Best charging voltage for longevity of LiPo?

Batteries, Chargers, and Battery Management Systems.

Best charging voltage for longevity of LiPo?

Postby LI-ghtcycle » Wed Feb 02, 2011 1:19 am

I know I have seen where someone says they charge to less than the nominal 4.2V per cell to make their LiPo last longer, and after much searching, I cannot find anything.

Please enlighten me to what your prefered charging voltage per cell and why.

Thanks! :)
Last edited by LI-ghtcycle on Fri Feb 04, 2011 12:34 am, edited 1 time in total.
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby neptronix » Wed Feb 02, 2011 1:30 am

4.17v on my turnigy/zippy batteries, because that leaves me a lot of leeway to do bulk charges and not have to worry about a cell getting overcharged.

When i do bulk charging, i will be changing that to 4.15v.

Frankly, the nano cells are pretty new man.. i don't think anyone's had them long enough to have a good lifecycle count yet. Maybe the guys on rcgroups.com .
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby LI-ghtcycle » Wed Feb 02, 2011 1:35 am

True, I just added in the specific LiPo I am using in-case there would be any reason to charge it any different than any other LiPo.

I seem to remember someone stating that they charged their LiPo to just 3.9V each cell or something to get more cycles. I'm just seeing mine start to get to full capacity now after about 11 - 12 charge cycles, having to adjust for them being 6000 mah. Apparently the standard 5000 mah charge capacity hasn't been exceeded until now (got a odd "CAPA" message meaning it had exceeded the 5000 mah it was set on with out getting the voltage that would normally signal that it was reading charged for full capacity, so I'm going to have to go in a adjust it with the user settings.
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby AussieJester » Wed Feb 02, 2011 1:51 am

LI-ghtcycle wrote:Please enlighten me to what your prefered charging voltage per cell and why.


4.15v per cell

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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby neptronix » Wed Feb 02, 2011 2:06 am

LI-ghtcycle wrote:True, I just added in the specific LiPo I am using in-case there would be any reason to charge it any different than any other LiPo.


Completely understandable. I am more talking about keeping the cells in balance though. ( not overcharging extends their life, ya know. )

LI-ghtcycle wrote:I seem to remember someone stating that they charged their LiPo to just 3.9V each cell or something to get more cycles.


This is what people do with lifepo4 & other lithium-ion batteries, but this low charging rate stretching out the cell life in lithium polymer hasn't been proven yet.

And the nominal voltage on these are quite high, IE it sustains a higher voltage than regular lipo, so 3.9v might be charging it to 50% capacity or less !!

Have yet to see a discharge graph for these though.
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby LI-ghtcycle » Wed Feb 02, 2011 3:03 am

Bummer! Doesn't look like this charger allows me to change this value anyway ... hmm AND it has an annoying defect where the Ch 1 back light goes out for no apparent reason.

The local hobby shop that I bought it from has offered to replace it with the same model, maybe I can get them to give me credit towards another one. 8)

I'd actually like to up-grade to that 4 channel that Dr Bass was talking about ... hopefully they can get it or something similar. I have the Imax B6 Duo, I think it's the B6 Quattro.
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby adrian_sm » Wed Feb 02, 2011 3:53 am

Looks like you may be able to change the calibration, which may allow you to artificially lower the voltage. I only skim read the discussion, but looks the balance accuracy is pretty dodgy, and that you can only do the calibration once, then the firmware disables the menu. :(

Anyway, it may be of use... check out the discussion here.
http://www.rcgroups.com/forums/showthread.php?t=827821
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby neptronix » Wed Feb 02, 2011 3:57 am

LI-ghtcycle wrote:Bummer! Doesn't look like this charger allows me to change this value anyway ... hmm AND it has an annoying defect where the Ch 1 back light goes out for no apparent reason.

The local hobby shop that I bought it from has offered to replace it with the same model, maybe I can get them to give me credit towards another one. 8)

I'd actually like to up-grade to that 4 channel that Dr Bass was talking about ... hopefully they can get it or something similar. I have the Imax B6 Duo, I think it's the B6 Quattro.


Yeah, get your money back, don't waste your time on anything other than icharger/hyperion!
OR... if you have a 'lilo' setting, that may work ( 4.10v ). Whatever the hell lilo is!

