HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 04, 2012, 05:08 PM
Registered User
Free fall's Avatar
United States, OR, Portland
Joined Apr 2012
33 Posts
Help!
Nimh battery drain

Hi. I'm fairly new to the world of rc planes. I've had good luck with lipo batteries. I just purchased a Nimh battery and I seem to be having issues with it holding a charge.

I am trying to set up a receiver with two servos. I bought a new Elite 1500 mah Nimh 2/3A battery. When I plug the battery into the receiver and bind the receiver I can get about 30 seconds of operation from the servos before the servos stop moving.

I'm using a Spektrum DX6i and AR6210 receiver.

I have a voltmeter to check the battery. I charge the battery to 6 volts before I connect it to the receiver. After things stop working - as described above - checking the battery shows around 4 volts.

Do I have a bad battery? Am I doing something wrong?
Free fall is offline Find More Posts by Free fall
Reply With Quote
Sign up now
to remove ads between posts
Old May 04, 2012, 05:30 PM
characters welcome!
Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
26,210 Posts
How long are you charging it and at what amp rate? It may be "false peaking" where the charge rate is too high to keep the charger from stopping the charge. The initial charge of a nimh receiver pack should be via your "wall wart" charger that came with your radio overnight after which it can be charged on your fast charger at .5 amps.

mw
Mark Wood is offline Find More Posts by Mark Wood
Reply With Quote
Old May 04, 2012, 05:30 PM
Expo/DualRates = Lack of Skill
typeRA's Avatar
San Diego, CA
Joined Mar 2009
789 Posts
How are you charging the battery?
typeRA is offline Find More Posts by typeRA
Reply With Quote
Old May 04, 2012, 06:14 PM
Registered User
Free fall's Avatar
United States, OR, Portland
Joined Apr 2012
33 Posts
I'm using a Hitec X1 AC Plus charger. I'm no expert in it's use. Maybe I'm not charging the battery long enough.

How can I tell if the battery is fully charged?

Thanks for the help.
Free fall is offline Find More Posts by Free fall
Reply With Quote
Old May 04, 2012, 06:22 PM
Expo/DualRates = Lack of Skill
typeRA's Avatar
San Diego, CA
Joined Mar 2009
789 Posts
The battery will get warm (not hot) when full.

Try charging at 150mA for 14-16 hours.
typeRA is offline Find More Posts by typeRA
Reply With Quote
Old May 04, 2012, 06:23 PM
Pompano Hill Flyers
Miami Mike's Avatar
Miami Lakes, Florida, USA
Joined Mar 2003
8,484 Posts
Quote:
Originally Posted by Free fall View Post
I'm using a Hitec X1 AC Plus charger. I'm no expert in it's use. Maybe I'm not charging the battery long enough.

How can I tell if the battery is fully charged?
The X1 AC Plus Battery Charger is a peak charger and should stop automatically, so you probably won't be able to make it charge for 14-16 hours. Just carefully read the manual and make sure you're using it properly.
Miami Mike is offline Find More Posts by Miami Mike
Reply With Quote
Old May 04, 2012, 06:55 PM
Registered User
Free fall's Avatar
United States, OR, Portland
Joined Apr 2012
33 Posts
Ok, thanks.

I'm charging it at 1.0 amps for an hour. I'll see what that is does.

The instruction manual is not very helpful. I'm pretty new to electronics.

I thought that the battery would have come fully charged. But obviously wasn't.

Anyway,thanks.
Free fall is offline Find More Posts by Free fall
Reply With Quote
Old May 04, 2012, 09:45 PM
Field Darter
bobbyhigh's Avatar
Singapore, Singapore
Joined Oct 2011
31 Posts
I recommend Eneloop NiMHs if you can get your hands on them.
bobbyhigh is online now Find More Posts by bobbyhigh
Reply With Quote
Old May 05, 2012, 04:59 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,565 Posts
Quote:
I'm charging it at 1.0 amps for an hour.
There is your problem.

New or ones not used*cycled) in the past few weeks ned tobe formed (slow charged).
A slow charge is fix rate (non peak) at aprox. 1/10C for 14 to 16 hours. In your case that woukld be a 150 mA rate charege. Many chargers jump from 100 to 200 and in case 100 would be best but 200 would work.

As mentioned above charge until warm. There are hundreds of places on the web with great Ni chareging and care info one being.

http://www.hangtimes.com/rcbattery_faq.html

Snip

Quote:
Q: What’s ‘cycling’ and why do I need to do it?

*


A: Battery‘cycling’ in it’s simple form is the two step process of charging and then discharging the battery under controlled conditions. Normally the purpose of the procedure is to ‘condition’ or ‘format’ a new pack or to verify the capacity or check the condition of a pack that’s been in service. ‘Routine’ cycling, or discharging before recharging a pack after every use is not necessary for either NiMH or Nicad packs, and discharging to ‘zero’ voltage under load is in fact harmful. A ‘cycler’ or controlled discharger will limit the discharge voltage level to prevent damage to the pack, whereas ‘leaving the switch on’ in your radio system to discharge a pack is very poor practice and may result in damage your radio system components or the battery.
I strongly suggest you use the link and read the complete post
everydayflyer is offline Find More Posts by everydayflyer
Reply With Quote
Old May 05, 2012, 05:04 AM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by Free fall View Post
.......I'm charging it at 1.0 amps for an hour........
There's the answer straight away .... you bought a 1500mAh NiMh pack = 1.5AH .... and you charge at 1A for 1 hour.

