I just bought a brand new 7.4 volt 2100 mah lithium polymer battery I have a hobbico quick field charger MKII. Should I trickle charge the battery at first if not then at what amp and for how long, also on a regular bases at what amp should I charge it for and how long do I charge it. Please give me as much information as possible as I am new to lithiums and now that if improperly charged they can explode.

THANKS!

First of all STOP! PKid, you need to read the instructions included with your Lipo's. Lipo's, if I'm not mistaken, require a special charger and a special charge rate or something like that. Your thinking just like I did when I frist bought Lipo's, but then I started reading the forums here on RCU just to find out what I had. I bought a Kokam charger for a person selling it in the market place and now can charge my Lipo's safely. I do monitor them through out the charge just to be on the safe side and place them in a coffee can while there charging. PLEASE read more before you hook them up and cause a problem or loose your new batteries due to miss use.

Actually, the Hobbico will do the job on lithiums, but it doesn't charge them to 100% of capacity. Lithium Ions (old technology) had a full capacity voltage of 4.1V per cell, which is what the Hobbico charges to. Lithium Polymers have a full voltage of 4.2V per cell. While charging to 90% certainly won't hurt the packs (and may actually extend pack life), you're certainly not getting the full run-time that the pack can deliver.

Here's some good Lipo guidelines:

__________________________________________________ ______________

Failure to follow the following guidelines could result in: Loss of property, injury, or death due to fire or explosion.

Battery discharging, charging, electric motors, spinning propellers, and flying models all have the potential for serious injury to persons and damage to property. In purchasing these products, the user agrees to accept responsibility for all such risks, and not to hold the manufacturer, distributors, or retailers - (including all owners and employees) - responsible for any accident, injury to persons, or damage to property.



CHARGING DO'S:

DO use a charger capabable of charging Lithium-Polymer batteries. Some accepted chargers are:
Anything manufactered by Schulze or Orbit with a Lithium-Polymer charge cycle.
Apache 1-2 or 1-4 cell charger
BEL 2-3 cell Lithium-Ion/Polymer charger
AstroFlight Model 109
Kokam 1-4 cell charger
Great Planes Triton
Plantraco LPD-400
Qualcom 830 Lithium-Ion 2-Cell charger
DO charge in a fire safe box in an area that has non-combustible materials.
DO inspect the cells/pack if a boat/car/aircraft crash or collision has occurred. If malforming has occurred see below for proper disposal of Lithium-Polymer cells. Do not attempt to repair damaged cells.

DO keep a chemical fire extinguisher in the vicinity that Lithium-Polymer cells are being used.

DO check pack polarity and voltage prior to first use. 2-Cell Voltage should be between 7.4 - 7.6, 3-Cell Voltage should be between 11.2 - 11.4. If it's not, please contact us.


CHARGING DO NOT'S:

DO NOT charge on carpet, cloth, wood, or anything else flammable.
DO NOT charge Lithium-Polymer cells unattended. All cells can "vent", no matter the chemistry (Ni-Cad, Ni-Mh, Li-Ion, Li-Poly), however Nickel Cadmium and Metal-Hydride cells come in a metal can, with a venting device. If the cell needs to vent, it can safely do so via a mechanism in the end of the cell. Lithium-Ion/Polymer cells have no vents, and in the event they need to vent the cell is ruptured and a fire can start.
DO NOT charge at over 1C current. C = mAh / 1000. Example: 850 mAh / 1000 = .85A charge rate
DO NOT discharge at over the manufacturers specified rate. Each cell has it's own nominal and maximum discharge ratings clearly marked on the pack, and on the individual product pages.
DO NOT discharge lower than 3.0 volts per cell.
DO NOT charge to more than 4.2 volts per cell.
DO NOT crush, pinch, poke, or in any way deform the cell. Lithium-Polymer cells do not have a hard case. Malformation can cause the cell to internally short out, and burst into flame. If a cell is deformed, dispose the pack as per disposal methods below.
DO NOT continue to use any cell that has increased (commonly known as "ballooning") in size. Cells that have a "bloated" appearance have been damaged, and pose a fire hazard. Dispose of the pack as per disposal methods below.
DO NOT allow the cells to exceed 160F degrees. Doing so will reduce the life of the cell, and increase the risk of fire. We have proven that with just one discharge cycle where 200F Degrees was obtained cell capacity was reduced by 20%.
DO NOT assemble cells of unknown capacity. Doing so will cause cell imbalance, and eventually a cell failure (and possibly a fire) could result.
DO NOT store your packs where small children or animals can get to them. Lithium has a sweet smell, which by animals/children could be thought of as candy. Lithium is toxic (death could occur) if injested.


