BQ24650: BQ24650RVAT 24 volt

thanks for the fast answer

so i can supply 27 V

can i get the MPPT voltage resistors value that i need and the FB resisotors value ?

Hi Shraga,

   Please refer to the datasheet for the equations. They are explained in detail in section 8. Detailed Description.

Hi

we still have lot of problems with the board

we can get a working well 

we need help with charging 2 cell battery 24 volt

we stuck with low charge current and after short time the board goes to stat 2 and stope to charge

Hi Shraga,

   STAT2 indicates charge termination. Once the charge regulation voltage is reached, the charger will shift form CC to CV charging phase, where output voltage is regulated and charge current is allowed to taper down. Once termination current is hit while in CV phase, charger will terminate and STAT2 will show end of charge.

Most likely you are inserting a nearly fully charged battery in your test.

the problem is that the battery is not fully charged.

the battery is 23 volt and has to be charged

can we send the schema, maybe we did something wrong ?

Shraga 

Hi Shraga,

    Yes you can share the schematic, and I will review.

8802.charger.pdf

did you see the schematic ?

Hi Shraga,

   Here are my comments:

• C4 should be 1uF
• As you are charging lead-acid battery, the current schematic oes not account for float charge of lead acid battery. By just having the resistor divider feedback at VFB, this will charge for Li-ion battery. The recharge threshold for Lead-acid battery (float charge) is much lower than the recharge threshold for Li-ion battery.
• MPPSET point based off 499k R13 and 69k R16 result in an MPPSET setpoint of 9.9V. The MPPSET point is the regulation point for the input regulation loop. If current draw from the input source causes the input voltage to droop, the charger will regulate the input voltage (usually maximum powerpoint of solar panel or input adapter) by reducing charge current. Currently you have the regulation point under battery voltage so this loop will not help. Once input voltage droops below battery voltage, the charger will turn off the converter and enter a low quiescent current mode.

Here is link to app note for using BQ24610 to charge lead acid battery. The same mechanism is used for BQ24650. https://www.ti.com/lit/an/slua992/slua992.pdf?ts=1592578696641&ref_url=https%253A%252F%252Fwww.google.com%252F

Dear Mr. Kedar

I can't understand from the answer what we did wrong, the schematic, parts value calculation or the IC that we are using ?

Why the board doesn't working with 24 V battery , 

The application that you sent don't have MPP set point  

Thank you in advance 

Shraga

Dear Mr. Kedar

We get the information and:we did change the next items 

1. VFB resistor to R17 499K & R29 43K

2. MPPT resistors to R13 499K & R16 47K

3. We also tide the TERM_EN to GND

The results was that the charger started to charge at 600 to 700 MA.

Can we get explanation why it is started to charge and why we dot get more current ?

thank you in advance

Shraga.

Hi Shraga,

   The app note  i linked previously was to show the mechanism of float charge and its importance in lead acid battery charging. The concept behind float charge is the same for BQ24610 even though it doesn't have MPPSET pin.

As battery gets close to end of charge, it enters CV phase, where output voltage is accurately regulated, and charge current is allowed to taper down until it hits termination.

What voltage do you observe on MPPSET pin?