Help with DC-DC converter output voltage

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ceriw asked May 6, '24

Help with DC-DC converter output voltage

Hi,

I've got a 50A DC-DC converter (TS800C) that I want to use to charge a 24V wheelchair from a 12V system.

The output voltage is always higher than the set voltage in TSConfig. I've set it at 27.5V an with no load, it outputs 29.5V. Even with a 10A load its still 28.3V.

What have I set wrong?

Screen grabs of TSConfig attacched.

Many thanks

tsconfig

noload.jpg (168.2 KiB)

loaded.jpg (160.5 KiB)

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ceriw commented · May 08 at 08:43 PM

Bumping post as I still haven't figured this out.

Thanks

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Answer 1 · 2024-05-08T23:15:09Z

xxn5ac answered · May 08 at 11:15 PM

Sometimes DC-DC converters need a load to regulate. I would try a resistive load that would sink something like 20mA to see if it straightens up. For 27.5V this would be a 1370Ω. You don't have to get the exact value, of course. Something in the 1-3.5k range should allow you to test this. Do you have access to a drawer full of resistors where you could grab one and test?

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ceriw commented · May 09 at 09:59 AM

Tried that but no effect. Light loading it sits about 2V above the set voltage. I need to load it to about 15A before the voltage approaches what I'd expect.

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ceriw ceriw commented · May 09 at 07:37 PM

Had a bit longer on this today. it would appear that it is just a 2V offset - output always stays 2V higher than the setting. My other voltage measurements seemed to be the soft knee of the temperature controlled current setting.

I've set the target voltage 2V lower than I want, and everything is working as expected. As it's an older unit, I'm guessing that some internal reference has drifted.

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