Go read reviews about that quattro. It is basically 4 ultra cheap chargers in one. It could actually be worse than what you have right now.
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby LI-ghtcycle » Wed Feb 02, 2011 1:21 pm

Thanks for the heads-up, going to see if I can get money back or trade for Icharger or Hyperion
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby NickW » Wed Feb 02, 2011 5:00 pm

adrian_sm wrote:Looks like you may be able to change the calibration, which may allow you to artificially lower the voltage. I only skim read the discussion, but looks the balance accuracy is pretty dodgy, and that you can only do the calibration once, then the firmware disables the menu. :(

Anyway, it may be of use... check out the discussion here.
http://www.rcgroups.com/forums/showthread.php?t=827821


Yeah, That's one of the problems with a lot of the knock-offs in particular (though it's probably not unheard of from legit ones either). Most likely they've just copied the firmware verbatim including all of the calibration values, skipping the factory calibration completely. Depending on the tolerance, and variation from the one they copied from, the values could be way out.

Since they've locked the eeprom on some of them (where the calibration values are likely stored), You would likely need to erase and reprogram the microcontroller with the firmware, then go through the factory calibration.

I would guess that the legit one probably has only the flash locked, not the eeprom. (That's how it should be, at least.)

It looks like most of that info is in the thread.
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby liveforphysics » Wed Feb 02, 2011 5:18 pm

neptronix wrote:
LI-ghtcycle wrote:True, I just added in the specific LiPo I am using in-case there would be any reason to charge it any different than any other LiPo.


Completely understandable. I am more talking about keeping the cells in balance though. ( not overcharging extends their life, ya know. )

LI-ghtcycle wrote:I seem to remember someone stating that they charged their LiPo to just 3.9V each cell or something to get more cycles.


This is what people do with lifepo4 & other lithium-ion batteries, but this low charging rate stretching out the cell life in lithium polymer hasn't been proven yet.



Why do you speak of things you know nothing about?


Charge to 4.15v to 3.5v if you're looking to get ~80% of the capacity, and extend the cycle life by a HUGE margin, like 10x.
I charge over-size the pack and charge to 4.125 and discharge to 3.55v if I'm just making normal shallow cycles (like if I know i'm not going to be riding over 30miles or something, so no need to fill it up to the top).

If I'm trying to pack it full for a big long trip or something where I'm cutting it close on range, I make sure they are in balance, and charge to 4.35v. You can actually get another ~1.5Ah into a 5Ah cell going from 4.15v to 4.35v, and clear up to 2 additional Ah going to 4.42v, but each charge event like that takes many 10's of cycles of life out of the pack.
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby LI-ghtcycle » Wed Feb 02, 2011 10:14 pm

Thank you all, lots of good info here!

I thought I had read this somewhere and I couldn't find it .... I'm going to have to take the charger back tomorrow, it's been a crazy day, Muphy's been working over-time. :roll: :lol:

I wonder what you would recommend for a charger? I am seriously thinking about getting that Hyperion for 14S, that way I could charge 12S (three 4S bricks in my case) at a time, and eventually up-grade to a Meanwell Supply ...

Or I could go for one of the iChargers for less money, but I am thinking in the long run, that 14S charger/balancer and wow it sounds like it can even be used sans suppl with a plug-in for the wall?

Nice!
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby neptronix » Wed Feb 02, 2011 11:26 pm

neptronix wrote:This is what people do with lifepo4 & other lithium-ion batteries, but this low charging rate stretching out the cell life in lithium polymer hasn't been proven yet.


liveforphysics wrote:Charge to 4.15v to 3.5v if you're looking to get ~80% of the capacity, and extend the cycle life by a HUGE margin, like 10x.
I charge over-size the pack and charge to 4.125 and discharge to 3.55v if I'm just making normal shallow cycles (like if I know i'm not going to be riding over 30miles or something, so no need to fill it up to the top).


Is this proven for lipo though? there are long term studies for lithium ion batteries showing that a shallow discharge / charge can add amazing amounts of cycle life, and i have seen them. But lipo ... sounds like a good idea, and not charging to top voltage is a good idea anyway to prevent overcharging disbalanced cells, but.. are there any studies pointing to shallow charging extending the life of lipo batteries?

liveforphysics wrote:You can actually get another ~1.5Ah into a 5Ah cell going from 4.15v to 4.35v, and clear up to 2 additional Ah going to 4.42v, but each charge event like that takes many 10's of cycles of life out of the pack.


Yeah, but you're a professional lipo stuntman.. ;)
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Re: Best charging voltage for longevity? Turnigy Nano Tech L

Postby LI-ghtcycle » Wed Feb 02, 2011 11:32 pm

You know, I think we should put together a fund and have LFP combine two of his favorite hobbies, flamethrower and LiPo distruction!! :shock: :mrgreen:

I bet he could build a rocket with LiPo as fuel and get that thing into orbit! :twisted: :twisted: :twisted:
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