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Charging flight battery with controller...is it possible?

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So based on that it should work as the drone battery is 2250mAh?
2250mAh is the capacity of the battery and is not related to it's voltage. Basically what that is saying is that the battery has the capacity to deliver 2250mA for a period of one hour, or 1125mA for two hours etc. (current/time).

For charging you need a potential difference between the batteries to force current to flow from the higher potential (V) to the lower. Current will continue to flow and increase the potential (V) of the battery being charged until its potential reaches that of the charging potential.

You will see this with car batteries. If you have ever checked a car battery (nominally 12v) whilst...

neggy

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because 2 batteries in parallel will only charge to the average voltage between the two batteries, assuming the batteries are the same voltage rating.

think of it more like the higher charge battery discharging into the lesser charged one until they are equal.
 

Ashjuk

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So based on that it should work as the drone battery is 2250mAh?
2250mAh is the capacity of the battery and is not related to it's voltage. Basically what that is saying is that the battery has the capacity to deliver 2250mA for a period of one hour, or 1125mA for two hours etc. (current/time).

For charging you need a potential difference between the batteries to force current to flow from the higher potential (V) to the lower. Current will continue to flow and increase the potential (V) of the battery being charged until its potential reaches that of the charging potential.

You will see this with car batteries. If you have ever checked a car battery (nominally 12v) whilst it's being charged you will probably find the charging voltage is around 14v. If the potential of the charger and the recipient are the same then no current will flow.

In the case of the drone battery accepting a charge from the controller. Yes, it probably would work to some degree if the drone battery was depleted so that its potential was less than that of the controller. It would also take a very long time as the potential difference between the two batteries would not be that great, and as such very little current would flow.

The time taken to charge a battery is dependant upon the potential difference between the charger and the battery. The greater the difference the quicker the battery charges. But the battery must be able to handle the charge voltage and current being supplied which is why battery chargers are regulated so as not to overload the battery.
 
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scro

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Also worth mentioning that the controller battery is a lower voltage (3.6V) than the flight battery (7.7v). The 2 batteries have a similar overall energy capacity. The mAh rating needs to be considered in conjunction with the battery voltage to determine the energy capacity.
 

Ashjuk

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Also worth mentioning that the controller battery is a lower voltage (3.6V) than the flight battery (7.7v). The 2 batteries have a similar overall energy capacity. The mAh rating needs to be considered in conjunction with the battery voltage to determine the energy capacity.
In that case the controller would only ever work as a charger when the flight battery was less than 3.6v, and then it would only recharge to that level. Once the potential of both batteries were equal charging would cease.
 

scro

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There is very often DC to DC conversion going on with batteries, power banks and charging circuits to compensate for battery voltage varying over the charge/discharge cycle. USB power banks, for example, have some circuitry to manage incoming and outgoing voltages, so that they can charge up a phone's battery to 100%, while they get depleted to below the phone battery's voltage.

Technically, you could arrange it so that the controller charges the flight battery, however the real reason you can't is because there is no benefit to being able to do this. Charging up one depleted flight battery would essentially drain a full controller battery down to empty. The 2 cells inside the flight battery can, and do get individually be charged - that is why there are more than 2 contacts on the battery pack.
 
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