Thank you for being a valued part of the CNET community. As of December 1, 2020, the forums are in read-only format. In early 2021, CNET Forums will no longer be available. We are grateful for the participation and advice you have provided to one another over the years.

Thanks,

CNET Support

General discussion

Can a lithium ion battery be overcharged?

Jan 14, 2005 8:25PM PST

Recently I bought a SONY DCR-HC40 camcorder, the SONY BC-TRP charger and an extra SONY NP-FP70 lithium ion battery pack (quick charge battery). I charged the battery that came with the camcorder (NP-FP50) in the SONY BC-TRP charger and, by mistake left the battery in the plugged in charger overnight.
1) Is it possible to overcharge a lithium ion battery by leaving it in the plugged in charger overnight, as I did?
2) According to the instructions for the charger, I can leave the battery in the charger for an hour after the charge light goes out (indicating a full charge) and the battery will charge even more. Are there any disadvantages in doing that?
Thanks.
Richard

Discussion is locked

- Collapse -
Yes.
Jan 14, 2005 11:58PM PST

But a proper charger will not do that.

- Collapse -
Yes, but....
Jan 15, 2005 7:09PM PST

Thanks for your response.
1) My lithium ion battery is the SONY NP-FP70 Battery Pack. Does the fact that the battery is called a battery pack mean that it has built in circuitry to prevent an overcharge?
2) Is there any way of knowing if my SONY BC-TRP charger has the circuitry for preventing an overcharge?
3) If I charge my battery in my camcorder (SONY DCR-HC40), can I assume it has the built in circuitry to prevent an overcharge?
Thanks again.
Richard

- Collapse -
Not so fast...
Jan 15, 2005 10:14PM PST

1) My lithium ion battery is the SONY NP-FP70 Battery Pack. Does the fact that the battery is called a battery pack mean that it has built in circuitry to prevent an overcharge?

No. I write with some authority since I've dissected too many and there is no such circuit in the battery. From a system perspective it doesn't belong there.

2) Is there any way of knowing if my SONY BC-TRP charger has the circuitry for preventing an overcharge?

You'll have to ask, but the key clues are:

a. The documention tells you to not leave it plugged in overnight.
b. The battery gets too hot and melts the plastic.

3) If I charge my battery in my camcorder (SONY DCR-HC40), can I assume it has the built in circuitry to prevent an overcharge?

a. One can't assume anything.
b. But from what I read on that model, you plug it in and forget about it. To do that, it would have a proper charge circuit.

Bob