On Thu, 1 Feb 2018 12:45:45 -0800 (PST), wrote:

On Thursday, 1 February 2018 20:12:30 UTC, Archibald Tarquin Blenkinsopp wrote:
On Thu, 01 Feb 2018 08:33:20 GMT, Harry Bloomfield
wrote:
ss used his keyboard to write :

Charger for a mobility scooter. One charger not working, I opened it up and
as per image below it looks like some kind of fuse has blown.
Text on the board looks like 3A/2500AR.

Can anyone confirm and identify what I would need to replace.
I have limitations on electronic stuff but could probably manage to solder
this part if I can find a replacement.

https://imgur.com/a/QTZ0e

From what I can see in the image, it looks like a wire ended fuse which
has exploded. That suggests a serious fault.

Also from what I can see, it looks like a fairly crude charger.
transformer, bridge, then possibly a relay switching the charge current
on and off, driven by a basic voltage across the battery sensing
circuit.

Cobblers!

One does not need an NTC thermistor in a "crude" charger.

I would have serious doubts that terminal Voltage plays a big part in
the control feedback. The control is via current monitoring so a more
stable source of reference would be needed.

There would be no piddly little rectifiers in a "crude" charger
either, they would be after the tranny and would need to handle a few
Amps, assuming the charge process was to take less than 24 hours.

Incidentally an exploded fuse is a fairly minor fault from a
diagnostics perspective. Generally a few seconds with a DMM will find
the problem.

As to what happens when the little plastic thing with legs = 3 is
found to be S/C, is a completely different story.

AB

I'm puzzled by your comments. What sort of lead acid charger is not voltage regulated?


NT

The statement was "terminal Voltage".

Direct Voltage regulation isn't really an option. Have you tried
charging a 12Volt lead acid battery from 12Volts?

Have you tried charging from 14Volts?


Can you suggest a few drawbacks to using a supply regulated to give
either Voltage, or even one in between those values?

The internal resistance of a battery is dependent on a number of
things, age, temperature and the amount of charge stored, therefore
the terminal Voltage of the battery isn't the best starting point for
control.

AB