battery is 6A so 3A is the maximum charging current to get the longest life, 1.2A would be the best choice for prolonged life.
Regards,
Curtis