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RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 4/6/2005 11:36:15 PM   
eggvoel


 

Posts: 42
Joined: 2/21/2005
From: Manchester, ME, USA
Status: offline 		Thanks Luke and Mark. I wasn't going to charge them together, just try to boost the voltage for flying. But, I'm not going to experiment. Larry

(in reply to lthibault)
       Post #: 26

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 4/21/2005 9:23:15 PM   
Greg Covey



Posts: 4381
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		Hi Luke,

To answer your "three general questions about Kokam Li-Poly batteries":

The best maintenance for Lithium cells is not always the most practical. Ideally, you want to keep them at 1/2 charge (3.6v/cell) and in a cool if not cold place. This ensures their capacity over long term. For me, this is a total pain in the neck so I typically will ignore all of it and keep them charged so they are ready to go when I am. My R/C time is limited so the Lithium cells must meet my schedule and one of the biggest assets of Lithium is that you can charge it weeks in advance and they will stay ready to fly when you are.

No need to re-peak Lithiums after a week or two. Now, that being said, we are creatures of habit and if you've been in electric flight long enough, you just don't feel right until you have checked each pack's charge before going out. It can be a hard habit to break!

Always set the charging rate around 1C or around the pack capacity. This does not have to be accurate but don't use 2C. Also anything under 1C is just as good...it just takes longer.

Good luck!


_____________________________

Visit my Web Hangar at www.gregcovey.com/rc.htm

(in reply to eggvoel)
       Post #: 27

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/5/2005 9:00:45 AM   
mega quake


 

Posts: 1
Joined: 5/5/2005
From: , WA, USA
Status: offline 		hello I know your not polyquest but I'm sure you can help I have a pq 20c 11.1v 1800mah 3s lipo battery and I was woundering what an afordable charger would be I have a pcm gaurd to insure I do not toast the batt just alittle confused alot of the chargers skip my mah does this matter they go 1500mah 1700mah 2000mah will chargers like this work for me the tp425 is like this but the multiplex 2010 says it is automatic just want to protect my investment

(in reply to RCadmin)
       Post #: 28

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/6/2005 3:53:00 AM   
Fred Marks


 

Posts: 180
Joined: 8/5/2003
From: Frederick, MD, USA
Status: offline 		Mega: Our first and foremost concern is that you be successful with Li Po cells. We have been the primary promoter and developer of them for the RC application for three years; long before Polyquest was ever known. Your needs now and for some time will be met admirably by the FMA/Kokam LIPO 503 charger that you may study at www.fmadirect.com You may then purchase on-line or order from one of our fine distributors or your local hobby shop.

_____________________________

Electroman

(in reply to mega quake)
       Post #: 29

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/13/2005 8:48:03 PM   
whvandy


 

Posts: 41
Joined: 10/20/2002
From: Gap, PA, USA
Status: offline 		I am converting a Kyosho Me-109 40 to electric. I have a Mega ACn 22/45/3 motor and gearbox. (gear ratio unknown). Turning a 12-6 3-bladed prop. Castle Creations ESC and was trying to use a 14 cell NiMH sub c pack. The pack is to heavy I think, and doesn't turn the motor very fast. I'm very new to trying electric conversions, but I'm thinking maybe changing to a brushless motor, and for sure going to Li-Poly. What are your suggestions for motor and battery applications? Thanks, William Vandenberg whvandy@yahoo.com

(in reply to Fred Marks)
       Post #: 30

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/14/2005 6:25:03 PM   
Greg Covey



Posts: 4381
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		Hi William,

I'm a bit confused by your question because the Mega ACn 22/45/3 is a brushless motor. Is this what is currently in your .40-size Me-109 or did I misinterpret something?

You can easily convert from a 14-cell NiCd/NiMH pack to a 4-cell Lithium pack. Since the Mega motor is capable of drawing 40-60amps, I would a 4-cell Kokam 3.2AH pack because it can deliver 64amps continuous current.



