No problem... this is extremely minimal charging. In Massachusetts, I would suggest that before winter storage you first FULLY charge all your batteries AND take an amp meter reading with everything turned off...so you understand the parasitic loads. You may find they exceed the approximately ONE amp hour a day you will be putting back into your batteries on a SUNNY day!
You should disconnect the negative terminal of your batteries after fully charging. Then you will have no losses except a very small self discharge rate that ALONE will still leave your batteries 70% or more charged after 3 months of storage. And you will be protected from sub zero freezing temps. THEN you can attach the solar device to the battery terminals directly (since the cig lighter will not work) if you want to further protect them.
2015 Georgetown 280DS
2014 Vespa LX150 2014 StellaAuto 125