High Voltage Forum

General electronics => Electronic Circuits => Topic started by: FilipŠebík on December 21, 2018, 07:46:35 PM

Title: Isolated Series Li-ion Charger
Post by: FilipŠebík on December 21, 2018, 07:46:35 PM

Hello people, I will build my own Boom Box but I don't want to use bulky Pb or GEL accumulators so I will use Li-ion batteries and they will be 4S1P pack or 4S2P. So I wanted to get a charger module off of ebay, but I didn't find any that can be LEGIT 100% working balance chargers so I decided to make my own scheme.

EDIT: (Accidentally pressed enter) It works with 4S batteries connected through NC contacts of DPDT and when its plugged into a charger, the charger will supply the load, the relays will open and the batteries will individually charge using TP4056 modules from ebay (that's why there are no LEDs in the scheme) and when the charger gets disconnected, then the relay will open and the batteries will supply the load
EDIT2: Wrong attachment
EDIT3: Schematic errors... What a nice day it was :(

Title: Re: Isolated Series Li-ion Charger
Post by: the_anomaly on December 22, 2018, 01:06:53 PM

I don't see a current sense resistor on the battery pack so I don't think you will be able to charge them accurately.  You need to be able to count the coulombs of charge going into and coming out of the battery to know to keep charging/discharging or not.  I have some doubts about this chip TP4056X.  Texas Instruments makes a lot of battery management chips like the bq40z50-r2 which would work well for you http://www.ti.com/product/BQ40Z50-R2 (http://www.ti.com/product/BQ40Z50-R2)

Title: Re: Isolated Series Li-ion Charger
Post by: FilipŠebík on December 22, 2018, 03:51:25 PM

I didn't bother with putting led's before the resistors on pins 6 and 7. They respectively show the charging and charged status of the battery and the IC TP4056 is working as I've used it before and it doesn't need current sense resistor on the batteries.

Also I don't want to use any other IC, because they are in SMD packages only and I don't have the right equipment to solder SMD components. And the TP4056 is very common 18650 Li-ion charging circuit on ebay and youtube and it comes as a module from ebay even with protection https://www.ebay.ie/itm/Micro-USB-TP4056-li-ion-li-po-lipo-Battery-Charger-Module-Discharge-Protection/272986428636?hash=item3f8f4254dc:m:mZvOYFXrR8CXcgPDwxGjHyg:rk:3:pf:0 (https://www.ebay.ie/itm/Micro-USB-TP4056-li-ion-li-po-lipo-Battery-Charger-Module-Discharge-Protection/272986428636?hash=item3f8f4254dc:m:mZvOYFXrR8CXcgPDwxGjHyg:rk:3:pf:0)

Also if the battery gets discharged (one of them), the 4S protection board I will use contains Under Voltage Protection, so it turns off the control mosfet and this interrupts the current flow into RL.

Title: Re: Isolated Series Li-ion Charger
Post by: station240 on December 23, 2018, 12:59:50 PM

You can get tp5000 modules off ebay too, higher efficiency and charge at 2A by default.

Title: Re: Isolated Series Li-ion Charger
Post by: sjsimmo on December 24, 2018, 01:26:17 AM

I've also used the TP4056 and they work fine, although they're limited to 1A charging current. The have internal current sense resistors, so they don't need one externally (just a current set resistor is required).  :)


Ideally the 'temp' pin should be wired to the battery with a NTC in series, but this is only really needed if it's going to be on charge, with an old/faulty battery, and you're not around to keep an eye on it.