I posted about my 25 amp one last spring. Thanks again to Red31 for finding it.
rv.net threadI didn't get a lot of use out of it last summer because I broke a connector and took a while to fix it. It does work (no independent power supply required; tip on hookup in the linked thread). The quality is low, particularly in the connectors area. I think the state of charge accuracy slips over time as it fails to take into account the inefficiency of the charging process. For example, if current flows into the battery after it is fully charged, the amp-hour count increases but the battery does not get more than fully charged. I am quite pleased with it for the $25 I paid and expect it will serve me well for several years as I gradually upgrade things (have 100 watts of solar now).