If you use the correct electronic relay... they are not load sensitive, and will flash at the same rate, with, or without LED's/Lamps loading them, or high(14.5V), or low(12V) voltage supplied. Of course they will need to be installed properly. There are good, and bad electricians too. So just because they can wire, and repair, commercial, or residential 120/240 volt systems, does not necessarily mean they can't do an even better job on a 12 volt system. All depends on experience, knowledge, and the willingness to learn.