Joined: 02 Jan 2008
Posts: 18
Location: blacktown syd
stall current questions
does anybody no the stall current of an oatly 24v scooter motor?? i no the runing current is 6a
can they be run direct from the shaft no reduction??
Also i have a 24v victor 885 speed controller with a surge curent of 200a for 2 sec and 300a for 1, so ma ques for that IS... if i hook up both of the 24v motors to ma speed controller runing of 1x 24v 4.2 ah battle pack will that fry my speed controller ?? considering it is stil only getting 24v frm the batt pack??
ty all.
-duff-
Tue Jan 29, 2008 9:39 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
It sounds like you are using the 24V, 100W scooter motor. I don't know what the stall current is, but the Victor 885 will probably only get warm if you stall the motor. I have run my 885 controllers into shorted drill motors and even after the motor has melted, the ESC is barely warm. Would that be a 2.4AH battlepack rather than 4.2? If so it can't supply more than 50A Continuous and perhaps 70A surges - that means the limiting factor is the cells and the Victor should always be safe under normal conditions. Short the wiring or the FET tabs and all bets are off... _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Tue Jan 29, 2008 10:15 pm
maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
We don't have good experiences with NiMH packs of 4200mAh.
They tend to melt their soldering before anything else goes.
The 3600 Sanyo or the 3700mAh GP's are our prefered packs
Tue Jan 29, 2008 11:05 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
you can get a rough idea with a multi meter.
put it in the lowest ohms mode.
put the probes together and you will get a base line (say 0.7 ohms or so) then measure the resistance of the motor. Give the motor a really really slow turn (just a little) and see if you hit a lower spot. Subtract the leads from the motor (1.3 - 0.7 = 0.6 ohms) volts / resistance = amps ergo in this example 24/ 0.6 = 40A.
That's going to be wrong but its probably within 20-30% or so. _________________ Mechanical engineers build weapons, civil engineers build targets
Tue Jan 29, 2008 11:36 pm
kkeerroo Experienced Roboteer
Joined: 17 Jun 2004
Posts: 1459
Location: Brisbane
quote:Originally posted by Valen:
you can get a rough idea with a multi meter.
put it in the lowest ohms mode.
put the probes together and you will get a base line (say 0.7 ohms or so) then measure the resistance of the motor. Give the motor a really really slow turn (just a little) and see if you hit a lower spot. Subtract the leads from the motor (1.3 - 0.7 = 0.6 ohms) volts / resistance = amps ergo in this example 24/ 0.6 = 40A.
That's going to be wrong but its probably within 20-30% or so.
Also don't forget to subtract the meters test leads from the total. Touch the probes together and you'll get reading of 0.4 or 0.5ohms or such unless your using really high quality leads. Even my good leads read 0.2 on a good day but that may just mean my meter needs calibrating. _________________ Get Some!!!
Secretary of the Queensland Robotics Sports Club inc.
Wed Jan 30, 2008 8:39 am
Knightrous Site Admin
Joined: 15 Jun 2004
Posts: 8511
Location: NSW
quote:Originally posted by Valen:
you can get a rough idea with a multi meter.
put it in the lowest ohms mode.
put the probes together and you will get a base line (say 0.7 ohms or so)
then measure the resistance of the motor. Give the motor a really really slow turn (just a little) and see if you hit a lower spot.
Subtract the leads from the motor (1.3 - 0.7 = 0.6 ohms)
volts / resistance = amps ergo in this example 24/ 0.6 = 40A.
That's going to be wrong but its probably within 20-30% or so.
Joined: 17 Jun 2004
Posts: 1459
Location: Brisbane
I could have sworn that wasn't there this morning. Hmmm. Maybe I need more sleep. _________________ Get Some!!!
Secretary of the Queensland Robotics Sports Club inc.
Wed Jan 30, 2008 4:35 pm
iluvmatools
Joined: 02 Jan 2008
Posts: 18
Location: blacktown syd
no no its def a 4.2 ah lol i ordered a 3.8 ah battle pack ffrom robot market place but got 4.2 ah booyeah it cost a small fortune so i would wanna hope so lol:) ty afor the posts
Wed Jan 30, 2008 5:19 pm
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