I need to recharge Li-Ion cells w/ undervoltage lockout?

I have 2 Apple A1175 macbook batteries that will not charge, regardless of what I have done to the computer or the battery. I believe that this is due to the batteries having sat for much too long, and eventually the cells got depleted (causing what i believe is undervoltage lockout on the charge controller circuit).

I believe I can get these batteries functional again by charging the cells again.
Thing is, I don't want to take apart the batteries to charge each cell individually. Is there a way to somehow trick the charge controller into letting current through the batteries? I read somewhere that a 5-15v pulse will do it, but I am not sure if that is true... Any pinouts for the battery would be helpful as I have not been able to find a pinout for them at all. Again they are apple A1175 batteries (from the old bulky aluminum 15 inch macbook pros)


Edit: I also understand (mostly) the hazards of li-ion technology. I understand they are extremely hazardous under an uncontrolled charge condition. I also understand that by doing this, they might blow up in my face entirely, causing burns and possibly a fire. 

sort by: active | newest | oldest
npaisnel1 year ago

Oh, I seem to have two profiles on here, depending on which computer I use..I am both npaisnel, and NeilP20

npaisnel1 year ago

Yes, I got the pack to work

Charged my new Amazon pack that was not recognised by the Mac with a Hobby Charger (iCharger 3010b) set to 3 series LiPo and a 0.5 amp charge rate.
10-20 minutes brought it up to 11.4 volts...from its initial 9.8 volts.

At this voltage the mac now recognises it and starts charging.

It does not seem to charge continuously ..it charges for, from a few minutes to a few seconds, then cuts out. I am guessing this is a balance issue and the cells are out of balance, ..so the BMS board within the pack is doing its job and bleeding off the high cells

NeilP201 year ago

Problem is going to be that the voltage lockout (Low Voltage Cut Out or LVC) circuit prevents the pack from being charged from the external pins.
Looking at the battery (A1185) with it the right way up, and pins facing you, you need the first and last small connectors. Not worked out what the large contacts connect to.
But the first ont he left is negative, and the last is positive.
The pack, internally , is made up of 6 cells, in a 3 series 2 paralel (3s2p) configuration.
Trouble is, the positive pin on the right hand side, is connected to the pack via the LVC cut out (solid state relay / MOSFET) ..so I'd imagine that you can not charge the pack, as it is dissocnnected from the pack until the cell voltages come back up.
>>>>>>>unless of course there is some sort of charge sense built in to the pack BMS(Battery management system ) board that detects as higher voltage on the output pins..from an external source, and allows current to flow.
not tried it yet myself.

Charging maximum voltage should be 4.2volts x 3 as LiPo is maxed out at 4.2 - 4.22..any more and you risk over charging .

So if you open the pack up and charge to 12.6 volts, or a bit less, maybe just to 11.6- 12 volts, that wil ensure that the the cells are all now above the LVC point of 2.7 volts per cell, so the packl can be topped off via the correct method...plugged in to the computer

KirillM1 year ago

I know it has been a long time since the post appeared first. But I'd like to know how you solved the problem? Did you find the way to charge the battery without disassembling it?

gim4613 years ago

Some pinouts for Macbook A1185 battery (not Pro) here...



Re-design4 years ago
I"ve had to do that on some nicads that go to my cordless drills before. Most of the time the charge controller is in the charger not the power pack. The power pack will have a temp. sensor usually. When My nicads get too low to kick on the charger I manually hook them to a charger set on 18 volts for 10-15 seconds then try them in the charger.

I don't see why doing the same but using the correct voltage for your Li-ion batteries would hurt them.