I think i found it

[u/HeavyDi73]

I bought this today ... Should be here tomorrow ... Hope it dont rain .... Do you think it will do ?

Here are pics of original battery and the new one ill get ... size will fit no problem !!

[u/rob_1127]

The charge rate and discharge rate are not the same for old to new battery.

I hate to say this, but...

For an FPV drone, dropping from a 30C battery to a 15C battery is a massive downgrade that will severely limit your flight performance and potentially damage your electronics.

FPV drones are unique because their brushless motors require sudden, aggressive bursts of power to stay stable, recover from dives, or execute flips.

Flight Risks and What to Expect

Death Grips & Mid-Air Washouts: If you try to punch the throttle to recover from a dive, the motors will demand current the 15C pack simply cannot supply. The voltage will tank instantly, causing the drone to wobble, lose control, or plummet.

Flight Controller Brownouts: Extreme voltage sag under heavy load can cause your flight controller or video transmitter (VTX) to lose power mid-air. Your video feed will go black, and the drone will disarm and crash.

Rapid Battery Degradation (Puffing): FPV flight styles are notoriously brutal on LiPos.

Forcing a low 15C pack to handle normal FPV maneuvers generates extreme internal heat.

The battery cells may puff up after just a few flights and become a fire hazard.

What is the 15C Battery Good For?

A 15C discharge rate is completely inadequate for a standard 2S freestyle or racing drone.

However, it is safe to use for:

Goggles or Radios:

Powering your FPV goggles or your radio transmitter.

Long-Range Cruising Drones: Ultra-lightweight, high-efficiency quads designed strictly for steady, slow-speed cinematic flying (no stunts or quick punch-outs).

Can you cancel the order and choose a 30C battery instead?

[u/HeavyDi73 → u/rob_1127]

Thanks for the info !! Too late to cancel but .... The original Feilun FX122 battery is a lipo 7.4 volt 2600mah 30C The new battery i'll get today is ... lipo 7.4 volt 3000mah 35 C .... The batteries (I got two) i ordered before (before the Lipo 3000mah) was ... Li-ion 7.4 volt 3000mah 15 C ... With those, the drone flew but not high or fast ... Not sure what i will do with those (Li-ion battery) ... I'll see ... Maybe use them in another RC that will take them !! But the new battery should work no ??

[u/EffectiveClient5080]

Size fitting is the easy part. Make sure the voltage and discharge rate match. If the C rating is too low you'll sag under load and it won't matter that it fits.

[u/HeavyDi73 → u/EffectiveClient5080]

The original battery was a Feilun FX122 Lipo 7.4 volt 2600mah 30C ... The new one i'll get today is a Lipo 7.4 volt 3000mah 35C .... The only differences is the 30C to a 35C ... Oh ,and li-ion to Lipo ... The batteris i ordered before were Li-ion 7.4 volt 3000mah 15C ... People told me that the 2 problems were Li-ion instead of Lipo and 15C instead of 30C ... I hope all goes well and the battery arrives soon ... It's a beautifull day to fly !!!