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Batteries explained and Battery pack maintenance

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Unread 6-23-2007, 12:32 AM   #1
FastEddy
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Batteries explained and Battery pack maintenance

Table of Contents:


Recommended Care for NIMH batteries


Maximum battery performance and maximum battery life rarely go hand in hand. It is SPC’s goal to optimize battery performance AND battery life.

If you are a sponsored racer or you are fortunate enough to not have to pay for your batteries you may want to stop here. For everyone who buys their batteries and wants to get the most from their investment, these instructions are for you.


IB4200SHV's and IB3800s

Charging – IB, Sub-C Type, Nimh Packs:

SPC’s does not recommend cycling newly assembled packs with a charger/discharger. During the matching process the individual cells were cycled numerous times. Once assembled, SPC packs are ready for immediate race use.

Charge with a NiMH compatible charger that utilizes a linear charge mode. Check your chargers operating instructions for specific recommended charger settings. If you have access to a digital temperature gun, take a temperature reading of the pack immediately after charge completion. If necessary, adjust the charger DV (voltage peak) cutoff so that the final temperature for the charged pack is between 110° F and 120° F. Final temperatures over 125° F may reduce pack performance and operating life.



SPC tested numerous charge rates looking for the best, overall discharge performance curve. Numerous packs were charged at various rates, ranging from 4-Amps to 8-Amps. The best discharge curves were obtained when packs were charged at 6-Amps. Discharge performance dropped off with charge rates over 6-Amps. Charging at 5-Amps provided the best compromise between pack performance and pack life. If you want slightly more performance, charge at 6-Amps, but be warned, a 6-Amp charge rate may reduce battery pack life. If you don't mind monitoring your charging pack, try the following; charge at 6-Amps to approximately 3,000 mah capacity, then drop the charge rate back to 5-Amps to finish. This will maximize the benefits of both charge rates. After a pack has peaked remove it from the charger, do not allow it to trickle charge. Trickle charging after a peak charge will generate heat that may damage the pack.

Try to time charging so the pack finishes just before your race. If the pack sets for 5 to 10 minutes before race time, re-peak it for a minute or two at 5-Amps. If it sets for more than 15 minutes (it's cool), re-peak at 5-Amps. When re-peaking, monitor the pack to prevent it from over heating. NEVER leave a charging pack unattended. Lastly, don't attempt to charge a pack that is unreasonably cold. If the pack temperature is below 40 F, allow the pack to warm to room temperature before charging.

Race Use - IB, Sub-C Type, Nimh Packs:

If done correctly an IB4200SHV or IB3800 NiMH battery pack can be raced/used twice in one day without pack damage. For example, charge then race a pack in the first qualifying heat. After the qualifying heat, remove the pack from your vehicle and allow it cool. It is not necessary to completely discharge the pack after the first run of the day. For cooling, place the pack on the floor or in front of a cooling fan. It must set for at least two hours and be completely cool before recharging. After the cooling period, recharge the pack in time for the main.

Maintenance Discharging - IB, Sub-C Type, Nimh Packs:

If a pack is unusually hot after use, wait for it to cool before discharging further. A discharge rate of 10-Amps is a good, moderate discharge rate, but any reasonable rate up to 20-Amps is acceptable with the following exception: Except for testing purposes, avoid discharge rates greater than 20-Amps. High discharge rates create extreme heat and extreme heat kills batteries!

As a pack, never discharge any IB, sub-C type, Nimh cell below 0.9 volts per cell, or 3.6 volts total for a 4-cell pack and 5.4 volts total for a 6-cell pack. NEVER run a pack down until your RC car is just barely moving. Never discharge IB, sub-C type, Nimh packs with light bulb strings that do not have automatic low voltage cutoff hardware attached. NEVER dead short IB3800 cells or battery packs. Dead shorting causes permanent cell failure! Plus the potential for personal injury is very real. IB sub-C type, Nimh cells are very sensitive to over discharging. It is better to never discharge them after a race than to over discharge them. DO NOT OVER DISCHARGE YOUR IB, SUB-C TYPE, NIMH PACKS!

Storage - IB, Sub-C Type, Nimh Packs:

How a pack should be stored depends upon how long the pack will set before being used again. If you know you'll be racing again within a week, discharge your pack to 0.9v/cell and store it in a cool, dry area. If a pack will set for a month or more discharge it to 0.9v/cell, let cool then charge to approximately 50% or more of full capacity. Once a month charge until full, then discharge to 0.9v/cell. Allow the pack to cool, then charge to 50% and store. During the storage period, repeat the charge/discharge/charge cycle once per month.