You are not even denting the charge at that ... a) it's too fast a rate, b) you are only about half the time needed to charge the pack.

You should be for long life - charging at 1/10th of pack mAh .... which as another said is 150mA ... and you should charge for 14+ hrs.

The usual guideline is 1.4 x the pack capacity in charge .... the reason for this is the battery as it gets charged is more resistant to charge coming in .. the last bit of charge can take as long as the majority ... and you are not even close with your 1A at 1hr.
solentlife is offline Find More Posts by solentlife
Reply With Quote
Old May 05, 2012, 06:09 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,565 Posts
Quote:
The usual guideline is 1.4 x the pack capacity in charge .... the reason for this is the battery as it gets charged is more resistant to charge coming in ..
Slight correction:

Ni cells do not charge at 100% effeciency and thus the reason for part of the extra 40% cgharge time ,also in a series wired battery cells will not all charge at the same rate as ones with higher IR wilkl charge slower and ones with lower IRs will have discharged fater under use so the extra is to get them all completely full (balanced).

There is a lot more to it than tjhis and the link I provided is a great place to start. One could spend weeks reading all of the care and feeding of Ni cells / batteries and still not read it all. Some of the data is good based on facts / experience and some is BS and is just what someone read or heard some where and repeated.

Not all NiMH cells are created equaly. Some are good for low drain applications such as Transmitters ,some good for higher drain such as receivers / servos and some are good for very high drain such as powering a motor for electric flight. Non are really best for all of these applications.

Charles
everydayflyer is offline Find More Posts by everydayflyer
Reply With Quote
Old May 05, 2012, 12:32 PM
222 km/hr Parkjet flyer
solentlife's Avatar
Latvia / UK visits
Joined Jan 2010
8,335 Posts
Quote:
Originally Posted by everydayflyer View Post
Slight correction:

Ni cells do not charge at 100% effeciency and thus the reason for part of the extra 40% cgharge time ,also in a series wired battery cells will not all charge at the same rate as ones with higher IR wilkl charge slower and ones with lower IRs will have discharged fater under use so the extra is to get them all completely full (balanced).

There is a lot more to it than tjhis and the link I provided is a great place to start. One could spend weeks reading all of the care and feeding of Ni cells / batteries and still not read it all. Some of the data is good based on facts / experience and some is BS and is just what someone read or heard some where and repeated.

Not all NiMH cells are created equaly. Some are good for low drain applications such as Transmitters ,some good for higher drain such as receivers / servos and some are good for very high drain such as powering a motor for electric flight. Non are really best for all of these applications.

Charles
Fair do's ... true but my comment is based on what a senior Tech at Mallory batteries told me years ago ..... and anyway whatever the reason - if the OP applies the 1.4x rule - he wont go far wrong,......
solentlife is offline Find More Posts by solentlife
Reply With Quote
Old May 05, 2012, 01:05 PM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,565 Posts
Quote:
senior Tech at Mallory batteries told me years ago
and for Nicads in general of that day he was correct for ones charged at 1/10c however things are never that simple.

Charged at 1/15 C or 1/20C then the charge time has to be increase by more than linear. IE instead of 28hr. at 1/20C it is more like 40 hours at 1/20C. Then today most are NiMH not Nicad and they vary a lot depending on what they were designed / manufactured for application wise.

There are still a great many experts that clearly state LiPolys should only be charged at a Max. of 1C and many state that charging slower give them longer life. IMO based on thousands of cycles at charge rates between 3C and 12C that is BS if one is refering to todays 20C plus discharge rated LiPolys and a decent balancing charger.

Most fail to except the fact that charging to 4.2 per cell, discharging below a resting voltage of 3.7 per cell, leaving fully charged for over a few hours etc. takes a lot more cycles from most LiPolys than charging them at 3 to 5C does.


Charles
everydayflyer is offline Find More Posts by everydayflyer
Reply With Quote
Old May 05, 2012, 01:10 PM
Registered User
richard hanson's Avatar
United States, UT, Salt Lake City
Joined Oct 2007
6,592 Posts
DX6i comes with spring clips for individual cells -

The absolute easiest -most foolproof for the DX6i, is to buy from some battery source - the Eneloop charger and 4-or-8 cells AA size
Use the Eneloop charger
put in the cells- run em till they are low -then remove and replace with recharged cells
This works - and the clips work very well
If you buy from some sources - a package of 8 AA cells and 4 AAA cells plus the charger is 30 bucks- Costco offered this arrangement a number of times
richard hanson is offline Find More Posts by richard hanson
Reply With Quote
Old May 05, 2012, 01:15 PM
Registered User
Free fall's Avatar
United States, OR, Portland
Joined Apr 2012
33 Posts
Ok, thanks. I'm learning a lot here. Thanks for the link.
Free fall is offline Find More Posts by Free fall
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold new spektrum dx8 2000mah nimh batterynew spektrum dx8 2000mah nimh battery ohsnap Aircraft - General - Radio Equipment (FS/W) 1 Nov 09, 2012 10:13 AM
Question Trying not to drain the battery on Honey Bee V2... mihax209 Micro Helis 14 Apr 10, 2012 05:06 PM
Question Battery drained overnight? unitoo1 Batteries and Chargers 12 Mar 23, 2012 03:45 AM
Question 450 has more lift as battery drains GooberSB Electric Heli Talk 36 Mar 16, 2012 03:48 PM
Sanyo 720mah NiMH max current drain? Ben74 Power Systems 8 Aug 03, 2001 12:52 AM