Category: SCIENCE!

I may be only 28, but I remember when RadioShack was a place of wonder and excitement in the pre-web days. Back then, cellphones had yet to be in widespread use, and one could buy any number of electronic components from employees who were also hobbyists and geeks.
Now, it’s a glorified mall cellphone kiosk with a few token items for hobbyists, but those are tucked away in the back, seemingly out of shame.
As a scientist and a tinkerer, I enjoy getting data on things that I’m working on. As an example, if I was building a solar array that would charge batteries, I’d want to know the current voltage on the batteries in the array (to determine state-of-charge) and the current from the panels to the charge controller and from the batteries to the load.
Going with this example, I was in RadioShack yesterday with a friend (she needed a new coin-cell battery for her calculator) and asked if they had panel voltmeters and ammeters (see here for an example) for such a system.
One of the employees thought about it, and said “No, I’m afraid we don’t carry those. Sorry.” Although not the answer I was looking for, he was honest and helpful, which I appreciate.
The other employee said, “Why do you want that? Why not just use one of the multimeters we have here?”, waving at the back of the store.
Me: “I already have three multimeters, and they all max out at 10 amps, and they can only support such currents for 30 seconds with a few minutes to cool down. I’d like something that can handle 20-50 amps indefinitely. Panel meters don’t require batteries, which is a major benefit. Also, I’d like something a bit more elegant to put into a display console.”
Employee: “Why not use one of the clamp-type multimeters we have to measure larger currents?”
Me: “The ones you have here only work on AC, not DC, which is what I’ll be working with.”
Employee: “Why not power your multimeters with a small solar cell or power them from the source and mount them in your console?”
Me, suspecting this conversation has started going downhill: “Because the multimeters are not rated for the currents I’ll need them for, a solar panel would provide intermittent power by not working at night [where knowing the state of charge is important], and the source voltage is very different from what the meter requires, as the meter runs on AA batteries. Panel meters are much more appropriate, and look quite a bit nicer.”
Employee: “Why would you need to deal with such currents at all? The biggest solar panel that RadioShack sells is a 5 watt panel that sits on your car dashboard that keeps your car battery topped off.”
Me: “I have no use for such a panel at all; my project would involve an array of big panels that would charge a battery bank that could power a small house. I’d like a permanently-wired, nice looking console that would have some meters in it so I could know, at a glance, the current state of the battery bank.”
Employee: [blank look]
Me: “Nevermind. Have a nice day.”
I have no problem with an expert (or even an enthusiastic amateur) discussing project requirements with me. Indeed, they may have a better idea of setting up such a system than I, which would be very helpful.
However, I rather dislike it when someone not only makes inappropriate suggestions, but argues about basic design goals (e.g. I want a nice-looking monitoring console, not a kludge of multimeters and wires running everywhere). Yes, I could put some shunts into the circuit and measure high currents safely with a standard multimeter; such a setup would be great for testing and bench work, but not for a final product.
RadioShack certainly isn’t what it used to be.
Fortunately, the internet allows me to order the meters I want for less than $10 each, and have them shipped to me from Thailand in less than a week. I also don’t need to interact with people like this RadioShack employee.