HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Oct 12, 2010, 09:02 AM
Registered User
KragerÝ, Norway
Joined Jun 2010
731 Posts
Discussion
Use pararell wire on big heli to get more flight time?

I have a pararell wire that I use on my FPV easystar, so I can use 2x 2200 mah to get 4400 mah. If I understand this right, to use two batteries like I do with these, doesn't give me 6S battery, and the voltage is the same when I use two 2200 mah in pararell. I just got to be 100% sure before I try it, so can I use two 6S 5000 mah packs together and still have a 6S setup 25.2V? I don't want to destroy my stock esc and motor doing this if I over amp, or over voltage is. I get 25.2 V with two 6S 5000 mah packs?

Sorry for this noobie question, but i cannot crash this heli.

Thanks,

Petter
Voguna is online now Find More Posts by Voguna
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 12, 2010, 09:06 AM
Registered User
Basingstoke, UK
Joined Aug 2010
1,292 Posts
Quote:
Originally Posted by Voguna View Post
I have a pararell wire that I use on my FPV easystar, so I can use 2x 2200 mah to get 4400 mah. If I understand this right, to use two batteries like I do with these, doesn't give me 6S battery, and the voltage is the same when I use two 2200 mah in pararell. I just got to be 100% sure before I try it, so can I use two 6S 5000 mah packs together and still have a 6S setup 25.2V? I don't want to destroy my stock esc and motor doing this if I over amp, or over voltage is. I get 25.2 V with two 6S 5000 mah packs?

Sorry for this noobie question, but i cannot crash this heli.

Thanks,

Petter
Two batteries of the same type and voltage approximately doubles the capacity but keeps the voltage the same.

To be certain, verify with a voltmeter/multimeter before plugging anything in.
tom66 is offline Find More Posts by tom66
Reply With Quote
Old Oct 12, 2010, 09:08 AM
Registered User
KragerÝ, Norway
Joined Jun 2010
731 Posts
Thanks.

I think I will try to hover 1 meter over the ground, and see if I get double flight time, or atleast 70-80% more flight time.
Voguna is online now Find More Posts by Voguna
Reply With Quote
Old Oct 12, 2010, 09:10 AM
Praying for better weather
Coyote64's Avatar
Joined Dec 2007
4,180 Posts
If you use two batteries in pararell you will get the same voltage but twice the current.

If you wire two in series you will get double the voltage but the same current capacity

So pararelling two 6S 5000mah will give you 25.5v at 1000mah,
Coyote64 is offline Find More Posts by Coyote64
Reply With Quote
Old Oct 12, 2010, 09:24 AM
Registered User
KragerÝ, Norway
Joined Jun 2010
731 Posts
The current is the Mah, right? :P
I dont get double amps, etc?
Voguna is online now Find More Posts by Voguna
Reply With Quote
Old Oct 12, 2010, 09:32 AM
Registered User
Basingstoke, UK
Joined Aug 2010
1,292 Posts
You have to understand the difference between mA, mAh, and the power a device can supply.

I don't wish to get technical but V = IR (ohm's law) means that current is proportional to voltage and resistance.

When you have a supply rated at 1A, swapping it for a supply rated at 600mA will probably not work, because the gadget needs 1A. But, if you have a supply rated at 1A and swap it for a 2A supply it will work, but you will have spent extra money for the tolerance band you have created, which is good.

Battery capacity just tells you how much energy is in the battery, not what it can output.

In short a load only draws as much current as necessary so putting two batteries in parallel will not cause problems.
tom66 is offline Find More Posts by tom66
Reply With Quote
Old Oct 12, 2010, 09:52 AM
Honey Badger
Blue Chip's Avatar
United States, FL
Joined Oct 2005
1,814 Posts
whoops...double post.
Blue Chip is offline Find More Posts by Blue Chip
Last edited by Blue Chip; Oct 12, 2010 at 11:11 AM.
Reply With Quote
Old Oct 12, 2010, 09:52 AM
Honey Badger
Blue Chip's Avatar
United States, FL
Joined Oct 2005
1,814 Posts
Short answer - yes - red to red and black to black will double the battery life without changing the voltage.

