Our van has two Maxxfan Deluxe 7500k ceiling fans that have worked rather well…..until recently. As soon as we replaced our AGM battery to a Lithium battery one of our fans would shut down as soon as you tried to use it. We would get an alarm and a flashing green light from the fan and then it would go dead. After looking online I found others complaining about the “green light of death”. Turns out the fan can’t handle the voltage increase of a lithium which is usually in the high 13 to low 14 range compared to an AGM that is in the 12-13 range. Apparently Maxxfan’s don’t come with a voltage regulator built in and have a very tight tolerance on what voltage it will accept before it simply shuts itself down. This is a poor design choice by Maxxfan since many people are upgrading to Lithium batteries these days.
Some people online say you simply need to order a new control board for the fan which costs about $70. Others say you only need to do that if the board is fried and that many people with the green light of death don’t have a fried control board its just that you need to drop the voltage down. In order to bring the voltage down you need to install a voltage regulator or voltage step down device. A regulator will step up and step down the voltage to keep the output voltage at a set level. A step down simply makes the output no more than a set level. I decided to get a step down as my issue is not having too low of voltage. I was able to find an adjustable DC voltage step down circuit board for the correct amperage (10 amps) on Amazon for around $12.
This board is small enough to install it in the fan housing but I decided to install it by my fuse box as I have an easy space to access it in case I need to adjust it or remove it from my system. This also allows me to have the board in close proximity to the fuse controlling the power to the fan in case there was a short in the step down circuit board (this was bought on Amazon after all do you never know what the quality is). The setup is easy, simply have positive and negative coming out of the fuse box (with a fuse on the positive side) and going into the “input” side of the step down circuit board. Then have a positive and negative coming out of the “output” of the step down circuit board and connect that to your positive and negative of the ceiling fan. To set the voltage you have a voltage reader on the output of the board and then turn a small screw on the board and watch the voltage reading change until you get to the level you want, in my case around 12 volts.
Boom, no green light of death for the fan and I am back in business. I have not noticed any heat build up on the circuit but that is something you should monitor in the beginning. But considering it is dropping down only 1.5-2 volts on a 7-10 amp draw I would not expect much (if any) heat build up.