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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> RE: Welcome to the FMA Direct - Kokam LiPo Support Forum
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RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 8/21/2005 12:23:35 AM   
djcb


 

Posts: 5
Joined: 12/4/2004
From: Macungie, PA, USA
Status: offline 		What is the safe cut-off voltage for a two cell Li Poly that should be programmed into an ESC?

(in reply to lthibault)
       Post #: 76

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 8/23/2005 1:22:38 PM   
Fred Marks


 

Posts: 180
Joined: 8/5/2003
From: Frederick, MD, USA
Status: offline
quote:

ORIGINAL: djcb

What is the safe cut-off voltage for a two cell Li Poly that should be programmed into an ESC?


5.7 to 6V. Most ESCs are set for 5.2V and that is a little low. If you set the cut-off for 6v= 3V/cell, just be aware that certain cells exhibit a "sag" in voltage if full throttle is applied abruptly. If that happens, compromise by dropping cut off to 5.7V. However, the more appropriate action is to open throttle slowly to the max that does not cause cut off on takeoff or launch. Tale-offs made by advancing throttle to a little less than full are more realistic than "jackrabbit" takeoffs.


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Electroman

(in reply to djcb)
       Post #: 77

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 8/25/2005 9:30:57 AM   
Lazyflier


 

Posts: 40
Joined: 9/26/2004
From: Lancaster, CA, USA
Status: offline 		Hearing from some people that Lipolys need a break in period. Have not seen this info in the packs. Is it true or just a false rumor that needs to be clarified? I have not used a break in routine on my packs and they seem to be fine.

(in reply to Fred Marks)
       Post #: 78

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 8/25/2005 7:16:05 PM   
Greg Covey



Posts: 4450
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		A very small benefit derives from break-in of cells by running multiple cycles of low charge rate and low discharge rate. LiPo cells are not nearly as affected by this as, say, NiMH cells. If one wishes to take the time to cycle a pack before first use, a small fraction of one percent of normal capacity is gained for up to 10 cycles. However, the gain seems hardly worth the time it takes and the fact that you have taken ten cycles off the life of the pack to do it. At most, it is recommended that the pack not be hit with max charge rate or max discharge rate for the first few runs. This gives cell chemistry an opportunity to form in the absence of high temperature incurred by running at high discharge rate.

In practice, I always charge at 1C and just go fly!



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(in reply to Lazyflier)
       Post #: 79

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 8/25/2005 7:55:24 PM   
jatoboy


 

Posts: 5
Joined: 5/7/2005
From: Princeton, IL, USA
Status: offline 		I'm fairly new and I need some help on my charge settings for my Kokam 1500 lipo pack. I have a MRC Super Brain 969. I need to know how much amps to set it at. Also what about max voltage. Please let me know if there is anything else I need to know.

(in reply to Greg Covey)
       Post #: 80

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 8/26/2005 1:12:43 PM   
Red Scholefield



Posts: 5033
Joined: 12/8/2001
From: Newberry, FL, USA
Status: online
quote:

ORIGINAL: jatoboy

I'm fairly new and I need some help on my charge settings for my Kokam 1500 lipo pack. I have a MRC Super Brain 969. I need to know how much amps to set it at. Also what about max voltage. Please let me know if there is anything else I need to know.



WARNING

The MRC 969 is not suited for use with Lithium batteries. It has no charge control and it has the real danger of causing the cells to burst into flame.


_____________________________

Red S.
AMA 951 Leader Member
Disclaimer: What I have written here are my thoughts and in no manner shape or form reflect the views of RCU

(in reply to jatoboy)
       Post #: 81

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 8/26/2005 3:25:03 PM   
jatoboy


 

Posts: 5
Joined: 5/7/2005
From: Princeton, IL, USA
Status: offline 		Ok, thanks a lot. A little after i posted the message I found some posts that said the same thing.

< Message edited by jatoboy -- 8/26/2005 8:49:09 PM >

(in reply to Red Scholefield)
       Post #: 82

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/10/2005 2:28:34 PM   
KINGS KID


 

Posts: 18
Joined: 9/10/2005
From: NILES, MI, USA
Status: offline 		I'M RUNNING AN ASSOCIATED T4 BRUSHLESS, AND AM WONDERING HOW LONG RUN TIMES WILL BE WITH THE SCORPION 64'S AND HOW LONG BATTERY LIFE (# OF CHARGES), I RUN THIS TRUCK OFFROAD.
THANKS, KINGS KID

(in reply to RCadmin)
       Post #: 83

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/10/2005 6:34:48 PM   
Greg Covey



Posts: 4450
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		I can't tell you how long the run time will be without knowing the average current draw.

As for the # of charges, the number will be between 200 and 500 charges. The more you draw near 64amps, the warmer the pack gets which reduces your lifespan on the pack.


