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replace NiMh with a LiPo - 12/19/2012 1:16 AM   
sparky4lawndart



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I have a 20cc warbird... I have an airtronics RDS8000 I love... 8 channel rcvr... Hitec servos all around... Eflite retracts...

I have 3 6v 2200 NiMh battery packs in the plane... one for ignition, one for the rcvr/servos, and one dedicated to the retracts...

I've seen big planes with LiPo packs.. I have a bunch of 3s 2200MAh 20c packs for my foamies..

How do I / what do i buy to replace the 3 NiMh packs with one LiPo???

thanks in advance... (let's see if this is fast enough)!!!

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RE: replace NiMh with a LiPo - 12/19/2012 1:34 AM   
BuschBarber


 

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quote:

ORIGINAL: sparky4lawndart

Let me try this post again... apparently I'm too slow typing and the RCUniverse gods don't like that...

I have a 20cc warbird... I have an airtronics RDS8000 I love... 8 channel rcvr... Hitec servos all around... Eflite retracts...

I have 3 6v 2200 NiMh battery packs in the plane... one for ignition, one for the rcvr/servos, and one dedicated to the retracts...

I've seen big planes with LiPo packs.. I have a bunch of 3s 2200MAh 20c packs for my foamies..

How do I / what do i buy to replace the 3 NiMh packs with one LiPo???

thanks in advance... (let's see if this is fast enough)!!!

I have been using Lithium batteries for my Tx and Rx for years. 2cell LiPos charge up to 8.4v (4.2v/cell). I have been using a 6v voltage regulator for the Rx and a 5v voltage regulator for the Ignition (unless the Ignition supports 6v). Recently, I switched to A123/LiFe battery packs. 2cell LiFe batteries charge to about 7v but quickly drop to 6.6v and stay at that level throughout the discharge cycle. You can replace your 6v NiMh with LiFe and not have to use a voltage regulator unless your Ignition only supports 5v. You can also use 3cell LiFe Tx packs.

I use FMA 4S and 10S chargers as they are excellent for all Lithium battery charging. They give me the voltage readings for each cell and balance the cells very well.

Lithium cells hold their charge for months and charge quickly. You probably know that since you fly electrics. I don't use NiCad or NiMh anymore. Eneloops are ok for Tx's, but still take much more time to charge than Lithium cells.

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RE: replace NiMh with a LiPo - 12/19/2012 1:54 AM   
flyinwalenda


 

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Status: online 		To use lipos you will need a voltage regulator for the ignition and the receiver. 


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RE: replace NiMh with a LiPo - 12/19/2012 1:56 AM   
sparky4lawndart



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Status: offline 		never having had a LiFe battery ... I don't think my Hobby People TAZR charger would charge one... (/sad face)

how about a solution that includes the 3s LiPos i already got? It'll be tough to buy a $100 LiFe battery AND a new charger...

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RE: replace NiMh with a LiPo - 12/19/2012 1:58 AM   
sparky4lawndart



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Status: offline 		which voltage regulator... my LHS focuses mainly on cars... they have to order everything I ask for...

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RE: replace NiMh with a LiPo - 12/19/2012 2:05 AM   
BuschBarber


 

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quote:

ORIGINAL: sparky4lawndart

never having had a LiFe battery ... I don't think my Hobby People TAZR charger would charge one... (/sad face)

how about a solution that includes the 3s LiPos i already got? It'll be tough to buy a $100 LiFe battery AND a new charger...

EPbuddy LiFe batteries cost $25 for a 2cell 2500mah pack. Turnigy LiFe packs are even cheaper. I have been using them for a couple of years. You can purchase an FMA 4S charger for $60. Even cheaper for a refurb.

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RE: replace NiMh with a LiPo - 12/19/2012 2:07 AM   
BuschBarber


 

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ORIGINAL: sparky4lawndart

which voltage regulator... my LHS focuses mainly on cars... they have to order everything I ask for...

I have used MPI voltage regulators or SmartFly voltage regulators. My LHS carries the Castle Creations BEC and BEC Pro which work fine as voltage regulators.

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RE: replace NiMh with a LiPo - 12/19/2012 4:17 AM   
sparky4lawndart



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Status: offline 		I realized I didn't ask a more fundamental question...

will a single 2200MAh LiPo have the same "umph" that three distinct 2200 6v NiMh packs have? I just realized that I may be cutting off my nose in spite of my face... or not see the trees through the forest.. or something like that.. you know what i mean...

