Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

Register Log in
  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Battery protection low voltage disconnect issue

Status
Not open for further replies.
SolarTrap

SolarTrap

Computer
May 5, 2014
89
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

 
Replies continue below

Recommended for you

Sort by date Sort by votes
Try blocking the light hitting the LED's, I suspect the LED's are generating a small voltage that you are seeing.
 
Upvote 0 Downvote
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).
 
Upvote 0 Downvote
Lift the pins that tie FS8205A to ground and see if the voltage changes. Alternative, cut the trace(s) to those pins.
 
Upvote 0 Downvote
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.
 
Upvote 0 Downvote
So that leaves U4, which sits between the battery and ground.
 
Upvote 0 Downvote
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.
 
Upvote 0 Downvote
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?
 
Upvote 0 Downvote
To solve the puzzle: attached is the fixed circuit.
In- and output to the mosfet module was swapped
image_zhkxd0.png
 
Upvote 0 Downvote
Well - that would do it. Thanks for the update.
 
Upvote 0 Downvote
Status
Not open for further replies.

Similar threads

jabba99
  • Locked
  • Question
replicating an old circuit- unexpected voltage drop
2
Replies
23
Views
2K
IRstuff
IRstuff
xtal01
  • Locked
  • Question
min NiMH charge voltage and extra parts
Replies
1
Views
785
EnzoAus
EnzoAus
Zabee.Khan
  • Locked
  • Question
Voltage step up
Replies
2
Views
793
LionelHutz
LionelHutz
Helepolis
  • Locked
  • Question
Low Voltage System wiring (5-24VDC), Rules of Thumb? 1
Replies
2
Views
307
danw2
danw2
Ahmed Helwa
  • Locked
  • Question
Alkaline AA battery gauging
Replies
3
Views
261
hacksaw
hacksaw

Part and Inventory Search

Sponsor

Back
Top Bottom