iPhone SE + 6S only charging when screen active

[AGibb]

Hi all, just had a couple of phones in the last week exhibit the exact same symptoms, where by they will detect prompt to boot, boot sequence looks pretty normal, USB ammeter will spike to 1 amp but then fall off just as the phone finishes booting and drop to about .2 - .3 amps while the screen is on, and down futther to .07 or just 0 when the screen is off.

I've witnessed this earlier in the week on an SE, and have a 6S currently in for repair following liquid damage, removed U3800 to relieve a vcc_main short and left it off for now. Then booted the phone and noticed the poor charge rate so went back in and replaced tristar, still exhibiting the exact same behavior.

Anyone else seen this? I'm pretty sure I have another 6S there that was a spare device sitting up for a while that had tristar replaced a long time ago, but I went to charge this device up the other day and now that I think about it I think it was displaying the same symptoms...

Random hypothesis: The phone isn't seeing the battery and behaving like it does on DCPS, only drawing the amount of power it needs at any given moment. However it doesn't drop dead when you plug out lightning cable so the battery is still providing power to the board also...?

[crea2k]

When iv seen this before iv replaced tristar, Tigris and active diode in one go and it always resolved it. No idea which it is that causes it but that's always fixed it for me.

[Jessa_the_Professa]

This can also be charge port—as in 3 new ports are like this but a native pull works, or crud in battery connector—incomplete contact on gas gauge. I had one like this that I swore was state-specific charging but was solved by screwing everything down.

also could be software—I think I heard about a phone identical to this last week, in which case something like software could be it

[eDigitCom]

What is a gas gauge of a iPhone
has it something to do when the battery has reached 100% and it stops the battery chagring circuit ??