No fuse in battery charger for 8.4v bike light battery?

Manc33 · Post by **Manc33** » 5 Dec 2019, 4:17am

This might not be all that bicycle related but it is about those 8.4v bike lights or more specifically, the chargers for them.

I suspect none of these have fuses no matter which one you buy, but are they safe like that?

This is my own one (used many times, not exploded yet). It hasn't got a fuse anywhere on the circuit board.

Can you buy plugs that are just fuses? I mean let's say no fused version of this charger exists, can't you buy like a female to male plug that this plugs into, where the separate plug on its own gives you a fuse between the wall and the battery pack?

China. :roll:

tim-b · Post by **tim-b** » 5 Dec 2019, 6:31am

Hi
Assuming that I'm still current (sorry) on this, plug/chargers fall outside the specific regs that apply to plugs and sockets, but are subject to BS EN standards
The plug top fuse is there to protect the 230V cable, except that no cable means no fuse.
There are specs for separation distances of the input and output; the transformer will see to that because there isn't a direct connection (which is why you can have a shaver socket in your bathroom). There are also specs to ensure that if a cable breaks off internally that it can't creep within that specified distance (the black flexible widget where the output emerges probably sees to that)
There are specs about socket pin dimensions and this and the general quality of some products is mainly where problems arise
Search RAPEX notifications for "battery charger", set filters so that all years and all alert submitted by countries are ticked and you'll see where the problems are
Regards
tim-b
EDIT to add RAPEX link

rjb · Post by **rjb** » 5 Dec 2019, 8:28am

I had a similar concern with a 18650 battery charger purchased on flebay from China. Despite having CE markings I had read reports of poor construction and safety concerns. I opened mine up and soldered a short length of mains cable and fitted a 13 amp plug with a 3 amp fuse.

gaz · Post by **gaz** » 5 Dec 2019, 8:33am

Manc33 wrote:Can you buy plugs that are just fuses?

An extension lead or even a 2/3 way plug will put a fuse between the charger and the wall.

My ancient (unused) cateye lead-acid battery lights are fused between the battery's input/output socket and its terminals.

tatanab · Post by **tatanab** » 5 Dec 2019, 8:38am

rjb wrote:Ipurchased on flebay from China. Despite having CE markings

Beware, depending on space between the characters, CE can signify Chinese Export.
https://www.cemarkingassociation.co.uk/ ... port-logo/

hamster · Post by **hamster** » 5 Dec 2019, 11:18am

If I read the PCB printing correctly, the axial component next to the left hand red cable is actually a fuse (1A 250V AC).

Brucey · Post by **Brucey** » 5 Dec 2019, 11:28am

hamster wrote:If I read the PCB printing correctly, the axial component next to the left hand red cable is actually a fuse (1A 250V AC).

I agree it does look like that. However the component itself can't be seen well enough to identify it....?

cheers

pwa · Post by **pwa** » 5 Dec 2019, 11:35am

If it isn't a brand I know of, on sale in reliable shops, I wouldn't have it anywhere near a socket in my house. There have been plenty of stories of Chinese made electrical stuff with CE marks that mean nothing. I'd pay more and get something I can trust.

hamster · Post by **hamster** » 5 Dec 2019, 11:37am

@Brucey: Agreed! Would need detail of the component markings. However the PCB slot to avoid tracking looks appropriate.
The design actually looks reasonably decent with attention paid to gaps and clearances, far better than some I've seen.

Manc33 · Post by **Manc33** » 5 Dec 2019, 4:36pm

Of course just a 2-way plug thing would do it, can't believe I didn't think of it. :oops:

Those all have a 13A fuse though, don't these things explode way before that like under 5A?

I don't know enough about electricity to know how all of that works.

Sorry folks that picture is pretty bad, here's better ones showing everything...

tim-b · Post by **tim-b** » 5 Dec 2019, 6:02pm

Hi

...is actually a fuse (1A 250V AC)

I think that it's marked T1A (T1 is the transformer), and that it's a bridge rectifier
Regards
tim-b

pete75 · Post by **pete75** » 5 Dec 2019, 6:42pm

Samsung is a reputable company. Their mobile phone chargers don't have a fuse. That's because they don't have a mains cable. The plug top fuse is there to protect a mains cable.

tatanab · Post by **tatanab** » 5 Dec 2019, 9:09pm

The upright part, T1A, is indeed a 1A fuse https://www.littelfuse.com/~/media/file ... atalog.pdf

Syd · Post by **Syd** » 5 Dec 2019, 9:21pm

tim-b wrote:Hi
...is actually a fuse (1A 250V AC)

I think that it's marked T1A (T1 is the transformer), and that it's a bridge rectifier
Regards
tim-b

T1A is a slow blow (time delay) 1 amp fuse.

Mr Evil · Post by **Mr Evil** » 5 Dec 2019, 9:24pm

hamster wrote:If I read the PCB printing correctly, the axial component next to the left hand red cable is actually a fuse (1A 250V AC).

Yes, it looks like a fusible resistor to me.

pete75 wrote:Samsung is a reputable company. Their mobile phone chargers don't have a fuse. That's because they don't have a mains cable. The plug top fuse is there to protect a mains cable.

There's no cable to protect, but you still want something to prevent the power supply itself from catching fire in the event of a fault. I bet that Samsung's chargers have some sort of overcurrent protection, fuse or otherwise.

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