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(in reply to whvandy)
       Post #: 31

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/15/2005 12:35:14 AM   
Fred Marks


 

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

ORIGINAL: whvandy

I am converting a Kyosho Me-109 40 to electric. I have a Mega ACn 22/45/3 motor and gearbox. (gear ratio unknown). Turning a 12-6 3-bladed prop. Castle Creations ESC and was trying to use a 14 cell NiMH sub c pack. The pack is to heavy I think, and doesn't turn the motor very fast. I'm very new to trying electric conversions, but I'm thinking maybe changing to a brushless motor, and for sure going to Li-Poly. What are your suggestions for motor and battery applications? Thanks, William Vandenberg whvandy@yahoo.com


How to determine the propulsion your airplane needs

1. Determine the wattage needed to fly the aircraft intended. The detailed aerodynamic analysis required is not within the scope of this document. However, if Electrocalc or Motocalc can be accessed, those programs will help. If the designer or a review has defined the wattage required, you are half way there. Rest assured; this is a question our service and sales departments receive many times a day!
2. If you have little information, at least find the weight of the airplane, use the table below for a ball-park figure, then refine the results later.
· Indoor and micro flyers 25 w/lb
· Park and backyard flyers for Speed 280 to Speed 400 25 to 50 w/lb
· Speed 400 up to brushless sport-scale trainers 50 to 75 w/lb
· Maneuverable, higher performance sport-scale & 3D 75 to 150 w/lb
· AMA/FAI pattern competition & F5A gliders 150 to 250 w/lb
3. The low end of each category is flyable and sedate.
4. The higher end of each category is much hotter and demands skill.
5. Within each category, wing loading has an effect. Wing loading is the weight divided by wing area, usually lbs per square foot. Higher wing loading imposes higher power loading to fly properly and pushes the requirement toward the upper end of the scale. ( Your ME 109 probably hass a p[retty high wing loading. Please give us the weight and the wing area for further analysis) 6. Once the power loading (w/lb) is known, determine what motor and ESC can deliver the needed wattage. Both motor and ESC specs will give a range of voltage, usually as cell count. Take care not to mistake Ni Cd cell count for Li PO. One Li Po cell = three Ni Cd or Ni MH cells. CAUTION: Some ESCs specify upper voltage limits and upper amperage limits. In some cases both may not be permitted simultaneously. Check the specifications and demand to know.
7. Pack requirements are by peak wattage that may be demanded only for a few seconds each flight, while overall pack capacity sets flight time. Li Pos are almost never run at peak load for a whole flight. If they are, the pack is under-designed and may be damaged.
8. A rule of thumb for success and long life is to allow for a 25% margin. Because Li Pos are so light, this is not really a burden.
9. Divide peak watts by planned nominal voltage of 3.7V X the number of cells in series, e.g., a 3S pack is 11.1 V, nominal to determine peak amps..
10. If you can, measure the amperage in a short static run using a watt meter or an ammeter to confirm the estimate. NOTE: This can save you the cost of a pack and is well worth-while.
11. The capacity required depends on desired flight time per charge. You may elect to have a pack with a lot of capacity and fly multiple flights per charge or use a smaller pack and recharge between flights.
12. The standard most recommend with modern 4th generation cells is the “ten minute flight”. Ten minutes is about the average flight time for glow or electric. Most club fields have some limit on flight time after which one must relinquish the frequency pin.
13. FMA/Kokam HDR packs charged with our cell balancing chargers may be recharged in 20 minutes and this makes the “10 minute pack” very practical. Two packs then allow almost continual flying.
14. The capacity required = desired flight time in hours X average current drain in amps.
15. The capacity for the 10-minute flight = 0.167 X average current in amps.
16. You may enter peak current and voltage in LIPOCALC II, available in the Li Po Compendium at www.fmadirect.com LIPOCALC II will provide the specification for the pack you need. Then reduce throttle setting to approximate the average current anticipated to see what flight time will be.















_____________________________

Electroman

(in reply to whvandy)
       Post #: 32

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/18/2005 7:35:11 AM   
voodoo51


 

Posts: 58
Joined: 8/24/2002
From: UPLAND, CA, USA
Status: offline 		a few q's, say I want to run two 3s packs in parallel on on a board what state do my lithiums have to be in?and how do you check? I have a triton charger rated max 4 li cells i think. Can I charge my sx 3s batts in parallel with 6 cells 6s? does it recognize it as 3 total?. And how can I make my two 2100 in parallel manualy wire to wire and charge at once versus using a board, and at one state?

(in reply to Fred Marks)
       Post #: 33

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/18/2005 4:07:51 PM   
Greg Covey



Posts: 4381
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		As long as the Lithium packs are of equal cell count, equal cell type (and capacity), and, the pack voltage is within a few tenths of a volt form each other, then you can charge them in parallel.

Once you use them in parallel, you can also continue to charge them in parallel as one bigger 3s pack.



