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Old 05-11-2010, 03:44 PM   #1
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Default Trying to save a lipo?

So I have a pack that has 1 low voltage cell.

Cell 1: 1.06v
Cell 2 - 4: ~3.7v

I heard that if you charger at like .5a on nimh setting you can possibly try to recover the pack.

I put the pack on nimh setting and it was at 11.xx volt, and i watched it go up to 12.04volts in about 4mins. and pulled it...

Tried to charger it a lipo and it says low voltage again...

I know a 4s max voltage is around 14.8v, so should i leave it on nimh setting its get a little higher than 12v? say maybe 13.5v?

Thanks guys...
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Old 05-11-2010, 03:52 PM   #2
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A 4S nominal voltage is 14.8V. Max voltage is 16.8 (4.2V/cell). I would charge it on NiMH a bit longer but be darn sure you are watching things like a hawk. If you have a cell overcharge, it can get out of hand pretty quick (FIRE).
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Old 05-11-2010, 03:55 PM   #3
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blah i honestly meant 4.2x4 = 16.8 not 14.8 ha....

Ok How much longer are we talking, or at least around what voltage would you say call it quits...
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Old 05-11-2010, 03:58 PM   #4
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I dont know much about lipos or electricty...

But looking at it like this...

Assuming i can pump the same voltage into each cell, in order to wake up the low voltage cell, it would need 2 more volts?

If each other cell got 2 more volts, that would sent them way past 4.2v?
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Old 05-11-2010, 04:33 PM   #5
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Haven't ever used one, but I hear there are chargers that can charge through the balance lead and allow you to specifically charge one of the cells. You may need to find someone with one of these, maybe your hobby shop.

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Old 05-11-2010, 05:30 PM   #6
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I'm going thru the same thing on some of my HK batteries that I just rec'd.
Brought them up to voltage with Nimh setting at 1.0A and I watch it as it gets up the fairly quickly. On a 4S, I would think you could let it get up to 14V-15V and then charge it up as a lipo.

Mine wont let me charge with the balance lead on the Nimh setting but I found that just connecting them will give the battery a slow balance and thats what has actually saved 2 of them so far. If you have that option, that what I recommend if you cant get the one bad cell up to the proper voltage. I did this after charging and discharging several times.

Letting the charger (Triton 2EQ) do this took a few hours but it saved me some headaches for sure.
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Old 05-11-2010, 05:38 PM   #7
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I havea triton EQ so i think i can,...

in lipo mode with the balancer plugged in, it freaks out, im gonna run it on nimh for a while to about 14-15v, then try the slow balance...
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Old 05-11-2010, 05:42 PM   #8
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I have found that my GT Power charger (10.0a/200w) does a better job of balancing than my other charger (5.0a/50w) -- sorry, can't remember the name of it.

The older charger will get the cells in balance and seems to accept them being 3 one-hundredths apart -- ie 4.17 and 4.20. The GT Power charger will take much longer and get the cells to within 1 one-hundredth apart -- ie 4.20 and 4.21.

This leads me to believe that some chargers simply do a better job of truly balancing than others. Probably something to do with the processor, chipset and programming quality.

When they are partially out of balance, the balance charge takes a lot longer to complete, but I suppose it is worth it in the long run.

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Old 05-11-2010, 05:47 PM   #9
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Quote:
Originally Posted by agarabaghi View Post
I havea triton EQ so i think i can,...

in lipo mode with the balancer plugged in, it freaks out, im gonna run it on nimh for a while to about 14-15v, then try the slow balance...
I'm not sure if yours has it but on mine, it has a data readout screen.....one portion shows all the individual cells as they are charging/discharging/balancing. This way you can see how the bad cell is doing and whether or not it looks like its going to come back up.
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Old 05-11-2010, 05:50 PM   #10
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I can access that screen when the low voltage error pops, but i have not tried to see it while charging. Do you know the button sequence to change the view while charging?
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Old 05-11-2010, 05:58 PM   #11
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try lipo charge set at .1 amp

Don't try to balance it, balancer won't work below 3 volt, just charge it for 15-30 minutes. Check the cell volts and if it's above 3.0 then balance it like normal.

Had a cell at 2.63 in a 2 cell pack that I was able to bring back with the above action.

IF I can do this with a Poli-Max B6 from Hong Kong (ebay) you should be able to do this with almost any lipo charger that will charge at .1 amp per cell
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Old 05-11-2010, 05:59 PM   #12
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so leave the balancer unhooked...

that would be the same as the nimh setting now?
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Old 05-11-2010, 06:10 PM   #13
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Quote:
Originally Posted by agarabaghi View Post
I can access that screen when the low voltage error pops, but i have not tried to see it while charging. Do you know the button sequence to change the view while charging?
Most chargers built in China have a LCD display like the one shown on the Youtube vid!

http://www.hobbypartz.com/thac6smbachw.html
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Old 05-11-2010, 06:15 PM   #14
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Quote:
Originally Posted by agarabaghi View Post
so leave the balancer unhooked...

that would be the same as the nimh setting now?
no...Lipos' charge constant current first then constant voltage...nimh charge by voltage and current at the same time and end at "delta peak"
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Old 05-11-2010, 06:45 PM   #15
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ok so try to charge at 1amp on lipo setting with no balance for a bit
and watch it...
wish me luck!
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