Li-Ion Battery Charging

Measured it!

Did you measured without load, or with battery charging? those chargers work first at CC/CV so voltage is lower than end voltage at beginning :slight_smile:

Wouldnt it be Labeled as cccv charger if it would be one? It is a dumb tiny brick

But i measured it without load.

If you are using not CC/CV brick then I can tell you Fire incoming :wink: But don’t worry all the chargers normally are just CC/CV supplies with some protection like @Pedrodemio mentioned low current cut-off

Are you Sure? Does Not the bms protect the battery against over Charge?

Nope, BMS protects only over current over voltage (some over temperature) :slight_smile: Charger disconnects then its finished charging not BMS.

Some decent ones has some more protections :slight_smile: But all those BMS require CC/CV charger :slight_smile: BMS does not regulate charging current :slight_smile:

No I said charging overnight is bad coz you stay at 4.2V Say you put it on charge at 11 and wake up at 9am by 3am It will be standing at 4.2V

Scroll up to the first message and look at the first edit of it.

Yes, but that’s a whole point I was trying to say it doesn’t stay 4.2V after charger disconnects. Afterwards voltage per cell drops

I know that.

But still 4.2 for some time then maybe 4.19 but it’s still harmful.

It’s pointless to argue with you…

@Kug3lis you’re the only one arguing.

I answered your questions, and Changed my opinion to what you’ve said. But Now i’m seeing people say that IR does go up if batteries stand near full Charge, and It’s becoming clear that you just wan’t to prove me wrong on something.

the only reason I edited the first message is coz you made me think I was spreading misinformation and I knew you read it so I edited it coz I wasn’t 100% sure the statement was true.

PS removed the solved tag Not sure my minds set on "IR only Changes from cycles.

Lipo and Li-Ion likes to be stored for longer at low voltages ( somewhere between 3.5 and 3.95V) They don’t like to be charged fast continuously. They like to be used from 80% to 20% (like 4.05V till 3.5V without load) If you charge them till 4.2V they hate to be charged with high currents above 80%.

Long story short. Store them for longer periods below 3.95V, charge them slowly and try to use them from 80% till 20%. When you use them wile riding don’t worry about anything as long as you don’t discharge them to 0%. But by setting a cutoff end of 3.0V for Li-Ion or 3.3V for Lipo that won’t happen.

(These values are for conditions under load so don’t be surprised that they are lower)


And let us not forget the DieBie MS :wink: Of Course - we can question whether it is available for “consumers” as nobody sells it yet. However, it shows of quite good so far (I was in the group buy) and after a few software update iterations it can surely be very good.

By default the iCharger 1010B+ charges li-ion at 4.1V. Just my two cents

Lipo are basically dead (at least mine) at ~3.2-3.3V they don’t really have something to push :slight_smile: I think my cut off is like 3.4V/cell right now. Fast charging depends on chemistry and model and etc… For e.g. my lipos are charged at 5C without any permanent damaged or capacity loss (doesnt even get warm), I have over few hundred cycles like that :slight_smile: And always follow the capacity coloumb in/out of battery so even after over 200 cycles capacity loss is like max 10%

Some older Li-ion had max voltage of 4.1V/cell newest we use right now use 4.2V/cell

I am just gone quote this answer here as it has really good explanation about voltages :wink:

For information on battery matters for most battery chemistries a good starting point is often the excellent site at Battery University. NB: What I have written below is based both on experience and on input from a wide range of sources, including battery university.

Assume for following discussion a manufacturers spec of

  • Maximum current = CCmax (usually 1C for LiIon but may be other for specific cells). Assume CCmax is 1C for the cell in question for convenience. Actual spec will be as per datasheet and is temperature dependant and also depends on how many charge/discharge cycles you wish to achieve before the battery turns to mush and/or is reduced to say 70% of original capacity.

  • Maximum voltage of Vmax - usually 4.2V or less. Say 4.2V for now. As for current, the maximum Voltage applied will affect cell longevity (and capacity on a given charge). Charging at a terminal voltage of much above 4.2V will shorten you cell life, may lead to metallic lithium plating out and can lead to the exciting and equipment eating “vent with flame” battery meltdown phenomenon.