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(in reply to voodoo51)
       Post #: 34

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/30/2005 3:04:14 PM   
wgregoryl



Posts: 42
Joined: 10/27/2003
From: West Palm Beach, FL, USA
Status: offline 		I've already asked this of Greg via PM, but want to put it up here as well. I have a Kokam 2000 3s 15C that was involved n a crash yesterday. The battery is now nearly "L" shaped, and although the outer shell is not broken, I would assume this pack is done. How would one properly dispose of one of these batteries? I can see our local garbage truck bursting in flame when he goes to compact the load if the battery were in the wrong place.

Thanks in advance for your time!

Greg Lotz

(in reply to Greg Covey)
       Post #: 35

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/30/2005 5:41:39 PM   
Fred Marks


 

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

Any time any battery, no matter what chemistry, takes a whack and is dented, bent, etc, it should be disposed of properly. Dr Keith Shaw tells us he inspects all his Ni Cd, Ni MH, and Li Po packs periodically and discards any that have a dent in the envelope. Any pack of any type must be fully discharged to a avoid possible fire if the trminals are shorted ina trash bin. As you know, Ni Cd contains cadmium, a carcinogen, and must be disposed of via an appropriate recycler. In Europe, Ni Cds will be banned within a year or so. Li Po is environmentaly friendly but must be disposed of properly. Here is how you do it.
1. Since your pack is damaged, it may already have the seal on cells broken. If you can see places on each cell that have penetration, just drop the mess in a container of salt water for a few hours and then trash it.
2. If the pack still shows 3.8V or more, discharge it by running the motor in a secure area or put a light bulb load across the pack until it is discharged.
3. If the pack is not penetrated, use a # 11 blade to slice very gently through the plastic envelope in an area where the innards are not pressed tightly to the envelope. As you cut, think of yourself as a surgeon who wants to slice ever so carefully though the pertinium so as not to nick the liver! DO NOT POKE WITH THE SHARP POINT.
4. Now place the pack in salt water for a few hours then chuck the pack in the trash as it is now completely inert.
5. Finally: Consider enclosing your replacement pack in FMA Direct IMPAD that is so effective that an egg dropped on a sheet from six feet does not break but instead, bounces. IMPAD is reusable and enough is provided to do several smaller packs.


--------------------------------------------------------------------------------

IMPAD-.250X6X12
from Receivers IMPAD $6.95 Qty.



IMPAD-.250X6X12
from Electric Flight Accessories IMPAD $6.95 Qty.



IMPAD-.250X6X12
from LiPo Chargers and Accessories IMPAD $6.95 Qty.




--------------------------------------------------------------------------------



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Electroman

(in reply to wgregoryl)
       Post #: 36

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/30/2005 7:13:32 PM   
mizr3en



Posts: 39
Joined: 5/26/2005
From: Ridgefield, CT, USA
Status: offline 		I am sure these questions were previously answered, but I am still confused on these li-po batteries. Would they damage an esc that is being used with a NiMH pack? Will the 11.1v packs damage a motor(370) currently being run on 7 nimh cells (because i would assume the discharge rate is much higher), and would the 2 cell pack supply enough power? thanks, and by the way this would be for a micro helicopter.
Nick

(in reply to Fred Marks)
       Post #: 37

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/30/2005 9:04:32 PM   
Greg Covey



Posts: 4381
Joined: 5/24/2003
From: Rochester, NY, USA
Status: offline 		Hi Nick,

The switch to Lithium cells will not damage an ESC as long as you stay within the manufacturers specifications. For example, on your setup mentioned, you are currently running a 7-cell NiMH pack on a Speed 370 motor. The voltage of the 7-cell pack, prop, and gearbox ratio (if used) determine the current draw of the motor from the pack. If you switch from a 7-cell NiMH pack to a 2-cell Lithium pack, this current draw will be very similar. Since the Lithium cell energy density is twice that of the NiMH cell you can use that fact to either reduce weight of the pack or increase flight duration or a combination of both.

Tell use your 7-cell NiMH size and I'll suggest a replacement Lithium pack.

Welcome to RC Universe!


_____________________________

Visit my Web Hangar at www.gregcovey.com/rc.htm

(in reply to mizr3en)
       Post #: 38

RE: Welcome to the FMA Direct - Kokam LiPo Support Forum - 5/30/2005 9:46:39 PM   
mizr3en



Posts: 39
Joined: 5/26/2005
From: Ridgefield, CT, USA
Status: offline 		thanks for the recommendations, my 7 cell pack was preasembled, its AAA 650mAH, with a JST/BEC connector, but i wouldnt mind switching over to