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This module that I got from ebay

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has a cut-off voltage of 2.5V which is way too low. At that point your Lipo is probably dead. Anyone succeeded in increasing this to higher voltage? I would like to have it at 3.3V .

bortek
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  • Look carefully at the module, I see a TP4056 but also 2 other ICs. It is not the TP4056 doing the cut-off. Also: a LiPo is quite depleted already at 3.3 V, why do you need a lower cut off voltage? Some experienced engineers decided that 3.3 V is good, why do you disagree with that 3.3 V? – Bimpelrekkie Feb 28 '18 at 13:16
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    I think you misunderstood the question, perhaps I wasn't clear. This module cuts off at 2.5V and this is too low. I want it to instead cut off at 3.3V – bortek Feb 28 '18 at 13:33
  • I'm sure it can be modified but we'd need to see a schematic in order to determine how. – Finbarr Feb 28 '18 at 13:37
  • Different lithium battery chemistries can have different cutoff voltages. What type of lithium battery type was this board specified for? For example, some lithium batteries do have a lower recommended cutoff voltage. – Nedd Feb 28 '18 at 14:21
  • Is this board configured for LiFePO4? –  Feb 28 '18 at 14:28
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    Indeed I had 2.5 V and 3.3 V mixed up! I do think that 2.5 V is " hardcoded" in the battery protection chip so you would have to replace it to get 3.3 V. – Bimpelrekkie Feb 28 '18 at 14:29
  • According to this discussion it is not possible. Doh. But who know :)

    https://forum.banggood.com/forum-topic-154248.html

     – bortek Feb 28 '18 at 14:48

1 Answers1

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On many of these typical lipo chargers the small 6 pin chip is the over/under protection component. If that part is a DW01 (as it looks to be), then all of the parameters are preset internally.

Even if you added a resistive divider to the sense pin you would be altering both the overcharge and undercharge values.

Here is the data sheet for the DW01 chip: http://www.ic-fortune.com/upload/Download/DW01x-DS-17_EN_53550.pdf

So if this does not match your requirements you need to buy a new board and/or try returning the original one.

Nedd
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  • Yeah I guess I am stuck with it. Thanks for the answers. – bortek Feb 28 '18 at 19:06
  • One last idea is something that was in an earlier comment, regarding LiFePo battery types. This battery type does have a lower minimum voltage (some at 2.5V). So you might just purchase this type of battery to use with the charger, (but do verify all the spec's on the battery first). – Nedd Mar 01 '18 at 02:45
  • Yet another idea. If you looked over the DW01 spec sheet you can see that there are several versions of the same chip with different internal presets. There might be a version of the chip that is actually compatible with your specific Li battery type. Additionally, since the charger design is very common there may even be other chip makers that have a 100% compatible chip. I'm mentioning this just in case your ordered the set of 12 boards, you could somewhat reduce your losses by ordering a few of the correct DW01 chips and make the replacement. – Nedd Mar 01 '18 at 07:23
  • I have unfortunately no LiFePos only regular 18650 Lipo cells and. Yes I have ordered as set of 12 boards but they were so cheap that its not worth crying :)

    Problem is that I cannot find any board on ebay that has 3.3 as undervoltage. All I find have 2.5 which is strange since LiFePo are not so common and are pricy and 18650 is the most widespread. So I would expect more modules that would suite it.

     – bortek Mar 01 '18 at 13:57