Battery cut off voltage

Hi,

My project is powered by a single li ion battery. I am using a TP4056 module to charge it and act as a final line of defense against over discharge.

The problem is the TP4056 module's over discharge protection voltage is 2.5v, which is way too low. I want to cut off power when the cell is at around 3v. How can I acheive this?

Hi, The TP4056 is a CHARGING module as I understand it, it has no control over the discharge voltage level and cutoff.

Can you post a diagram of how you have it connected and how you expect it to disconnect the battery when it gets to low?

Thanks.. Tom... :)

The TP4056 is a Lithium charger IC, normally in an 8 pin package - no other components.

Have you perhaps bought a board that has the TP4056 IC on it and a pile of other components ?

There are boards fitted with a TP4056 that also have a pile of other components including a low voltage cutoff IC, the DW01, you can replace that with a FS312F that has a cut-off of 2.9v.

Yeah sorry I meant a TP4056 module which has other components. My bad.

One like this: click here

srnet: There are boards fitted with a TP4056 that also have a pile of other components including a low voltage cutoff IC, the DW01, you can replace that with a FS312F that has a cut-off of 2.9v.

So do I just replace the chips in the same configuration without any extra modification?

Read the data sheets to determine if one is a direct substitute for the other.

jremington:
Read the data sheets to determine if one is a direct substitute for the other.

After looking at the datasheets it appears that both chips support the same pin configuration.

I also checked the typical application circuits; they are both the same.

What else do I have to check?

Hi,
So this is what you have;

Micro USB 3.7v 3.6V 4.2V 1A 18650 TP4056 Lithium Battery Charger Module Charging Board Li-ion Power Supply Board

Feature:

Charge module: Linear charging
Current: 1A adjustable
Charge precision: 1.5%
Input voltage: 4.5V-5.5V
Full charge voltage: 4.2V
Led indicator: Red is charging Green is full charged
Input interface: Micro USB
Work temperature: -10° to +85°
Inversed polarity: NO
Size: 25 x 19 x 10mm

Note:

  1. Ampere meter can only be connected to 5v input end of the module.
  2. It is better that the charging current is 37% of the battery capacity. If you charge to the battery of 1000mAH, current of 400 is enough.
  3. The connection wire should not be too thick.
  4. Make sure the connect point is good.
  5. If the input voltage is too high, like 5.2v, the current will be less than 1000mA, it is normal. It is protection function, auto-substract the charging current to avoid burn damage to chip.
  6. NO Reveral polarity.


Tom… :slight_smile:

What else do I have to check?

Whatever it takes to convince [u]yourself[/u] that a direct substitution is possible.

TomGeorge: Hi, So this is what you have;

Tom.... :)

Yes boss!

jremington: Whatever it takes to convince [u]yourself[/u] that a direct substitution is possible.

Sorry but I'm not sure what you mean. Are you satisfied that they can be replaced directly? Thanks!

I attached an image from the datasheet regarding the overdischarge protection voltage of the FS312; but I can’t make sense of it. For instance, what is VODL? (3rd row from top)

Sorry but I'm not sure what you mean.

Study the data sheets until you are convinced whether a chosen course of action is correct. If you have specific questions, post those.

Are you satisfied that they can be replaced directly?

Do you put more weight on the opinions of unknown people encountered on the forum, than on data you have carefully gathered for yourself?

I don't, and ALWAYS do my homework. But there are times when for example a data sheet is unclear, in which case it is useful to have a well informed discussion with peers of what might be meant.

jremington: I don't, and ALWAYS do my homework. But there are times when for example a data sheet is unclear, in which case it is useful to have a well informed discussion with peers of what might be meant.

I trust you people! You have a high post count so your opinion must be valuable and I bet you know what you're talking about!!

On post #11 I asked a question regarding the datasheet. Can you please guide me if possible? Thanks!

What datasheet?

This official data sheet for the FS312F does not have any entry related to the photo you posted in reply #11.

But, for the record, in my opinion the two chips appear to be interchangeable as far as circuit design and pinout is concerned.

jremington: What datasheet?

This official data sheet for the FS312F does not have any entry related to the photo you posted in reply #11.

But, for the record, in my opinion the two chips appear to be interchangeable as far as circuit design and pinout is concerned.

Thank you! I opened a datasheet that came up from a Google search. I will try swapping the two chips and I will report on the result. Thanks!!

After taking a second look at the battery datasheet I do still feel that a cut off voltage of 2.9v is a bit low. A cut off voltage of around 3.1v would be ideal.

Is there another chip like the FS312F but with a over discharge protection voltage of 3.1v?

Implement your own shutdown in software, and use the chip as backstop protection.

Why do you think 2.4V, or 2.9V, is too low? I suspect there are literally billions of batteries protected with the DW01, and I haven't heard of any problems related to the overdischarge voltage level.

jremington: Implement your own shutdown in software, and use the chip as backstop protection.

I thought about that; but how do you switch off the project from software? I guess using mosfets?