Any Problem in Letting IPhone 4 Battery Drop to 0?

It should not be problem, but avoid leaving the battery in an uncharged state as this can cause it damage. The phone turns off before the battery is completely discharged anyway to guard against this just do not leave it for days like that. Apple recommend having a complete battery cycle (go from fully charged to depleted and back to charged again) once a month anyway.

1. MY subaru 4WD GLF does not charge the battery!?

Its the alternator that is not charging the battery. Take it to autozone to get it checked before buying a new one

2. What would be a better battery to buy online for my laptop?

Check Ebay and buy one that has more cells than the one you have now. We have a Ausu Acer One Netbook. Bought it used and it hardly holds a charge but it has the small battery pack so I checked ebay and you can get a 6 cell or even a 9 cel for that netbook ( I have not yet becuse the wife wo not spent the money). So see what yours has and just see if you can get a bigger one to replace it with.

3. My iPhone 5 sounds like the battery is loose?

Iphone 5 Loose Battery

4. Car battery won't hold charge.?

Do not mess with the airbag, you can get badly hurt. Obviously you have a short in the charging system, that too needs a Professional mechanic

5. Battery drains only when i'm accelerating.?

Possible a loose or worn belt going to the alternator

6. how a battery behaves in parallel to the charger with a shared load but with a voltage difference

The charger seems to be limited to 5A, so if the loadbattery tries to draw more than that, the charger will reduce its output voltage to a lower value until no more than 5A are drawn from the charger.As long as the charger's voltage is higher than the battery's voltage, current will flow into the battery and charge it. If the load draws 5A or more, the charger's voltage will drop and finally reach the battery's voltage and any extra current draw beyond the 5A will be sourced from the battery. If you are wondering if the setup will work:Yes, it can work as desired, if the charger is not too smart and can handle extended periods of maximum output current.A "smart" charger may detect that something seems to be wrong with the battery because it seems to draw much more current/accept much more mAh than it should. The most simple safety mechanism that could get into your way is just a safety timer in the charger set to turn off after a certain time after which the battery should definitely be fully charged. Notice that in your circuit the battery will never be charged but in fact be discharged although the charger is connected, which may trigger a couple of different safety mechanisms in the charger

7. 300zx white smoke by the battery?

Not changing the oil wo not cause the smoke unless you added oil to the reservoir and spilled some. You might want to check your wiring harnesses. I had to change my harnesses out. The heat from the engine bay and the age of the car makes the wiring brittle. I would change your oil ASAP. If you have not already done so, I would definitely do the 120,000 mile timing belt change; no matter what the mileage is on the car. If the car sat at all, the belt is probably dry rotted. If it lets go, you have a VERY costly engine rebuild on your hands.

8. How to keep the regulator cool while battery powering the arduino and accessories?

Use en external voltage regulator (go switch-mode if you care about battery life) that is adequately cooled

9. My PSP battery doesn't seem to last long?

Return the battery for a new one

10. How much does it cost to replace the battery in a hybrid car?

The local Honda dealership quoted around $4,500 to replace the small NMH power pack in my 2000 Honda Insight. I see online people advertising NMH replacement packs from $2,000 and up (mostly used).So, I decided to put my own pack together using Li-ion cells, instead. Depending on which chemistry to use, a replacement pack can run from $1,000 and up, depending on kWh. I chose a new type of high-power cells, meaning they can handle the highest acceleration and the highest brake-regen power that's possible from any HEV motor.For the 2000 Honda Insight, here is what the NMH pack frame looks like:So, the new Li-ion cells will fit inside this frame in its own epoxy/glass box. I'll be using a chemistry that won't heat up, so no active cooling will be necessary. This chemistry is almost like a supercapacitor, so it can discharge/charge at 10C without getting very warm. The electric motor in this 1st generation Insight is not capable of more than 1. 5C, so this pack will last for over 20,000 cycles or over 50-yrs if I drove it hard 365-days a year. However, I plan to install a cooling/heating system anyway, because the car might be parked in the Summer sun or in below-freezing temperatures for a week or more (airport). Li-ion cells will start to degrade if stored in temperatures above 50C (122F), and will be damaged if charged at temperatures below 0C. How much does it cost to replace the battery in a hybrid car?