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charging lipo batteries - 7/13/2008 5:45:40 PM   
ridedirt


 

Posts: 3
Joined: 7/13/2008
From: Simi Valley, CA, USA
Status: offline 		I am new to electrics. I recently purchased a GP "Reactor" and all the electrics they suggested. LipoCharge 4. Equinox ballancer, 2 Lipo electirc fly 3200 batteries. I have only flown the plane once and have not been able to re-charge the batteries. The packs were drawn down to 8.9 and I had to dead stick land. I ballanced the batteries with the Equinox un-pluged from the charger. After the ballancing was complete, I pushed the button 3 times to get it to go to inteface, then pluged it into the charger. The green light came on momentarily, then went to amber sounding the alarm. I have tried many alternatives, but have been unsuccessful in re-charging them.

Can anyone out there HELP ME. I am so frustrated!!!

TM
       Post #: 1

RE: charging lipo batteries - 7/13/2008 5:53:50 PM   
jumper666


 

Posts: 247
Joined: 7/14/2006
From: N. Richland Hills , TX, USA
Status: offline 		Wait for more optimistic replies, but lipo's can be drawn down too far and "killed". Hopefully that is NOT what happened to you.

(in reply to ridedirt)
       Post #: 2

RE: charging lipo batteries - 7/13/2008 6:19:38 PM   
tIANci



Posts: 8451
Joined: 1/15/2004
From: Kuala Lumpur, MALAYSIA
Status: offline 		ridedirt ... Lipo are best when you discharge the voltage to no less than 3.1V per cell. So for your 3S packs you must ensure the total reading is no less than 9.3V. For me I find that anything less than 3.3V is no fun to fly if you are power hungry. Most of the times I stop when I feel the power is low and its usually about 3.4V. As for your problem:

First thing is you need to check your ESC, make sure that your cut off is at high ... that means about 3.1V-3.3V per cell depending on the ESC. Be EXTREMELY careful with the cheaper China made ESC as some have HIGH CUT set at 3.1V, so you can imagine if you were to use LOW CUT.

Your problem:

The battery voltage is too low and the charger will not charge it.

You solution:

This is to be done VERY CAREFULLY. Get a multi charger and set the charger to NiMH and then charge it for like 10-15 mins. Its pretty safe to do so as the lipo will not over charge in 10-15 mins if charged on a NiMH setting of 1C. Means charge it at 3.2A. This will bring the battery voltage back up. I have done it a few times before.

_____________________________

Its nice to be important, but its more important to be nice ...
www.rcheadz.com

(in reply to jumper666)
       Post #: 3

RE: charging lipo batteries - 7/13/2008 6:27:32 PM   
ridedirt


 

Posts: 3
Joined: 7/13/2008
From: Simi Valley, CA, USA
Status: offline 		I don't understand. My voltage read 8.9.

(in reply to tIANci)
       Post #: 4

RE: charging lipo batteries - 7/13/2008 7:34:59 PM   
tIANci



Posts: 8451
Joined: 1/15/2004
From: Kuala Lumpur, MALAYSIA
Status: offline 		Dude ... the voltage should read 9.3V ... 8.9V may be too low for the charger. Get it now?

_____________________________

Its nice to be important, but its more important to be nice ...
www.rcheadz.com

(in reply to ridedirt)
       Post #: 5

RE: charging lipo batteries - 7/13/2008 7:54:46 PM   
CloudSkipper


 

Posts: 294
Joined: 2/1/2008
From: Helsinki, FINLAND
Status: offline
quote:

ORIGINAL: tIANci
Your problem:

The battery voltage is too low and the charger will not charge it.

You solution:

This is to be done VERY CAREFULLY. Get a multi charger and set the charger to NiMH and then charge it for like 10-15 mins. Its pretty safe to do so as the lipo will not over charge in 10-15 mins if charged on a NiMH setting of 1C. Means charge it at 3.2A. This will bring the battery voltage back up. I have done it a few times before.

Looks like a neat trick. I'll remember that one. Hopefully I won't need it.

(in reply to tIANci)
       Post #: 6

RE: charging lipo batteries - 7/14/2008 2:16:36 AM   
ridedirt


 

Posts: 3
Joined: 7/13/2008
From: Simi Valley, CA, USA
Status: offline 		Thank you, I reread your first response and now understand. I will give your suggestion a try.

(in reply to tIANci)
       Post #: 7

RE: charging lipo batteries - 7/14/2008 4:10:22 AM   
tIANci



Posts: 8451
Joined: 1/15/2004
From: Kuala Lumpur, MALAYSIA
Status: offline 		Happy to be of assistance ... hehehehe ...

_____________________________

Its nice to be important, but its more important to be nice ...
www.rcheadz.com

(in reply to ridedirt)
       Post #: 8

RE: charging lipo batteries - 7/25/2008 2:52:37 AM   
lilbanchee


 

Posts: 293
Joined: 7/2/2006
From: Chula Vista, CA, USA
Status: offline 		Actually, there is ABSOLUTELY NOTHING special about lipo chargers, other than they charge a lipo battery up to the max cell voltage of 3.7v per cell, and only charge at a rate of about 1C. You can use a regular NiMH charger set for a low charge rate (keep it at about .5 amps for a ~2500 mah pack to be safe), and use a voltage monitor between the battery and the charger. Once it reads about 3.6-3.7v per cell, then unplug the battery. If it starts to get warm, then unplug immediately, to keep it from warming up any more, and causing damage. Also, you really have to keep watch on it if you do do this.

But 8.9v is way to low. NEVER trust your speed controlls auto cutoff. Land before it cuts off. But do set it for about 10v.

And I thought the minimum voltage a lipo can reach is 3.7v per cell, and 4.2v max. This means that a maximum voltage for a 3 cell lipo is 12.6v, and 11.1v minimum.

Am I right, or did I miss something when I read the manuals that say don't discharge below 11.1v????

_____________________________

Life is short, fly more!

(in reply to tIANci)
       Post #: 9

RE: charging lipo batteries - 7/27/2008 10:55:54 PM   
Cook2Fly


 

Posts: 34
Joined: 7/19/2008
From: LITTLE ROCK, AR, USA
Status: offline 		Hello I recently had a similar problem. I let my 2200 mah get to low by accidently leaving it plugged to the speed control while sitting on the work bench
Apparently the esc will draw power even when switched off!!! the battery got down so low that my charger would recognize it and no charge.. DEAD BATTERY
I brought it to my LHS and the guy there told me it was toast, but there was one thing he could try. He then used a multi charger and force charged it to
restablish pathways in the cells or something. Whatever he did was dangerous, time consuming, and it took constant eyes on the battery and charger.
After an hour of slowly force charging the battery it was brought up to the 3.1 or so v per cell. I do not reccomend trying this at home we did it on a concrete
floor in a shop with a metal bucket and fire extinguisher nearby. He saved my 70 $ battery and didnt charge me a dime! I still fly on it today. Guys like that make this hobby great.
Repeat do not try this by yourself, go to someone with experience ,and that is safety minded. Thanks for letting me share. Steve

(in reply to lilbanchee)
       Post #: 10

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