# Can anyone explain how this battery charger works?

Started by February 13, 2022
```https://imgur.com/a/b8l5qKQ

Look at the circuit diagram.  The positive of the battery is only connected through a capacitor.  How can a capacitor possibly pass DC current to allow the battery to charge?
```
```On Sunday, February 13, 2022 at 3:33:49 PM UTC-5, Commander Kinsey wrote:
> https://imgur.com/a/b8l5qKQ
>
> Look at the circuit diagram. The positive of the battery is only connected through a capacitor. How can a capacitor possibly pass DC current to allow the battery to charge?

Maybe it's an AC battery?  They are very useful for grid storage applications as long as you can control the phase.

What makes you think that component is a capacitor?  I'm assuming you drew the schematic.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
```
```On Sun, 13 Feb 2022 20:55:51 -0000, Rick C <gnuarm.deletethisbit@gmail.com> wrote:

> On Sunday, February 13, 2022 at 3:33:49 PM UTC-5, Commander Kinsey wrote:
>> https://imgur.com/a/b8l5qKQ
>>
>> Look at the circuit diagram. The positive of the battery is only connected through a capacitor. How can a capacitor possibly pass DC current to allow the battery to charge?
>
> Maybe it's an AC battery?  They are very useful for grid storage applications as long as you can control the phase.
>
> What makes you think that component is a capacitor?  I'm assuming you drew the schematic.

I've learned from someone on Quora that it's actually a PTC Fuse - a resettable semiconductor fuse.

The second image in the link shows a brown disk, which I thought was a ceramic capacitor.  Looks like it's to stop a busted battery from being overcharged when a cell has died.
```
```On Sun, 13 Feb 2022 21:56:55 -0000, jkn <jkn_gg@nicorp.f9.co.uk> wrote:

> On Sunday, February 13, 2022 at 9:16:58 PM UTC, Custos Custodum wrote:
>> On Sun, 13 Feb 2022 12:52:31 -0800 (PST), jkn <jkn...@nicorp.f9.co.uk>
>> wrote:
>> >On Sunday, February 13, 2022 at 8:33:42 PM UTC, Commander Kinsey wrote:
>> >> https://imgur.com/a/b8l5qKQ
>> >>
>> >> Look at the circuit diagram. The positive of the battery is only connected through a capacitor. How can a capacitor possibly pass DC current to allow the battery to charge?
>> >
>> >What else might that yellow thing be, other than a capacitor?
>
>> A thermistor or a VDR, to provide current limiting.
>> Regarding operation, power diodes tend to have a higher Vf than small
>> signal diodes or transistor junctions, so once the diode goes into
>> conduction it produces a large enough voltage to turn on the
>> transistor and the red LED, indicating that charging is taking place.
>> The green LED merely indicates that power is applied to the circuit.
>
> My (probably futile) hope was that he might answer it himself,
> or at least try to...

I didn't expect two completely different devices to look identical.  So how the fuck am I supposed to tell which one is?
```
```Commander Kinsey wrote:
=====================
>
>>
> > What makes you think that component is a capacitor? I'm assuming you drew the schematic.
>
> I've learned from someone on Quora that it's actually a PTC Fuse - a resettable semiconductor fuse.
>
** It's "self resetting".

Goes high resistance when hot and drops backs when cool.

> The second image in the link shows a brown disk, which I thought was a ceramic capacitor.

** Shame about the odd markings.

>  Looks like it's to stop a busted battery from being overcharged when a cell has died.

**  Nope.

Would only act on a short or reverse connected battery.

.....  Phil

