View Full Version : battery question

07-29-2008, 10:16 AM
just been out driving and testing props ( x438,x437 and x640) on my H&M drifter S. 8XL and hydra 240. 2X8,4 4500mah in serie (the OSE ones).

when running the boat with graupner k series 40mm the batteries would be around 105f. after a 4-5 minute run.
now that i tested the mettal props the batteries are 140f after 3 minutes. do even the small x438 and x637 pull that much more amp then a k series 40mm ?

charged all 6 batteries now and they all drained about 2000-2500 mah.
would the air temp cause this ? ( 93f in the air 77 in the pond)

07-29-2008, 11:07 AM
What is your system voltage?
Are those metal props balanced and sharpened?

07-29-2008, 11:10 AM
16,8v ( 2x 8,4)
yes they are by cmdi racing

07-29-2008, 11:23 AM
Are you getting noticeable increase in speed with metal props?

07-29-2008, 11:50 AM
there are more speed with the 637 and the 640. its less speed with the 438. but the batteries are just as hot with the 438.
the goal it self was to get more runtime. but even with the x438 there is less runtime then with the k40

07-29-2008, 12:31 PM
I would stay with k40 then, seems like it's more efficient. When trying different props its very helpful to measure your current draw with the data logger. Eagle flight v3 is what i used to use. Just make sure it's waterproofed well. Mine died from water getting in.