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Old 09-18-2008, 01:23 AM   #1
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Questions?? Q about LiPo voltage cutoff...

So:

I'm new to LiPo, and I'm attempting to be a bit cautious in my endeavors. I'm running a MM 7700kV/MM ESC with a Venom 4000mAh 2S 7.4V LiPo. From everything I've seen (including the battery's packaging), it says not to run below 6V... is this correct? Even with a bit of timing pulled on the MM, it seems to only want to run for, say, 7-10 minutes, and I might be a bit generous. And in case it makes any difference, I've only run the battery about 4 times now from full charge (4.24V/cell) to 6v. I guess I'm not too sure what to expect as far as "break-in" -- are they similar to the way Nickel Metals break in?

Throw me a bone here, fellas.
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Old 09-18-2008, 06:24 AM   #2
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No break, no discharging just repeaking, and no lipo charger will exept lipo below 6v as this can make the battery go POP!!
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Old 09-18-2008, 08:18 AM   #3
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You are at the limits on that lipo. Be sure to check the temp on it and don't get it over 140 degrees or it will not last very long. Running it to cutoff voltage is not very good either for it to last. You really need the highest c rated batt with the most milliamp rating that your allowed with that hot of a motor. I have ruined some lipos with a 7700 so i know first hand how to kill em.
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Old 09-18-2008, 09:34 AM   #4
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MiMh cut-off voltage is .9-1v. Lipo cut-off is 6v or 3v per cell, i.e. 1C 3v, 2C 6v, 3C 9v. While charging NiMh called peaking, Lipo's called Balancing. A true lipo charger will charge at 1amp & drop down while chargeing. Lipo voltage will not charge over 8.4v. NiMh take 3 charges to equalizes the calls for peaking. Lipo's can be charged anytime, Balancing depends on use.

Temp of cell, NiMh gets hot during peaking. Lipo, Useing a true charger, I haven't had it go over 2% of ambient temp during Balancing.. I run only 5000mah lipo, my charger only puts out 5amps @ 8.4v max, which is good enough for me. Been useing lipo for about a year now, and brushless motor. Happy useing the combination ever weekend races. Follow manufactures maintenance and storage of lipo's. Think you'll be happy with use of lipo's, cuz NiMh is on its way out.

Running Lipo's with Novak or Tekin ESC you set the cut-off voltage. Insures the life of lipo's.
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Old 09-18-2008, 12:01 PM   #5
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Originally Posted by latemodel13 View Post
You are at the limits on that lipo. Be sure to check the temp on it and don't get it over 140 degrees or it will not last very long. Running it to cutoff voltage is not very good either for it to last. You really need the highest c rated batt with the most milliamp rating that your allowed with that hot of a motor. I have ruined some lipos with a 7700 so i know first hand how to kill em.

I think I found the limits last night -- ran it to the 6v cut on the ESC, now the charger not only says "Low Battery Voltage", but even when I connect the balance plug, it tells me "Not Connected". I think I may have smoked it.

What do you recommend I do for a V cutoff? 6.5V? I have to go buy a new battery today, so it would be nice to have some insight on what my setting should be.


P.S. Is my current battery salvageable? Probably not, there goes 70 bucks down the tubes.
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Old 09-18-2008, 12:10 PM   #6
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I also need some help with my LiPo's. I have an SMC 5000 28C lipo which I am using with an LRP TC Spec ESC. I have been told that it has an automatic cutoff but I don't know what voltage it is at. Can anyone help?
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Old 09-18-2008, 06:56 PM   #7
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Quote:
Originally Posted by Fear View Post
I think I found the limits last night -- ran it to the 6v cut on the ESC, now the charger not only says "Low Battery Voltage", but even when I connect the balance plug, it tells me "Not Connected". I think I may have smoked it.

What do you recommend I do for a V cutoff? 6.5V? I have to go buy a new battery today, so it would be nice to have some insight on what my setting should be.


P.S. Is my current battery salvageable? Probably not, there goes 70 bucks down the tubes.
5000mah 11.1v lipo's ran to cut-off of 9v. Charger came with same error. Charger has capability of checking voltage on all three cell of lipo. Voltage of the three cells were 3.58v, 2.96v, 2.96v. Two cells were low, the other 3.58, average of all three cell are 3v. Its fine to recharge the pack. Made a note for future problems, not to concern as of yet. Maybe after 5 cycles I'll check again.
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Old 09-18-2008, 07:00 PM   #8
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I also need some help with my LiPo's. I have an SMC 5000 28C lipo which I am using with an LRP TC Spec ESC. I have been told that it has an automatic cutoff but I don't know what voltage it is at. Can anyone help?
2C 7.4v cut-off @ 6v. 3C 11.1v at 9v.
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Old 09-18-2008, 10:00 PM   #9
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do not set cut off or lipos limit...try to discipline on lipos..stop when u feel power drop...hehehe...there are so many question reg lipos...why?...
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Old 09-19-2008, 04:02 AM   #10
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Quote:
Originally Posted by Fear View Post
I think I found the limits last night -- ran it to the 6v cut on the ESC, now the charger not only says "Low Battery Voltage", but even when I connect the balance plug, it tells me "Not Connected". I think I may have smoked it.

What do you recommend I do for a V cutoff? 6.5V? I have to go buy a new battery today, so it would be nice to have some insight on what my setting should be.


P.S. Is my current battery salvageable? Probably not, there goes 70 bucks down the tubes.
First of all set the voltage cutoff to 6.4v on the mamba max.Second check the voltage on individual cells.At least one (or both cells) must be under 3v thats why the charger says "low battery voltage".If so try to charge the pack without the balancer.If still not charge try to charge for a minute each cell individualy on NiMh mode as 3 cells NiMh.Cells must wake up after this.Stop the NiMh charging and charge the pack as 2s Lipo.If you want you can use the balancer.And never again set the lipo cutoff on the mamba on autolipo on below 6.4v.Good luck.
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Old 09-19-2008, 11:02 AM   #11
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First of all set the voltage cutoff to 6.4v on the mamba max.Second check the voltage on individual cells.At least one (or both cells) must be under 3v thats why the charger says "low battery voltage".If so try to charge the pack without the balancer.If still not charge try to charge for a minute each cell individualy on NiMh mode as 3 cells NiMh.Cells must wake up after this.Stop the NiMh charging and charge the pack as 2s Lipo.If you want you can use the balancer.And never again set the lipo cutoff on the mamba on autolipo on below 6.4v.Good luck.
Thanks, that's the exact info I got from the LHS.
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Old 09-20-2008, 03:17 PM   #12
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Quote:
Originally Posted by Fear View Post
I think I found the limits last night -- ran it to the 6v cut on the ESC, now the charger not only says "Low Battery Voltage", but even when I connect the balance plug, it tells me "Not Connected". I think I may have smoked it.

What do you recommend I do for a V cutoff? 6.5V? I have to go buy a new battery today, so it would be nice to have some insight on what my setting should be.


P.S. Is my current battery salvageable? Probably not, there goes 70 bucks down the tubes.

Some Lipo chargers will allow you to do a manual charge at .1 - .25 amps. I did this to mine and brought it back to life. Becareful as doing this could cause an explosion. I used a flameproof sack.

Does anyone know which charges will allows the "manual charge"? I know the Cell Pro 4S does, but anything else?
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Old 09-20-2008, 03:18 PM   #13
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Here is another charger that might work.

http://www.hobbycity.com/hobbycity/s...harger_(lipoly)
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Old 09-22-2008, 05:17 AM   #14
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bump
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Old 09-22-2008, 06:32 AM   #15
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bump

wtf? why are you bumping this?
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