MacBook Pro late 2011 will NOT CHARGE the BATTERY

MacBook Pro late 2011 model. This laptop will NOT CHARGE the BATTERY.

As soon as the battery dips below 95% , the laptop will eventually drain the battery and NOT TURN ON anymore. The BATTERY INDICATOR LIGHT is not working on this laptop. It is also unplugged from the logic board permanently now…but still in place inside the laptop. Also, the MagSafe charger only shows a GREEN LED… never ORANGE.

However, if the laptop is plugged in AND the battery does not drain below 95% then ALL other functions of the the laptop seems to be working fine with the MagSafe powering it.

I know this because I have been using the laptop now for over 6 months in this condition.

When the battery drains, I have a spare battery & spare MacBook Pro which I plug the batteries into for charging my 2 laptop batteries. After a full charge, I reinserted a full battery to the main laptop. Then again, I can keep using the laptop until the battery drains below 95%, then to 0%, which is usually when I'm traveling and it's not plugged in full time.

The 2 batteries are just different age so they drain at different rates. Otherwise both batteries can be used in my main laptop.

From time to time, I do not have a usable battery while I need the laptop and use, in which case I can turn on the Macbook without a battery inserted by:

- holding the power key down for 5 seconds,

- then connecting the MagSafe connector and continuing to hold down the power key for another 10 seconds.

...This DOES turn ON the laptop however the fan is running full time.

Fortunately, I have a spare 2010 MacBook Pro that doesn't turn on but does charge batteries properly, which I am using to charge my batteries & troubleshoot with parts. In all my tests, charging works on the spare laptop but not my main working laptop.

It have never had any water damage as far as i know….

At one point nearer the beginning of the 6 months of not charging... The laptop, SUDDENLY STARTED CHARGING FINE & everything worked normally again. This lasted for a week or 2 weeks, then back to no charging... VERY STRANGE...???

=== TESTS:

These are the things that I have TRIED TO FIX my main laptop's ability to charge the battery with NO RESOLUTION:

- Resetting the SMC, the PRAM, PVRAM, as well as ALL PERMUTATIONS, with and without the battery inserted, of all these resets for other year MacBooks too.

- Replaced the MagSafe DC-In Board unit from the spare MacBook that was able to charge the battery. The spare MacBook was able to charge batteries with both MagSafe DC-In Board units!

- Tried with two different magsafe Chargers on the non charging laptop & the spare laptop. Again, the magsafe chargers both only worked with the spare laptop.