This is an old wives tale. This is dangerous to electronics, and tell you NOTHING
1....It does not tell you if the thing is not charging because it simply may have been running too slow to charge
2....If it would have kept running it doesn't tell you the charging system is OK, because it might be damaged and still putting "just enough" out to run the ignition
Did you do what I suggested? Turn on the light switch and probe the dimmer switch. What to you read?
