bq24074 current limit question

General project help for Adafruit customers

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
Ethanator10000
 
Posts: 1
Joined: Thu Aug 04, 2022 1:23 am

bq24074 current limit question

Post by Ethanator10000 »

I'm a bit confused by the capability of the Adafruit bq24074 charger module. One line in the description says "Will always draw the most current possible from a solar cell - up to the max charge rate!". Does this mean that the maximum amount of current drawn from the solar panel will be whatever is selected by soldering closed the jumper?

And then the next line says "Smart load sharing automatically uses the input power when available, to keep battery from constantly charging/discharging, up to 1.5A draw. Load output is regulated to no-more-than 4.4V" So how much current can really be drawn from this solar panel? Is it 1.5A? Is it what is selected with the jumpers? Or am I misunderstanding something here?

Is this 1.5A just for Load Out, and that's in addition to what is selected with the jumper to be used to charge the battery? Or is the 1.5A available for both Load Out and charging the battery combined? Or is it whatever is selected with the jumper that is the limit for Load Out plus charging the battery?

User avatar
colin_t1
 
Posts: 6
Joined: Mon Apr 26, 2021 5:57 am

Re: bq24074 current limit question

Post by colin_t1 »

I'm no expert but I've been doing a bit of research into the bq24074 recently so I can give what I think are the answers to your questions.
Does this mean that the maximum amount of current drawn from the solar panel will be whatever is selected by soldering closed the jumper?
no - the maximum current drawn from the solar panel is 1.5A (or the maximum current the solar panel can output). The maximum battery charge current can be 0.5A, 1A, or 1.5A depending on the jumpers
So how much current can really be drawn from this solar panel? Is it 1.5A? Is it what is selected with the jumpers?
The maximum current is 1.5A this can be split between load out and the battery with the maximum battery current determined by the jumpers.
Is this 1.5A just for Load Out, and that's in addition to what is selected with the jumper to be used to charge the battery? Or is the 1.5A available for both Load Out and charging the battery combined? Or is it whatever is selected with the jumper that is the limit for Load Out plus charging the battery?
The input current limit is 1.5A and this has to be shared with Load Out and charging the battery. You can draw more current on load out but that would involve putting the battery in discharge mode.

As I say this is just how I understand it so I'd be interested if someone with more expertise could confirm or correct this.

EDIT - to avoid confusion I've updated this in line with Bill's answers
Last edited by colin_t1 on Wed Aug 10, 2022 8:27 am, edited 1 time in total.

User avatar
adafruit_support_bill
 
Posts: 88099
Joined: Sat Feb 07, 2009 10:11 am

Re: bq24074 current limit question

Post by adafruit_support_bill »

The 0.5A, 1.0A & 1.5A jumpers on the face of the board control the maximum charge current to the battery.

The EN1 & EN2 jumpers on the back control the maximum input current to the board.

Assuming that the panel is capable of supplying the maixmum input current, the actual charge current at any point will be the input current minus the load current.

If the load current exceeds the input current, there will be a net discharge from the battery.

Locked
Please be positive and constructive with your questions and comments.

Return to “General Project help”