Originally Posted by dr/owned
Well remember that the battery voltage drops progressively the closer it gets to being depleted and required a recharge. It's actually quite a narrow range from full to empty if I'm remembering right, maybe on the order of 3-5V for a 14 V battery.. Thus I'd suspect if you tried to throw in a lower voltage battery then you would end up with screwed up battery percentage readings in windows, or the motherboard power circuitry would simply think you're an idiot and refuse to deal with it. I don't think it would help any charging problems since that's dealt with by the charger (except in some cases where the computer is smart and realized with a full battery + charger to power itself directly from the charger and not charger-> battery -> computer).
PS - I bought a replacement non-OEM battery from Amazon and an extra (for my bag) charger from ebay, both matching the specs of OEM and they both work fine.
That's interesting... I don't know too much about rechargeable batteries. When you say the charger, you mean the charging circuit on the motherboard, or the ac/adapter, or some element inside the battery?
I think either voltage battery can be used. If 10.8v were electrically incompatible, they would have have made the connectors (main and extended) mechanically incompatible to insure no problems, or had some other protection. Those selling 10.8v batteries do claim it's compatible, and I tend to think that the laptop (charger and all) is able to handle both voltages correctly, somehow. The "smart battery IC" is necessary for calibration, so I assume it's helping to track that battery's empty/charged voltages over the life of the battery. The laptop would have to allow for different voltages for older batteries, owners with multiple batteries, and batteries being used in multiple laptops. So I tend to think this should work, I just don't know that for a fact.
I wonder if the "charging circuit" (not to mention the main battery) was damaged in either of two problems; 1) charging the original battery with an inadequate a/c adapter causeing overheating and 2) not making sufficient electrical contact with the docking station, also causing high resistance (someone put it on the dock improperly). So, if the electronics were damaged by resulting heat, they probably have less tolerance to further heat and running current through them with a lower voltage is a good way to avoid that.
But before I spend $30-80 or so on a new non-refundable battery just to troubleshoot, I wish I had a more concrete idea on any of these issues.
Incidentally, both my batteries were on the laptop last night and it appeared to have charged my main battery to 96% for once, and my extended battery to 65%. The only difference was the ac adapter (65w, versus 135w, both hp).