simplistic Li-ion charger dunt work why ?  - Page 1
Forum section: electronics / projects

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 01, 2015, 07:00:02 pm
content: SI2302DS i am using here ... gets hotA li-ion charger ...i am makingAttached is simulation circuitmade in livewireNotes : the load is simulated with LED (battery at the end is not there , due to simulator limitation )

author: Siwastaja
author_rank: Super Contributor
timestamp: November 01, 2015, 07:19:56 pm
content: I can't see any kind of lithium ion charging circuit. Did you post a wrong image?Please refrain from charging li-ion cells with your own circuits unless you are sure about what you are doing. Especially don't charge cheap cells from no-name manufacturers.

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 01, 2015, 07:45:39 pm
content: this is a simulation in live wire ! in the sim software the load as lithium is not there so i added a LED (approxima tion in wrong ways )i know about 4.2V cutt off , and litiums low cut votage , studied power banks , made opamp based ones ,This is just 6Rs (india n rupee) i wan t to make it workcircuit and i have super premium cells(true capacity)

author: homebrew
author_rank: Frequent Contributor
timestamp: November 01, 2015, 07:48:00 pm
content: Yes, of course it gets hot! You have designed a linear regulator!The power has to be dissipated somewhere. As far as I can see the N-fet is the only place where that could happen. That's why its getting hot.Apart from that: Dangerous approach anyway. If that thing WOULD work - go through the failure modes:What if the Q2 shorts out? -> LiPo burns!What if the INPUT is shorted? -> LiPo burns / Fet burns (Body Diode!)What if Q1 dies, or any of the control voltages gets disconnected? -> Wack the power right in!!! -> Q2 full on -> LiPo burnsSo please don't burn down your or other houses... LiPos are not fun if you make them angry ...

author: dave_j_fan
author_rank: Regular Contributor
timestamp: November 02, 2015, 06:33:21 pm
content: why wd u say the well designed mosfet circuit will make mosfet short1-2 chip fuses will protect thatany one with similar idea with better suitable MoSFET .. or i need to pulse the mosfet to keep cool ?probably the fet is not fully on so more heating

author: Delta
author_rank: Super Contributor
timestamp: November 02, 2015, 06:49:07 pm
content: Mr J Fan,My first post on here was for help with recharging Li-ion cellshttps://www.eevblog.com/forum/beginners/carging-voltage-for-3-8v-li-ion-batter/msg616292/#msg616292After learning about the technicalities and (more importantly) the serious hazards of Li-ion, I took the advice and bought a TP4056 module (mini usb socket for power, solder pads for battery connection - easy) for next to nothing on eBay. I would strongly recommend you do the same. This will stop you ruining your cells (reducing capacity) and ruining your house (setting it on fire).

author: homebrew
author_rank: Frequent Contributor
timestamp: November 02, 2015, 09:27:11 pm
content: Quote from: dave_j_fan on November 02, 2015, 06:33:21 pmBecause that is a usual failure mode of mosfets. In general it is wise to think of all the things that go wrong - especially in safety relevant settings.