HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Oct 04, 2005, 06:25 PM
Registered User
R Hudson's Avatar
Waukesha, WI
Joined Dec 2002
563 Posts
Charging large NIMH packs in series?

I'm having a bit of a brain cramp, coupled with the fact that I have never charged more than one pack at a time before.

I have two 10-cell NIMH packs that I run in series to power an electric heli. I use a Y-connector so the batteries plug-in to the ESC separately.

My question is, if it is safe to run the packs in series this way, is it also safe to charge them the same way? So, rather than charging separately, charging them together as if they were just one larger pack.

Please help! My brain isn't working properly today!
R Hudson is offline Find More Posts by R Hudson
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 04, 2005, 06:44 PM
know it all
Miami, Fl
Joined Nov 2003
2,949 Posts
if both packs have the same capacity, and they have been discharged in series then they are ok for series charging.. never parallel charging. Charge in series at the 1C rate.

If the packs have always been used in series then they should have the same capacity.

Herm
hermperez is offline Find More Posts by hermperez
Reply With Quote
Old Oct 04, 2005, 09:08 PM
Registered User
Cosmic's Avatar
Czech Republic, Plzeň Region, Město Touškov
Joined Feb 2002
535 Posts
Yep, no problem. I do the same with 3 x 10 cell GP3300 packs for my Funtana.
Cosmic is offline Find More Posts by Cosmic
Reply With Quote
Old Oct 05, 2005, 10:56 AM
Registered User
R Hudson's Avatar
Waukesha, WI
Joined Dec 2002
563 Posts
Thanks guys!

I thought that you could, but I wasn't sure.

Up to this point, they haven't been used together, but I was thinking of discharging, then charging together very slowly at say, a .1C rate to balance the cells, then using them together regularly.

Does this make sense or is it a NO-NO?
R Hudson is offline Find More Posts by R Hudson
Reply With Quote
Old Oct 05, 2005, 01:09 PM
know it all
Miami, Fl
Joined Nov 2003
2,949 Posts
it is a good idea to balance the cells occasionally in a pack, 0.1c for 24 hours.. both your packs may not have the same capacity, so if you plan to use them in series dont discharge them all the way.. always land with a 20% reserve.. that should prevent a pack or cell from frying. Only matched packs should be discharged near 100%.

I use a countdown timer from the kitchen section at walmart, I attach it to my Tx antenna with a clothes pin. I always land with a 20% reserve.

Both packs have approximately the same amount of cycles?

Herm

Quote:
Originally Posted by R Hudson
Up to this point, they haven't been used together, but I was thinking of discharging, then charging together very slowly at say, a .1C rate to balance the cells, then using them together regularly.

Does this make sense or is it a NO-NO?
hermperez is offline Find More Posts by hermperez
Last edited by hermperez; Oct 05, 2005 at 01:25 PM.
Reply With Quote
Old Oct 05, 2005, 03:06 PM
Registered User
R Hudson's Avatar
Waukesha, WI
Joined Dec 2002
563 Posts
Yes, approximately the same cycles.

Also, am considering the same for two NICAD packs as well, same scenario.
R Hudson is offline Find More Posts by R Hudson
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Charging LiPo packs in series olly Batteries and Chargers 2 May 28, 2009 06:18 PM
Charging Large LiPoly Packs in Series? Brill 1 Batteries and Chargers 12 Apr 23, 2005 06:31 PM
Charging 2 packs in series with Supernova? Tram Batteries and Chargers 2 Oct 14, 2004 06:44 PM
charging 2 packs in series JerseyJerry Batteries and Chargers 4 Sep 05, 2004 11:29 PM
Charging packs in series Reco Power Systems 5 Jun 15, 2002 04:21 AM