If your question around powering up the AP ( even 3850 is not using as WLC), then still it is not recommended. You have to use 1500 power injector to do this.
Below from this 1550 - Getting Started Guide
"To provide inline PoE, you must use the 1500 power injector (AIR-PWRINJ1500-2=). Other power injectors, PoE switches, and 802.3af power sources cannot provide adequate power, which may cause the access point to malfunction and cause possible over-current conditions at the power source."
HTH
Rasika
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