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Convert Hobbico Nexstar from NiMH to LiPo

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Old 08-25-2012, 01:06 PM
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usc1990
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Default Convert Hobbico Nexstar from NiMH to LiPo

Hi,

I am very much a rookie with electric flight and just am getting started with electric planes after some time away from the hobby. I'm currently flying a Hobbico Nexstar electric RTF from Tower Hobbies. The model came with two 8 cell 9.6V 3600 mAh NIMH batteries.

The manual had instructions to convert the plane to LiPo power. The exact wording the from manual is:

"The NexSTAR EP Select can also be fl own with a 5-cell
Lithium-Polymer (LiPo) set up. If you decide to go with LiPo
batteries, you will need the following items:
❏ *2S 3200mAh 7.4V 20C Discharge w/Balance (GPMP0622)
❏ *3S 3200mAh 11.1V 20C Discharge w/Balance (GPMP0623)
(*Use them together for a 5S set-up)"

I'm "guessing" the instructions are so because there are two leads for batteries from the ESC. Two questions:

1) Would it be better to convert to a single battery and get a new ESC than the conversion how-to listed above from Hobbico? If I did goto a single battery, any advice on what type?

2) The part numbers listed by Hobbico for LiPo conversion are not available anymore. I can get two very similar batteries but they are listed as 25C discharge batteries instead of 20C - does that make any difference?


Thanks very much!!

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Old 08-25-2012, 01:48 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

A single pack vs. a 2s and a 3s is pretty much preference. I think that splitting the packs is more versatile cuz you can use it in a 2s and 3s and 5s application. As far as the esc connection is concerned it will not matter if you use 2 or 1 pack and connection because ultimately there are only 2 wires from the esc and the 3rd wire simply jumpers the two packs together, right? To use one connector with 5 pack you could eliminate one and simply use the two main wires thus having one connector on battery and one on the esc. You can also use a "jumper" on one of the existing connectors to use a single pack.

For batteries the 25 C is actually a bit better rating than 20C so that's fine. Use 20C minimum. HobbyKing and Hobbypartz seem to have the best deals on almost all lipos , but there's a ton of great deals and vendors out there.

Hope this addresses all of it and helps you.
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Old 08-25-2012, 01:59 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

Yes that helps. The ESC has two connectors coming from it for the two battery packs, I don't think they are jumpered together. I'll probably go with two LiPos like the manual suggested and it will give flexibility like you indicate. Thanks on the advice on the 25C versus 20C. I attached an image of the ESC too so you can see the wiring.

Thanks!!

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Old 08-25-2012, 02:50 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

I to fly the nexstar and when I first started flying I crashed using NMH batteries. I bought another one and now I fly with the 2 and 3 cell and I also fly with the single 18.5 5000. They also seem to be equal in power and a much improvment from NMH. I also use the jumpe when using a single battery.
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Old 08-25-2012, 02:55 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

See that your esc really only has one red and one black wire for battery power. The black wire going from connector to connector is the "jumper" wire and all it does is put the two packs in series. See that the jumper hooks the one packs' + to the other pack's -

This helps a lot if you toggle between 1 pack and 2 series packs. http://www.scriptasylum.com/rc_speed/wiring.html
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Old 08-25-2012, 04:01 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

Thanks to both of you - the "light" just came on.

The link was very helpful - I'm gonna bookmark that one!
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Old 08-25-2012, 08:50 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

I love my Nextstar Electric with Lipos. I did not change a thing except switching from NiMH to Lipos.
It went from a dog to an awesome trainer (especially on grass fields)

The key is to keep the milli-amps the same for both batteries.

I use one 2S 7.4 volt 3350 mAh (25C) and one 3S 11.1 volt 3350 mAh (25C) Lipo packs.

Together they give you 18.5 volts, 3350 mAh (25C) since they are connected in series.

My other set of Lipo packs is 3800 mAh (30C) and they work just fine as well and give me longer flights.


Since the Lipo packs are lighter.... check your balance (CG).... mine did not require any adjustment (I also removed the auto correction ball underneath the rear fuselage.

Bottom Line: Just plug in the Lipos into the two deans connectors the same as you did with the NiMH and keep the milli-amps the same.

Be prepared for a whole new plane that will jump off the field on take-off & haul ass with the power of those Lipos and less weight !!!!

-Chuck
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Old 09-24-2012, 10:03 AM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

Just to finish the thread in case anyone else needs the info. I did convert the Nexstar to LiPo. I bought a Turnigy 5 cell, 5000mAh battery from Hobby King. Everything was super (except that I lost the battery hatch yesterday on the test flight - it flew off out in the middle of the soy bean field and I couldn't find it!)

Again, thanks all for the advice.
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Old 09-24-2012, 02:10 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

Excellent , thanks for the update. One battery to deal with (and no hatch,lol) I still haven't got this plane , but I still want it. How much flight time can you get with 5sx5000 mah?
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Old 11-06-2012, 03:47 PM
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Default RE: Convert Hobbico Nexstar from NiMH to LiPo

Guess what? I finally ordered one and even though the rimfire is supposed to be for 4s they are getting away with 5s easily it seems. Does anyone have any current , prop , data on 5s and 4s power?

How big of prop can this plane take? I like to use a much lower kv and bigger prop on mine. To me that big motor is just fine , but a 10x5 prop?

Also how much does the plane weigh without batts? Mine will have the PA removed too.

You guys must be having success and great fun because you aren't back to post anymore, right?
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