Getting into long range fpv. Heard the praises of lithium ion so pulled the trigger on a 4s 27100 5000mah pack.

The flight time was... not what I was expecting. 1100mah on my Rekon5 would get me around 10mins. For sh**s and giggles, I put a massive 3000mah lipo on it and got 15mins of flight time. Flew terribly, but it stayed up there.

Slap a 5000mah Lion pack on it and the flight time is about the same as the 3000mah. The lion pack is much lighter so... what?! Also, when I first take off, I swear I dump about a volt immediately. Could be my brain not working though, I have spent 7mins waiting for satellites.

I also have not adjusted to a lower voltage floor like I've heard the lions can reach. I figured "Hey, 5000mah. It should still outperform without adjusting anything." Maybe I was being too naive.

Am I crazy for expecting maybe 20mins of flight time from a li-ion 5000mah pack when my 3000mah lipo gets 15mins?

Thanks!
Chuck

Li-ion packs are not all built the same. A lot over state their capacity. I recommend building your own pack with real cells from Panasonic, LG or Sony. Or buy packs from reputable brand.

Just go look at YT for power tool battery pack comparison. It parallels the quad industry too.

Most likely, the 5000mah pack you have in reality is just a 3000mah pack.

Is your pack made up of Samsung 50S cells? There's going to be a fairly large chunk of that pack's life at the lower end of the voltage range. (stop around 2.7-2.8ish per cell) Also it's pretty normal to see voltage sag from Li-Ion cells as they don't have a super low internal resistance like a LiPo does.

what kv version do you have?

lipos woa buddy flies thw recon regular on 650mah 4s battery on the 1800kv motors :-) that brings up to 8min flighttime.

the rekon5 can carry some weight, but it needs some voltage, power consisdency. i believe it works beat on lipos and provides a huge range of choices.
depends on your kv if need to go for a 3-6s lipo for the best flighttime; over 15min with acceptable flightperformance.
its a famous quad, there should be a lot examples next to david cledons suggeations :-)

(11-Jul-2023, 04:58 PM)randomchuck Wrote: .... on my Rekon5 would get me around....

Last year my Rekon5(6S, analog VTX) flew over 30 minutes on a Li-Ion 4S Molicel INR-21700-P42A 4200mah. You just need good high current batteries.

(11-Jul-2023, 06:06 PM)voodoo614 Wrote: Li-ion packs are not all built the same. A lot over state their capacity. I recommend building your own pack with real cells from Panasonic, LG or Sony. Or buy packs from reputable brand.

Just go look at YT for power tool battery pack comparison. It parallels the quad industry too.

Most likely, the 5000mah pack you have in reality is just a 3000mah pack.

The pack was a ZOHD Lionpack Max 21700 4S1P 5000mAh from the GetFPV website. I thought it was a safe purchase since the reviews were decent. I had also heard 21700's could have a higher capacity than 18650's. Definitely should do some more research. Ha.

(11-Jul-2023, 09:48 PM)Suros Wrote: Is your pack made up of Samsung 50S cells? There's going to be a fairly large chunk of that pack's life at the lower end of the voltage range. (stop around 2.7-2.8ish per cell) Also it's pretty normal to see voltage sag from Li-Ion cells as they don't have a super low internal resistance like a LiPo does.

I swear I saw the battery manufacturer for this thing somewhere. Supposedly 27100T 5000mah. I stopped my testing when I saw 14v on the OSD, because I was afraid Betaflight had a voltage cutoff. I'm reading it doesn't. I really should read more. Lol. I'll push it further next time, thank you.

(12-Jul-2023, 12:28 AM)hugnosed_bat Wrote: what kv version do you have?

I had the 4s/2600kv version. Emphasis on had.

(12-Jul-2023, 04:41 PM)randomchuck Wrote: I swear I saw the battery manufacturer for this thing somewhere. Supposedly 27100T 5000mah. I stopped my testing when I saw 14v on the OSD, because I was afraid Betaflight had a voltage cutoff. I'm reading it doesn't. I really should read more. Lol. I'll push it further next time, thank you.

I think I found what it uses. Looks like Panasonic 21700T cells. Those are rated at 4800mAh, so still pretty close to the claim of the pack. Looks like those are rated to go down to 2.75v before being super dead.

(12-Jul-2023, 05:21 AM)LiPoFly Wrote: Last year my Rekon5(6S, analog VTX) flew over 30 minutes on a Li-Ion 4S Molicel INR-21700-P42A 4200mah. You just need good high current batteries.

30mins is nice! Thank you for sharing the battery you use. I've considered building my own packs, but I reasoned myself out of it. The money saved didn't seem like much at the time.

OP, you have a good pack. 4800mah and not 5000mah as claimed. I think, like other are saying, you are not taking the voltage down low enough and landing way before you have too. I suggest, flying around a field where you can find towards the end of your pack just to see how long you can actually fly. This way, you can safely gauge how long you can fly for.

That's good advice, thank you. I'll run 'er down further.