5v DC fan from 3.7v lipo battery

Thread Starter

Goose007

Joined Aug 10, 2020
2
Hello,
I am trying to power a 5v DC fan at maximum RPM, and I am using 3.7v lipo for space and weight savings. I have the circuit hooked up to a charging circuit (https://www.amazon.com/dp/B01LHD9D7E?ref=ppx_pop_mob_ap_share) and then to boost converter.

XL6009 DC DC boost converter module (https://www.amazon.com/dp/B07L64GJ42?ref=ppx_pop_mob_ap_share)

This circuit works well without load and I can adjust voltage from 5-25v. I can even setup a LED driver, and push a high forward voltage LED (5.5v) with no problems.

When i hook the 5v DC fan which is rated at 150mA the circuit shows 3v instead of the preset 5v. If I increase the voltage it simply outputs the same 3v. I can't imagine I'm drawing too much current but can't imagine what else is wrong. The fan works great if I plug it directly into a 5v source. I'm new with electronics and feel like I'm missing something simple.
 
Last edited:

ronsimpson

Joined Oct 7, 2019
1,026
Usually this happens when the fan (at startup) pulls much more than its rated current, and goes beyond the limit of the power supply. While the XL6009 "5A switch" that does not mean you can get 5A out of it. More like 1A.

Now I know. The XL6009 shuts down if the input voltage drops below 3.6V. The battery might be at 3.7V with no load but under load and with long wires the XL6009 might see the voltage drop below 3.6V.
 

Thread Starter

Goose007

Joined Aug 10, 2020
2
@ronsimpson thank you for this input. I wonder if I'm dropping below 3.6V I'll check this out thank you. I tried this step up (https://www.amazon.com/gp/product/B07L76KLRY/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1), and had the same problem as above but probably because the amperage ratings are low.

Oddly enough the little brother of the XL6009 WORKED... I've even tried multiple of the XL6009 without luck. (https://www.amazon.com/gp/product/B07F7ZCDZM/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1). Why would that be do you think?
 

ci139

Joined Jul 11, 2016
1,696
fuzzy/approximate :: try -- filter (RC or LC or RDC or LDC) before motor + a flyback diode or RC filter in parallel to
 
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