If you were going to go and fly all day Saturday.. would a single charge on that LiPo have the same longevity as 3 distinct NiMh packs??? am i setting myself up for a crash?

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RE: replace NiMh with a LiPo - 12/19/2012 1:53 PM   
Zeeb



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I'm not trying to be disparaging, but you're asking for trouble IMHO with your experience level when trying to convert a gas powered model from 3 separate NiMH batteries to one LiPO.

I'd say that your 20C battery may not be the best solution for such a task, you'll need to verify what voltages your servos, rx, ignition module and retracts can take. Then line up the appropriate regulators since I don't think a lot of what you've got will take an unregulated LiPo voltage. Those would most likely be linear regulators unless you're wanting to spend some cash for the newer more capable switching type regulators. Those will cost you as much or more than the LiFe batteries and charger mentioned.

We've not talked about wiring, connectors or switches yet either.....

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RE: replace NiMh with a LiPo - 12/20/2012 6:54 PM   
flyinwalenda


 

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Status: online 		I would get a regulator with a redundant port. Install one lipo to the main regulator port for the electronics. Install a second lipo to the redundant port . You could tap off the lipo used for redundancy and use it to power the ignition. Lipo receiver and ignition packs are typically 2 cell (7.4volts) 1800-2200 at 5C.. With lipos or Lifes you will realize more flights between charges compared to Nicds or Nmhs. Plus they will have longer life span  too .


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RE: replace NiMh with a LiPo - 12/23/2012 7:58 AM   
chuckk2


 

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Status: offline 		I prefer Lipos and switching voltage regulators.  The voltage regulator(s) should be capable of at least 5-6A continuous.
It's even possible to use isolating diodes with multiple Lipos, due to the voltage margins.

Some testing I did showed that NMIH and NIcads can be marginal when they are not at close to full charge.
By marginal I mean excessive voltage droop under load.  Digital servos and/or electric retract gear can increase the problem.
Sanyo's Enloop NMIH battery charts for 2500mah cells show that a 2A or greater load  may result in an undesired voltage droop.


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RE: replace NiMh with a LiPo - 12/23/2012 7:47 PM   
4*60


 

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Status: offline 		Use the lipos with. Becs if you wish, but people should know that life packs are available for$10 or less and chargers capable of all chemistries are available for $30 orl ess.
You should also understand that 2200 mah is 2200 mah unless higher voltage on a regulator but a 2s 2200 lipo has very little extra capacity.  Difference might be voltage drop on nimh.
Nimh unless lsd like eneloop also lose charge in storage. With life if you forget to chsrge they have about the charge they had on the last flying day, so you probably get away with the error.

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RE: replace NiMh with a LiPo - 1/5/2013 5:04 PM   
rexbirk


 

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Status: offline 		I have three 30cc planes and two 50cc size planes on A123 or LiFe. My 30cc have one battery (2300mah), no regulator and use an IBEC battery eliminator to power the ignition from the receiver flap channel. This gives me a cutoff switch on the transmitter. I have been using this setup for two seasons. Couldn't be happier. I get 5 10 minute flights on 800 to 900 mah from the battery.

My 50cc size planes use the same setup except with two batteries running thru separate switch's to different ports on the receiver. I use a cheap Hobbyking Accucell 6 charger, $30.00 or so. I have 6 of these chargers. They charge all the common battery types I use.

The A123 batteries charge amazingly fast and do not lose charge when stored. I get mine thru Milehigh Rc. Similar price to Epbuddy. I get mine with Deans connectors and made long balance leads for my charger so I can balance in the plane.

Much safer chemistry for charging in the plane than LiPo.

I'm not going back to NiMh!


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RE: replace NiMh with a LiPo - 1/5/2013 9:26 PM   
pilotpete2



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RE: replace NiMh with a LiPo - 1/6/2013 1:35 AM   
mithoangel


 

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Status: offline 		To use lipos you will need a voltage regulator for the ignition and the receiver. 


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RE: replace NiMh with a LiPo - 1/6/2013 12:07 PM   
rexbirk


 

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quote:

ORIGINAL: mithoangel

To use lipos you will need a voltage regulator for the ignition and the receiver. 



Unless your servos, receiver and igntion are rated for lipos which most are not.



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