The added weight may reduce the flight time some though.

If you went red to black then used the red off of one battery and the black off of the other you would double your voltage.
Blue Chip is offline Find More Posts by Blue Chip
Reply With Quote
Old Oct 12, 2010, 10:16 AM
Praying for better weather
Coyote64's Avatar
Joined Dec 2007
4,180 Posts
Current is measured in amps, 500ma is 500 mili-amps, or 0.5 amps. 1000ma is 1 amp.

Mah is how many ma your battery can provide for 1 hour, hense mili amp hours mah

So parallelling two 5000mah gives you 10000mah or 10 amp for 1 hour

So if your motor takes 20 amps then you dived your 1 hour (60 mins ) by 20 ( amps ), telling you a flight time of 30 mins
Coyote64 is offline Find More Posts by Coyote64
Reply With Quote
Old Oct 13, 2010, 05:14 AM
Registered User
Basingstoke, UK
Joined Aug 2010
1,292 Posts
Quote:
Originally Posted by Coyote64 View Post
Current is measured in amps, 500ma is 500 mili-amps, or 0.5 amps. 1000ma is 1 amp.

Mah is how many ma your battery can provide for 1 hour, hense mili amp hours mah

So parallelling two 5000mah gives you 10000mah or 10 amp for 1 hour

So if your motor takes 20 amps then you dived your 1 hour (60 mins ) by 20 ( amps ), telling you a flight time of 30 mins
That's somewhat correct, but not quite. Because of the internal resistance of the battery drawing 10 amps from it will probably give you 40-50 minutes. But it's a useful approximation.
tom66 is offline Find More Posts by tom66
Reply With Quote
Old Oct 13, 2010, 12:20 PM
Praying for better weather
Coyote64's Avatar
Joined Dec 2007
4,180 Posts
Yeas its only an example Tom, after all its powering servos, cameras and receiver units too, not just the motor. Im trying to explain it as simply as possible rather bring in lots of variables and factors that will cloud the overall message
Coyote64 is offline Find More Posts by Coyote64
Reply With Quote
Old Oct 13, 2010, 12:25 PM
Registered User
KragerÝ, Norway
Joined Jun 2010
731 Posts
Thanks guys.

Can I use the paraell wire to charge BOTH batteries at the same time? For example charge two 2200 Mah packs at 2.2 A?
Voguna is online now Find More Posts by Voguna
Reply With Quote
Old Oct 13, 2010, 12:49 PM
Spektrum Dev Team
aaronredbaron's Avatar
United States, IL, Champaign
Joined Apr 2002
1,110 Posts
Quote:
Originally Posted by Voguna View Post
Thanks guys.

Can I use the paraell wire to charge BOTH batteries at the same time? For example charge two 2200 Mah packs at 2.2 A?
you can, but you have to be really careful about balancing and only doing it when the batteries are matched and in the same state of charge... its probably best just to not do it unless you really understand the dangers of LiPos.

Are you trying to double your flight time on a 600 size heli (I'm assuming a Trex 600) by doubling the battery capacity? not gonna work out too well. You will end up carrying so much extra payload in your extra pack you are going to be pulling significantly more current to maintain flight, and its not going to double the flight time. You would probably see a small increase in flight time, but at the expense of a very heavy disk loading, and you might just smoke your ESC and/or motor trying to do it!

