Author Topic: Need help on battery protection/charger project  (Read 832 times)

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Offline yannickgTopic starter

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Need help on battery protection/charger project
« on: March 06, 2020, 05:08:04 pm »
Hi, I hope I'm not asking too much but I'm really stuck on this project and need help from a more experienced person.

I have a single 18650 Li-Ion cell that I'm trying to protect with the AP9101 chip and also charge with the MAX1555 chip. Here's my schematic, I checked and rechecked everything and I can't seem to make it work. Right now I'm unsure about how I interconnected the two ICs, maybe it's all wrong from the start... :-//

944894-0

Any input is welcomed and thanks!!!
« Last Edit: March 06, 2020, 10:36:19 pm by yannickg »
 

Online SiliconWizard

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Re: Need help on battery protection/charger project
« Reply #1 on: March 06, 2020, 05:42:31 pm »
One obvious mistake is that you connected the global GND both to the battery's neg terminal and to the external DC source neg terminal, which doesn't make sense, it will just make the protection IC useless and probably confuse it enough to cause it not to work.
 

Offline yannickgTopic starter

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Re: Need help on battery protection/charger project
« Reply #2 on: March 06, 2020, 08:38:04 pm »
Schematic mistake, sorry about that. The DC ground is actually connected to P-. Would that be right?

I updated the schematic.
« Last Edit: March 06, 2020, 09:24:44 pm by yannickg »
 

Offline norand

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Re: Need help on battery protection/charger project
« Reply #3 on: March 08, 2020, 02:12:37 pm »
Without a proper look, few things I have noticed:

  • The *POK/*CHG line is an open drain, and hence your LED2 is connected the wrong way round (see attached image). You may also want to tie it to your external 5V source as oppose to your Lithium ion cell, so the power comes from the source and not the battery.
  • Schematic mistake, sorry about that. The DC ground is actually connected to P-.
      Yes this is correct, but I don't see the change in SCH?
  • It would also be worth checking your cell voltage, and making sure it isn't below the deep discharge threshold.

When you say:
I can't seem to make it work.
It would be better to describe what part is not working, what parts have you measured to verify it is nor working etc. Hard to help you when there is little information :D Hope this helps.
 


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