How do you know when the battery is fully charged?

Atwood

Atwood

As the title suggests, what I want to know is how do I know if the battery is full?
Does anyone have any good ideas
 
When it says 'Boom' it was full..

For your region, you better ask this on RcGroups.com.
 
It is not easy to tell whether a certain battery is fully charged of not. The voltage tells you something but by no means all.
A fully charged LiPo battery will have a voltage of 4.2Volt per cell but only when you just take it from the charger. If you leave the battery for a couple of hours the voltage will go down a bit. It is perfectly normal if the voltage goes down to around 4V per cell.
When you “measure” the capacity of the battery with a “capacity gauge” it may tell you the battery is 80% full. This is not correct because you took it from the charger only a couple hours ago.

The only way to make sure if the battery is fully charged is connecting it to a suitable charger and see what is does. If you connect a fully charged batter the charger will almost certainly start charging but stop very soon because the voltage will go up to 4.2V per cell very quickly.
If the charger does not stop very quickly the battery was not fully charged and you will have to wait until it is.

Good luck, and be safe! Modern batteries contain a lot of energy and can be (very) harmful is you don’t treat them with respect! If you are not sure, read the instruction manuals!
 
Niek zei:
For your region, you better ask this on RcGroups.com.
Klik om te vergroten...

Why not give an answer?

It depends what kind of battery. For any lithium based battery you can check the voltage with a simple LiPo checker.
LiPo and Li-Ion are full when they are 4.1~4.2v per cell. LiFe normally 3.5~3.6v
NiCad and NiMh can be checked with a small load like 1A and measure the voltage. If the voltage is 1.2v or higher per cell it is full.

If you van to design a charger or just keeping an eye on one. With Lithium based the charging current gets lower, when it has reached 1/10th of the started charging current it is close to full.
With NiMh and NiCad it is a bot difficult but with fast charging they do become warm. Computer chargers will detect a small voltage drop when it has become over the top.
 
Ernst Grundmann zei:
It is not easy to tell whether a certain battery is fully charged of not. The voltage tells you something but by no means all.
A fully charged LiPo battery will have a voltage of 4.2Volt per cell but only when you just take it from the charger. If you leave the battery for a couple of hours the voltage will go down a bit. It is perfectly normal if the voltage goes down to around 4V per cell.
When you “measure” the capacity of the battery with a “capacity gauge” it may tell you the battery is 80% full. This is not correct because you took it from the charger only a couple hours ago.

The only way to make sure if the battery is fully charged is connecting it to a suitable charger and see what is does. If you connect a fully charged batter the charger will almost certainly start charging but stop very soon because the voltage will go up to 4.2V per cell very quickly.
If the charger does not stop very quickly the battery was not fully charged and you will have to wait until it is.

Good luck, and be safe! Modern batteries contain a lot of energy and can be (very) harmful is you don’t treat them with respect! If you are not sure, read the instruction manuals!
Klik om te vergroten...
Thank you very much.Let me know something that doesn't exist in books or anywhere else.:thumbsup:
 
Roelof zei:
Why not give an answer?

It depends what kind of battery. For any lithium based battery you can check the voltage with a simple LiPo checker.
LiPo and Li-Ion are full when they are 4.1~4.2v per cell. LiFe normally 3.5~3.6v
NiCad and NiMh can be checked with a small load like 1A and measure the voltage. If the voltage is 1.2v or higher per cell it is full.

If you van to design a charger or just keeping an eye on one. With Lithium based the charging current gets lower, when it has reached 1/10th of the started charging current it is close to full.
With NiMh and NiCad it is a bot difficult but with fast charging they do become warm. Computer chargers will detect a small voltage drop when it has become over the top.
Klik om te vergroten...
Thank you very much for your detailed answer. I really know a lot from it.
 
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