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-   -   I need some new batteries (http://www.rcuniverse.com/forum/beginners-85/11245942-i-need-some-new-batteries.html)

s7jstep1 09-30-2012 09:19 AM

I need some new batteries
 
Hey guys. I recently got my first plane and had a couple of questions. It's a hobbyzone supercub and it is the nimh version. I traded it for about $30 worth of old Rc car electronics and the guy included a stock nimh battery. I can tell that the battery has set on the shelf for a while because it doesn't hold a charge for more than a few days and it only charger to about 750mah. I want to get some new packs but if I'm goin to buy batteries, I want some good lipos. I got my turnigy car lipos from Hobbypartz and I love them. I want to get like 3 or 4 packs for the plane but I'm not sure what to get. I was thinking around a 2000mah 3s lipo. I plan on modding the battery box to make it fit. What is a popular cheap pack to go with. Also, can I use the stock esc with an external voltage cutoff or do I need a new esc? Thanks

bikerbc 09-30-2012 10:22 AM

RE: I need some new batteries
 
I am not too farmilliar with electrics but one thing that comes to mind is the balance....That will change with your battery weight...You will need to rebalance....

KitBuilder 10-01-2012 03:08 PM

RE: I need some new batteries
 
This is a great first plane.. quite durable and easy to fly. First, the esc is most likely for brushed motors which is fine as your not changing that but the issue is low voltage cutoff.. The ESc would need to be adjusted to cut off or limit motor providing you notifcation that voltage was low if you werent timing your run. Since your cub was setup for NIMH the voltage cutoff is diff than lipo and you don't want to go below 3.7.. more like 3.9 per cell to be safe on your lipos.

2000mah would be to much for the cub.. i'd go with 1500 mah. Very important.. for lipo you will need a balancing charger to keep the cell voltage in sync.

Here is the info for the cub:
Motor Size: 480 brushed
Radio: 27MHz 3-channel proportional
Prop Size: 9 x 6
Recommended Environment: Outdoor
********Charger: DC powered 3S Li-Po balancing charger*************
*******Recommended Battery: 3S 11.1V 1300 Li-Po (included)*********

s7jstep1 10-01-2012 10:23 PM

RE: I need some new batteries
 

Quote:

ORIGINAL: KitBuilder

This is a great first plane.. quite durable and easy to fly. First, the esc is most likely for brushed motors which is fine as your not changing that but the issue is low voltage cutoff.. The ESc would need to be adjusted to cut off or limit motor providing you notifcation that voltage was low if you werent timing your run. Since your cub was setup for NIMH the voltage cutoff is diff than lipo and you don't want to go below 3.7.. more like 3.9 per cell to be safe on your lipos.

2000mah would be to much for the cub.. i'd go with 1500 mah. Very important.. for lipo you will need a balancing charger to keep the cell voltage in sync.

Here is the info for the cub:
Motor Size: 480 brushed
Radio: 27MHz 3-channel proportional
Prop Size: 9 x 6
Recommended Environment: Outdoor
********Charger: DC powered 3S Li-Po balancing charger*************
*******Recommended Battery: 3S 11.1V 1300 Li-Po (included)*********
okay cool. i do have a lipo charger that i use with my rc cars. ill probably get like 4 1500mah batteries so i can get some good time in the field. this is my first plane and i want to get as much practice as i can

jester_s1 10-02-2012 05:11 AM

RE: I need some new batteries
 
3.7v per cell is the midpoint on a lipo. Usually a low voltage cutoff is at 3v. That said, if you make your first few flights short and measure the capacity you used, you can set a timer to stop flying around the 2/3 mark and never worry about overdischarging your batteries. No LVC needed.

s7jstep1 10-02-2012 12:21 PM

RE: I need some new batteries
 
Won't I need a new esc anyway? My super cub is the version with the nimh batteries. They are the 7 cell so that makes them 8.4 volts. Will that stock esc handle a 3s lipo?

s7jstep1 10-08-2012 11:04 PM

RE: I need some new batteries
 
i was told that if i go with a 3s lipo, my stock esc will work with it. i just have to pull the jumper wire and re-prop to a 9x6. is this correct? if so im looking at these batteries http://www.hobbypartz.com/77p-sl1300-2s1p-20c-2222.html

and these props http://www.hobbypartz.com/88e-prop-9x6-grey.html

does this seem right? if i pull the jumper on my esc, can i safely run to the lvc without damaging the battery?
thanks

jester_s1 10-09-2012 07:13 AM

RE: I need some new batteries
 
That depends on where the LVC cuts off. You'll want it at 9v if you plan to depend on it to save your battery. If it's going to have the same LVC as it had for Nimh batteries, you'll ruin the Lipo. That said, if you're flying to the LVC even with it set right you're going to reduce the lifespan of your batteries. The LVC is really there as a safety net for when the pilot forgets to set his timer. The timer is the real way to save your batteries, set to stop flying when you still have 1/4 to 1/3 of your charge left.

s7jstep1 10-09-2012 09:32 AM

RE: I need some new batteries
 
yeah thats what i plan on doing i just want to cover my butt if i forget. do those props look okay?

s7jstep1 10-09-2012 11:55 AM

RE: I need some new batteries
 
just realized the batteries i posted are the 2s version. im meant to post the 3s version http://www.hobbypartz.com/77p-1300mah-3s1p-111-25c.html

im also wondering if these props will work
http://www.hobbypartz.com/88e-prop-9x6-grey.html

i was trying to get my batteries and props in the same order but if those wont work, ill order from 2 seperate places

s7jstep1 10-14-2012 10:09 PM

RE: I need some new batteries
 
i ended up getting the batteris in the link with some 10x6 props. got my ddeans on them and hopefully ill be flying soon.

jester_s1 10-15-2012 05:57 AM

RE: I need some new batteries
 
Do check your amp draw to be sure you aren't exceeding the limits of your motor or ESC. With more volts you'll draw more amps and have more watts. If that's a bigger prop than what you had before, that will make you draw more amps too.

s7jstep1 10-16-2012 09:43 AM

RE: I need some new batteries
 
i flew for 40 minutes on 2 batteries and i had no issues. the props are the same diameter as my old ones but with a smaller pitch


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