Using a bench power supply

[Ohm_slaw]

I am trying to get a Bafang G062 1000W motor through the autotune procedure for the PhaseRunner. I keep getting “instantaneous under voltage.”

I blame the bench power supply that I am using. The test passes when I use the bike’s own battery. My inline DC power meter says that the test pulls 8A with the battery. However - the bench power supply is rated to 10A and it won’t run. ???

Is the power supply crap? Does anyone here run larger motors with a bench power supply?

I had thought about wiring in some capacitors but that adds some cost. It’s also a little dangerous.

Suggestions? I would like something that will run motors on the bench without having to splice into the bike’s battery.

 

[amberwolf]

It probably does pull 8A semi-continuous. But the instantaneous peak when first engaging the motor may be *much* higher, even though it's a very very short time.

Extra capacitors may help as long as they can contain enough energy. It might be as simple as doubling the capacitance you already ahve in the controller--if it has 1000uF now, adding another 1000uF (rated for *at least* the voltage you're using, or higher) might keep the voltage from dipping too low during those large transient current spikes.

 

[Ohm_slaw]

Thanks!

Something like this?

https://www.ebay.com/itm/184500333554

How do you bleed off the charge once you’re done? Having the thing sitting around charged up would make me a little nervouse.

 

[amberwolf]

Something like this?

https://www.ebay.com/itm/184500333554

Probably overkill, but I dont' see why it wouldn't help. With that size cap, I recommend a "precharge" circuit when hooking it up to the power supply each time. Something like a 10kohm resistor (if using small-wattage types like you might have laying around) from the positive lead of the cap to the positive PSU terminal. When it's finished charging up the cap to the same voltage as the PSU is set to, then you can short across it with a regular-sized "battery lead" wire.

If you're using a high-wattage resistor (like a big ceramic block type, or the metal-heatsinked ones), you can use a much lower resistance (like 1k-5kohm). There's a bunch of threads and posts around the forum about precharge / pre-charge / pre charge setups, also called anti-spark, that show how to figure out what resistance and wattage are best to use for a particular setup. (I'm too tired to remember the math right now)

How do you bleed off the charge once you’re done? Having the thing sitting around charged up would make me a little nervouse.

Just turn off the PSU with the controller attached and still "on". The controller will drain it, especially if you try to drive a motor with it for a second.

Alternately, use the precharge resistor across the cap terminals. (it might get hot so don't hold it with your fingers. )