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(in reply to KINGS KID)
       Post #: 84

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/11/2005 2:39:21 AM   
KINGS KID


 

Posts: 18
Joined: 9/10/2005
From: NILES, MI, USA
Status: offline 		OUR AMP DRAW IS BETWEEN 20&25 AMPS
THANKS KINGS KID

(in reply to Greg Covey)
       Post #: 85

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/14/2005 1:20:58 AM   
Greg Covey



Posts: 4450
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		Let's take the worst case of 25amp draw on a 6.4AH Scorpion pack.

25amps for 1 hour = 25AH

Divide 25AH by 6.4AH to get 3.9

Divide 1 hour by 3.9 to get .256 hours

Multiply .256 by 60 to get 15.4 minute run time

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(in reply to KINGS KID)
       Post #: 86

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/16/2005 6:09:21 AM   
Slocan Floats


 

Posts: 8
Joined: 5/3/2005
From: New Denver, BC, CANADA
Status: offline 		I crashed and bent my Kokam battery packs today , can I staighten them and will they be safe ?There is no bheat and the voltages is up where it should be. See picture.[image][/image]

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(in reply to RCadmin)
       Post #: 87

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/16/2005 5:09:39 PM   
Fred Marks


 

Posts: 180
Joined: 8/5/2003
From: Frederick, MD, USA
Status: offline
quote:

ORIGINAL: Slocan Floats

I crashed and bent my Kokam battery packs today , can I staighten them and will they be safe ?There is no bheat and the voltages is up where it should be. See picture.[image][/image]


The integrity of your pack has clearly been compromised. It would be unwise to continue use of the pack. To dispose of the pack, please observe the following :

1. Store the pack in a safe area where no flammable materials are present. A metal or ceramic storage container with a cover is best. A closed charcoal grill is a good storage place until you have neutralized the cells.
2. Place a light load on the cells via series connected 12V light bulb(s) or a motor and check voltage occasionally to see that voltage goes well below 2.5V per cell. This is a very important step as a charged cell has tremendous stored energy.
3. With voltage depleted, and working at the charcoal grill, use a fresh # 11 hobby knife blade as you would a scalpel to make a small incision in the edge of each cell. Cut lightly as if cutting a tummmy just over an intestine! This is so that the plates are not penetrated.
4. Place the cells in a container of salt water for at least 24 hours. Then you may dispose of the cells in the trash.
5. Contact Customer Service at FMA Direct with a copy of your purchase information to receive a personal courteous solution to your loss.
6. When you replace the pack, be certain to provide a protective sheath of FMA IMPAD around it. Exposed lithium packs can be risky. You risk damaging the pack in the event of a crash which reduces your investment security at the same time as it increases the risk of fire. I still crash on occasion so my plan for protecting the exposed packs is to wrap them in a super impact absorber from FMA Direct called IMPAD. It is packaged in 12" x 6" sheets and can protect an egg from cracking when the egg is dropped on to IMPAD at four feet off the ground.

When pack heat is not an issue (e.g. you are not stressing the pack in the application), the pack can be wrapped in an IMPAD pouch using a simple Velcro strap to hold the pack inside the pouch. When pack heat is an issue, IMPAD end-caps can be made to allow air flow through the cells in the pack while protecting it from a blunt force. The new Skyvolt packs from FMA Direct allow air to flow between the cells for maximum performance and longevity. For either technique, I used clear shipping tape to form the pouch or caps.

(To view pictures of a pack so protected click below and open Page 1, Post #6)

http://www.rcgroups.com/forums/showthread.php?t=381477







< Message edited by Fred Marks -- 9/16/2005 5:19:18 PM >

_____________________________

Electroman

(in reply to Slocan Floats)
       Post #: 88

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/18/2005 6:26:17 AM   
mikekomm



Posts: 167
Joined: 8/26/2002
From: Northridge, CA, USA
Status: offline 		Two questions. First, in a previous post, did you recommend storing our LIPO cell packs in the freezer?

Second, what is the technology that allows the Skyvolt system to charge Lipo's at a 3C rate (20 minutes).

(in reply to lthibault)
       Post #: 89

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/18/2005 7:34:37 PM   
Fred Marks


 

Posts: 180
Joined: 8/5/2003
From: Frederick, MD, USA
Status: offline
quote:

ORIGINAL: Jacket Man

Two questions. First, in a previous post, did you recommend storing our LIPO cell packs in the freezer?

Second, what is the technology that allows the Skyvolt system to charge Lipo's at a 3C rate (20 minutes).



# 1 I said that you can store them in refrigerator, not a freezer. Thye must be hermetically sealed and should have a dessicant in with them so that no moisture is formed. I do not see any significant advantage to storage in a refig but they must not be stored in a hot area. the trunk of your car is verboten.

2. That technology is proprietery and part of the way we stay two years ahead of the pack.

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(in reply to mikekomm)
       Post #: 90

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 9/18/2005 8:25:04 PM   
mikekomm



Posts: 167
Joined: 8/26/2002
From: Northridge, CA, USA
Status: offline