Charging the 9X $8 Battery - Balancing the Pack?

Nicad, NiMH, Lithium, A123? If it's transmitter or receiver batteries you want to talk about, do it in this forum.

Charging the 9X $8 Battery - Balancing the Pack?

Postby aesmith » Sat Dec 22, 2012 9:48 am

Hi all,

A follow up after I've been using this modification for a while. How do you guys make sure that the pair of cells stay balanced? I think mine is getting out of balance because when I charge it the charger breaks off the charge before completion, after hitting 8.4V for a while, with a "Disconnection" message. I assume that's one of the cells topping out and the protection circuitry being triggered and going open circuit. Also once the pack's in service the voltage drops really rapidly to 7.4V or 7.5V, then very much slower from there.

So for all you more experienced guys using this modification, how do you charge, and do you fit and use a balance lead?

Thanks, Tony S
aesmith
 
Posts: 101
Joined: Tue May 04, 2010 11:45 am
Location: Scotland

Re: Charging the 9X $8 Battery - Balancing the Pack?

Postby quarry44 » Sat Dec 22, 2012 10:13 pm

I charge it with my 4-button charger,on the li-ion (3.6v)setting.I don't have a balancing lead on it.Bruce mentioned in the original video that's it not really necessary to balance a 2-cell pack,but I suppose there's nothing to stop you from fitting a balancing lead.
I did fit a balance lead on my 2-cell LiFePo4 packs I made up,but it's balanced within seconds,so probably not necessary.
quarry44
 
Posts: 383
Joined: Fri Aug 19, 2011 6:58 am

Re: Charging the 9X $8 Battery - Balancing the Pack?

Postby aesmith » Sun Dec 23, 2012 11:34 am

quarry44 wrote:I charge it with my 4-button charger,on the li-ion (3.6v)setting

Isn't that a bit low? I suppose it depends on the actual cells, the data sheet for mine says to charge to 4.2V (overcharge protection cuts in at 4.25).
aesmith
 
Posts: 101
Joined: Tue May 04, 2010 11:45 am
Location: Scotland

Re: Charging the 9X $8 Battery - Balancing the Pack?

Postby quarry44 » Sun Dec 23, 2012 8:56 pm

The 3.6 volts is the nominal voltage of the battery.A fully charged one will be around 4.2volts.
quarry44
 
Posts: 383
Joined: Fri Aug 19, 2011 6:58 am

Re: Charging the 9X $8 Battery - Balancing the Pack?

Postby aesmith » Sat Jan 12, 2013 4:56 pm

I ended up fitting a balance lead and it turned out it was needed. On charge one cell when quickly to 4.2 whereas the other took a long time to get the last little bit. The voltage doesn't drop so quickly while the set's in use now either.
aesmith
 
Posts: 101
Joined: Tue May 04, 2010 11:45 am
Location: Scotland

Re: Charging the 9X $8 Battery - Balancing the Pack?

Postby michielbeets » Fri Feb 01, 2013 5:11 pm

Hi,
I had similar thought about balancing. After a lot of online reading I posted this on my blog: http://www.rcgroups.com/forums/member.php?u=406549
It is based on this site: http://scriptasylum.com/rc_speed/lipo.html
Put in 2S and highlight "show balancer wire hookup".
What do you think?
michielbeets
 
Posts: 4
Joined: Wed Jan 16, 2013 8:32 pm

Re: Charging the 9X $8 Battery - Balancing the Pack?

Postby aesmith » Sat Feb 09, 2013 4:41 pm

Cheers, that makes sense. What I actually did was to add two addition leads. As well as the balance lead I added a power lead with a servo type connector which I can connect directly to my charger. That removes a bit of the risk from the pack having two compatible connectors wired differently.
aesmith
 
Posts: 101
Joined: Tue May 04, 2010 11:45 am
Location: Scotland


Return to Receiver/transmitter Batteries

Who is online

Users browsing this forum: No registered users and 5 guests