Battery Break-in Procedure:

Contrary to popular beliefs that lithium polymer battery packs need no "break-in" period, before you run new Apogee packs continuously at their maximum discharge rate, we recommend you cycle the battery packs at no more than 7C for a minimum of 15 cycles down to 3.0V per cell or until the PROPERLY SET Low Voltage Cut-Off (LVC) on your ESC kicks in. All Apogee packs are to be charged at a maximum 1C.

By following this break-in procedure, your batteries will run much cooler when you run them continuously at the maximum discharge rates.

How do I calculate 7C?

If your battery pack capacity is say 1050 mAh with a charge rate of 1.05 A, 7C is simply 7 x Charge Rate or:

7 x 1.05 A = 7.35 A

In this case with the 1050 mAh pack, you should discharge no more than 7.35 A.

How do you cycle an Apogee pack?

If you have a lithium polymer charger (e.g. Triton/Orbit/Schulze) that has a lithium battery discharge cycle, discharge your battery at the 7C rating or lower until the 3.0V per cell reached.

If you don't have a charger with a lithium discharge cycle, you can discharge through your speed controller. Make sure the speed controller LVC is configured properly for the number of cells.

If you have a WattMeter or inductive pickup ampmeter, choose the prop/gearing that gets you closes to 7C, and fly normally for 15+ flights to the properly set LVC.

Charge and repeat for 14 or more cycles.



Disposal Procedure:

Discharge the cell/pack to 2.5 volts per cell. That would be 5.0 volts for a 2-cell pack and 7.5 volts for a 3-cell pack.
Find a container that is large enough, once filled with water, to immerse the cell pack under water. Fill the container with water and saturate the water with salt; that is, add enough salt so the salt can no longer dissolve.
After the pack has been discharged to 2.5V per cell, place the cell or pack into the salt water solution. This will deplete the rest of the energy in the cell/pack. Allow cell/pack to soak for 24 hours.
Take the cells out of the solution. Check the voltage is 0 volts.
Discard cell/pack in the trash.

Battery Storage Procedure:

If you plan to store your batteries for periods of greater than 4 weeks at a time, it is necessary to store your batteries in a 50% discharge state. This is irrespective of battery voltage!

How do you get to a 50% discharge state?

If you have a watt meter (Astro, Medusa, etc.), you can monitor and discharge 50% of the pack capacity. For example, after you fully charge a pack, discharge the pack until 50% of the pack capacity is discharged.

If you don't have a watt meter you can follow these general guidelines. With a fully charged pack, fly 1/2 the time you normally fly. For example, if you get 20 minutes of normal flying time, fly 10 minutes to get to "50%" discharge state.

Yes I understand that but my battery is not a kokam or a known company brand that I bought off ebay for $30
THANKS!!!!

Same rules apply to your no-name pack as to any other pack on the market.

LiPoly packs don't benefit from being slow-charged, but exceeding the 1C charge rate could yield disastrous results.

Another good bit of info to know is the max. average discharge rate for that pack. If you try to pull more amps out of the pack than it is rated for, you can destroy the pack with disastrous results. There are many 2100mah cells on the market right now with many different discharge rates.

The discharge rate is measured in "C" (as in 8C, 15C, etc.). In the simplest terms, multiply the number discharge rate by the amp capacity of your pack (2100mah = 2.1A). If you had 8C cells, than your maximum average discharge rate would be 16.8 amps (8x2.1). Exceeding that amp draw for long periods of time can cause the cells to swell, burst or just burn out.

Most packs have a maximum discharge rate that can be maintained for 60 seconds but it's always safer to gauge your battery needs by the average max. discharge not the maximum amp discharge.

If it is not marked on your pack, thenm contact the person you bought it from and ask them what the average maximum discharge rate and the maximum discharge rate.

Don't confuse this with charging the battery. That's always 1C (in your case 2.1 amps or 2100mah) or less.

BB

Hey Matt,
Feel free to elaborate or correct me. I've seen a few packs get fried this way by new flyers and I want to save him some trouble.