Most reviews on Amazon.com for the Deltran Battery Tender are positive, as of 2016, noting that it’s durable, well constructed and that it does not overcharge batteries. Some negative reviews note that it overcharges batteries or does not work.
One reviewer states that two infrequently used cars, installed with Deltran tenders, always start without a problem. Another reviewer states that the tender does not overcharge batteries, so there is no need to monitor the charging process, and that it effectively charges a fully drained car battery. One review notes that the Deltran Battery Tender is well-made and well-priced, and another adds that the product is in use every day in both extreme hot and cold temperatures, has survived multiple falls, and still functions. One unhappy customer states that the battery tender is low-quality and overcharges batteries.