×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Battery protection low voltage disconnect issue

Battery protection low voltage disconnect issue

Battery protection low voltage disconnect issue

(OP)
Hello all,

just got my first EasyEDA project back from JCLPCB and it’s almost as I envisioned it.
My issue is the under voltage protection. It correctly disconnects the battery but I can still measure 0.7V between Vcc and GND.

My question: how to track down this issue?

I have attached the full circuit, the bottom part is the charger which was a public circuit I just integrated. It seems to be a standard implementation of the parts.

Thanks in advance,
Markus

https://files.engineering.com/getfile.aspx?folder=...

RE: Battery protection low voltage disconnect issue

Try blocking the light hitting the LED's, I suspect the LED's are generating a small voltage that you are seeing.

RE: Battery protection low voltage disconnect issue

I'm with Clash3. Check again in darkness.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Battery protection low voltage disconnect issue

(OP)
I ran the darkness experiment and it has no impact. I do not even understand why it would matter as the battery monitor disconnects GND from Battery Minus (via the FS8205A component).

RE: Battery protection low voltage disconnect issue

Lift the pins that tie FS8205A to ground and see if the voltage changes. Alternative, cut the trace(s) to those pins.

RE: Battery protection low voltage disconnect issue

0.7V is suspiciously a Si diode voltage.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Battery protection low voltage disconnect issue

(OP)
So i removed the FS8205A and I still measure 0.7V
what I can measure now is a is -0.2V (when the battery is completely removed) coming from the 25x WS2812 LEDs when they are exposed to light.

RE: Battery protection low voltage disconnect issue

So that leaves U4, which sits between the battery and ground.

RE: Battery protection low voltage disconnect issue

(OP)
This means I remove R8 as a test?

RE: Battery protection low voltage disconnect issue

Seems reasonable. That's the problem with unexpected conduction - keep removing items until the conduction goes away on the paths that seem most likely first. Same thing with mystery short circuits in car wiring.

RE: Battery protection low voltage disconnect issue

The circuit may be entirely correct but the components selected might have a problem - do you have a link to the data sheet of the U4 component?

RE: Battery protection low voltage disconnect issue

(OP)
To solve the puzzle: attached is the fixed circuit.
In- and output to the mosfet module was swapped

RE: Battery protection low voltage disconnect issue

Well - that would do it. Thanks for the update.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close