139 jockey
Member
I have just finished building my second multi, and DW SJ6 with Axi 4120/20, 14x7 props, WKM. Flew for the first time yesterday and seems to be going well, obviously still a lot of tuning to do yet though.
I am running 2x 5500 MHA 5s batteries in parallel, so about 11000mha total @ 18.5V. I put a clamp meter on the power leads yesterday and established it is using 50 amps in the hover ( no payload, IE camera ) thus lets say 8800 mah usable (%80 of battery capacity) / 50 amps = 10.5 minuites. This is a bit shorter than I hoped for given there was no pay load.
The questions for the gurus out there are
1) Is my maths OK? I am totally new to this and if any one can correct me, hence educate me, then congratulation. Unfortunatly I am almost uneducateable.
:black_eyed:
2) Is this about what other guys are getting endurance wise?
3) It seems to me that running @ 6s( IE 22.2V) is more efficent. I realise that engine RPM will increase ( rated @ 450 KV so 450*3.7 extra volts = 1665 extra possible RPM) but that shouldn't change the RPM that the engines are auctually operating at. IE the props will spin @ the same speed as now with 5 s to produce the same thrust.
4) Given the above I would like to consider the possibility of going to 6s. A 8000 MAH 6s battery weighs about 1100 grams, where as a 3 s 8400 MAH weighs only 750.Is it a reasonable concept to run 2x 8400 MAH 3s batteries in series giving 22.5v, hence more efficent, whilst saving a lot of weight?
There are probably pages already written about this basic stuff for begineers like me so if no one can be bothered replying please point me in the direction of any existing threads.
Cheers,
Rick.
I am running 2x 5500 MHA 5s batteries in parallel, so about 11000mha total @ 18.5V. I put a clamp meter on the power leads yesterday and established it is using 50 amps in the hover ( no payload, IE camera ) thus lets say 8800 mah usable (%80 of battery capacity) / 50 amps = 10.5 minuites. This is a bit shorter than I hoped for given there was no pay load.
The questions for the gurus out there are
1) Is my maths OK? I am totally new to this and if any one can correct me, hence educate me, then congratulation. Unfortunatly I am almost uneducateable.
:black_eyed:
2) Is this about what other guys are getting endurance wise?
3) It seems to me that running @ 6s( IE 22.2V) is more efficent. I realise that engine RPM will increase ( rated @ 450 KV so 450*3.7 extra volts = 1665 extra possible RPM) but that shouldn't change the RPM that the engines are auctually operating at. IE the props will spin @ the same speed as now with 5 s to produce the same thrust.
4) Given the above I would like to consider the possibility of going to 6s. A 8000 MAH 6s battery weighs about 1100 grams, where as a 3 s 8400 MAH weighs only 750.Is it a reasonable concept to run 2x 8400 MAH 3s batteries in series giving 22.5v, hence more efficent, whilst saving a lot of weight?
There are probably pages already written about this basic stuff for begineers like me so if no one can be bothered replying please point me in the direction of any existing threads.
Cheers,
Rick.