Equalizing Trays - IB, Sub-C Type, Nimh Packs:

Even if a battery pack is new or fairly fresh, place it on an equalizing tray before the next day of racing. After traying allow the pack to cool completely before charging. If the pack is older and/or well used, tray it after every run. The only tray that SPC recommends for the IB3800 cells is the Novak Smart Tray. The Novak Smart Tray should never be set lower than 0.9 volts. After discharging a pack on a tray don't be surprised if it false peaks shortly after the start of the next charge cycle. This is especially true for older packs. Simply restart the charge.


GP3300s & GP3700s

Charging – GP3300s & GP3700s:

SPC does not recommend cycling newly assembled packs with a charger/discharger. During the matching process the individual cells were cycled numerous times. Once assembled, SPC packs are ready for immediate race use.

Charge with a NiMH compatible charger that utilizes a linear charge mode. Check your chargers operating instructions for specific recommended charger settings. If you have access to a digital temperature gun, take a temperature reading of the pack immediately after charge completion. If necessary, adjust the charger DV (voltage peak) cutoff so that the final temperature for the charged pack is between 125° F and 130° F. Final temperatures over 135° F may reduce pack performance and operating life.

SPC tested numerous charge rates looking for the best, overall discharge performance curve. Numerous packs were charged at various rates, ranging from 4-Amps to 8-Amps. The best discharge curves were obtained when packs were charged at 6-Amps. Discharge performance dropped off with charge rates over 6-Amps. Charging at 5-Amps provided the best compromise between pack performance and pack life. If you want slightly more performance, charge at 6-Amps, but be warned, a 6-Amp charge rate may reduce battery pack life. If you don't mind monitoring your charging pack, try the following; charge at 6-Amps to approximately 3,000 mah capacity, then drop the charge rate back to 5-Amps to finish. This will maximize the benefits of both charge rates. After a pack has peaked remove it from the charger, do not allow it to trickle charge. Trickle charging after a peak charge will generate heat that may damage the pack.

Try to time charging so the pack finishes just before your race. If the pack sets for 5 to 10 minutes before race time, re-peak it for a minute or two at 5-Amps. If it sets for more than 15 minutes (it's cool), re-peak at 5-Amps. When re-peaking, monitor the pack to prevent it from over heating. NEVER leave a charging pack unattended. Lastly, don't attempt to charge a pack that is unreasonably cold. If the pack temperature is below 40 F, allow the pack to warm to room temperature before charging.

Race Use – GP3300s & GP3700s:


If done correctly a GP3300 or GP3700 NiMH battery pack can be raced/used twice in one day without pack damage. For example, charge then race a pack in the first qualifying heat. After the heat, remove the pack from your vehicle and allow it cool. It is not necessary to completely discharge the pack after the first run of the day. For cooling, place the pack on the floor or in front of a cooling fan. It must set for at least two hours and be completely cool before recharging. After the cooling period, recharge the pack in time for the main.

Maintenance Discharging – GP3300s & GP3700s:

If a pack is unusually hot after use, wait for it to cool before discharging further. A discharge rate of 10-Amps is a good, moderate discharge rate, but any reasonable rate up to 20-Amps is acceptable with the following exception: except for testing purposes, avoid discharge rates greater than 20-Amps. High discharge rates create extreme heat and extreme heat kills batteries!

As a pack, never discharge below 0.9 volts per cell, or 3.6 volts total for a 4-cell pack and 5.4 volts total for a 6-cell pack. NEVER run a pack down until your RC car is just barely moving. When discharging with light bulbs, NEVER allow the bulbs to go out. Remove the pack from the discharge bulbs as soon as you notice the bulbs dimming. NEVER dead short your batteries! Any voltage improvements are negligible at best and the potential for pack damage and/or personal injury is very real. More packs are killed by over discharging than by over charging. It is better to never discharge your packs after a race than to over discharge them. DO NOT OVER DISCHARGE YOUR PACKS!

Storage – GP3300s & GP3700s:

How a pack should be stored depends upon how long the pack will set before being used again. If you know you'll be racing again within a week, discharge your pack to 0.9v/cell and store it in a cool, dry area. If a pack will set for a month or more discharge it to 0.9v/cell, let cool then charge to approximately 50% or more of full capacity. Once a month charge until full, then discharge to 0.9v/cell. Allow the pack to cool, then charge to 50% and store. During the storage period, repeat the charge/discharge/charge cycle once per month.

