Fitting Li-po battery to mobile phone. Possible? Easy? - Page 1
Forum section: electronics / general

author: ThunderZed
author_rank: Regular Contributor
timestamp: April 10, 2022, 04:07:23 pm
content: I'd just want to know if it's possible to supply a common mobile phone with a 2 wired 3.7V Li-po battery likethis oneinstead of its proper Li-ion battery, egthis one.If yes, how?

author: kjr18
author_rank: Regular Contributor
timestamp: April 11, 2022, 04:13:03 pm
content: That one Nokia type battery you showed has a 82kohm resistor between GND and third connector. It is called BSI - Battery Size Indicator. Some newer batteries will have more connections, like cell temperature. I think new phones (mainly smartphones) use batteries that have built-in chips that monitor battery and relay all this information via some sort of data connection, I2c, 1wire or something like that. It all depends on what battery you want to replace.

author: ThunderZed
author_rank: Regular Contributor
timestamp: April 11, 2022, 04:45:17 pm
content: Exactly the BL-5C I pointed to. I'd like to adapt/fit/arrange a Li-po battery instead of it to supply an old Nokia phone that carried that Li-ion battery on, if possible and easy.

author: Nusa
author_rank: Super Contributor
timestamp: April 11, 2022, 11:58:22 pm
content: A mobile phone with an easily removable battery is no longer "common"....they're mostly history now. But one of the things people liked about those replaceable batteries was the ability to replace the battery with a space charged ones as required.

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 12, 2022, 01:00:01 am
content: Quote from: ThunderZed on April 10, 2022, 04:07:23 pmI suppose so. First thing will be to go there:http://www.cpkb.org/wiki/Nokia_BL-5C_batteryAs said above, you need to connect a 82k resistor between the BSI pin and ground to emulate this battery. Second thing is that the original battery is about 1000mAh, whereas the one you pointed to is half of that. Third thing is that the original battery is very likely a Li-ion battery with a 4.1V max voltage, as opposed to 4.2V for a typical LiPo battery. Note that in this direction it should not be an issue, the internal charger will just not charge the new LiPo to its full capacity. But I'd suggest getting a similar capacity so that battery life will be similar, and the charging current will be adequate. Also, with half the capacity, the phone will probably not estimate the state of charge properly.So, get a 1000mAh battery to begin with.Other than this, I think it has good chances of working. Those "old" batteries did not contain electronics with identification (along with a fancy connector), as more recent batteries do.

author: ThunderZed
author_rank: Regular Contributor
timestamp: April 12, 2022, 02:28:23 pm
content: I see. I've foundjauch quartz lipo batterieshave a quite good range of sizes and capacities to choose between and I'd say a battery likeLP523450JU(950mAh, 5.4x34.8x52.5) could be good for the job.I'm just afraid about the relationship between 1) this battery sizes (especially its longest side), 2) how much room will be necessary for the resistor and 3) the phone housing, which is good for a 53.3x34.1x5.7 original battery. I mean I've to fit all the necessary in a room of 0.8mm (53.3-52.5) x 34.1mm among the new lipo battery and the inferior side of the phone housing (where the 3 contacts relies).Now my question is: how to join/match/connect the 2 battery wires and the 3 phone springy contacts? The only condition I wish is that whatever you'll suggest will be easy to disconnect/connect only by my hands. If I've got more room I'd use a pair of very common crocodile clips but they're too big.

author: SiliconWizard
author_rank: Super Contributor
timestamp: April 12, 2022, 05:21:58 pm
content: For the connection, one "easy" approach would be to reuse the shell (or part of it) of the original battery. I don't know how hard/easy it is to open without butchering it completely, though.

author: Nusa
author_rank: Super Contributor
timestamp: April 12, 2022, 06:26:34 pm
content: The easy approach is to just connect an external usb battery pack to the usb connector.

author: strawberry
author_rank: Super Contributor
timestamp: April 12, 2022, 09:12:49 pm
content: did it when my cell died. replaced with 18650 cell, no problemwithout original cell control board phone will shutdown and wont charge