Powering battery charger module

[Gaber Mohamed Boraey]

Hello

I have that charger ,

which is Bosch brand , now it’s broke,
and I need make replacement circuit do same function

The battery are 3 li-ion in series with 1.8 ah, I think

I’ve found that module , please look at the link

XL4015 Step Down DC Module with CV/CC Control | Makers Electronics

Description The XL4015 is an adjustable DC-DC Step-Down power supply buck converter module with adjustable constant current (cc) and constant voltage (cv) adjustment. The module is a 300KHz set frequency step-down PWM buck DC-DC module that can handle an adjustable load range of 0-5A (maximum)...

makerselectronics.com

This module take different input voltage, and provide up to 5 ampere, I will use charging current for about 450 ma, which is 25% the battery capacity , maybe less

And the charging voltage I will set to 12.6 v , which is 4.2 v *3 ,

My question, powering this module with this adapter enough?

Adapter 9V 2A with Dual Jack | Makers Electronics

Features: This product is a universal 9V 2A 18W external conversion power adapter. Wide input range, high precision voltage. Input: 110~240V AC 50/60Hz Output: DC 9V 2A Cable Length (Approx.): 90cm Input Connector Standard: (EU Plug) DC plug Dimension: 5.5mmx2.5mm and 4mmx1.7mm DC conduction...

makerselectronics.com

Regards

 

[BradtheRad]

the charging voltage I will set to 12.6 v

Your link is a step-down buck converter. If you power it with 9V, you cannot expect 12.6 V output. Even though 'wall-wart' adapters are notoriously inaccurate, you're still taking a chance.

 

[Gaber Mohamed Boraey]

Your link is a step-down buck converter. If you power it with 9V, you cannot expect 12.6 V output. Even though 'wall-wart' adapters are notoriously inaccurate, you're still taking a chance.

How you suggest to power this module and get output I need?

 

[Gaber Mohamed Boraey]

Isn’t it power input equal power output?

For 450ma and 12.6v the power is 5.67 watt
And for 9v and 2A the power is 18 watt

so much more than the power to be taken from the module,
How you think?

 

[BradtheRad]

Internally your original charger had/has its power supply able to provide sufficient voltage so it could go up to 10.8 V (according to your photograph). Even that level is below your expected maximum 12.6 V.

On that basis you cannot charge three 4 V Li-ion cells in series. You'll need to try something different, like installing a higher voltage adapter than 9V. Or you can charge fewer cells in series. Or you can charge cells individually.
Or if you have 3 cells connected permanently in a pack, then any charging method needs to avoid abusing them.

An important point: Li-ion type are reported in the news as causing explosions and fires. You need to learn about battery management systems (BMS), and whether Bosch installed such smart circuitry in your charger, or whether it's inside each cell.

 

[Gaber Mohamed Boraey]

like installing a higher voltage adapter than 9V.

Like how much voltage?

 

[BradtheRad]

Like how much voltage?

Maybe you plan to build your own charger, rather than use parts from the Bosch unit? It's okay to home-brew your own, although you can expect to spend several evenings making adjustments of charge rate, final voltage, etc. You need the correct connector to hook up the battery pack.

To answer your question about power supply, it needs 3 or 4 volts cushion above the output of the buck converter. This assumes the units are genuine and available. Did you notice one link states 'out of stock'?

 

[Gaber Mohamed Boraey]

To answer your question about power supply, it needs 3 or 4 volts cushion above the output of the buck converter. This assumes the units are genuine and available.

Okay, and how about ampere considerations if I need about 500ma at output?

 

[BradtheRad]

Okay, and how about ampere considerations if I need about 500ma at output?

Although it's easy to say the power source should provide 500mA, there's more to consider for the fact a battery is present. Its changing voltage affects everything. Its voltage opposes voltage from the charger. As the battery charges its voltage changes over time. And its ability to store electricity in the form of electrochemical energy changes.

The net effect can be calculated on paper... However the reality is you can't be sure what is the overall schedule of battery voltage versus charging current over time.

This is where you must plan to spend several evenings experimenting. Does a battery draw too much charging current at any time? Enough to be hazardous? Should you install a resistor in the current path? What ohm value? A transistor? 500mA is sufficient to make a small cell hot. You really ought to position a thermistor touching every Li-ion cell, to tell you whether a cell is or isn't hazardous.

These replies are coming from a distance, and I can't design an ideal charger for your battery pack.

 

[Gaber Mohamed Boraey]

Although it's easy to say the power source should provide 500mA, there's more to consider for the fact a battery is present. Its changing voltage affects everything. Its voltage opposes voltage from the charger. As the battery charges its voltage changes over time. And its ability to store electricity in the form of electrochemical energy changes.

The net effect can be calculated on paper... However the reality is you can't be sure what is the overall schedule of battery voltage versus charging current over time.

This is where you must plan to spend several evenings experimenting. Does a battery draw too much charging current at any time? Enough to be hazardous? Should you install a resistor in the current path? What ohm value? A transistor? 500mA is sufficient to make a small cell hot. You really ought to position a thermistor touching every Li-ion cell, to tell you whether a cell is or isn't hazardous.

These replies are coming from a distance, and I can't design an ideal charger for your battery pack.

Here is Bosch battery pack , take a look and let me know if add anything to you

Btw. I don’t design charger, the module is already designed as charger, i only need to power it right not to load on the power supply neither on the module and the battery to be safe
Take a look

 

[BradtheRad]

I have no hands-on experience with charging Li-ion type. Usual advice says use the charger that came with your device. Notice your battery pack has several cautionary symbols.

The small types I've recharged are nicad and Nimh. They're designed to be tolerant of consumer use and abuse.

Battery life is limited no matter what type. After a few years my cell phone (with Li-ion battery pack) did not hold a charge, it operated less time as it aged. Your batteries should be tested individually for their condition. I wish I could help you more.

 

[Gaber Mohamed Boraey]

Okay thanks for your care to answer and try to help

I will try the way I’ve told you and will see

I hope if any other engineer see our discussion and can say something to help or have better ideas or experts