  • Minimum current of Icv_min when charging at Vmax. This is the minimum that current should be allowed to fall to when charging in CV mode. When in CV mode, charging is terminated when current drops to this level. Icv_min is typically set at somewhere between 25% of Icc (early charge termination) and say 10% of Icc (maybe sometimes even 5% of Icc). The lower Icv_min is set the longer current trickles into the battery at Vmax in CV mode. Setting a low value of Icv_min adds slightly to the energy that can be stored in the battery on a given cyccle AND utterly tears the battery apart inside and shortens it life.

These two important points apply:

The maximum voltage AT the battery (1 cell) under maximum constant current CCmax is Vmax = 4.2V in this case.

BUT the maximum voltage AT the battery (1 cell) under ANY current is also Vmax. If the battery will not accept Imax when Vmax is applied then CC mode is no longer appropriate. Charging should be CV (or terminated if Icharge at Vmax is <= Icv_min - see below)

An important point here is where you measure what you call “the charging voltage”. This is properly measured at the cell electrodes as close to the cell internals as possible. In practice anywhere on the (usually) weld-attached tabs should be OK as at the max allowed current the voltage drop across the tabs should be minimal. As long as the voltage at the actual cell is <= Vmax then the voltage at other points in the charger may be > Vmax if the charger design requires it.

Consider: Apply a “true” constant current source to a discharged LiIon cell. There will be lead resistance external to the cell so the voltage elsewhere to the system may be higher than at the battery terminals. Ignore that for now - comment on this at end. For a discharged LiIon battery the terminal voltage will be somewhere around 3V and will slowly rise as CC is applied.

After about 40 to 50 minutes of charging a LiIon cell at 1C (= CCmax in this case) from fully discharged the TERMINAL voltage will reach 4.2V. This is where you stop applying CC and apply a CV of Vamx (= 4.2V in this case) at whatever current it takes to keep the voltage at 4.2V (up to a maximum of CCmax.)

The following paragraph may sound a little complex but it is important. It does make sense - read and understand if you care about the answer to the question that you asked. It is a fallacy to think that you must apply a higher voltage at the cell to get it to accept CCmax when Vcell is at Vmax. This IS true if the battery is fully charged or is charged above the point in the cycle where Vcell first reaches Vmax when charging at CCmax. BUT that is because you are then trying then to do something which is outside the proper charging “envelope”. IF a LiIon cell will not accept CCmax when Vmax is applied it should be charged at not above Vmax until Ibattery falls to Icv_min. If you apply Vmax and Ibattery is below Icv_min then the battery is fully charged and you should remove Vcharge. Leaving a battery connected indefinitely to a voltage source of Vmax when Icharge is less than Icv_min will damage the battery and reduce or greatly reduce its cycle life.

Charging voltage is removed when Icharge falls below Icv_min to prevent potentially irreversible electrochemical reactions and to prevent Lithium metal “plating out”. If Vmax is set at 4.15V then charge capacity is reduced noticeably but cycle life is extended. If Vmax is set at 4.1V charge capacity is significantly reduced and cycle life is significantly extended. The loss of capacity per cycle that occurs when Vmax is reduced leads to an overall INCREASE in total lifetime capacity as the extension in life cycles rises faster than the per cycle capacity falls. If you care mainly about highest capacity per charge set Vmax as high as allowed and accept low cycle life. If you can tolerate say 80% to 90% of max possible capacity per cycle, set Vmax lower and get more overall energy storage before replacement.

The graph below from Battery University article How to Prolong Lithium-based Batteries shows what happens when Vmax is increased above 4.2V.


At the end are 3 tables from the same battery University page which show the effects on cycle life from varying various parameters (depth of discharge, temperature, Vmax)

Internal voltage versus terminal voltage:

There will be internal resistance in the cell so the “real” potential in the cell proper during charging at CC will be less than at the terminals. At CV the internal voltage will approach the external voltage as Icharge “tapers off”.

IF you want to play ‘fast and loose’ with all manufacturers’ specs and all advice given you can assume that you can ‘allow’ for this resistance and guestimate a true internal voltage which is lower than the terminal voltage. May the force be with you and with your battery, and may it live long and prosper - but, it probably won’t.

Three excellent tables from Battery University showing how cycle life varies with various parameters.

That confuses me, never heard about a BMS without over charge protection, even the cheapest have it AFAIK.

Over charge is overvoltage :wink: It disconnects charging if Vcell exceeds 4.2V What I meant that BMS will not disconnect your charger if it finishes charging

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:joy::rofl: Classic misreading…