Battery pack help

Thread Starter

Aadek

Joined Feb 27, 2023
3
Hi I'm having some issues designing a circuit for a project I'm working on.

It's a 48v Ebike battery but im including USB C charging so i can charge my phone on the go and i was thinking of including the option of charging the battery pack via USB C in case i dont have the normal charger for the pack. all that being said i bought a IP2368 USB C charging board (Link)
I also have a step down Converter (Link) to convert the 48v to 12v a voltage the charging circuit can handle.
Then i bought a boost converter (Link) so that when im trying to charge the battery pack via USB C i have a charge voltage
i also bought some Diodes (Link) because i want to keep the power when trying to charge the pack via USB C from back flowing through the Step Down Converter. In all honesty this is where im kinda stuck I know that the IP2368 needs to have the 12v signal from the step down to monitor the battery voltage so it knows its not over charging my BMS will cut off power incase of too low or high of a voltage. i completely burned through some small wire during a test and i dont know exactly where to put the diodes in the circuit. If anyone could offer some advice that would be great.

Thank your for your help.
Tyler
 

KeithWalker

Joined Jul 10, 2017
3,063
What is the capacity of your 48V battery? The average capacity appears to be around 15AH. If you are just going to step-up the USB-C 5V,(5A max) to 48V charge voltage, you will be limited to a charge current of 0.52A . That will take almost 30 hours to charge the pack from the USB-C. If you use a smart charger that can communicate using the USB 3.1 C technology with an additional 12V charging supply, you would be able to charge it much faster (up to 8A).
I suggest that you carefully check the specs of everything you plan on using, including the battery charge current and voltage, and draw up an inter-connection diagram to see if it it feasible.Show us a copy and we will discuss it with you.
 

Thread Starter

Aadek

Joined Feb 27, 2023
3
the IP2368 can do PD charging so my PD USB C wall socket can charge at 20v 5a so 100w
ill look up how to do a connection diagram, thank you for the help so far
 

Thread Starter

Aadek

Joined Feb 27, 2023
3
This is a rough diagram of the circuit i was trying to build the stepdown converter does nothing to reduce the flow of voltage backflowing through it so when the IP2368 is in charging mode it outputs 16.8v through the stepdown converter do i need to put diodes on the legs parrallel to the boost converter too make sure the voltage is only going through it during charging via USB C? the boost converter i have has virtually no back flow so imnot worried about the voltage going from the output to the input.
the only thing messing this all up for me is trying to allow for chargiong the battery via USB C if i take that option off i have it figured out how to wire it but im trying to retain that function the battery im using is a 14s 4p 6.0ah 302wh battery
Battery diagram.PNG
 

KeithWalker

Joined Jul 10, 2017
3,063
There is some very important information missing in your posts:
What does the normal charger supply to the battery?
What is the BMS you show in your diagram? Is it the motor control module?
Does the battery pack have any built-in electronics? If so, you need to know what is there. It may not work with the IP2368 charger module.
What is the maximum allowable charge current for the battery? You will need to make sure that this is not exceeded.
Why do you have a step-down converter followed by a boost converter?
Why is the boost converter shorted out?
 

MrSalts

Joined Apr 2, 2020
2,767
What is the capacity of your 48V battery? The average capacity appears to be around 15AH. If you are just going to step-up the USB-C 5V,(5A max) to 48V charge voltage, you will be limited to a charge current of 0.52A . That will take almost 30 hours to charge the pack from the USB-C. If you use a smart charger that can communicate using the USB 3.1 C technology with an additional 12V charging supply, you would be able to charge it much faster (up to 8A).
I suggest that you carefully check the specs of everything you plan on using, including the battery charge current and voltage, and draw up an inter-connection diagram to see if it it feasible.Show us a copy and we will discuss it with you.
I think you are confused. He doesn't want to change the e-bike with a USBC charger - he wants to change his phone via usb-c FROM his e-bike.
 

KeithWalker

Joined Jul 10, 2017
3,063
I think you are confused. He doesn't want to change the e-bike with a USBC charger - he wants to change his phone via usb-c FROM his e-bike.
I am not confused. Adek stated "It's a 48v Ebike battery but im including USB C charging so i can charge my phone on the go and i was thinking of including the option of charging the battery pack via USB C in case i dont have the normal charger for the pack."
 

Juhahoo

Joined Jun 3, 2019
302
Your reference for USB charging board is targeted to max 4S lithium packs, so it has already a boost converter build in. I dont see any practical way how you can charge with it a 52V system. Do not attempt to further connect an other boost converter after it !

There are numerous ways you can charge 52V pack, the best is to use commercially available products because I don't think you can build one easily by yourself.

There are USB-C chargers that output 20V/5A = 100W, so using this as a power supply, you still need a boost converter battery charger to reach 52V but it is more simple than converting 52V from 5V.

However, bear in mind that USB-C chargers are "intelligent" chargers, they negotiate with the device to get the maximum power output, so you need a build a functional communication between the power supply and the charger.
 

Alec_t

Joined Sep 17, 2013
14,280
How do you plan to get balanced charging of the cells in a 12S (48V) battery pack when your charger is only rated for charging a 4S (16V) pack? Simply boosting the 16V to >48V would leave cells unbalanced, which could be hazardous unless each cell has its own BMS..
 
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