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Low Voltage Cut-off too low?

Old 01-04-2009, 10:59 PM
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meesier42
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Default Low Voltage Cut-off too low?

So I went flying today, and I ran the battery to the low-voltage cut-off, unfortunately, when I went to go charge it, each cell was well below the 3.2V cut-off.

I have a Mojo Extreme RC 20A ESC and a Scorpion 2215-18 Motor, How do I adjust the Low-Volt cut-off to the appropriate cut-off??
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Old 01-04-2009, 11:11 PM
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Murocflyer
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3.0 volts is LVC on most ECS. Let me have a look at that one.

Frank
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Old 01-04-2009, 11:16 PM
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It looks like 3.2V is the correct LVC for newer High C LiPos. This comes from the Man.

http://www.rcgroups.com/forums/showthread.php?t=466758

He also recommends a soft LVC. I can't find that particular ESC though to see if it can be adjusted.

Frank
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Old 01-04-2009, 11:21 PM
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meesier42
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its this one
http://store.extremercproducts.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=EPR&Product_Code=SC20A&Category_Code=C31


I got it as part of the power kit from DW Foamies
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Old 01-04-2009, 11:26 PM
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I wonder, since I did most of the flying today at 1/3-1/2 throttle, is it possible that the soft cut-off feature wasn't noticable since I was a low throttle settings? and the first sign of LVC that I had was the hard cut-off at 3.0V.
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Old 01-04-2009, 11:37 PM
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Originally Posted by meesier42 View Post
I wonder, since I did most of the flying today at 1/3-1/2 throttle, is it possible that the soft cut-off feature wasn't noticable since I was a low throttle settings? and the first sign of LVC that I had was the hard cut-off at 3.0V.
Flying at low throttle does not change LVC but since there is way less battery 'voltage sag' when it DOES hit LVC the real voltage will be lower. Soft cut-off is pretty pronounced.

Did you look a the specs?

[Low Voltage Cutoff: Yes]


Now that is real reassuring information.

Q: Say there Mr. engineer, does your ESC have an LVC?
A: Absolutely, it certainly does.
Q: And that setting is....?
A: Oh, a good one, yes, a very good one.


They say it's programmable. You didn't get anything from them?


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Old 01-04-2009, 11:40 PM
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meesier42
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since it came with the power kit, I didn't get any paper work on the ESC or the motor. I see that it is programmable, but I have no idea how to program it, or even if I can set the LVC to 3.2V cut-off
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Old 01-04-2009, 11:46 PM
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Shoot DWF an email and ask if no one has any experience with those Mojos. DWF's customer service is top notch.

Frank
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Old 01-04-2009, 11:56 PM
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From the DW site:
http://www.shop.depronwest.com/produ...5&productId=47


Low Voltage Cutoff/Cell Type

Auto Calibrating Variable End Point

Those are like the Great Planes type. They change based on initial voltage. The GP are set at 67%. Do some math > they are awful. If you fly awhile, remove the battery, and start again flying that to LVC you take your lipo out. Personally I think the GP type ESC are so poor they should be boycotted into non-existence. A LOT of the current crop of ESC are poor. Recommend you read instructions for ANY you plan to buy. If you can't find instructions or can't understand them....well, I wouldn't go there.

It will NOT be voltage programmable. Your only viable options are to discard or fly by time, a better option anyway.
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Old 01-05-2009, 12:19 AM
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meesier42
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I found the write up the Mike has posted on his forum, appartently the cut-off is set to 3.0V per cell, which is exactly where it cut-off, so, it looks like I maybe looking for a different ESC, I would rather not destroy my brand new 20C Lipos. Maybe I'll just set the timer on my radio and only fly for 6-7 minutes and avoid the LVC altogether.
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Old 01-05-2009, 01:33 AM
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Originally Posted by meesier42 View Post
I found the write up the Mike has posted on his forum, appartently the cut-off is set to 3.0V per cell, which is exactly where it cut-off, so, it looks like I maybe looking for a different ESC, I would rather not destroy my brand new 20C Lipos. Maybe I'll just set the timer on my radio and only fly for 6-7 minutes and avoid the LVC altogether.
That's the best way to do it. I usually fly to about 25%, note the minutes on that and then subtract one just in case.

Frank
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