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Old Feb 08, 2010, 04:12 PM
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Question
OK to use LiPo in place of NiMH?

I have a plane that uses NiMH 6 cell 7.2V. Any problem switching out the connector and using a LiPo of comparable voltage / current rating?
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Old Feb 08, 2010, 04:14 PM
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Depends on the plane/ESC. If the ESC isn't lipo compatible, then no. If it is, then yes.
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Old Feb 08, 2010, 05:30 PM
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Plane is a Hobby Zone Phantom Firebird that I am scrapping. Is there a way to tell if the ESC is LiPo compatible?
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Old Feb 08, 2010, 05:37 PM
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I'm not sure, but I do know that if you search, you will probably find a big thread containing the information that you need to know. It somewhere on these boards. You probably could stick a 2S lipo in there and be fine, but do a little research.
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Old Feb 08, 2010, 06:11 PM
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Quote:
Originally Posted by dixonr7 View Post
Plane is a Hobby Zone Phantom Firebird that I am scrapping. Is there a way to tell if the ESC is LiPo compatible?
An ESC doesn't care where the voltage comes from, just so it is not too much. Usually, when folks talk about LiPo vs Ni compatable, they are referring to LVC (Low Voltage Cutoff). LVC is built into some ESCs to protect the battery from being over discharged.

The more important question is if the ESC will take the increased voltage. Since the Firebird will also accept, I think, a 7 cell Ni, you should be just fine with a two cell LiPo. Just time your flights, and when it starts getting doggy, land. Check your LiPo voltage - after a few minutes resting, it should be close to 7.6 volts, 3.8 volts per cell. If it is much lower, you flew too long.

Do note that you can not use the charger that came with the Firebird to charge LiPos - it must be a LiPo charger.

Bill
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Old Feb 08, 2010, 06:46 PM
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Thank you for the great advice!
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Old Feb 08, 2010, 07:08 PM
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Dixon,

Even if you cannot determine if the ESC has an LVC setting for LiPo you can still use it. All you need to do is make sure you don't over discharge the LiPo by flying too long. To do this fly for a moderate amount of time, say half of what your generally fly. Five minutes after you land measure the battery voltage. If it is not less than 3.7volts per cell then increase the time of your next flight by a minute. when the battery is at 3.7 volts per cell you are at the optimum flight time.

BTW you should not be flying to LVC anyway. LVC on most ESC's is set to 3.0 volts per cell. This is too low. Your batteries will last longer if you don't run them down more than 80% of their rated voltage. Also you should not discharge more than 80% of their capacity (I.E. 80% of a 2200mah battery would be 1760ma.)

Sticking to the 80/80 guideline will prolong the life of you LiPo.

Lastly if you are not going to use the battery for a period of several weeks then discharge it to approximately 3.85 volts per cell for storage.

Glen
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Old Feb 08, 2010, 09:06 PM
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Thanks Glen. All good info!
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Old Feb 09, 2010, 10:59 AM
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Battery meter

You could use a battery meter that alerts you when the voltage is at a dangerous level. It has led's plus a siren to alert you when you can't see the led's. They will chirp at you however, when your under a heavy load (vertical climb). Works out great for when you forget to set your timer on your radio or, cold weather flying, which shortens your flight time. I picked mine up for $5 on eBay.

Hope this helps,
Flyaddiction33
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Old Feb 09, 2010, 11:34 AM
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can you buy plug in LVC units, if so may be worth spanding a few bucks for one
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