When the power level of my small rover go bellow 25%, the Chemical Battery kicks in, regardless of the solar panels charge rate.
Sometimes, when this happen, I get a massive spam of identical warnings regarding the low power level. On one ocasion, I counted more than 60 identical warnings.
My guess is that this is happening because the Chemical Battery + Solar Panel Charge Rate on the Small Rover are very similar with the default Drain Rate (It's possible to see this on my picture bellow). So, when driving around with 25% power level, in a small fraction of time, the power level goes above and bellow 25% multiple times rapidily, causing the multiple warnings.
If this is the case, it could be easily avoided by making the Chemichal Battery kick in only when bellow 20% power level (since there is no warning for this power level).