Like many people in Nocatee, Florida, we have a golf cart. Nocatee requires that all golf carts be electric. Cool.
But electric carts require charging, which requires either an onboard charger, or a separate device in your garage. We bought our cart used, and it came with a charger, a big, heavy linear, transformer based box.
They seldom fail, but ours was used and developed a glitch. The cart is Mitzi's project, so she took it into a service provider to get it checked out. A cord was bad and something else was wrong, and they quoted her a price that seemed outrageous. She'd done some homework before she brought it in, trying to figure out if it was the charger or the cart's onboard computer, a little controller that manages the charger so it doesn't overcharge the batteries. So she knew there were new chargers she could buy that were more efficient and cost less than the price she was quoted.
So she essentially donated the old charger to the service company and ordered a new one from that online store with all the trucks.
It's significantly smaller and lighter the old one, so I knew it had a switching-type power supply. We plugged it into the cart and it worked as advertised.
We went to an event on Saturday about 6 miles from the house. A twelve-mile round trip is going to mean a significant recharge upon return. Came home, plugged it in and carried on as usual.
I went out back to "play with radios." I wasn't hearing the usual traffic I heard on 20 meters, so I switched over to the medium wave AM band and whoa! The "noise floor," the amount of static present on the band, was enormous. A local station would come through, but something was clearly putting out a lot of rf racket and I had a pretty good idea what it was.
I put the Panasonic RF-2200 away and grabbed a little handheld radio and tuned it to an empty frequency, noise was still present, went into the garage and went over to the golf cart charger and unplugged it from the cart. Noise went away.
These things are only Class A FCC Part 15 certified, which is to say, they aren't designed to not emit radio frequency interference. The paperwork even tells you so, and suggests that if it causes problems for your neighbors, you'll have to correct it at your expense. I don't think our neighbors listen to much AM radio, so I doubt we'll get many complaints.
But I like listening to radios, so now I have to figure out how to quiet this thing down. When it's in idle mode, it checks on the charge status every 15 minutes or so and adds a bit of charge if necessary. So it's fairly quiet most of the time. I'm only going to hear a problem when it gets back from a trip to the river or the grocery store.
It looks like I'm going to have to get a filter, the kind the marijuana growers use for their grow lamps. And maybe wrap the DC line through a large ferrite.
I'm going to play with it a bit, using a software defined radio dongle, and a nanoSA (nano spectrum analyzer), to try and get an idea what parts of the spectrum are most affected, and to see how much difference the remedies make.
I worry, though, about if or when a bunch of my neighbors get these cheap chargers.
Originally posted at Nice Marmot 05:49 Monday, 22 May 2023