I bought the 40 amp DC to DC charger a few weeks before my battery arrived. The charger arrived quickly and the product looked good quality. Once the battery arrived the return date had already passed for the DC to DC charger. I installed everything as per the instructions, but unfortunately there was an issues with the charger. I emailed Eco-Worthy with the issue and they were very responsive. They walked me through several troubleshooting steps, but in the end there was something wrong with the unit. Eco-Worthy apologized for the inconvenience and are sending me a replacement unit. I requested them to downsize the unit to a 20 amp, which they agreed to and will also be refunding me the price difference of the two units. I'm very pleased with my interaction with Eco-Worthy. The customer service was second to none. Highly recommend dealing with them.