```
```On Mon, 14 Feb 2022 09:47:41 +1100, Commander Kinsey <CK1@nospam.com>
wrote:

> On Sun, 13 Feb 2022 21:56:55 -0000, jkn <jkn_gg@nicorp.f9.co.uk> wrote:
>
>> On Sunday, February 13, 2022 at 9:16:58 PM UTC, Custos Custodum wrote:
>>> On Sun, 13 Feb 2022 12:52:31 -0800 (PST), jkn <jkn...@nicorp.f9.co.uk>
>>> wrote:
>>> >On Sunday, February 13, 2022 at 8:33:42 PM UTC, Commander Kinsey
>>> wrote:
>>> >> https://imgur.com/a/b8l5qKQ
>>> >>
>>> >> Look at the circuit diagram. The positive of the battery is only
>>> connected through a capacitor. How can a capacitor possibly pass DC
>>> current to allow the battery to charge?
>>> >
>>> >What else might that yellow thing be, other than a capacitor?
>>
>>> A thermistor or a VDR, to provide current limiting.
>>> Regarding operation, power diodes tend to have a higher Vf than small
>>> signal diodes or transistor junctions, so once the diode goes into
>>> conduction it produces a large enough voltage to turn on the
>>> transistor and the red LED, indicating that charging is taking place.
>>> The green LED merely indicates that power is applied to the circuit.
>>
>> My (probably futile) hope was that he might answer it himself,
>> or at least try to...
>
> I didn't expect two completely different devices to look identical.  So
> how the fuck am I supposed to tell which one is?

The text on it, fuckwit.
```
```On Sun, 13 Feb 2022 22:54:07 -0000, Phil Allison <pallison49@gmail.com> wrote:

> Commander Kinsey wrote:
> =====================
>>
>> > What makes you think that component is a capacitor? I'm assuming you drew the schematic.
>>
>> I've learned from someone on Quora that it's actually a PTC Fuse - a resettable semiconductor fuse.
>>
>   ** It's "self resetting".
>
> Goes high resistance when hot and drops backs when cool.
>
>> The second image in the link shows a brown disk, which I thought was a ceramic capacitor.
>
> ** Shame about the odd markings.

Those aren't shown in the pictures.

>>  Looks like it's to stop a busted battery from being overcharged when a cell has died.
>
> **  Nope.
>
>   Would only act on a short or reverse connected battery.

One cell shorted, much higher current flows, duh.  Now fuck off Rod.
```
```On Sunday, February 13, 2022 at 5:34:04 PM UTC-5, Commander Kinsey wrote:
> On Sun, 13 Feb 2022 20:55:51 -0000, Rick C <gnuarm.del...@gmail.com> wrote:
>
> > On Sunday, February 13, 2022 at 3:33:49 PM UTC-5, Commander Kinsey wrote:
> >> https://imgur.com/a/b8l5qKQ
> >>
> >> Look at the circuit diagram. The positive of the battery is only connected through a capacitor. How can a capacitor possibly pass DC current to allow the battery to charge?
> >
> > Maybe it's an AC battery? They are very useful for grid storage applications as long as you can control the phase.
> >
> > What makes you think that component is a capacitor? I'm assuming you drew the schematic.
> I've learned from someone on Quora that it's actually a PTC Fuse - a resettable semiconductor fuse.
>
> The second image in the link shows a brown disk, which I thought was a ceramic capacitor. Looks like it's to stop a busted battery from being overcharged when a cell has died.

It won't do that.  It is simply a fuse that prevents too high a current from flowing, such as if you connected the battery backwards.

I'm not sure what this circuit is supposed to do.  It doesn't look right to me.

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209
```
```On Sun, 13 Feb 2022 23:02:03 -0000, Rick C <gnuarm.deletethisbit@gmail.com> wrote:

> On Sunday, February 13, 2022 at 5:34:04 PM UTC-5, Commander Kinsey wrote:
>> On Sun, 13 Feb 2022 20:55:51 -0000, Rick C <gnuarm.del...@gmail.com> wrote:
>>
>> > On Sunday, February 13, 2022 at 3:33:49 PM UTC-5, Commander Kinsey wrote:
>> >> https://imgur.com/a/b8l5qKQ
>> >>
>> >> Look at the circuit diagram. The positive of the battery is only connected through a capacitor. How can a capacitor possibly pass DC current to allow the battery to charge?
>> >
>> > Maybe it's an AC battery? They are very useful for grid storage applications as long as you can control the phase.
>> >
>> > What makes you think that component is a capacitor? I'm assuming you drew the schematic.
>> I've learned from someone on Quora that it's actually a PTC Fuse - a resettable semiconductor fuse.
>>
>> The second image in the link shows a brown disk, which I thought was a ceramic capacitor. Looks like it's to stop a busted battery from being overcharged when a cell has died.
>
> It won't do that.  It is simply a fuse that prevents too high a current from flowing, such as if you connected the battery backwards.

Surely a higher current would flow if the battery became 9 cells instead of 10 because one failed and became zero volts?  Ever tried charging a car battery with 14V when it only contains 5 working cells?  The others boil.

> I'm not sure what this circuit is supposed to do.  It doesn't look right to me.

It's the (5 hour) charger for a very cheap cordless drill.  The input is a 14.4V wall wart.  The output is to a pack of NiCad cells.  It's worked fine for years, until I can no longer find replacement NiCad cells, so I'm converting the battery packs to LiIon.
```
``` Commander Kinsey wrote:
=====================
>
> >> The second image in the link shows a brown disk, which I thought was a ceramic capacitor.
> >
> > ** Shame about the odd markings.
> Those aren't shown in the pictures.

**  Not YOUR charger ??
How deceitful.

> >> Looks like it's to stop a busted battery from being overcharged when a cell has died.
> >
> > ** Nope.
> >
> > Would only act on a short or reverse connected battery.
>
> One cell shorted,

** Is a short.

Fuck off you bullshitting, charlatan IDIOT.

.....  Phil

```