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Old Sep 29, 2006, 07:36 PM
Registered User
Georgetown, TX
Joined Sep 2006
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Questions for a first time plane and radio setup..

Ok, the background: I have a GWS Slow Stick plane and I purchased a JR XF421 radio. I also purchased a 800 mAh Li-Po battery, and ECS and a Li-Po charger.

My questions:

The Slow Stick instructions don't refer to a second battery for the receiver, yet the JR radio came with a seperate batter for the receiver and I don't see how the receiver would work without it. Is this right? Do other radios not have a seperate battery for their receiver? Is this a mistake to use this radio (if it requires a second battery) for this plane or will it be ok?

How long should I charge (especially on the initial charge) the Li-Po battery? The battery didn't come with any instructions and the charger instructions don't refer to that issue. The instructions for the radio say to charge the radio battery (a Ni-Cad) and radio for 20-24 hours initially and then around 14 hours each time after that. Does this also apply to the Li-Po? The charger says it trickle charges once the battery is fully charged, so I assume that I don't have to worry about over-charging, is that right?

Thanks for any help.
Dave
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Old Sep 29, 2006, 08:01 PM
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Tres Wright's Avatar
Forney, TX
Joined Mar 2002
15,165 Posts
These days you don't see separate battery packs on any but the very biggest electric planes. Most ESCs come with "BEC" (battery eliminator circuitry) that powers all the on-board gear off of the same pack that powers the motor. It works through the throttle channel on the receiver.

Do not even think about charging that li-po pack with that charger!!! You need to know beyond any doubt that the charger works with the pack you have, and what the charger settings need to be and how long it needs to charge. It sounds like you either have a cheap charger or perhaps one that is not designed for li-po's. Charging li-po's at the wrong rate is EXTREMELY DANGEROUS, there have been cars and homes lost to fires that were started by a li-po bursting due to improper charger settings. I suggest you research the particular charger you have to make sure it is adequate for charging li-po's. These days most manufacturers post charger data online. If you can't find it, invest in a better charger. You also need to know how many cells are in your li-po pack (probably 2 but might be 3) and what size it is (in mah).

Good luck!
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Old Sep 29, 2006, 08:31 PM
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Georgetown, TX
Joined Sep 2006
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I have a Li-Poly Smart Charger 2500. The website I bought both the charger and the battery showed that it would work with the battery. The battery (not the radio receiver battery) is a Li-Po 2 cell 800 mAh battery. I'm using the 2 cell setting (it has a 1,2,3 and 4 cell settings) and I'm charging it at the 700 mAh setting (since it doesnt have an 800 setting. it has a 2500, 2000, 1700, 1200, 700 and 250 mAh settings). This should be ok, right?

Ok, as for the ECS. The Jeti 006 I bought has 5 pins and a 2 pin jumper. There are 4 settings available. Ni/Br On, Ni/Br Off, Li/Br On and Li/Br Off. Which setting should it be on to only use one battery?
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Old Sep 30, 2006, 09:12 AM
Tao Jones industrial ave.
Wisconsin, USA
Joined Apr 2005
168 Posts
Your battery charger at the settings you list should be OK.
Don't know anything about that reciver. Are those jumper settings perhaps for a low voltage cut-off ( cuts motor when battery gets low ) ?
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Old Sep 30, 2006, 10:10 AM
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Tres Wright's Avatar
Forney, TX
Joined Mar 2002
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Quote:
Originally Posted by Sendero
I have a Li-Poly Smart Charger 2500. The website I bought both the charger and the battery showed that it would work with the battery. The battery (not the radio receiver battery) is a Li-Po 2 cell 800 mAh battery. I'm using the 2 cell setting (it has a 1,2,3 and 4 cell settings) and I'm charging it at the 700 mAh setting (since it doesnt have an 800 setting. it has a 2500, 2000, 1700, 1200, 700 and 250 mAh settings). This should be ok, right?

Ok, as for the ECS. The Jeti 006 I bought has 5 pins and a 2 pin jumper. There are 4 settings available. Ni/Br On, Ni/Br Off, Li/Br On and Li/Br Off. Which setting should it be on to only use one battery?
Whew, OK you had me worried there for a minute but it sounds like you're fine on the charger. Please make sure you never accidentally charge a 2 cell pack with the charger set to 3 cells, this has been the cause of most li-po fire accidents. Make sure to use a clay pot, li-po blanket, etc. to charge your packs in just to be sure. You are correct in going down to the next charge rate, you want to make sure you never charge li-po's over "1C", or 800 mah for your pack. Charging under that rate is no problem, so 700 is fine.

The "br on/ br off" probably refers to the prop brake. This depends on what type of plane it is, and your personal preferences. If it's a sailplane you want the prop brake on so the prop will stop spinning and fold back when you shut the throttle off. However, if it's a 3D plane you might want want the brake off so that the prop keeps spinning and doesn't throw you into a sudden stall condition.

The "Ni/ Li" is referring to the battery type (Nicad/ NiMH or Li-po).

So you want either Li/Br On or Li/Br Off depending on your desired prop brake setting.

EDIT- I just saw that you mentioned you're putting this on a Slow Stick. I would suggest you turn the brake on, if you're trying to land and shut the power off with brake off the prop can spin so slowly that it can stall your plane.
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