One thing you have to remember is most RC helis are built for 3D, and you don't need to spin 2200 RPM on your 600 for FPV. If you re-gear it for about 1700-1850, you'll get longer flight times just by dropping the headspeed, and it will be more tame for FPV anyway. For extended flight times, you need to look at an HV power system, the stock Trex 600 motor is limitied to 6s and isn't very efficient. Going HV you can use a much better quality and more efficient motor, and going HV will keep the current draw down. If you set it up with a 10s 4000 mAh pack with Neu motor, and gear it for lower head speeds, you may be able to actually reach that double flight time you're trying to reach. One thing to keep in mind... the Trex 600 doesn't like to carry a lot of extra weight, and it can get kinda wonky in a fast decent with a heavy payload... It tends to get into a vortex ring state condition where it settles with power, with a heavy payload....
aaronredbaron is offline Find More Posts by aaronredbaron
Reply With Quote
Old Oct 13, 2010, 12:51 PM
Future-proof EVERYTHING
DarkHeli's Avatar
NY
Joined Jul 2008
762 Posts
Quote:
Originally Posted by Voguna View Post
Thanks guys.

Can I use the paraell wire to charge BOTH batteries at the same time? For example charge two 2200 Mah packs at 2.2 A?
Unless the batteries have been used EXACTLY the same, I wouldn't trust it. If one for example is 2000 mah due to aging and the other is still 2200, it could make the lower capacity battery overheat/start fire.

The same goes to your paralleled batteries. They both have to be in similar condition, otherwise one will die early.
DarkHeli is offline Find More Posts by DarkHeli
Last edited by DarkHeli; Oct 13, 2010 at 01:01 PM.
Reply With Quote
Old Oct 13, 2010, 01:11 PM
Registered User
KragerÝ, Norway
Joined Jun 2010
731 Posts
I see. I cannot say I am totally agreed with you.. I have a PS1 2XPT camera mount, a Nikon D90 and two 6S 5000 packs. I have flied some with this payload now, and I tested 2 packs 5000 mah, and got 7-8 Min with 95 % idle up headspeed. I had used 8500-9500 mah. I will used 95% on the idle up, just to see it it could keep the power up all the time, and it did. I will use a much lower headspeed. But I cannot get to low, it will just start shaking when I try to give some pitch.






Quote:
Originally Posted by aaronredbaron View Post
you can, but you have to be really careful about balancing and only doing it when the batteries are matched and in the same state of charge... its probably best just to not do it unless you really understand the dangers of LiPos.

Are you trying to double your flight time on a 600 size heli (I'm assuming a Trex 600) by doubling the battery capacity? not gonna work out too well. You will end up carrying so much extra payload in your extra pack you are going to be pulling significantly more current to maintain flight, and its not going to double the flight time. You would probably see a small increase in flight time, but at the expense of a very heavy disk loading, and you might just smoke your ESC and/or motor trying to do it!

One thing you have to remember is most RC helis are built for 3D, and you don't need to spin 2200 RPM on your 600 for FPV. If you re-gear it for about 1700-1850, you'll get longer flight times just by dropping the headspeed, and it will be more tame for FPV anyway. For extended flight times, you need to look at an HV power system, the stock Trex 600 motor is limitied to 6s and isn't very efficient. Going HV you can use a much better quality and more efficient motor, and going HV will keep the current draw down. If you set it up with a 10s 4000 mAh pack with Neu motor, and gear it for lower head speeds, you may be able to actually reach that double flight time you're trying to reach. One thing to keep in mind... the Trex 600 doesn't like to carry a lot of extra weight, and it can get kinda wonky in a fast decent with a heavy payload... It tends to get into a vortex ring state condition where it settles with power, with a heavy payload....
Voguna is online now Find More Posts by Voguna
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion does a higher mAh on a lipo only give you more flight time or more power?? john-rcg Batteries and Chargers 26 Oct 09, 2006 08:54 AM
Discussion Can I get more flight time Bretskee Batteries and Chargers 1 May 02, 2006 01:10 PM
What config to change to get more flight time jyzoom Castle Creations 3 Nov 01, 2005 09:06 AM
What config to change to get more flight time jyzoom Micro Helis 8 Oct 27, 2005 02:16 PM