Hand crank torch - NiMH charging

S

sambo

New Member

• Jan 23, 2019

• #1

Hi there,

So I am interested in the charging of NiMH batteries, some websites say that they should not be charged over 0.1C, some say 0.5C some say not over 1C.

I bought this wind up torch with a 80mah 3.6v batteries pack and noticed the current flow is around 200 mA, this is 2.5C.

So my question is, is it ok to go over 1C and if so, how far can this stretch?

Cheers

 

dknguyen

Well-Known Member

Most Helpful Member

• Jan 23, 2019

• #2

The current flow when you wind it is 2.5C?

The faster you charge it, the smarter the charger has to be. Also the faster you charge it, the less charges you will get out of the battery.

 

S

sambo

New Member

• Jan 23, 2019

• #3

"Also the faster you charge it, the less charges you will get out of the battery."

Oh really, how does that work?
Surely Qin = Qout

 

rjenkinsgb

Well-Known Member

Most Helpful Member

• Jan 23, 2019

• #4

If the charge current is too high, the cell can heat up and it can also produce excess gas, causing venting.

Both shorten the overall life of the cell.

 

gophert

Well-Known Member

Most Helpful Member

• Jan 23, 2019

• #5

sambo said:

"Also the faster you charge it, the less charges you will get out of the battery."

Oh really, how does that work?
Surely Qin = Qout

Click to expand...

He means, the fewer number of charges you will get over the lifetime of the battery. Charging faster than recommended is hard on batteries and decreases their lifetime.
.
.

 

dknguyen

Well-Known Member

Most Helpful Member

• Jan 23, 2019

• #6

Yeah. Fewer

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Jan 24, 2019

• #7

Your mistake is imagining it's well designed, it's just cheaply thrown together with no design considerations, and not expected to have much of a lifetime anyway - but to be fair it NEEDS to charge it as rapidly as possible, who wants to stand there winding a torch for 24 hours?. The shortened life of the battery isn't a consideration in this application.