Is It The Motors ?

[aburn09]

As the title says are my motors killing my batteries ?
I have two almost identical 5 inch quads based on the Chameleon they have different Fc's but the same 20amp little bee esc's and dalprop cyclone 5045 props......however the red one has emax 2205s 2300kv motors and the orange one has racerstar 2200 2600kv motors......Now I've just recently bought some new 4s 1500mah batteries which with the orange racerstar motors I'm getting a good 4 and half minute flight with no problems and when I check them when I land each cell shows around 3.5v........ however the red emax quad is killing the batteries I'm lucky to get just over 3 minutes of flight time (I'm not thrashing it either) before the battery alarms start going on the quad and when I bring it in the 4 cells are nearer 3v and one sometimes goes under !!
I'm not too sure whether my battery checker is correct as the under 3v cell when I put it on my mains charger shows all cells are nearly the same around 3.2 volts?
But I'm thinking of taking the emax motors off and replacing them with racerstars ?

https://m.banggood.com/4X-Racerstar-2207-BR2207S-Fire-Edition-2500KV-3-6S-Brushless-Motor-For-RC-Drone-FPV-Racing-Frame-Kit-p-1284981.html?rmmds=search

Any advice would be appreciated 

[ched]

Are the emax motors older and maybe bearings failing?

Looking at specs at 27Amps they all seem to have an efficiency of about 2.3g/W the emax do seem to have max lift at 1180gms vs BR2207S 1120gms.

I have a couple of the same batteries, long story but they were replacements for some very naff ones from Amazon.
So where can you buy them as I do like them?

[aburn09]

Ched the motors are old they have been in a few scrapes over the years whereas the Racerstars are about 6 months old so you may be onto something with the bearings although they spin freely but I think it maybe time to swap them out for something newer like the racerstars in the description.......As for the Batteries you are correct they do come from Amazon they were two for £29.99
Amazon.co.uk
GOLDBAT 1500mAh 4S 100C 14.8V Lipo Battery

One other thing Banggood do those racerstars in either 1600,2200 or 2500kv  which ones should I go for I'm thinking 2500kv ?

[ched]

Cheers for batt info. I bought 2 cheap ones from amazon that were listed as GARTPOT 1500mAh 4S 75C for £18 for the 2!!! I wrote a poor review as even when fully charged on punch out they sagged enough to set low batt alarm off so no where near 70C more like 10C!!! The seller apologised and sent me 2 x GOLDBAT 1500mAh 4S and they are great. I edited the review to say seller sent replacements and the new ones 'GOLDBAT' were good!

As for motors looking at the RacerStar 2207s on a 5045 prop both the 2200 and 2500 work OK If you are using the 20A esc then the 2200kv pull less amps but both exceed the 20A esc you have by quite a margin (2200 = 28.5Amps 2500 = 32.5Amps) Ok so they are probably static thrust bed measurements so in flight current draw should be 25-30% lower. To put that in context your emax 2205 have a max current of 33Amps!

What sort of flying do you do?  If its racing then 2500kv, freestyle then 2200kv might be a little low as the torque on the 2207 should allow higher pitch props but the current draw might be too high.

I believe that the taller stator (7mm) gives more torque at the higher end, so a more linear throttle. I would guess a more linear throttle is probably better for freestyle.

It's a difficult one, how do you find the 2205 2600kv you currently have? According to the specs it looks like you should run a 4" prop on 4S.

After a bit of googling I think if it were me I would go 2500kv on the basis that your current motors are 2600kv and you are happy with those but the 2207 will be capable of pulling more current than your current motors. The 2207 will have more torque so should be capable of spinning up the props faster so that could translate into faster acceleration but on the same prop top speed might be higher on the old 2205 motors. If it wasn't for the current limits I might be inclined to say the 2207 2500kv could run a little more pitch to compensate for lower rpm.

Hopefully some other more experienced people on here will offer some more hands on advice.

[aburn09]

Cheers Ched I only fly freestyle so not thrashing the batteries so i'd rather have a slightly longer flight time so I'm confused whether the 2200 or the 2500 would be a better bet ? 
If on paper it's only about 20 seconds of flight time difference for the 2200kv motors then I'd rather  go for the higher punchier 2500kv motor

[shawdreamer]

were racerstars are concerned and your looking for flight time over agility Id lean toward the 2200- 2300kvs

the 2500-2600kv's dont sound like much difference power wise but on 4s they do like to nom nom the amps quite heavily.....but they dont disappoint performance wise for it though imho ::)

[aburn09]

So would the 2200kv rather than the 2600kv be a better bet ?
https://m.banggood.com/4X-Racerstar-2207-BR2207S-Fire-Edition-2200KV-3-6S-Brushless-Motor-For-RC-Drone-FPV-Racing-Frame-Kit-p-1284983.html?rmmds=search
Although i don't thrash the quads a little power burst does sound nice 

[shawdreamer]

the fire Ed. 2207's are quite the little powerhouses even in 2200kv format so for what your wanting they should more than suffice, A few will tell you the 2600's should really only be used with 4" props while the 2200's are good for 5" and low pitch 6".

I say bollix to that.... I run my 2600's on tri and quad bladed 5" often high pitch props and they perform like troopers, while the 2200's I often run high pitch tri's from 4" upto 6" props and they dont seem to have issue, for that reason I treat racerstar KV ratings as in a more broader simplistic fashion.....if you want faster spinning motors/more speed go with 2600, if your right with a little less speed and want maybe an extra minute in the air go with 2200's... jobs a goodun

[ched]

For extra air time 2200kv. Remember the 2207 will give you more torque so they will feel faster on throttle changes.

[aburn09]

Thanks for all your help guys i do appreciate it.......I must say the motors sizes prop sizes etc gets quite confusing but from what replies you've supplied I think for flight time and still having a punch the 2207 2200kv look like the safe bet....I could go for the older racerstar 2205 2600kv motors like I have on the orange quad which are fine but I'm assuming that the newer 2207 racerstars in the 2200kv will be just as good if not better ?