Equalizing Trays – GP3300s & GP3700s:

Even if a battery pack is new or fairly fresh, place it on an equalizing tray before the next day of racing. After traying allow the pack to cool completely before charging. If the pack is older and/or well used, tray it after every run. The Integy Indi Octane tray has an automatic cutoff that prevents over discharging. The Trinity Real-Time 2.5 tray works well and discharges faster, but it will pull the cells down to zero volts if left unattended. If you use the Trinity tray, monitor the discharge and disconnect each cell as the individual light bulbs go out. The Novak Smart Tray should be set to 0.9 volts if the pack is to be stored for a week. Prior to the next use equalize the cells down to 0.3 volts. After discharging a pack on a tray don't be surprised if it false peaks shortly after the start of the next charge cycle. This is especially true for older packs. Simply restart the charge.


RC1100P Mini Packs

Charging – RC1100 Mini Packs:


Charge with a NiMH compatible charger that utilizes a linear charge mode. Check your charger's operating instructions for specific recommended charger settings. A fully charged 1100 pack should be warm to the touch when charging is complete. SPC recommends a charge rate of 1-Amp or less. After a pack has peaked remove it from the charger, do not allow it to trickle charge. Trickle charging after a peak charge will generate heat that may damage the pack. NEVER leave a charging pack unattended. Lastly, don't attempt to charge a pack that is unreasonably cold. If the pack temperature is below 40 dF, allow the pack to warm to room temperature before charging.

Race Use – RC1100 Mini Packs:

If done correctly a NiMH battery pack can be raced/used twice in one day without pack damage. For example, charge then race a pack in the first qualifying heat. After the heat, remove the pack from your vehicle and allow it cool. It is not necessary to completely discharge the pack after the first run of the day. For cooling, place the pack on the floor or in front of a cooling fan. It must set for at least two hours and be completely cool before recharging. After the cooling period, recharge the pack in time for the main.

Maintenance Discharging – RC1100 Mini Packs:

If a pack is unusually hot after use, wait for it to cool before discharging further. A discharge rate of 5-Amps is good. Except for testing purposes, avoid discharge rates greater than 5-Amps. High discharge rates create extreme heat and extreme heat kills batteries!

As a pack, always discharge to 0.9 volts per cell, or 5.4 volts total for a 6-cell pack. NEVER run a pack down until your RC car is just barely moving. When discharging with light bulbs, NEVER allow the bulbs to go out. Remove the pack from the discharge bulbs as soon as you notice the bulbs dimming. NEVER dead short your batteries! The potential for pack damage and/or personal injury is very real! More packs are killed by over discharging than by over charging. It is better to never discharge your packs after a race than to over discharge them. DO NOT OVER DISCHARGE YOUR PACKS!

Storage – RC1100 Mini Packs:

How a pack should be stored depends upon how long the pack will set before being used again. If you know you'll be racing again within a week, discharge your pack to 5.4 volts and store it in a cool, dry area. If a pack will set for a month or more discharge it to 5.4 volts, let cool then charge to approximately 50% or more of full capacity. Every other month of storage charge the pack until full, then discharge to 5.4 volts. Allow the pack to cool, then charge to 50% and store. During the storage period, repeat the charge/discharge/charge cycle every other month.



ASSEMBLY PRODECURE FOR SUB-C NIMH BATTERIES

Sub-C Battery Assembly:

Using sandpaper or Dremel tool with a sanding drum, lightly sand the cell ends. Wipe the sanded ends clean with rubbing alcohol or electrical motor cleaner. After aligning the cells in a soldering jig, apply a small amount of a quality soldering flux to the cell ends and battery bar ends. Do not tin the cell ends or battery bars. Lead is great for soldering but is a relatively poor electrical conductor.

A good solder joint will have smooth, consistent solder flow around the bar end, with minimal solder between the bar and cell. Place a battery bar across two cells; melt a modest BB-sized amount of solder to the tip of a high quality, hot, soldering iron. While holding the battery bar tightly to the cell, apply the iron tip to the battery bar. The solder should immediately flow over and around the bar and to the cell. Remove the iron while continuing to hold the bar down and allowing the solder to cool. If the solder does not flow smoothly within 1 to 3 seconds, remove the iron. Wait for the cell to cool completely before attempting to re-solder. Do not hold the soldering iron to a cell for more than 3 seconds. Serious cell damage will result!

The IB3800 cells are especially sensitive to soldering-heat related damage on the positive terminal. After obtaining a good solder joint, repeat for remaining cells.

-- Information was written for SPC batteries by SPC. This information can be used for most brands of batteries. --

http://www.steelcityhobbies.com/SPC.shtml
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Unread 8-02-2009, 7:40 PM   #2
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All about Batteries-Amps, Volts, C ratings, etc.


BATTERIES EXPLAINED


This brief discussion is intended to clear up a few terms and concepts around electricity as it applies to electric R/C.


Think of electricity like water. Volts = pressure, Amps = flow

Volts is like pounds per square inch, psi. Says nothing about how much water is flowing, just how hard it is being pushed. You can have 100 psi with zero water flow.

