View Full Version : running a 3s and 4s pack together
3sgte
10-17-2007, 08:18 AM
im kind of new to the gaui 550. my question is i am now running my xes with stock gaui 890kv motor on 2 3s 2200 packs and was wondering if i could run it with a 3s pack and a 4s pack to give me 7s?? is that ok to do? do i have to match the 2 packs as far as mah's like a 3s 2200 and a 4s 2200? will this give me more flight time if i turn the throttlle curve down to get the same hs as i had before with the 2 3s packs?
ukgroucho
10-17-2007, 08:26 PM
From a battery perspective I cannot think of any reason why it would not work - whether your motor and ESC can cope is another question (which I cannot answer).
Yes you need to match the packs in terms of capacity AND C rating - you should REALLY also use packs that are of a similar 'age' - i.e. don't use an old worn 3S pack with a brand new 4S.
As always with this kind of setup you need to carefully balance charge and check final resting voltages after a charge.
You will get longer flight times with the same HS and should get cooler components as less amps will be needed for the same kind of flying.
Crash549
10-18-2007, 01:16 AM
If you try it let us know how it works out.
3sgte
10-18-2007, 07:19 AM
i think i will try it and ill post my results. one question though, how much voltage can the stock 850-890kv gaui motor handle?
concept1
10-18-2007, 08:10 AM
motor will be ok, but not sure on the specs of the ESC. I am also wondering what the specs of the stock 50 amp esc are, I want to try 8s A123 cells which is about the same as 7s lipo
kgfly
10-18-2007, 09:35 AM
The ESC is only rated for 6s AFAIK so that is your first problem
Running at low throttle is highly inefficient and you may find your ESC and motor get hotter on 7s/75% than 6s/90%. You may be better off adjusting the gear ratio and keeping your throttle up above 85%.
I have been researching an 8s A123 setup and so far it is leading to a Z20-980kv and HV ESC (CC80HV maybe).
3sgte
10-18-2007, 06:31 PM
i am running a cc hv85 so i should be ok.
ukgroucho
10-18-2007, 06:43 PM
i am running a cc hv85 so i should be ok.
In which case you should definitely change your gearing to suit 7S. If you're gonna buy two or three 4S packs to mix with 3S packs then there is nothing to stop you trying 8S at some stage... well the motor might not like it but I see a Z20 orZ30 in your future :lol: