The short answer: should be no problem.
Originally Posted by CrownIsle
The long answer (I design hardware with lithium batteries and chargers): A lithium ion battery charger integrated circuit (IC) takes care of charge management. This chip is in the phone, not in the little cube or in your computer. Whatever you plug into your Z10 feeds this IC, but it modulates the voltage that the battery sees. It runs a "constant current, constant voltage" charge cycle to properly charge your battery even though your input charging voltage is a constant 5V. A really dead battery will charge with maximum current (looks like 1300mA off the wall cube which is quite fast) but starts with a lower voltage (maybe 3.6V). As the battery charges, the voltage will rise up to 4.2V but current is constant. Once the battery has reached 4.2V, the charge cycle switches to constant voltage mode and current starts ramping down. This is why you can do a quick charge on your battery in about two hours, but a full battery charge takes 4-6 hours. As the battery gets close to 100%, the charger IC will switch off. The battery will discharge a bit until the voltage is low enough to reactivate the charger. Depending on the current draw of the device, this "top-up" cycle might happen as often as every 15 minutes, or maybe as long as every 3 hours.
Lithium ion battery chemistry also does not have "memory" like other battery types, so you don't have to worry if you charge a half-full battery.
As far as what you plug in? You're probably good for anything 4.4V - 5.5V. Lots of the charger ICs I use are rated to 7V. If you plugged in a higher voltage, hopefully the charger circuit has over voltage protection and would just block that, but no guarantees. You really shouldn't ever plug in a power source that was not designed for a product. However, because BB uses a USB charger, you can safely plug in any USB charger to the Z10.
- The Z10 battery is 1800mAh (mAh = milliamp hours). If your device only draws 1mA, it will run for 1800 hours. It probably draws an average of 100mA, though, which is why it lasts 18 hours. Since the charger can provide 1300mA, technically you could charge the battery in 1800mAh/1300mA = 1.4 hours. BUT, the charging function is only about 80% efficient, and the full charging current is only done to about 80% of capacity.
- I had a battery app on my Z10 that always reported the charging current as 1300mA even when the battery was fully charged. I figured they were just detecting if the charger was plugged in and assuming that meant it was fast charging. I deleted that app.
- If you're charging from a powered USB 2.0 port, the most you can charge at is 500mA per the USB 2.0 spec -- that's all the USB power source is supposed to provide.
- There's a chance that old BB chargers were not built to supply 1300mA of current, so they might not be as good at charging the Z10.
- If you followed all this, you should be satisfied to know why a busy Z10 could indeed drain its battery while charging (the device is simply taking more current that what is being replenished by the maximum allowed charger current). There are a few other factors in there, but I don't think anyone's read this far.
Lastly, since this is a novel anyway, here's a link to a lithium ion charging IC that I've used (see page 9 of the datasheet for the charging profile):
Battery Management Products - Battery Charger Solutions - BQ24086 - TI.com
I tried to find a data sheet for the Qualcomm PM8921 power management IC that's in the Z10, but no luck. Qualcomm is not exactly an "open source" company... It likely runs a very similar charging profile as the TI part.