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Old 08-26-2008, 06:36 AM   #16
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I run my Mamba Max with a cut-off setting of 7V, but I've never actually gotten to it. I might as well turn it off in the future (maybe).

What I did was fully charge my 5000 mAh Lipo and then run the car for 5 mins. Then I checked the voltage at rest to check how much charge percentage the battery has. I've also confirmed that it was accurate by fully recharging the battery from that point and seeing how much charge it accepted back (thus I know how much I've used up).

I've never ran it below 3.75v/cell and never used up more than 3800 mAh out of 5000 so far. That's why I've never hit the 7V cut-off.

I doubt many of you would want to be that careful with your Lipos, but that's how I did it.

After a few cycles I found out I have about 35~ minutes of track time (racing or practicing) and that'll use up no more than 4000 mAh (80% of its full charge). So now I mostly run with a timer (on my watch) and count the total minutes ran so far. Never go past 35, and it's all good.
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Old 08-26-2008, 07:09 AM   #17
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Have you tried the LOA from www.apogeepacks.com
It is not a cut off but a loud obnoxious alarm....
If you run without a cut off you may only ruin your lipo but depending where and how you charge the lipo you may hurt yourself or you may hurt others or property...
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Old 08-26-2008, 07:14 AM   #18
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I have run a lipo without any cutoffs but like everyone has told you.....you must remove it from the track the minute you feel a "dump" lack of performance. Now this lack of performance is very slight and a new racer may not be able to notice this drop. When this "dump" happened, my cells were in the 3.6-3.8 range. I was running 3S lipo's. Call your esc manufacturer and see what type of cell cutoff they recommend. Good luck.
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Old 08-26-2008, 11:57 AM   #19
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[QUOTE=Drift_Buggy;4774407]Suppose you could come into the pits and check the voltage with a multimeter. Going by when it starts to drop hasn't got to do with the voltage but the mah.



Huh?
Mah is the number that shows how long your voltage should last, higher number = longer run times.
When your car slows, voltage has dropped.
You can see how long it ran and have an idea of what that combo of motor and battery will do.
Put it back on the charger and it will tell you where the voltage is.
Now you know how long it ran and where the voltage dropped to for that motor.
If you pull it as soon as it slows you will find it will be between 7.0 and 6.5 volts. Very safe voltage.
My Novak GTB speed control with lipo cutoff shuts off at about 6.5 volts.
The previous post is very true, if you run a brushed motor for a long time it will get seriously worked so limit your runtime with them.
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Old 08-26-2008, 12:05 PM   #20
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Product literature I've see recommends voltage cut-off for LiPo at 3.0V per cell, so 6.0V for a 2S LiPo.

I'm wondering if the voltage drop is more noticable in a brushed setup.

When I'm running my ST with brushless 5700Kv, the truck still has reasonable speed on a small by the time it hits the 6.0V cutoff. I mostly notice it is slow because the truck becomes easier to drive. But it definately is not running at a crawl at that point. With my 5000 mAh LiPo, I may even be able to run at that slower speed for another 3-4 minutes or so before cutoff. Now that I've had several runs with the LiPo I'm starting to recognize earlier when power starts dropping off. I don't want to risk running without some kind of cutoff or alarm.
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Old 08-26-2008, 12:17 PM   #21
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Would you like to use a product that merely emits a loud alarm once you hit a specified low voltage?

Quote:
Originally Posted by VVRC View Post
The problem is; is that I own a Slash and the ESC doesn't like LVC's....trust me i've tried them all....So I bought a new Tazer 15T ESC, but I like my XL-5 waterproof one better.....And I'm having some weird problems with my LVC I have now (Common Sense Cellshield)
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Old 08-26-2008, 12:31 PM   #22
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Regardless of Brushed or Brushless you should never run your car without a cutoff...Eventually you will run it below 3.0V per cell and it will Puff...
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Old 08-26-2008, 01:08 PM   #23
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i ran mine w/o a cut off and u know when u loose power i now have it set in the speedo and i have never hit the cut off u should fell it be for the cut off turns on
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Old 08-26-2008, 03:33 PM   #24
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I have flown 3D for years and never used a cutoff, (nothing worse than your esc cutting off while 5' off the ground in a hover) but I stop flying as soon as a feel a drop in power.

In surface I try to use a cutoff when I can but when I haven't been able to I do a couple of things,
First I run my car for a set time that I know will not drain the battery fully, say 6 min, then I charge the battery back up to see how much I used. I then use those figures to calculate how long it should run on a charge and use a timer set a few minutes short of my figures to protect my pack.

Second I pay very close attention to any drop in power and pull off asap.

Like most said, use a cutoff if at all possible but you can run without one if you are carefull. Also if you run cheap batteries you will have many more problems running without a cutoff.
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Old 08-26-2008, 04:07 PM   #25
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Quote:
Originally Posted by VVRC View Post
The problem is; is that I own a Slash and the ESC doesn't like LVC's....trust me i've tried them all....So I bought a new Tazer 15T ESC, but I like my XL-5 waterproof one better.....And I'm having some weird problems with my LVC I have now (Common Sense Cellshield)
Just a point of reference: Novak says their cutoff doesn't work with the new blue-cased XL-5 in the Slash, but does work with the older gold-cased XL-5. Apparently they're working on a fix. Anyone know of a cutoff that works with the blue Slash XL-5?
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Old 08-26-2008, 04:07 PM   #26
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What does 3D stand for?...As opposed to flying in 2 dimensions?
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Old 08-26-2008, 08:29 PM   #27
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Quote:
Originally Posted by haulin79 View Post
What does 3D stand for?...As opposed to flying in 2 dimensions?
Yeah, pretty much. 2D as in mostly going in the same horizontal plane, just turning left and right and changing the elevation by a little. 3D means highly acrobatic flight, with no regard to where the horizontal plane is.

I'm just guessing based on what I've seen. I've heard them refer to 4D flight when the plane has a variable-pitch-prop, meaning it can fly forward or even backwards.

It's just a name though. It's not a precise scientific term.
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Old 08-26-2008, 09:08 PM   #28
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Quote:
Originally Posted by haulin79 View Post
Would you like to use a product that merely emits a loud alarm once you hit a specified low voltage?
That would work!!! Like this one?
http://pfmdistribution.com/secure/sh...asp?itemid=203
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Old 08-26-2008, 09:11 PM   #29
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Quote:
Originally Posted by ruf View Post
Just a point of reference: Novak says their cutoff doesn't work with the new blue-cased XL-5 in the Slash, but does work with the older gold-cased XL-5. Apparently they're working on a fix. Anyone know of a cutoff that works with the blue Slash XL-5?
Simple answer......No!

For the past two weeks it has been my sole mission in life to find an LVC that works.....can find one!
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Old 08-27-2008, 05:40 AM   #30
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Yeah I think I killed one of my lipo's from running it too low in my Slash. The "stop when it starts to loose power" sounds good in theory, but not in real life
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