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Old Feb 08, 2004, 07:48 PM
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Middle TN
Joined Sep 2003
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Jeti 18 -3 cutting off at 9.5 volts

I just put an AXI 202826 in a sig lil Rascal with a jeti 18 -3 esc
trouble is when running on a 8cell 1100 ma nimh battery
the esc starts cutting out bad at 9.5 so a full charge lasts about 1 minute.
but if i put in one of my 11 volt lipo's in it then its like a rocket
not to scale when a lil rascal has unlimited vertical and is outa site in a couple seconds.
but the 9.5 cuttoff is nice on that since the lipo pack should not go under 9volts
if i put my 2cell 7.4 lipo in it flys for about 30 seconds then the esc cuts out.
help anyone know how to change the voltage cutoff on this esc??
nothing in the paper that came with it.

Thanks in advance
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Old Feb 09, 2004, 12:24 AM
BEC
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Auburn, Washington USA
Joined Jan 2001
12,939 Posts
How do you know it's cutting at 9.5V? If it were set there it should not even run on a two-cell LiPoly.

Which 18-3P is it? Red shrink wrap, gold label, white label? Black shrink wrap (Jeti/Hacker Master)? Or blue shrink wrap, silver label (Advance)? All but the new Advance don't have any special LiPoly setting and so should be cutting at about half the initial battery voltage or 5.3V, whichever is higher......
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Old Feb 09, 2004, 04:11 PM
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Middle TN
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Quote:
Originally posted by BEC
How do you know it's cutting at 9.5V? If it were set there it should not even run on a two-cell LiPoly.

Which 18-3P is it? Red shrink wrap, gold label, white label? Black shrink wrap (Jeti/Hacker Master)? Or blue shrink wrap, silver label (Advance)? All but the new Advance don't have any special LiPoly setting and so should be cutting at about half the initial battery voltage or 5.3V, whichever is higher......
Red shrink wrap, gold label.
if i put an 8cell pack in and run it for about 30-45 seconds it will start cutting off, i pull the pack check voltage wit a digital meter
it says 9.3 - 9.6 volts on average.
if i put a 2 cell lipo it runs about 30 seconds and starts cutting out
voltage check shows 7.1 - 7.2 volts
its like no matter what packs i put in in runs about 1 volt out and cuts out.
my 3 cell lipo pack runs for over 20 minute or more before it starts cutting out at about 9.4 volts
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Old Feb 09, 2004, 04:58 PM
BEC
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Auburn, Washington USA
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Ah - but the voltage of the battery, unloaded, is MEANINGLESS in this situation. What the ESC senses is the voltage under load.

Do you have any idea how much current it's drawing? (What prop on the 2208/26? And are you using the same prop on all three batteries?)

Specifically what batteries are they? There's a huge disparity in how much current various makes/capacities of batteries can deliver, whether they be lithium or nickel-based.

This sounds like a classic case of the battery not being up to the demand being put on it by the motor/prop combination and sagging to cutoff voltage quickly.
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Old Feb 09, 2004, 05:44 PM
Castle Tech
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Olathe, KS
Joined Aug 2003
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what BEC said...voltage under load is the real culprit here...BTW...20 minutes should be PLENTY of what you'd expect from a lipo pack.
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Old Feb 09, 2004, 06:42 PM
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Middle TN
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Quote:
Originally posted by BEC
Ah - but the voltage of the battery, unloaded, is MEANINGLESS in this situation. What the ESC senses is the voltage under load.

Do you have any idea how much current it's drawing? (What prop on the 2208/26? And are you using the same prop on all three batteries?)

Specifically what batteries are they? There's a huge disparity in how much current various makes/capacities of batteries can deliver, whether they be lithium or nickel-based.
using a 7x5E prop on all packs

pack #1 Kokam 2cell 640mah 7.4 volt runs about 20 - 40 seconds then cuts out.

pack #2 8cell nimh 1100 hobby lobbys b11x8s
ran 5 minutes wot a few minutes ago on bench then starts slowing down about 1 minute later it starts the cutting off, i can live with that wouldnt fly the lil rascal wot anyways so that should stretch it to 8 - 10 minutes normal.

pack #3 11.1 volt 1600 mah platinum polymer lipo after about 20 minutes of wot and half throttle it starts to slow land and check voltage its about 9.5 volts

have no idea how many amps i'm pulling.

Thanks
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