Since my Vanagon doesn't get the use it should sometimes, the battery can
go flat in a few weeks. I have been using this inexpensive solar maintainer
all summer at it has worked out great. It's not a charger, but it will
maintain whatever level the battery holds when the unit is plugged in. From
Amazon. There are a zillion choices but this is pretty close to the one I
bought.

<
https://www.amazon.com/dp/B07QJ8KZS9/ref=sspa_dk_detail_5?psc=1&pd_rd_i=B07QJ8KZS9&pd_rd_w=63j0Z&pf_rd_p=8a8f3917-7900-4ce8-ad90-adf0d53c0985&pd_rd_wg=yLuph&pf_rd_r=SHQ7MYYNCH43GESNJRS8&pd_rd_r=385b3a56-a80b-11e9-932e-a50aff64ee55
>

Jim