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Dec 03, 2012, 08:04 PM
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Discussion

Charge lipo to 4.2 V or 4.15 V


Hello,

I have a question, i`m told that it is better too charge my lipo`s too 4.15 V per cell rather then 4.2 V per cell.
What does this on my flying time, for example i now fly 10 minutes with a 5000mah 10S 25c pack what would it aprox be wenn i charge the lipo to 4.15 V per cell ?

Gr Frank
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Dec 03, 2012, 08:05 PM
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pda4you's Avatar
No real reason to undercharge batteries.
Dec 03, 2012, 08:19 PM
Registered User
There are several on this forum who have observed that when they charge to 4.15v they get more cycles out of the battery and the impact to their flight time is very minimal. One of them will chime in soon I'm sure.
Dec 03, 2012, 08:58 PM
Registered User
pda4you's Avatar
4.2v is still slightly undercharged. Agree the capacity loss is minimal. But the question is why stop there - is 4.1v better than 4.15v? It all adds up and to me 15 more cycles with less expensive packs isn't likely worth much - I just let the charger do its thing.

Mike
Dec 03, 2012, 08:59 PM
Registered User
Quote:
Originally Posted by pda4you
No real reason to undercharge batteries.
...if you have limitless lipoly refresh funds.

For the rest of us, deliberately undercharging lipolys has been empirically demonstrated to extend the number of useful cycles.

In the end, they're your batteries so treat them as you wish.
Dec 03, 2012, 09:03 PM
Detroit 2-stroke junkie
1320fastback's Avatar
My cheapo batteries never end their lives by the number of cycles I've put them thru.
It's usually a dead cell or internal wiring damage that takes them out.

For me... Chage them to full capacity.
Dec 03, 2012, 09:11 PM
Registered User
pda4you's Avatar
Quote:
Originally Posted by mrforsyth
...if you have limitless lipoly refresh funds.

For the rest of us, deliberately undercharging lipolys has been empirically demonstrated to extend the number of useful cycles.

In the end, they're your batteries so treat them as you wish.
Thanks I will.

So what is the magic number? 4.15v 4.1 4.0? How many more cycles? 10 - 50?
Dec 03, 2012, 10:32 PM
Space Coast USA
hoppy's Avatar
Here is a study that shows charging to 4.1V instead of 4.2V doubles the cycle life.
http://www.powerstream.com/lithuim-i...ge-voltage.htm

Make of it what you like.
Dec 03, 2012, 11:14 PM
Registered User
And it's for this very reason that the Chevy Volt limits usable capacity of its lithium battery to ~65% of available capacity. e.g. - The BMS undercharges and also limits DOD in order to extend useful life.

And, my personal 'magic number' is 4.15 volts / cell.
Dec 04, 2012, 12:51 AM
Sky Pilot
still4given's Avatar
Quote:
Originally Posted by mrforsyth
And it's for this very reason that the Chevy Volt limits usable capacity of its lithium battery to ~65% of available capacity. e.g. - The BMS undercharges and also limits DOD in order to extend useful life.

And, my personal 'magic number' is 4.15 volts / cell.
How do you limit it? Do you have a charger that can be adjusted to balance to that voltage or do you have to watch it and shut down at that voltage?
Dec 04, 2012, 01:57 AM
Registered User
Thread OP
Quote:
Originally Posted by mrforsyth
...if you have limitless lipoly refresh funds.

For the rest of us, deliberately undercharging lipolys has been empirically demonstrated to extend the number of useful cycles.

In the end, they're your batteries so treat them as you wish.
The reason i asked here was because i talked with someone from the army who
works with UAV`s, end he told me that they charge there lipo`s to 4,15 V a cell.
because off life extention from more the 40% on theyre lipos.
so 200 or close to 300 cycles on mine 10S ore 8S lipos sound great too me!


Gr Frank
Dec 04, 2012, 02:04 AM
Registered User
Quote:
Originally Posted by still4given
How do you limit it? Do you have a charger that can be adjusted to balance to that voltage or do you have to watch it and shut down at that voltage?
I have four iChargers, which have the capability to custom adjust termination voltage in .01V increments. I believe other chargers (FMA) have this same capability and one of the many reasons why I recommend high quality 'premium' chargers over lesser chargers. IMO, their true value pays great dividends in battery savings, safety, and reduced charge times.

Some other chargers can have their termination voltage adjusted lower by re-calibrating (tricked) to read a higher voltage than actual. Thus, when the charger reaches 4.2 volts/cell and terminates, actual voltage is lower.

Lastly, charging at faster charge rates, using 'fast charge' mode, and using long or small gauge charge leads can all contribute to lower termination voltage.

Mark
Dec 04, 2012, 05:23 AM
Proud to eat Kraut ;-)
Julez's Avatar
As mentioned previously, every 0.1V less doubles the cycle life.

My magic number is 4.15V as well, and 4.1V for LiIon.
Dec 04, 2012, 08:30 AM
I hate waiting for parts
Mike_Then's Avatar
I guess it really depends on the battery because I've got several packs that are on their 3rd season and are still going strong. And I rarely charge below 100%. My Hyperion chargers sound an alarm at 95% and if I'm impatient, I'll pull it off the charger at that time if the pack is balanced. Otherwise I let it charge to 100%.

As with most items concerning LiPo batteries, there are some hard/fast rules you should follow and the rest is "do what works best for you".
Dec 04, 2012, 12:13 PM
Registered User
My charger has 95% charge mode so what voltage would that end up being?

Also most of the chargers have that fast charge mode i think the end voltage after charge in this mode is much lower than 4.2v per cell so charge in this mode if you don't have a cut off voltage adjustment.


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