Amps is flow, like gallons per hour. You can have flow at low pressure and you can have flow at high pressure.

Amp hours is how much flow can be sustained for how long. It is used as a way of measuring how much electricity is in the battery. Like how many gallons of gas in your tank. It is a capacity number. Says nothing about flow or pressure, it is about capacity.

Amps and mili amps? We are just moving the decimal point around.

1 amp (short for ampere) = 1000 miliamps (mili means 1/1000 amps)

Examples

So a 7 cell NIMH or NICD pack provides 8.4V (pressure).

The motor will draw electricity from the pack at a certain flow rate, or amps.

If you have a have a 650 mili amp hour pack, it can deliver a flow of .650 amps (650 miliamps) for one hour. If you draw it out faster, it doesn't last as long. So your motor might pull 6.5 amps for 1/10 of an hour, or about 6 minutes.

An 1100 mAh pack has double the capacity of the 650 mAh pack, so it should last "about" twice as long.


What is C in relation to batteries?

C ratings are simply a way of talking about charge and discharge rates for batteries.

1C, = 1 time the rated mah capacity of the battery. So if you charge your 650 mah pack at 1C, you charge it a 650 miliamps, or .650 amps.

1C on an 1100 pack would be 1.1 amps.

2 C on your 1100 pack would be 2.2 amps

Motor batteries are often rated in Discharge C and charge C.

So an 1100 mAh pack (1.1 amp hour) might be rated for 10C discharge, so you can pull 11 amps ( flow ) without damaging the battery.

Then it might be rated at 2C charge rate (flow), so you charge it at 2.2 amps (2200 mAh)

If you have a 500 mAh pack - any kind - and it is rated at 16C that means it can deliver 8 amps.

If you have a 1000 mAh pack - any kind - and it is rated at 8C that means it can deliver 8 amps.

If you have a 1000 mAh pack - any kind - and it is rated at 12C that means it can deliver 12 amps

If you have a 1500 mAh pack - any kind - and it is rated at 8C that means it can deliver 12 amps

If you have a 1500 mAh pack - any kind - and it is rated at 20 C that means it can deliver 30 amps.

If you have a 3000 mAh pack - any kind - and it is rated at 10 C that means it can deliver 30 amps.

So, if you need 12 amps you can use a pack with a higher C rating or a pack with a higher mAh rating to get to needed amp delivery level.

One last point. Motor batteries vs. receiver batteries

Some batteries can sustain high discharge rates. Others can not.

Those used as transmitter/receiver packs typically are made for low flow/amp rates while those made for motor packs can sustain higher rates.

Having a 600 mAh pack does not tell you if it is a motor pack that can put out 6 amps, or if it is a transmitter/receiver pack that would be damaged if you tried to pull power at 6 amps. It is enough to say that they are different.

A motor pack could be used for a transmitter/receiver job, but a transmitter/receiver pack should not generally be used as a motor pack.

It is best to size your battery packs so they run somewhat below their maximum C rating. You will stress them less and they will last longer. For example, if your motor needs a pack that can deliver 10 amps, getting a 1000 mAh pack that is rated for 10C ( 10 amps ) will meet the spec, but it is running at its limit. A 15 C rated 1000 mAh pack would be better, or perhaps a 1300 mAh 10 C pack. In either of these cases, the pack will be less stressed and should handle the load much better over the long term.


Other Resources

Sizing Electric Power Systems -
http://www.rctower.com/forum/viewtopic.php?t=622

Basics:
http://www.modelaircraft.org/mag/FTGU/Part8/index.html

Lithium Batteries
http://www.rchobbies.org/lithium_bat...eakthrough.htm

New Electric Flyer FAQs
http://www.ezonemag.com/pages/faq/a105.shtml

A series of posts on electric power system basics
http://www.wattflyer.com/forums/showthread.php?t=1933
http://www.rcgroups.com/forums/showthread.php?t=417868

MotoCalc
MotoCalc will tell you everything you need to know: Amps, Volts, Watts, RPM,
Thrust, Rate of Climb, and much more! It is a popular tool for predicting
the proper motor, prop, battery pack for electric planes.
http://www.motocalc.com/

The Great Electric Motor Test
http://www.flyingmodels.org/motortest/index_e.htm

Electric Motors Described
http://adamone.rchomepage.com/guide5.htm

Last edited by Rolex; 8-02-2009 at 7:51 PM.
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Unread 6-07-2011, 1:32 PM   #3
Rolex
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An excellent article from a heli forum on LiPo batteries:

http://www.rchelicopterfun.com/rc-lipo-batteries.html
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