New answers tagged

0

Not only is it advisable; it is required. Every Li-ion cell must be used with a protector circuit. No ifs and buts. It must. So, yes, do use a protector. The TP4956 is just a charger, and only ensures that the cell is not overcharged. That is only 1/5 of the required protection. The cell also requires over-discharge voltage protection, charge over-current, ...


4

Option A looks the easiest to be a drop in replacement if you are comfortable with soldering. Lithium batteries are best kept cool. I know some people do solder to them but I prefer to avoid any risk to my finger. The tabs on the existing cell should be easy to snip to free the cell. At this point de-solder the remains of the tabs and then clean up using a ...


13

The correct solution is C, with a holder for the cell soldered to the board. Do not try to solder directly to the ends of the cell. Most batteries "don't like that." Lithium cells go further, and will actively protest against being soldered on. "Protest" as in "burst into flames" - maybe immediately, maybe days or weeks or ...


2

With the confounding effects of polarisation and the run down of the battery, it's not possible to define good repeatable conditions under which to define or measure the DC resistance. 1 kHz is chosen as being fast enough to eliminate these two contributions to the change in terminal voltage with current, aka cell resistance. Perhaps you'd like to have a ...


2

Why do they tell AC 1khz resistance Because that is the impedance of the battery for small variations of the load current. Suppose you have a device which consumes 100 mA on average. I say on average because it actually doesn't consume a constant current. It consumes 90 mA or 110 mA and switches between these values at 1 kHz so 0.5 ms 90 mA then 0.5 ms 110 ...


0

Yes that will not work as expected. Batteries need regulated current (CC mode) then a fixed limit voltage (CV mode = est. 4.1 to 4.25) until the current decays enough to call it fully charged. So using a LM317 voltage regulator or as a current limiter would work better or at least a power resistor and a DMM to monitor voltage and current. As always, do not ...


0

This is just a wild guess for your consideration as you seem to be way more knowledgeable than me. The R004 chips near the B- are current sensors Network that basically drives the MOSFETs permanently thus removing the load from the DW01A Chip this diagram is the opposite of what usually you find from the DW01A Chip datasheet so that when pin 1 (Low Voltage ...


0

Turns out one of DW01A chips was soldered in the wrong orientation. After resoldering, the BMS is working as intended.


2

A puffed up battery is a hazard and a punctured battery is a hazard. The battery was already damaged and you damaged it more by puncturing it. It can still explode or start a fire, damaging your phone and contents in it, or it might stop working at any moment, also preventing the use of phone until the battery is replaced.


6

Lithium-ion cells cannot tolerate overcharging at all. So the BMS balance channel is just one cell. Each cell or group of cells in parallel has to be managed independently of the others. The cells may be arranged into groups or modules for convenience but each cell, or group of paralleled cells, will be managed separately. They are typically arranged in ...


2

Batteries with N series cells like 6 or 12 for lead acid 12 or 24V are made with tight tolerances per cell, yet different cells may not match as well so balancing extends the life of series banks by equalizing the voltage. Thus VI=P bypass capacity to enable equal voltage on each under load charge or discharge. Added 6 Li-Ion cells =6S is a standard "...


0

The issue is the word "parallel". You can't put LiPol (or any very constant voltage discharge curve) batteries in parallel like you can an alkaline battery. Alkaline batteries have a significant voltage slope to their discharge curve (lead-acid acts similarly). As such, they can discharge to match voltages without burning up very much of their ...


0

Often, battery voltage is associated with the "state of charge". Meantime, voltage measurement of a battery varies upon the battery internal resistance (internal structure). The internal resistance, as well, depends on the temperature, load, charge status, aging, and some other factors. As OCV implies, after battery has been resting (no current ...


3

The chip you mention is for controlling the DC/DC converter that does the charging. It would be unwise to only use that chip for a Li-Ion system. You would have to combine that with the BQ769X series (7692 for 3-5, 7693 for 6-10, and 7694 for 11-15 cells). They may have chips for 1-2 cells, but I am not sure. The BQ769X series is an Analog Front End that ...


0

Since this BMS is being used on a 1S configuration, yours is equally effective as any other BMS so long as power-handling is not a factor. Making sure your parallel cells are matched for mAh and discharge rate is important, though; having one cell with very-low internal resistance and three high internal resistance will allow the BMS to charge the low-X cell ...


1

A BMS can have several distinct tasks, and not all tasks are required in all applications. Your proposed solution would be suitable for some of these tasks, but not for all. Protecting against overvoltage. Charging to a too high voltage can cause fire. Protecting against undervoltage. Discharging to a too low voltage can cause damage to the battery, ...


0

I'd like to ... be able to use the load while the battery is charging. You're overthinking it. You already have all you need. You don't need to change any components. What you have will already let you use the battery while it's charging. At any given time: If the load is using less current than the charger can put out, the battery will charge If the load ...


5

Not a good idea - Li-Ion batteries really need a proper CC/CV charger. Switching for a fixed voltage supply is not a suitable approach. The charging circuit shouldn't be dying after a month, unless the ICs are defective/counterfeit or wired up wrong. I would suggest identifying the cause of the fault, or using a different charger though one still designed ...


0

After reading the post you have linked i think your drawing is correct, at lest if you connect zeners in the right direction, and without schematic we cannot evaluate. The zener 3 (orange) is connected between the source of power that power the TP4056 (let's say for example a lab power supply), and should be forward biased towar right direction. I'm ...


Top 50 recent answers are included