Can you charge a 7V battery with a 5V charger
No, it is not advisable. The 5V 2A device does not sound like a charger, it sounds like a power supply, so it should not be connected to batteries anyway to prevent damage and fire.
Can I use 5V charger to charge 12V battery
No way it'll do 12V or any other chemistry. To charge any battery, you need to give it a voltage higher than what it's going to charge to.
Can I use 12V charger for 7.2 V battery
Well, sort of. It will depend somewhat on how much current the charger can supply, and the actual output voltage. If it is a lead/acid “12V” charger, it likely has a nominal output voltage of higher than 12 volts, and if it is above, say, 14.5V, you could charge two 7.2V batteries in series.
Can I charge lithium battery with 5V
You can't just connect 5v to a lithium-ion battery and expect it to work. What will happen is the cell will reach 4.2v or fully charged, then continue to rise, much past 4.3v it will start to heat up as it cannot accept any more charge. If you carry on the cell will vent, and might even catch on fire.
Can I charge 7.4 V battery with 5V
No. USB is 5V; not high enough for charging a 7.4V lithium battery. That's a 2S battery which should be charged with a dedicated 2S balanced charger for safety. Such a charger will need a supply of at least 8.4V, typically 9V, able to handle the required charging current.
What happens if you charge a 6V battery with a 5V charger
Secondly, a lower voltage charger will never be able to produce enough power to fully charge your 6V battery. It might charge your battery enough for you to get your device jump started, but that's about it.
What happens if I use a 5V adapter on a 12V device
That said, I'd suggest against using a 5 volt supply for a 12 volt device. For a start, if it really requires 2 volts (or close to it), you will have a problem because 12 x 2 = 24 watts, while 5 x 2 = 10 watts, so the power supply is under-specced to do the job at maximum load.
Can I use 5V charger for 12V device
Generally no as you need more volts in the charger to overcome the volts in the battery. However, if the battery cells terminate at the battery connections so that the individual cell voltage is less that 12v.
Can I charge a 7.2 V battery with a 6V charger
So a 6V charger won't charge a 7.2V battery very well, if at all, however a higher voltage one will normally work fine. If you're looking a DC adaptors rather than real chargers then it's different again.
What voltage should I charge a 7.2 V battery
If you want to charge it slowly, as stated in @hekete's answer, charge at a rate of C/10 (means 4000mA/10=400mA) for 16 hours and the charger's output voltage should be 1.4V per cell, which equals to (7.2V/1.2V) x 1.4V = 8.4VDC.
Can I use 5V instead of 3V
Very rarely you will find that this works, but only if the difference is small, and usually only on simple appliances or products. Your fan is a simple device, and the parts used may be able to tolerate the higher voltage… but be warned from what I said above.
What happens if you charge a lithium battery with a regular charger
Or higher. However if you have a power supply. Or you have a battery charger that you can put into power supply mode. Perfect because the actual bms in the battery.
What voltage should I charge a 7.4 V battery
In our case we have a 7.4V Lithium battery pack, which is nothing but two 18650 cells of 3.7V each is connected in series (3.7V + 3.7V = 7.4V). This battery pack should be charged when the voltage reaches down to 6.4V (3.2V per cell) and can be charged upto 8.4V (4.2V per cell).
Can I charge a 7.4 V battery with a 6V charger
Not without a voltage booster circuit. 7.4v sounds like two 3.7v Lithium ion cells in series, and 3v per cell is more or less flat. You'd need 8.4v to fully charge them – plus charge management electronics to make it safe.
Can I use 5V charger instead of 6V
No, a 5v adapter is never recommended to power a 6v device. Because we need a voltage higher than that of the battery before it will charge properly. As a device is required to run from the voltage rating it is given, hence if we use a 5v adapter for a 6v rated device, the device won't start at all.
Is it safe to charge a 6V battery with a 12V charger
charging an 6V battery with a 12V charger is not goo because the higher voltage can damage the battery and may cause problems. When a higher voltage is applied to a battery, it can cause the battery to overheat and explode.
Can I use a 7.5 V adapter for a 5V device
1 Answer. You should never use a significantly higher voltage rating adaptor on any kind of electrical device. If you do so you are risking damaging the equipment and anything else that you might have plugged into it.
Can I use 5V adapter for 12V device
That said, I'd suggest against using a 5 volt supply for a 12 volt device. For a start, if it really requires 2 volts (or close to it), you will have a problem because 12 x 2 = 24 watts, while 5 x 2 = 10 watts, so the power supply is under-specced to do the job at maximum load.
What happens if you put 12V on 5V
You cannot use a 12V power supply on a 5V. It will cause the device to draw more current than it is designed for and will likely burn out, causing fire hazards and explosions. In other words, if the applied voltage is more than the maximum rated voltage then the device will undoubtedly fail due to overvoltage.
Can I use a 5V adapter to power a 3V device
It could result in immediate failure that could result in smoke or even fire. Other times, it results in a shortened life of the appliance. Very rarely you will find that this works, but only if the difference is small, and usually only on simple appliances or products.
Can I charge A 7.2 V battery with A 6V charger
So a 6V charger won't charge a 7.2V battery very well, if at all, however a higher voltage one will normally work fine. If you're looking a DC adaptors rather than real chargers then it's different again.
Can I use A 9V charger for A 7.2 V battery
A 9V adaptor would over-charge the pack, quickly damaging either the adaptor or the battery.
Can I use a 7.5 V adapter for 5V
You should never use a significantly higher voltage rating adaptor on any kind of electrical device. If you do so you are risking damaging the equipment and anything else that you might have plugged into it.
Can I use 5V charger for 3V battery
Probably not directly. A 5V charger has a specified voltage. If 5V are applied to a discharged Lithium-Polymer battery (around 3V), the current going into the battery might be several times over the maxium tolerable charging current for a 380mAh battery, which would be 380mA (better is 100mA).
Do you need a special charger to charge lithium batteries
Therefore, we strongly recommend you use a Lithium battery charger. If this recommendation is neglected then it is best to choose AGM, Gel, sealed battery charge profiles to charge a Lithium battery.
