Aircraft Proving Grounds - Quick Field Charger

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Hobbico Quick Field Charger MkII

by Wayne Miller

Hi Wings,

The settings come into play when determining the proper charge rate for your battery pack. That is, how much amperage should go into the battery while charging.

I'll first explain a few things before talking about the settings and charger set up.

CHARGER SETTINGS
The setting adjustments on the charger is in amps and has increments such as 0.2, 0.4 etc. This is the amperage in amps that will go to your battery for charging. As a reference, you should remember that 1 milliamp is 1/1000 of an amp. Therefore 0.2 shown on the charger dial is 200 milliamps (shortformed as ma) or 0.2 amps.

BATTEY TYPE
The MKII charger also has settings for NiCd (Nickle Cadium), NiMh (Nickle Metal-Hydride) and Li-Ion (Lithium Ion) and LiPo (Lithium Polymer). You'll need to refer to the charger manual for the proper battery type set up (RED is for NiCD, YELLOW is for NiMh, and GREEN is for Lithium). According to Hobbico the charging of the Li-Ion's and LiPo's is the same. However, I have read someplace that this charger only charges LiPo's to 95% - which should be safer and is not a problem for me.

BATTERY CAPACITY
Each battery manufacturer gives two ratings to their batteries. The first is the charge rate and the second is the discharge rate. These ratings are always related to the capacity of the battery and is reffered to as "C". Therefore, if your battery is 800mah (milliamps per hour), that is, it has a capacity of 800mah.

BATTERY CHARGE RATE
The manufacturers will reference this when giving charge rates and discharge rates. Example, if a manufacture has sold you a 800mah battery, and its charge rate is 2C (or 800mah x 2 = 1600mah), then you would set your MKII charger to 1.6 (that is, 1.6 amps or 1600milliamps) to charge (a lower rate would be easier on your battery, but takes a little longer to charge). If the manufacturer rated your 800mah battery as having a trickle charge rate of C/10, this would mean the trickle charge rate would be 800mah / 10 or 80mah (trickle charge rate is set automatically on the MKII).

BATTERY DISCHARGE RATE
You also need to know how much current (that is amps) your batteries can safely supply to you motor. If the manufacter says the batteries can safely supply the current (rated in amps) at 2 times is capacity, they would state this a 2C discharge rate. If the 800mah battery pack was rated at 3C, it could safely supply 800mah x 3 = 2400mah (or 2.4 amps).

CHARGING BATTERIES
Now that we have established the above, you need to find out what rate your batteries will safely charge at, this will be rated in "C". You should get this from the manufacturer or the place who supplied your battery. As an example, I am going to use the 800mah battery with a charge rate of 1C. This means that a safe charge rate for the battery should be 1C (or 800mah). With this information I would set the MKII at 0.8 (800mah) to charge.

The MKII will automatically calculate the number of cells in your battery pack and will charge the battery automatically. Once the battery gets close to full charge full charge, the MKII will beep several times and the charge light will continue flashing (this lets you know it is in the "trickle" charge mode).

One note of caution, never ever try to "top up", or charge a battery pack, that you think is fully charged, always make sure the battery pack has been run just a little. Sometimes a fully charged pack will have a little "extra" voltage, and to the charger, this would appear as a discharged pack of the next size up (one more cell). This would cause the charger to try and charge as a pack with one more cell and would cause overcharging and overheating.

NOTES:
1. You must set the proper charge rate in amps on the MKII
2. The charger will automatically determine the number of cells in the battery pack
3. The MKII will automatically determine when the pack is fully charged.
4. The charger will continually beep if there is an error, or problem, with charging.
5. This charger will go into a trickle charge rate when the battery is charged (noted by 21? beeps then the light flashes). It will stay in trickle charge mode until turned off.
6. If the battery is not fully charged within 2 hours, the charger will automatically shut down.
7. Never charge a lithium battery over 1.0 amp - as stated in manual - never leave a lithium battery plugged in after charge.

SUMMARY FOR MKII BATTERY CHARGING
1. Find out the capacity of your battery, this will be stated in "C"
2. Find out the charge rate of the pack in "C"
3. Set the charger to that rate in step 2
4. Plug the battery in
5. Set the battery type (RED, YELLOW,GREEN) and let it charge (the charger determines charge time and when fully charged)

It should be fully charged within 2 hours, if not an error will occur.

You should also check the Hobbico site for any other updated information or safety information.

Sorry to be so long winded. The above is to the best of my knowledge, and comes from my experience and reading. If anyone else has any input, or corrections please feel free to jump in.

Hope this helps.

Wayne Miller